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Sample records for flooded paddy soil

  1. Flooding-enhanced immobilization effect of sepiolite on cadmium in paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qi-Hong; Huang, Dao-You; Liu, Shou-Long; Zhu, Han-Hua [Chinese Academy of Sciences, Changsha, Hunan (China). Key Lab. of Agro-Ecological Processes in Subtropical Region; Zhou, Bin [Chinese Academy of Sciences, Changsha, Hunan (China). Key Lab. of Agro-Ecological Processes in Subtropical Region; Chinese Academy of Sciences, Beijing (China). Graduate Univ.; Luo, Zun-Chang [Hunan Soil and Fertilizer Institute, Changsha (China)

    2012-02-15

    Little is known of the effect of sepiolite on the transformation of Cd in anthropogenically contaminated paddy soil under different moisture conditions; therefore, we studied the effects of sepiolite and flooding on the extractability and fractionation of Cd in paddy soils. The dynamics of soil Eh, pH, DTPA-extractable Cd, and different Cd soil fractions were studied in two typical paddy soils from south China that were spiked with 10 mg kg{sup -1} Cd following amendment with sepiolite at 5 and 10 gkg{sup -1} soil during a 30-day incubation period at 25 C, with either no flooding or continuous flooding conditions. The addition of sepiolite at two rates of 5 and 10 gkg{sup -1} soil resulted in an average reduction in soil Eh of 76 and 93 mV, increase in soil pH of 1.2 and 2.3 pH units, and decrease in DTPA-extractable Cd in soils of 1.43 and 2.53 mg kg{sup -1} under continuous flooding conditions, respectively. Sepiolite addition resulted in a significant decrease in the exchangeable Cd in the soils, and a significant increase, in the carbonate-bound and Fe/Mn oxide-bound Cd in the soils under both moisture conditions. Cadmium was also immobilized by flooding and by interactions between sepiolite application and flooding; these effects were greater in sandy paddy soil than in clay paddy soil. The immobilization of Cd in typical paddy soils was related mainly to changes in Eh and pH caused by the addition of sepiolite and flooding. Sepiolite can be used in the remediation of Cd-contaminated paddy soils, especially in sandy paddy soils, and flooding enhances the stabilization of Cd in paddy soils by sepiolite. (orig.)

  2. Biogeochemistry of paddy soils

    NARCIS (Netherlands)

    Kögel-Knabner, I.; Amelung, W.; Cao, Z.; Fiedler, S.; Frenzel, P.; Jahn, R.; Kalbitz, K.; Kölbl, A.; Schloter, M.

    2010-01-01

    Paddy soils make up the largest anthropogenic wetlands on earth. They may originate from any type of soil in pedological terms, but are highly modified by anthropogenic activities. The formation of these Anthrosols is induced by tilling the wet soil (puddling), and the flooding and drainage regime

  3. Effects of Carbon in Flooded Paddy Soils: Implications for Microbial Activity and Arsenic Mobilization

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    Avancha, S.; Boye, K.

    2014-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (originating from erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Microbial activity will enhance or decrease the mobilization of arsenic depending on their metabolic pathways. Among the microbes naturally residing in the soil are denitrifying bacteria, sulfate reducers, metal reducers (Fe, Mn), arsenic reducers, methanogens, and fermenters, whose activity varies based on the presence of oxygen. The purpose of the experiment was to assess how different amendments affect the microbial activity and the arsenic mobilization during the transition from aerobic to anaerobic metabolism after flooding of naturally contaminated Cambodian soil. In a batch experiment, we investigated how the relative metabolic rate of naturally occurring microbes could vary with different types of organic carbon. The experiment was designed to measure the effects of various sources of carbon (dried rice straw, charred rice straw, manure, and glucose) on the microbial activity and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. All amendments were added based on the carbon content in order to add 0.036 g of carbon per vial. The soil was flooded with a 10mM TRIS buffer solution at pH 7.04 in airtight 25mL serum vials and kept at 25 °C. We prepared 14 replicates per treatment to sample both gas and solution. On each sampling point, the solution replicates were sampled destructively. The gas replicates continued on and were sampled for both gas and solution on the final day of the experiment. We measured pH, total arsenic, methane, carbon dioxide, and nitrous oxide at 8 hours, 1.5 days, 3.33 days, and 6.33 days from the start of the experiment.

  4. Effects of sulfur in flooded paddy soils: Implications for iron chemistry and arsenic mobilization

    Science.gov (United States)

    Avancha, S.; Boye, K.

    2013-12-01

    In the Mekong delta in Cambodia, naturally occurring arsenic (amplified by erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Iron and sulfur both interact strongly with arsenic in paddy soils: iron oxides are strong adsorbents for arsenic in oxic conditions, and sulfur (in the form of sulfide) is a strong adsorbent under anoxic conditions. In the process of reductive dissolution of iron oxides, arsenic, which had been adsorbed to the iron oxides, is released. Therefore, higher levels of reduced iron (ferrous iron) will likely correlate with higher levels of mobilized arsenic. However, the mobilized arsenic may then co-precipitate with or adsorb to iron sulfides, which form under sulfate-reducing conditions and with the aid of certain microbes already present in the soil. In a batch experiment, we investigated how these processes correlate and which has the greatest influence on arsenic mobilization and potential plant availability. The experiment was designed to measure the effects of various sources of sulfur (dried rice straw, charred rice straw, and gypsum) on the iron and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. The two types of rice straw were designed to introduce the same amount of organic sulfur (7.7 μg/g of soil), but different levels of available carbon, since carbon stimulates microbial activity in the soil. In comparison, two different levels of gypsum (calcium sulfate) were used, 7.7 and 34.65 μg/g of soil, to test the effect of directly available inorganic sulfate without carbon addition. The soil was flooded with a buffer solution at pH 7.07 in airtight serum vials and kept as a slurry on a shaker at 25 °C. We measured pH, alkalinity, ferrous iron, ferric iron, sulfide, sulfate, total iron, sulfur, and arsenic in the

  5. Amendment damages the function of continuous flooding in decreasing Cd and Pb uptake by rice in acid paddy soil.

    Science.gov (United States)

    Ye, Xinxin; Li, Hongying; Zhang, Ligan; Chai, Rushan; Tu, Renfeng; Gao, Hongjian

    2018-01-01

    Combinations of remediation technologies are needed to solve the problem of soil contamination in paddy rice, due to multiple potential toxic elements (PTEs). Two potential mitigation methods, water management and in-situ remediation by soil amendment, have been widely used in treatment of PTE-polluted paddy soil. However, the interactive relationship between soil amendment and water management, and its influence on the accumulation of PTEs in rice are poorly understood. Greenhouse pot experiments were conducted to examine the effects of phosphate amendment on Cd and Pb availability in soil and their influence on Cd and Pb uptake into rice, on Fe and P availability in soil, and on the alteration of Fe amount and compartment on root surface among different water management strategies. Results indicated that Cd and Pb content in the shoot and grain were significantly affected by the different water management strategies in nonamended soils, and followed the order: wetting irrigation > conventional irrigation > continuous flooding. The application of phosphate amendment significantly decreased the variations of Cd and Pb absorption in shoot and grain of rice among different water treatments. The reasons may be attributed to the enhancement of P availability and the decrease of Fe availability in soil, and the decreased variations of Fe 2+ /Fe 3+ content in root coating after the application of phosphate amendment. These results suggested that the simultaneous use of phosphate amendment and continuous flooding to immobilize Cd and Pb, especially in acid paddy soils, should be avoided. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Impact of S fertilizers on pore-water Cu dynamics and transformation in a contaminated paddy soil with various flooding periods.

    Science.gov (United States)

    Yang, Jianjun; Zhu, Shenhai; Zheng, Cuiqing; Sun, Lijuan; Liu, Jin; Shi, Jiyan

    2015-04-09

    Impact of S fertilization on Cu mobility and transformation in contaminated paddy soils has been little reported. In this study, we investigated the dynamics and transformation of dissolved and colloidal Cu in the pore water of a contaminated paddy soil after applying ammonium sulphate (AS) and sulfur coated urea (SCU) with various flooding periods (1, 7 and 60 days). Compared to the control soil, the AS-treated soil released more colloidal and dissolved Cu over the entire flooding period, while the SCU-treated soil had lower colloidal Cu after 7-day flooding but higher colloidal and dissolved Cu after 60-day flooding. Microscopic X-ray fluorescence (μ-XRF) analysis found a close relationship between Fe and Cu distribution on soil colloids after 60-day flooding, implying the formation of colloidal Fe/Cu sulphide coprecipitates. Cu K-edge X-ray absorption near-edge structure (XANES) spectroscopy directly revealed the transformation of outer-sphere complexed Cu(II) species to Cu(II) sulphide and reduced Cu2O in the colloids of S-treated soils after 60-day flooding. These results demonstrated the great influence of S fertilization on pore-water Cu mobility by forming Cu sulphide under flooding conditions, which facilitated our understanding and control of Cu loss in contaminated paddy soils under S fertilization. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Response of Methanogenic Microbial Communities to Desiccation Stress in Flooded and Rain-Fed Paddy Soil from Thailand

    Directory of Open Access Journals (Sweden)

    Andreas Reim

    2017-05-01

    Full Text Available Rice paddies in central Thailand are flooded either by irrigation (irrigated rice or by rain (rain-fed rice. The paddy soils and their microbial communities thus experience permanent or arbitrary submergence, respectively. Since methane production depends on anaerobic conditions, we hypothesized that structure and function of the methanogenic microbial communities are different in irrigated and rain-fed paddies and react differently upon desiccation stress. We determined rates and relative proportions of hydrogenotrophic and aceticlastic methanogenesis before and after short-term drying of soil samples from replicate fields. The methanogenic pathway was determined by analyzing concentrations and δ13C of organic carbon and of CH4 and CO2 produced in the presence and absence of methyl fluoride, an inhibitor of aceticlastic methanogenesis. We also determined the abundance (qPCR of genes and transcripts of bacterial 16S rRNA, archaeal 16S rRNA and methanogenic mcrA (coding for a subunit of the methyl coenzyme M reductase and the composition of these microbial communities by T-RFLP fingerprinting and/or Illumina deep sequencing. The abundances of genes and transcripts were similar in irrigated and rain-fed paddy soil. They also did not change much upon desiccation and rewetting, except the transcripts of mcrA, which increased by more than two orders of magnitude. In parallel, rates of CH4 production also increased, in rain-fed soil more than in irrigated soil. The contribution of hydrogenotrophic methanogenesis increased in rain-fed soil and became similar to that in irrigated soil. However, the relative microbial community composition on higher taxonomic levels was similar between irrigated and rain-fed soil. On the other hand, desiccation and subsequent anaerobic reincubation resulted in systematic changes in the composition of microbial communities for both Archaea and Bacteria. It is noteworthy that differences in the community composition were

  8. Depth distribution of abiotic drivers of N mineralization and methane emission from a continuously and intermittently flooded Bangladeshi paddy soil

    Science.gov (United States)

    Akter, Masuda; Kader, Md. Abdul; Pierreux, Sofie; Boeckx, Pascal; Kamal, Ahammad Mostafa; Sleutel, Steven

    2016-04-01

    Water-saving irrigation such as AWD may significantly alter depth profiles of moisture content, pH, Eh and soil microbial activity. Modelling the effect of irrigation management on soil N mineralization, therefore requires detailed insight into depth distribution of these variables and dissolved organic carbon (DOC), and evolution of electron acceptors. We set up a field experiment at Bangladesh Agricultural University from January to May' 2015. The cultivated rice variety (BRRI dhan28) was grown under continuous flooding (CF) and alternate wetting and drying (AWD) management, with 120 kg N ha-1(N120) or without (N0)N fertilizer application. We measured soil mineral N and plant N uptake to evaluate N mineralization. CH4 emissions were monitored with timely gas sample collection and GC-analysis. Soil Eh at four depths and temperature at two depths were monitored continuously by Eh/T°-probes connected to a HYPNOS III data logger (MVH, The Netherlands). Simultaneously, soil solution from three depths were sampled with rhizon samplers to track DOC, Fe and Mn in solution. Over the growing season soil and air temperature increased by 8°C, and soil pH stayed near neutral (6.7 to 7.8). In all depths of AWD and CF, Eh dropped sharply to methanic conditions within 21 days after transplanting (DAT). Low redox-potential continued until 77DAT in all cases, except in the puddle layers under AWD, where redox raised to -200mV during drainage. Fe and Mn in soil solution increased gradually over the growing season, indicating continued reductive dissolution of Fe and Mn (hydro-)oxides. DOC increased continuously as well in all depths. Besides to release of DOC bound to pedogenic oxides upon their reductive dissolution, higher plant and soil microbial activity with increasing soil temperature (till 28°C) through the growing season explains the increasing DOC levels. Increasing methanogenic activity as indicated by the high CH4 emissions at 70-84DAT under both CF and AWD is

  9. Transport behavior and rice uptake of radiostrontium and radiocesium in flooded paddy soils contaminated in two contrasting ways

    International Nuclear Information System (INIS)

    Choi, Yong-Ho; Lim, Kwang-Muk; Jun, In; Keum, Dong-Kwon; Han, Moon-Hee; Kim, In-Gyu

    2011-01-01

    In order to investigate the transport behavior and rice uptake of radiostrontium and radiocesium in flooded rice fields, lysimeter experiments with two paddy soils were performed in a greenhouse. A solution containing 85 Sr and 137 Cs was applied in two different ways — being mixed with the top soil 27 d before transplanting or being dropped to the surface water 1 d after transplanting. Rice uptake was quantified with two kinds of transfer factor — TF m (dimensionless) and TF a (m 2 kg −1 -dry) for the pre- and post-transplanting depositions, respectively. For brown rice, the TF m values of 85 Sr and 137 Cs differed between the soils by factors of 2 (1.6 × 10 −2 and 2.5 × 10 −2 ) and 7 (2.2 × 10 −2 and 1.5 × 10 −1 ), respectively. Corresponding factors by the TF a values were 2 (2.5 × 10 −4 and 4.4 × 10 −4 ) for 85 Sr and 3 (1.1 × 10 −3 and 2.9 × 10 −3 ) for 137 Cs. Straws had several times higher TF m and TF a values of 85 Sr than of 137 Cs. The surface-water concentrations were substantially higher for the TF a than for the TF m , indicating the possibility of a much higher plant-base uptake for the TF a . In the TF a soils, 137 Cs and, to a lesser degree, 85 Sr were severely localized towards the soil surface, probably leading to an increased root uptake. The activity loss due to plant uptake and water percolation was generally inconsiderable. Time-dependent K d values of 85 Sr measured in a parallel experiment ranged from 20 to 170, whereas 137 Cs had much higher K d values. The use of TF a values instead of TF m values turned out to be a reasonable approach to the evaluation of a vegetation-period deposition.

  10. Evaluating the Effects of Metals on Microorganisms in Flooded Paddy Soils Using the SEM/AVS-Based Approach and Measurements of Exchangeable Metal Concentrations.

    Science.gov (United States)

    Kunito, Takashi; Toya, Hitomi; Sumi, Hirotaka; Ishikawa, Yuichi; Toda, Hideshige; Nagaoka, Kazunari; Saeki, Kazutoshi; Aikawa, Yoshio; Matsumoto, Satoshi

    2017-04-01

    We examined possible adverse effects of heavy metals on microbial activity, biomass, and community composition using the simultaneously extracted metals (SEM)/acid-volatile sulfide (AVS)-based approach and measurements of exchangeable metal concentrations in three paddy soils (wastewater-contaminated soil, mine-contaminated soil, and noncontaminated soil) incubated for 60 days under flooded conditions. Incubation under flooding increased pH and decreased Eh in all samples. AVS increased when Eh decreased to approximately -200 mV for the mine-contaminated and noncontaminated soils, while the wastewater-contaminated soil originally had a high concentration of AVS despite its air-dried condition. Addition of rice straw or alkaline material containing calcium carbonate and gypsum increased AVS levels under flooded conditions. We observed no apparent relationship between soil enzyme activity (β-D-glucosidase and acid phosphatase) and concentrations of SEM, [∑SEM - AVS], and exchangeable metals. Bacterial and fungal community composition, assessed using polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) analysis targeting rRNA genes, was largely influenced by site of collection and incubation time, but metal contamination did not influence community composition. We observed significant negative correlations between biomass C and [∑SEM - AVS] and between biomass C and ∑SEM, suggesting that [∑SEM - AVS] and ∑SEM might reflect the bioavailability of organic matter to microorganisms in these soils.

  11. Straw enhanced CO2 and CH4 but decreased N2O emissions from flooded paddy soils: Changes in microbial community compositions

    Science.gov (United States)

    Wang, Ning; Yu, Jian-Guang; Zhao, Ya-Hui; Chang, Zhi-Zhou; Shi, Xiao-Xia; Ma, Lena Q.; Li, Hong-Bo

    2018-02-01

    To explore microbial mechanisms of straw-induced changes in CO2, CH4, and N2O emissions from paddy field, wheat straw was amended to two paddy soils from Taizhou (TZ) and Yixing (YX), China for 60 d under flooded condition. Illumia sequencing was used to characterize shift in bacterial community compositions. Compared to control, 1-5% straw amendment significantly elevated CO2 and CH4 emissions with higher increase at higher application rates, mainly due to increased soil DOC concentrations. In contrast, straw amendment decreased N2O emission. Considering CO2, CH4, and N2O emissions as a whole, an overall increase in global warming potential was observed with straw amendment. Total CO2 and CH4 emissions from straw-amended soils were significantly higher for YX than TZ soil, suggesting that straw-induced greenhouse gas emissions depended on soil characteristics. The abundance of C-turnover bacteria Firmicutes increased from 28-41% to 54-77% with straw amendment, thereby increasing CO2 and CH4 emissions. However, straw amendment reduced the abundance of denitrifying bacteria Proteobacteria from 18% to 7.2-13% or increased the abundance of N2O reducing bacteria Clostridium from 7.6-11% to 13-30%, thereby decreasing N2O emission. The results suggested straw amendment strongly influenced greenhouse gas emissions via alerting soil properties and bacterial community compositions. Future field application is needed to ascertain the effects of straw return on greenhouse gas emissions.

  12. Transfer of technetium from soil to paddy and upland rice

    International Nuclear Information System (INIS)

    Yanagisawa, Kei; Muramatsu, Yasuyuki

    1995-01-01

    Soil-plant transfer factors (concentration ratio between the plant and soil) of technetium in paddy and upland rice plants were obtained from laboratory experiments. The transfer factor is one of the most important parameters for environmental radiation dose assessment. Technetium tracer ( 95m TcO 4 - ) was added to the soil prior to rice cultivation. The transfer factor of technetium for the hulled grains (brown rice) of paddy rice (≤0.0002) was much lower than for that of upland rice (0.021). The transfer factors for both types of hulled grains were much lower than in the leaves. The technetium decontamination rate from hulled grains by polishing was 34%, the percentage of the weight decrease being 12%. The concentration of technetium in the soil solution collected from the paddy rice soil (flooded conditions) decreased rapidly with time due to its adsorption on the soil. In the upland rice soil (non-flooded) solution, the decrease in the technetium concentration was fairly slow. The low transfer factors for the paddy rice plants could be explained by the immobilization of technetium in the flooded soil. The oxidation-reduction potentials (Eh) in the flooded soil decreased rapidly with time. We conclude that technetium tracer added as TcO 4 - to flooded soil is readily transformed to an insoluble form (e.g.TcO 2 ) under the reducing conditions provided by flooding. (author)

  13. Effects of Biochar on the Net Greenhouse Gas Emissions under Continuous Flooding and Water-Saving Irrigation Conditions in Paddy Soils

    Directory of Open Access Journals (Sweden)

    Le Qi

    2018-05-01

    Full Text Available In this study, we investigated the greenhouse gas emission under different application of biochar in the conditions of continuous flooding and water-saving irrigation in paddy fields, whereas, plant and soil carbon sequestration were considered in the calculation of net greenhouse gas emissions. The emission rates of methane (CH4, carbon dioxide (CO2, and nitrous oxide (N2O gases were simultaneously monitored once every 7–10 days using the closed-chamber method. As a whole, the net greenhouse gas emission in the water-saving irrigation was more than that of the continuous flooding irrigation conditions. Compared with the water-saving irrigation, the continuous flooding irrigation significantly increased the CH4 in the control (CK and chemical fertilizer treatments (NPK. The CO2 emissions increased in each treatment of the water-saving irrigation condition, especially in the chemical fertilizer treatments (NPKFW. Similarly, the soil N2O emission was very sensitive to the water-saving irrigation condition. An interesting finding is that the biochar application in soils cut down the soil N2O emission more significantly than NPKFW in the water-saving irrigation condition while the effect of biochar increased under the continuous flooding irrigation condition.

  14. Characterization and selection of biochar for an efficient retention of tricyclazole in a flooded alluvial paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    García-Jaramillo, Manuel, E-mail: mgarcia@irnas.csic.es [Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), P.O. Box 1052, 41080 Seville (Spain); Cox, Lucía; Knicker, Heike E.; Cornejo, Juan [Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), P.O. Box 1052, 41080 Seville (Spain); Spokas, Kurt A. [United States Department of Agriculture–Agricultural Research Service, 1991 Upper Buford Circle, Saint Paul 55108, MN (United States); Hermosín, M.Carmen [Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), P.O. Box 1052, 41080 Seville (Spain)

    2015-04-09

    Highlights: • Biochar CEC was inversely correlated with HTT. • Enhanced aromaticity was associated to an improved biochar adsorption of tricyclazole. • The SSA of the biochars was inversely correlated with DOC contents. • Adsorption of tricyclazole was related to high SSA and low DOC content of biochars. • The use of AC and biochar in conjunction provides the slow release of tricyclazole. - Abstract: Biochars, from different organic residues, are increasingly proposed as soil amendments for their agronomic and environmental benefits. A systematic detection method that correlates biochar properties to their abilities to adsorb organic compounds is still lacking. Seven biochars obtained after pyrolysis at different temperatures and from different feedstock (alperujo compost, rice hull, and woody debris), were characterized and tested to reveal potential remedial forms for pesticide capture in flooded soils. Biochar properties were determined by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy, specific surface area (SSA) assessment and scanning electron microscopy. In addition, dissolved organic matter (DOM) from these biochars was extracted and quantified in order to evaluate the effect on pesticide sorption. The biochars from alperujo compost presented very high affinity to the fungicide tricyclazole (55.9, 83.5, and 90.3% for B1, B4, and B5, respectively). This affinity was positively correlated with the pyrolysis temperature, the pH, the increased SSA of the biochars, and the enhanced aromaticity. Sorptive capacities were negatively related to DOM contents. The amendment with a mixture of compost and biochar endows the alluvial soil with high sorptive properties (from K{sub fads(soil)} = 9.26 to K{sub fads(mixture)} = 17.89) without impeding the slow release of tricyclazole.

  15. Characterization and selection of biochar for an efficient retention of tricyclazole in a flooded alluvial paddy soil

    International Nuclear Information System (INIS)

    García-Jaramillo, Manuel; Cox, Lucía; Knicker, Heike E.; Cornejo, Juan; Spokas, Kurt A.; Hermosín, M.Carmen

    2015-01-01

    Highlights: • Biochar CEC was inversely correlated with HTT. • Enhanced aromaticity was associated to an improved biochar adsorption of tricyclazole. • The SSA of the biochars was inversely correlated with DOC contents. • Adsorption of tricyclazole was related to high SSA and low DOC content of biochars. • The use of AC and biochar in conjunction provides the slow release of tricyclazole. - Abstract: Biochars, from different organic residues, are increasingly proposed as soil amendments for their agronomic and environmental benefits. A systematic detection method that correlates biochar properties to their abilities to adsorb organic compounds is still lacking. Seven biochars obtained after pyrolysis at different temperatures and from different feedstock (alperujo compost, rice hull, and woody debris), were characterized and tested to reveal potential remedial forms for pesticide capture in flooded soils. Biochar properties were determined by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy, specific surface area (SSA) assessment and scanning electron microscopy. In addition, dissolved organic matter (DOM) from these biochars was extracted and quantified in order to evaluate the effect on pesticide sorption. The biochars from alperujo compost presented very high affinity to the fungicide tricyclazole (55.9, 83.5, and 90.3% for B1, B4, and B5, respectively). This affinity was positively correlated with the pyrolysis temperature, the pH, the increased SSA of the biochars, and the enhanced aromaticity. Sorptive capacities were negatively related to DOM contents. The amendment with a mixture of compost and biochar endows the alluvial soil with high sorptive properties (from K fads(soil) = 9.26 to K fads(mixture) = 17.89) without impeding the slow release of tricyclazole

  16. Performance of duckweed and effective microbes in reducing arsenic in paddy and paddy soil

    Science.gov (United States)

    Ng, C. A.; Wong, L. Y.; Lo, P. K.; Bashir, M. J. K.; Chin, S. J.; Tan, S. P.; Chong, C. Y.; Yong, L. K.

    2017-04-01

    In this study phytoremediation plant (duckweed) and effective microbes were used to investigate their effectiveness in reducing arsenic concentration in paddy soil and paddy grain. The results show that using duckweed alone is a better choice as it could decrease the arsenic concentration in paddy by 27.697 % and 8.268 % in paddy grain and paddy husk respectively. The study also found out that the concentration of arsenic in soil would affect the performance of duckweed and also delayed the reproduction rate of duckweed. Using the mixture of effective microbes and duckweed together to decrease arsenic in paddy was noticed having the least potential in reducing the arsenic concentration in paddy.

  17. Soil structural behaviour of flooded soils

    International Nuclear Information System (INIS)

    Taboada, M.A.

    2004-01-01

    The objectives of this presentation are to: identify factors determining of the structural behaviour of flooded soils, as compared to those acting in upland soils; analyse the influence of reductive processes on aggregate stabilising agents; discuss mechanisms of structural deterioration and recovery during the flooding-drying cycle, on the basis of a case study: cattle trampling effects in the flooding Pampa of Argentina. Flooded soils, now known as Hydric soils, are characteristic of wetlands and irrigated fields cropped to rice (paddy soils). In them, water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year. Hydric soils belong to different taxa of the FAO-UNESCO Soil Map (2000). Fluvisols, Planosols and Gleysols are widespread distributed in the globe. The generation of redoximorphic features is due to different causes in each of them. Fluvisols are covered part of the year by surface water from river overflows; Planosols are soils having an impervious Bt horizon, supporting perched water during short periods; and Gleysols are soils affected by stagnant water tables during long periods

  18. Control of arsenic mobilization in paddy soils by manganese and iron oxides.

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    Xu, Xiaowei; Chen, Chuan; Wang, Peng; Kretzschmar, Ruben; Zhao, Fang-Jie

    2017-12-01

    Reductive mobilization of arsenic (As) in paddy soils under flooded conditions is an important reason for the relatively high accumulation of As in rice, posing a risk to food safety and human health. The extent of As mobilization varies widely among paddy soils, but the reasons are not well understood. In this study, we investigated As mobilization in six As-contaminated paddy soils (total As ranging from 73 to 122 mg kg -1 ) in flooded incubation and pot experiments. Arsenic speciation in the solution and solid phases were determined. The magnitude of As mobilization into the porewater varied by > 100 times among the six soils. Porewater As concentration correlated closely with the concentration of oxalate-extractable As, suggesting that As associated with amorphous iron (oxyhydr)oxides represents the potentially mobilizable pool of As under flooded conditions. Soil containing a high level of manganese oxides showed the lowest As mobilization, likely because Mn oxides retard As mobilization by slowing down the drop of redox potential upon soil flooding and maintaining a higher arsenate to arsenite ratio in the solid and solution phases. Additions of a synthetic Mn oxide (hausmannite) to two paddy soils increased arsenite oxidation, decreased As mobilization into the porewater and decreased As concentrations in rice grain and straw. Consistent with previous studies using simplified model systems or pure mineral phases, the present study shows that Mn oxides and amorphous Fe (oxyhydr)oxides are important factors controlling reductive As mobilization in As-contaminated paddy soils. In addition, this study also suggests a potential mitigation strategy using exogenous Mn oxides to decrease As uptake by rice in paddy soils containing low levels of indigenous Mn oxides, although further work is needed to verify its efficacy and possible secondary effects under field conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Behavior of technetium in paddy soils

    International Nuclear Information System (INIS)

    Yanagisawa, K.; Muramatsu, Y.; Ban-Nai, T.

    1997-01-01

    In order to understand the chemical form of soluble technetium in paddy soil and its availability to a rice plant, soil incubation and uptake experiments have been carried out using 95m Tc as a tracer. The chemical form of the soluble Tc was observed by gel chromatography and found not to be pertechnetate, but rather to be associated with soluble organic matter. An uptake experiment with rice seedlings using nutrient solution showed that this Tc-organic matter complex was less available than pertechnetate. (author)

  20. Fertilization increases paddy soil organic carbon density*

    Science.gov (United States)

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-01-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC. PMID:22467369

  1. Fertilization increases paddy soil organic carbon density.

    Science.gov (United States)

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-04-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC.

  2. Assessing nitrification and denitrification in a paddy soil with different water dynamics and applied liquid cattle waste using the {sup 15}N isotopic technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Sheng, E-mail: jszs@cc.tuat.ac.jp [Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Eco-environmental Protection Institute, Shanghai Academy of Agricultural Sciences, 1000 Jinqi Road, Shanghai 201403 (China); Sakiyama, Yukina; Riya, Shohei [Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Song, Xiangfu [Eco-environmental Protection Institute, Shanghai Academy of Agricultural Sciences, 1000 Jinqi Road, Shanghai 201403 (China); Terada, Akihiko; Hosomi, Masaaki [Institute of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)

    2012-07-15

    Using livestock wastewater for rice production in paddy fields can remove nitrogen and supplement the use of chemical fertilizers. However, paddy fields have complicated water dynamics owing to varying characteristics and would influence nitrogen removal through nitrification followed by denitrification. Quantification of nitrification and denitrification is of great importance in assessing the influence of water dynamics on nitrogen removal in paddy fields. In this study, nitrification and nitrate reduction rates with different water dynamics after liquid cattle waste application were evaluated, and the in situ denitrification rate was determined directly using the {sup 15}N isotopic technique in a laboratory experiment. A significant linear regression correlation between nitrification and the nitrate reduction rate was observed and showed different regression coefficients under different water dynamics. The regression coefficient in the continuously flooded paddy soil was higher than in the drained-reflooded paddy soil, suggesting that nitrate would be consumed faster in the flooded paddy soil. However, nitrification was limited and the maximum rate was only 13.3 {mu}g N g{sup -1} day{sup -1} in the flooded paddy soil with rice plants, which limited the supply of nitrate. In contrast, the drained-reflooded paddy soil had an enhanced nitrification rate up to 56.8 {mu}g N g{sup -1} day{sup -1}, which was four times higher than the flooded paddy soil and further stimulated nitrate reduction rates. Correspondingly, the in situ denitrification rates determined directly in the drained-reflooded paddy soil ranged from 5 to 1035 mg N m{sup -2} day{sup -1}, which was higher than the continuously flooded paddy soil (from 5 to 318 mg N m{sup -2} day{sup -1}) during the vegetation period. The nitrogen removal through denitrification accounted for 38.9% and 9.9% of applied nitrogen in the drained-reflooded paddy soil and continuously flooded paddy soil, respectively

  3. Distribution of tetraether lipids in agricultural soils - differentiation between paddy and upland management

    Science.gov (United States)

    Mueller-Niggemann, Cornelia; Rahayu Utami, Sri; Marxen, Anika; Mangelsdorf, Kai; Bauersachs, Thorsten; Schwark, Lorenz

    2016-03-01

    Rice paddies constitute almost a fifth of global cropland and provide more than half of the world's population with staple food. At the same time, they are a major source of methane and therewith significantly contribute to the current warming of Earth's atmosphere. Despite their apparent importance in the cycling of carbon and other elements, however, the microorganisms thriving in rice paddies are insufficiently characterized with respect to their biomolecules. Hardly any information exists on human-induced alteration of biomolecules from natural microbial communities in paddy soils through varying management types (affecting, e.g., soil or water redox conditions, cultivated plants). Here, we determined the influence of different land use types on the distribution of glycerol dialkyl glycerol tetraethers (GDGTs), which serve as molecular indicators for microbial community structures, in rice paddy (periodically flooded) and adjacent upland (non-flooded) soils and, for further comparison, forest, bushland and marsh soils. To differentiate local effects on GDGT distribution patterns, we collected soil samples in locations from tropical (Indonesia, Vietnam and Philippines) and subtropical (China and Italy) sites. We found that differences in the distribution of isoprenoid GDGTs (iGDGTs) as well as of branched GDGTs (brGDGTs) are predominantly controlled by management type and only secondarily by climatic exposition. In general, upland soil had higher crenarchaeol contents than paddy soil, which by contrast was more enriched in GDGT-0. The GDGT-0 / crenarchaeol ratio, indicating the enhanced presence of methanogenic archaea, was 3-27 times higher in paddy soils compared to other soils and increased with the number of rice cultivation cycles per year. The index of tetraethers consisting of 86 carbons (TEX86) values were 1.3 times higher in upland, bushland and forest soils than in paddy soils, potentially due to differences in soil temperature. In all soils br

  4. Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence

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    C. Mueller-Niggemann

    2012-03-01

    Full Text Available In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation, one flooded paddy nursery, one tidal wetland (TW, and one freshwater site (FW from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, δ13C, δ15N, lipids and n-alkanes and (ii one encompassing more labile properties or fast cycling components (Nmic, Cmic, nitrate, ammonium, DON and DOC. The macroscale heterogeneity in paddy soils was assessed by evaluating intra- versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric. Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV values of conservative parameters varied in a low range (10% to 20%, decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20–40% observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 yr paddy chronosequence under wetland rice cultivation

  5. Development and Rainfed Paddy Soils Potency Derived From Lacustrine Material in Paguyaman, Gorontalo

    OpenAIRE

    Nurdin

    2011-01-01

    Rainfed paddy soils that are derived from lacustrine and include of E4 agroclimatic zone have many unique properties and potentially for paddy and corn plantations. This sreseach was aimed to: (1) study the soil development of rainfed paddy soils derived from lacustrine and (2) evaluate rainfed paddy soils potency for paddy and corn in Paguyaman. Soil samples were taken from three profiles according to toposequent, and they were analyzed in laboratory. Data were analyzed with descripti...

  6. Soil Fertility Status on Organic Paddy Experiment

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    Mujiyo

    2015-07-01

    Full Text Available The study aims to determine fertility status of the soil after organic paddy experiments using kinds and doses of organic fertilizers. Experiment was conducted at greenhouse laboratory in Faculty of Agriculture Sebelas Maret University Surakarta. Experimental design used completely randomized design with 9 kinds of treatment was replicated 3 times. Experiments were the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations that are based on fulfilling nutrient requirements of 120 kg N ha-1. Result shows that the use of cow manure, Azolla fertilizers and Azolla inoculum had no effect on changes of soil fertility status. Soil fertility status was not significantly correlated with cow manure (0,16ns, Azolla fertilizer (0,26ns and Azolla inoculum (0,16ns. Average of final soil fertility status included fertile category, which was similar as the initial soil fertility status. Average of final soil properties of treatment but nevertheless was relatively higher than in no treatment, indicating the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations had greater impact to soil properties. Cow manure despite increased available K2O and dry grain, but it did not significantly increase the soil fertility status from fertile to very fertile. This was presumably due to the relatively short experiment period, only one planting season had not given significant effect to soil properties. Implication of this study is the use of cow manure, Azolla fertilizer, Azolla inoculum and its combinations although did not increase the soil fertility status but could maintain soil fertility status as the initial conditions before planting.

  7. Early drainage mitigates methane and nitrous oxide emissions from organically amended paddy soils

    DEFF Research Database (Denmark)

    Tariq, Azeem; Jensen, Lars Stoumann; de Tourdonnet, Stephane

    2017-01-01

    Elevated greenhouse gas (GHG) emissions, particularly of methane (CH4) from flooded rice production systems contribute to global warming. Different crop management strategies, such as drainage of paddy soils and climate-smart residue management, are essential in order to mitigate GHG emissions from...... flooded rice systems, but they often conflict with practical management preferences.The aim of this study was to assess the potential of early-season drainage for mitigating CH4 and N2O emissions from soils with and without added organic amendments in relation to native soil organic carbon (SOC). Rice...

  8. Soil type-depending effect of paddy management: composition and distribution of soil organic matter

    Science.gov (United States)

    Urbanski, Livia; Kölbl, Angelika; Lehndorff, Eva; Houtermans, Miriam; Schad, Peter; Zhang, Gang-Lin; Rahayu Utami, Sri; Kögel-Knabner, Ingrid

    2016-04-01

    Paddy soil management is assumed to promote soil organic matter accumulation and specifically lignin caused by the resistance of the aromatic lignin structure against biodegradation under anaerobic conditions during inundation of paddy fields. The present study investigates the effect of paddy soil management on soil organic matter composition compared to agricultural soils which are not used for rice production (non-paddy soils). A variety of major soil types, were chosen in Indonesia (Java), including Alisol, Andosol and Vertisol sites (humid tropical climate of Java, Indonesia) and in China Alisol sites (humid subtropical climate, Nanjing). This soils are typically used for rice cultivation and represent a large range of soil properties to be expected in Asian paddy fields. All topsoils were analysed for their soil organic matter composition by solid-state 13C nuclear magnetic resonance spectroscopy and lignin-derived phenols by CuO oxidation method. The soil organic matter composition, revealed by solid-state 13C nuclear magnetic resonance, was similar for the above named different parent soil types (non-paddy soils) and was also not affected by the specific paddy soil management. The contribution of lignin-related carbon groups to total SOM was similar in the investigated paddy and non-paddy soils. A significant proportion of the total aromatic carbon in some paddy and non-paddy soils was attributed to the application of charcoal as a common management practise. The extraction of lignin-derived phenols revealed low VSC (vanillyl, syringyl, cinnamyl) values for all investigated soils, being typical for agricultural soils. An inherent accumulation of lignin-derived phenols due to paddy management was not found. Lignin-derived phenols seem to be soil type-dependent, shown by different VSC concentrations between the parent soil types. The specific paddy management only affects the lignin-derived phenols in Andosol-derived paddy soils which are characterized by

  9. Evaluation of ferrolysis in arsenate adsorption on the paddy soil derived from an Oxisol.

    Science.gov (United States)

    Jiang, Jun; Dai, Zhaoxia; Sun, Rui; Zhao, Zhenjie; Dong, Ying; Hong, Zhineng; Xu, Renkou

    2017-07-01

    Iron oxides are dominant effective adsorbents for arsenate in iron oxide-rich variable charge soils. Oxisol-derived paddy soils undergo intensive ferrolysis, which results in high leaching and transformation of iron oxides. However, little information is available concerning the effect of ferrolysis on arsenate adsorption by paddy soil and parent Oxisol. In the present study, we examined the arsenate affinity of soils using arsenate adsorption/desorption isotherms, zeta potential, adsorption kinetics, pH effect and phosphate competition experiments. Results showed that ferrolysis in an alternating flooding-drying Oxisol-derived paddy soil resulted in a significant decrease of free iron oxides and increase of amorphous iron oxides in the surface and subsurface layers. There were more reactive sites exposed on amorphous than on crystalline iron oxides. Therefore, disproportionate ratios of arsenate adsorption capacities and contents of free iron oxides were observed in the studied Oxisols compared with paddy soils. The Gibbs free energy values corroborated that both electrostatic and non-electrostatic adsorption mechanisms contributed to the arsenate adsorption by bulk soils, and the kinetic adsorption data further suggested that the rate-limiting step was chemisorption. The zeta potential of soil colloids decreased after arsenate was adsorbed on the surfaces, forming inner-sphere complexes and thus transferring their negative charges to the soil particle surfaces. The adsorption/desorption isotherms showed that non-electrostatic adsorption was the main mechanism responsible for arsenate binding to the Oxisol and derived paddy soils, representing 91.42-94.65% of the adsorption capacities. Further studies revealed that arsenate adsorption was greatly inhibited by increasing suspension pH and incorporation of phosphate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Inhibition experiments on nitrous oxide emission from paddy soils

    Science.gov (United States)

    Xu, Xingkai; Boeckx, Pascal; Zhou, Likai; Van Cleemput, Oswald

    2002-08-01

    Rice fields using nitrogen-based fertilizers play an important role in the global N2O budget. However, our knowledge is still limited with regard to the mechanisms affecting the N2O emission and to the measures that can reduce the emission. This paper reports a study of N2O emission from paddy soils. The effects of urea, hydroquinone (HQ, a urease inhibitor), and dicyandiamide (DCD, a nitrification inhibitor) have been studied in pot experiments with and without rice plants and with and without addition of wheat straw. With no wheat straw amendment, all treatments with inhibitors, especially with HQ + DCD, had a much smaller N2O emission during the rice growing period than the urea treatment, whereas a substantially increased N2O emission was observed from a rice-free soil with inhibitors. The N2O emission from the rice-planted soil was exponentially positive correlated with the NO3--N concentration in the rice aboveground biomass. By comparing the total N2O emission from the rice-free soil and from the rice-planted soil, we found that urea application alone might induce an apparent plant-mediated N2O emission, being 0.39 +/- 0.08% of the applied urea N. Wheat straw incorporated into the flooded surface layer soil could increase the plant-mediated N2O emission significantly. However, application of HQ + DCD could reduce this emission (0.27 +/- 0.08% of the applied urea N, compared with 0.89 +/- 0.18% in the urea treatment). It also reduced the N2O emission from the rice-free soil and from the rice-planted soil. Stepwise regression analysis indicates that denitrification in the flooded surface layer soil was the main source of N2O emission from this wetland rice cultivation, particularly when wheat straw was added. A significantly nonlinear negative relation was found between the N2O emission and the CH4 emission when no wheat straw was added, but it was hard to quantify this trade-off relation when wheat straw was incorporated into the flooded surface layer soil.

  11. Effectiveness of lime and peat applications on cadmium availability in a paddy soil under various moisture regimes.

    Science.gov (United States)

    Chen, Yanhui; Xie, Tuanhui; Liang, Qiaofeng; Liu, Mengjiao; Zhao, Mingliu; Wang, Mingkuang; Wang, Guo

    2016-04-01

    In paddy soils, amendments and moisture play important role in the immobilization of cadmium (Cd). The effects of applying lime, peat, and a combination of both on soil Eh, pH, and Cd availability in contaminated soils were investigated under wetted (80 ± 5 % of water holding capacity) and flooded (completely submerged) conditions. In wetted soils, there was little change in Eh, compared to flooded soils where Eh reduced rapidly. Amendments of lime only or in a mixture with peat increased soil pH to different degrees, depending on the lime application rate. However, peat addition only slightly affected soil pH. The decreased Cd availability in flooded soils was related to submergence duration and was significantly lower than that in wetted soils after 14 days. Liming wetted and flooded soils decreased exchangeable Cd and increased carbonates or Fe-Mn oxides bound fractions, while peat addition transformed Cd from carbonates to organic matter bound fractions. The combined application of peat and lime generally showed better inhibitory effects on the availability of Cd than separately application of lime or peat. Higher application rates of lime, peat, or their mixture were more effective at reducing Cd contamination in flooded soil. This indicates that application of peat and lime mixture under flooded conditions was most effective for in situ remediation of Cd-contaminated soils. Further studies are required to assess the long-term effectiveness of the peat and lime mixture on Cd availability in paddy soils.

  12. Nitrogen and phosphorus changes and optimal drainage time of flooded paddy field based on environmental factors

    Directory of Open Access Journals (Sweden)

    Meng-hua Xiao

    2013-04-01

    Full Text Available While many controlled irrigation and drainage techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study was conducted to examine the changes of nitrogen and phosphorus of a flooded paddy water system after fertilizer application and at each growth stage so as to obtain the optimal drainage time at each growth stage. Four treatments with different water level management methods at each growth stage were conducted under the condition of ten-day continuous flooding. Results show that the ammonia nitrogen (NH+4-N concentration reached the peak value once the fertilizer was applied, and then decreased to a relatively low level seven to ten days later, and that the nitrate nitrogen (NO-3-N concentration gradually rose to its peak value, which appeared later in subsurface water than in surface water. Continuous flooding could effectively reduce the concentrations of NH+4-N, NO-3-N , and total phosphorus (TP in surface water. However, the paddy water disturbance, in the process of soil surface adsorption and nitrification, caused NH+4-N to be released and increased the concentrations of NH+4-N and NO-3-N in surface water. A multi-objective controlled drainage model based on environmental factors was established in order to obtain the optimal drainage time at each growth stage and better guide the drainage practices of farmers. The optimal times for surface drainage are the fourth, sixth, fifth, and sixth days after flooding at the tillering, jointing-booting, heading-flowering, and milking stages, respectively.

  13. Anaerobic ammonia oxidation in a fertilized paddy soil

    DEFF Research Database (Denmark)

    Zhu, Guibing; Wang, Shanyun; Wang, Yu

    2011-01-01

    Evidence for anaerobic ammonium oxidation in a paddy field was obtained in Southern China using an isotope-pairing technique, quantitative PCR assays and 16S rRNA gene clone libraries, along with nutrient profiles of soil cores. A paddy field with a high load of slurry manure as fertilizer...... was selected for this study and was shown to contain a high amount of ammonium (6.2–178.8 mg kg−1). The anaerobic oxidation of ammonium (anammox) rates in this paddy soil ranged between 0.5 and 2.9 nmolN per gram of soil per hour in different depths of the soil core, and the specific cellular anammox activity...

  14. Arsenic mobilization and immobilization in paddy soils

    Science.gov (United States)

    Kappler, A.; Hohmann, C.; Zhu, Y. G.; Morin, G.

    2010-05-01

    Arsenic is oftentimes of geogenic origin and in many cases bound to iron(III) minerals. Iron(III)-reducing bacteria can harvest energy by coupling the oxidation of organic or inorganic electron donors to the reduction of Fe(III). This process leads either to dissolution of Fe(III)-containing minerals and thus to a release of the arsenic into the environment or to secondary Fe-mineral formation and immobilisation of arsenic. Additionally, aerobic and anaerobic iron(II)-oxidizing bacteria have the potential to co-precipitate or sorb arsenic during iron(II) oxidation at neutral pH that is usually followed by iron(III) mineral precipitation. We are currently investigating arsenic immobilization by Fe(III)-reducing bacteria and arsenic co-precipitation and immobilization by anaerobic iron(II)-oxidizing bacteria in batch, microcosm and rice pot experiments. Co-precipitation batch experiments with pure cultures of nitrate-dependent Fe(II)-oxidizing bacteria are used to quantify the amount of arsenic that can be immobilized during microbial iron mineral precipitation, to identify the minerals formed and to analyze the arsenic binding environment in the precipitates. Microcosm and rice pot experiments are set-up with arsenic-contaminated rice paddy soil. The microorganisms (either the native microbial population or the soil amended with the nitrate-dependent iron(II)-oxidizing Acidovorax sp. strain BoFeN1) are stimulated either with iron(II), nitrate, or oxygen. Dissolved and solid-phase arsenic and iron are quantified. Iron and arsenic speciation and redox state in batch and microcosm experiments are determined by LC-ICP-MS and synchrotron-based methods (EXAFS, XANES).

  15. Temporal variability in trace metal solubility in a paddy soil not reflected in uptake by rice (Oryza sativa L.)

    NARCIS (Netherlands)

    Pan, Yunyu; Koopmans, Gerwin F.; Bonten, Luc T.C.; Song, Jing; Luo, Yongming; Temminghoff, Erwin J.M.; Comans, Rob N.J.

    2016-01-01

    Alternating flooding and drainage conditions have a strong influence on redox chemistry and the solubility of trace metals in paddy soils. However, current knowledge of how the effects of water management on trace metal solubility are linked to trace metal uptake by rice plants over time is still

  16. MAPPING OF SOIL DEGRADATION POTENCY IN PADDY FIELD WONOGIRI, INDONESIA

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    Mujiyo

    2016-06-01

    Full Text Available Sustainability of paddy field becomes the main concern as the media of biomass production, thus it is needed a datum and information about land characteristics to find out its degradation. Mapping of soil degradation potency in paddy field is an identification of initial soil condition to discover the land degradation potency. Mapping was done by overlaying map of soil, slope, rainfall and land use with standard procedures to obtain its value and status of soil degradation potency. Area mapping is an effective land for biomass production (natural forest, mixed farm, savanna, paddy field, shrub and dry field with approximately 43,291.00 hectares (ha in Sidoharjo, Girimarto, Jatipurno, Jatisrono, Jatiroto, Tirtomoyo, Nguntoronadi and Ngadirojo District. The result shows that soil degradation potency (SDP in Districts of Sidoharjo, Girimarto, Jatipurno, Jatisrono, Jatiroto, Tirtomoyo, Nguntoronadi and Ngadirojo are very low, low (DP II 20,702.47 ha (47.82%, moderate (DP III 15,823.80 ha (36,55% and high (DP IV 6,764.73 ha (15.63%. Paddy field covered 22,036.26 ha or about 50.90% of all area as effective biomass production, its SDP considers as low (DP II 16,021.04 ha (37.01% and moderate (DP III 6,015.22 ha (13,89%. Paddy field has a low SDP because it is commonly lies on flat area and conservation method by the farmer is maintaining the paddy bund and terrace. This study needs an advanced study to identify actual SDP through detail verification in the field, and also support by soil sample analysis in the laboratory.

  17. Lignin decomposition and microbial community in paddy soils: effects of alternating redox conditions

    Science.gov (United States)

    Cerli, Chiara; Liu, Qin; Hanke, Alexander; Kaiser, Klaus; Kalbitz, Karsten

    2013-04-01

    community appeared to be affected by alternating redox conditions more in quantity that in quality. Bacteria represented the largest portion of the living microorganisms, responding promptly to changes in soil redox status. However we did not detect any sign of lignin biodegradation. Relative short (3 weeks) changes in redox conditions had no effect on lignin decomposition or oxidation state. Also, lignin was not altered during oxic incubation. Since fungi represented only small portion of the microbial biomass in the studied soils, they were obviously not capable to cause much degradation, even under favourable conditions. On the contrary, changes in redox conditions strongly affected lignin extractability, regardless of the initial content and direction of change in both paddy and non-paddy soils. This was likely a result of (partial) dissolution and/or pH-induced changes of the surface properties of Fe and Mn hydrous oxides causing the release of mineral-associated lignin-derived phenols. Thus, we speculate that oxidised lignin fragments produced during the (oxic) dry period do not remain in the soils but percolate with water drainage during the flooding period.

  18. Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima

    International Nuclear Information System (INIS)

    Sakai, Masaru; Gomi, Takashi; Nunokawa, Masanori; Wakahara, Taeko; Onda, Yuichi

    2014-01-01

    We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean 134 Cs and 137 Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890 Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0–5 cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation. - Highlights: • Surface soil removal in a rice paddy reduced the radiocesium concentration in soil. • The radiocesium concentration in tadpoles decreased following decontamination. • Radiocesium levels in soil increased at 1 year following decontamination practice. • Reduction of radiocesium of soil can propagate to biota in rice paddies. - Decontamination practice reduced radiocesium concentrations in both soil and tadpoles that suggests reduction of radiocesium of soil can propagate to biota in rice paddies

  19. Soil removal as a decontamination practice and radiocesium accumulation in tadpoles in rice paddies at Fukushima.

    Science.gov (United States)

    Sakai, Masaru; Gomi, Takashi; Nunokawa, Masanori; Wakahara, Taeko; Onda, Yuichi

    2014-04-01

    We investigated the biological accumulation of radiocesium in tadpoles [Rana (Pelophylax) porosa porosa] in rice paddies with and without decontamination practice at Fukushima. Radiocesium was accumulated in surface part of soils both in the control and decontaminated paddies one year after decontamination. Mean (134)Cs and (137)Cs concentrations in tadpoles in the control and decontaminated paddies were 3000 and 4500, and 600 and 890 Bq/kg dry weight, respectively. Radiocesium concentrations in surface soil (0-5 cm depth) and tadpoles in the decontaminated paddy were five times smaller than in the control paddy. These results suggest that decontamination practice can reduce radiocesium concentrations in both soil and tadpoles. However, at the decontaminated paddy, radiocesium concentrations in surface soils became 3.8 times greater one year after decontamination, which indicates that monitoring the subsequent movement of radiocesium in rice paddies and surrounding areas is essential for examining contamination propagation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. [Response of mineralization of dissolved organic carbon to soil moisture in paddy and upland soils in hilly red soil region].

    Science.gov (United States)

    Chen, Xiang-Bi; Wang, Ai-Hua; Hu, Le-Ning; Huang, Yuan; Li, Yang; He, Xun-Yang; Su, Yi-Rong

    2014-03-01

    Typical paddy and upland soils were collected from a hilly subtropical red-soil region. 14C-labeled dissolved organic carbon (14C-DOC) was extracted from the paddy and upland soils incorporated with 14C-labeled straw after a 30-day (d) incubation period under simulated field conditions. A 100-d incubation experiment (25 degrees C) with the addition of 14C-DOC to paddy and upland soils was conducted to monitor the dynamics of 14C-DOC mineralization under different soil moisture conditions [45%, 60%, 75%, 90%, and 105% of the field water holding capacity (WHC)]. The results showed that after 100 days, 28.7%-61.4% of the labeled DOC in the two types of soils was mineralized to CO2. The mineralization rates of DOC in the paddy soils were significantly higher than in the upland soils under all soil moisture conditions, owing to the less complex composition of DOC in the paddy soils. The aerobic condition was beneficial for DOC mineralization in both soils, and the anaerobic condition was beneficial for DOC accumulation. The biodegradability and the proportion of the labile fraction of the added DOC increased with the increase of soil moisture (45% -90% WHC). Within 100 days, the labile DOC fraction accounted for 80.5%-91.1% (paddy soil) and 66.3%-72.4% (upland soil) of the cumulative mineralization of DOC, implying that the biodegradation rate of DOC was controlled by the percentage of labile DOC fraction.

  1. Mapping Flooded Rice Paddies Using Time Series of MODIS Imagery in the Krishna River Basin, India

    Directory of Open Access Journals (Sweden)

    Pardhasaradhi Teluguntla

    2015-07-01

    Full Text Available Rice is one of the major crops cultivated predominantly in flooded paddies, thus a large amount of water is consumed during its growing season. Accurate paddy rice maps are therefore important inputs for improved estimates of actual evapotranspiration in the agricultural landscape. The main objective of this study was to obtain flooded paddy rice maps using multi-temporal images of Moderate Resolution Imaging Spectroradiometer (MODIS in the Krishna River Basin, India. First, ground-based spectral samples collected by a field spectroradiometer, CROPSCAN, were used to demonstrate unique contrasts between the Normalized Difference Vegetation Index (NDVI and the Land Surface Water Index (LSWI observed during the transplanting season of rice. The contrast between Enhanced Vegetation Index (EVI and Land Surface Water Index (LSWI from MODIS time series data was then used to generate classification decision rules to map flooded rice paddies, for the transplanting seasons of Kharif and Rabi rice crops in the Krishna River Basin. Consistent with ground spectral observations, the relationship of the MODIS EVI vs. LSWI of paddy rice fields showed distinct features from other crops during the transplanting seasons. The MODIS-derived maps were validated against extensive reference data collected from multiple land use field surveys. The accuracy of the paddy rice maps, when determined using field plot data, was approximately 78%. The MODIS-derived rice crop areas were also compared with the areas reported by Department of Agriculture (DOA, Government of India (Government Statistics. The estimated root mean square difference (RMSD of rice area estimated using MODIS and those reported by the Department of Agriculture over 10 districts varied between 3.4% and 6.6% during 10 years of our study period. Some of the major factors responsible for this difference include high noise of the MODIS images during the prolonged monsoon seasons (typically June–October and

  2. Modelling Water Flow through Paddy Soils under Alternate Wetting and Drying Irrigation Practice

    Science.gov (United States)

    Shekhar, S.; Mailapalli, D. R.; Das, B. S.; Raghuwanshi, N. S.

    2017-12-01

    Alternate wetting and drying (AWD) irrigation practice in paddy cultivation requires an optimum soil moisture stress (OSMS) level at which irrigation water savings can be maximized without compromising the yield reduction. Determining OSMS experimentally is challenging and only possible with appropriate modeling tools. In this study, field experiments on paddy were conducted in thirty non-weighing type lysimeters during dry seasons of 2016 and 2017. Ten plots were irrigated using continuous flooding (CF) and the rest were irrigated with AWD practice at 40mb and 75mb soil moisture stress levels. Depth of ponding and soil suction at 10, 40 and 70 cm from the soil surface were measured daily from all lysimeter plots. The measured field data were used in calibration and validation of Hydrus-1D model and simulated the water flow for both AWD and CF plots. The Hydrus-1D is being used to estimate OSMS for AWD practice and compared the seasonal irrigation water input and deep percolation losses with CF practice.

  3. Temporal variability in trace metal solubility in a paddy soil not reflected in uptake by rice (Oryza sativa L.).

    Science.gov (United States)

    Pan, Yunyu; Koopmans, Gerwin F; Bonten, Luc T C; Song, Jing; Luo, Yongming; Temminghoff, Erwin J M; Comans, Rob N J

    2016-12-01

    Alternating flooding and drainage conditions have a strong influence on redox chemistry and the solubility of trace metals in paddy soils. However, current knowledge of how the effects of water management on trace metal solubility are linked to trace metal uptake by rice plants over time is still limited. Here, a field-contaminated paddy soil was subjected to two flooding and drainage cycles in a pot experiment with two rice plant cultivars, exhibiting either high or low Cd accumulation characteristics. Flooding led to a strong vertical gradient in the redox potential (Eh). The pH and Mn, Fe, and dissolved organic carbon concentrations increased with decreasing Eh and vice versa. During flooding, trace metal solubility decreased markedly, probably due to sulfide mineral precipitation. Despite its low solubility, the Cd content in rice grains exceeded the food quality standards for both cultivars. Trace metal contents in different rice plant tissues (roots, stem, and leaves) increased at a constant rate during the first flooding and drainage cycle but decreased after reaching a maximum during the second cycle. As such, the high temporal variability in trace metal solubility was not reflected in trace metal uptake by rice plants over time. This might be due to the presence of aerobic conditions and a consequent higher trace metal solubility near the root surface, even during flooding. Trace metal solubility in the rhizosphere should be considered when linking water management to trace metal uptake by rice over time.

  4. Characterization of Several Paddy Soil Types in Bogor, West Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Kurniati

    2016-01-01

    Full Text Available Paddy soil has different morphology and pedogenic characteristics compared to dry land, due to the influence of inundation during several months in a year. Puddling and drying that occurs in turns (redox cycle in paddy soil can lead to the formation of concretions or rusty Fe and Mn. The main purpose of this study was to understand the changing of the morphological and chemical properties as a result of changing of the dry land to paddy soil. Besides, the study also aimed to understand plow pan layer formation in Podsolic, Latosol, Regosol, and Andosol soil type. Results showed that content of soil density (bulk density of dry land ranged from 0.5 to 1.0, while paddy soil is 0.8 to 1.0 (g cm-3. Bulk density values in all four types of soils increased after the changing. Observation also demonstrated that severity levels of paddy soil is higher than dry land, especially in the second and third soil layers or under the surface of soils. Acidity of dry land was likely to be higher than paddy soil. There were no significant differences in nutrient such as C-organic, P and N. Meanwhile, using dithionite as solvent, paddy soil has higher Fe, Mn, and Al content than that of dry land, and remain the same when extracted with pyrophosphate and oxalate. From the four types of soil observed,the paddy soil showed formation of plow pan layer. This was shown by the soil severity level higher than the topsoil or other layers. Paddy soil had unique properties due to redox reaction, thereby providing soil discoloration i.e darker due to high solubility of Fe, Mn, and Al.

  5. Soil Burial of Polylactic Acid/Paddy Straw Powder Biocomposite

    Directory of Open Access Journals (Sweden)

    Noorulnajwa Diyana Yaacob

    2015-12-01

    Full Text Available The objective of this work was to study the biodegradability of polylactic acid (PLA/paddy straw powder (PSP biocomposites. Environmental degradation was evaluated by composting the biocomposite samples into the soil. Different techniques, including mechanical tests and scanning electron microscopy (SEM, were used to obtain a view of the degradation that occurred during the soil burial of the biocomposites. Results of the mechanical tests showed that an increasing content of PSP in the biocomposites decreased the tensile strength and elongation at break (EB, while it increased the modulus of elasticity after six months of exposure. Scanning electron microscopy on the surface after soil burial showed that the filler was poorly wetted by the matrix. This explains the reduction in tensile strength and the elongation at break after soil burial. Differential scanning calorimetry results indicated that the crystallinity of the biocomposites increased with longer composting periods.

  6. Phosphorus content as a function of soil aggregate size and paddy cultivation in highly weathered soils.

    Science.gov (United States)

    Li, Baozhen; Ge, Tida; Xiao, Heai; Zhu, Zhenke; Li, Yong; Shibistova, Olga; Liu, Shoulong; Wu, Jinshui; Inubushi, Kazuyuki; Guggenberger, Georg

    2016-04-01

    Red soils are the major land resource in subtropical and tropical areas and are characterized by low phosphorus (P) availability. To assess the availability of P for plants and the potential stability of P in soil, two pairs of subtropical red soil samples from a paddy field and an adjacent uncultivated upland were collected from Hunan Province, China. Analysis of total P and Olsen P and sequential extraction was used to determine the inorganic and organic P fractions in different aggregate size classes. Our results showed that the soil under paddy cultivation had lower proportions of small aggregates and higher proportions of large aggregates than those from the uncultivated upland soil. The portion of >2-mm-sized aggregates increased by 31 and 20 % at Taoyuan and Guiyang, respectively. The total P and Olsen P contents were 50-150 and 50-300 % higher, respectively, in the paddy soil than those in the upland soil. Higher inorganic and organic P fractions tended to be enriched in both the smallest and largest aggregate size classes compared to the middle size class (0.02-0.2 mm). Furthermore, the proportion of P fractions was higher in smaller aggregate sizes (2 mm). In conclusion, soils under paddy cultivation displayed improved soil aggregate structure, altered distribution patterns of P fractions in different aggregate size classes, and to some extent had enhanced labile P pools.

  7. CADMIUM SOLUBILITY IN PADDY SOILS: EFFECTS OF SOIL OXIDATION, METAL SULFIDES AND COMPETITIVE IONS.

    Science.gov (United States)

    Cadmium (Cd) is a non-essential element for human nutrition and is an agricultural soil contaminant. Cadmium solubility in paddy soils affects Cd accumulation in the grain of rice. This is a human health risk, exacerbated by the fact that rice grains are deficient in iron (Fe) an...

  8. Inhibition of sulfate reduction in paddy soils

    Energy Technology Data Exchange (ETDEWEB)

    Vamos, R

    1958-12-13

    The hydrogen sulfide formed in waterlogged soils is a serious problem in rice cultivation. It inhibits the uptake of water and nutrients and may even cause root-rot. Results can best be obtained by preventing the formation of hydrogen sulfide. It is formed mainly by reduction of sulfate for which the cellulose-butyric acid fermentation provides the hydrogen source. Addition of ammonium or potassium nitrate prevents the formation of H/sub 2/S. The hydrogen produced by butyric acid fermentation is used to reduce nitrate and consequently cannot be utilized by the sulfate-reducing bacteria as a source of energy. 6 references.

  9. [Effect of short-time drought process on denitrifying bacteria abundance and N2O emission in paddy soil].

    Science.gov (United States)

    Lu, Jing; Liu, Jin-Bo; Sheng, Rong; Liu, Yi; Chen, An-Lei; Wei, Wen-Xue

    2014-10-01

    In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting-drying process was simulated in laboratory conditions. N2O flux, redox potential (Eh) were monitored and narG- and nosZ-containing denitrifiers abundances were determined by real-time PCR. N2O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h. In addition, narG and nosZ gene abundances were increased rapidly with the drying process, and N2O emission flux was significantly correlated with narG gene abundance (P driving microorganisms which caused the N2O emission in the short-time drought process in paddy soil.

  10. Potential denitrification rates of subsurface soil under paddy fields receiving ground water with high nitrate concentration; Konodo shosantai chisso gan`yu chikasui no ryunyusuru suiden kasodo ni okeru dacchitsu kassei

    Energy Technology Data Exchange (ETDEWEB)

    Toda, H [Shizuoka Agricultural Experiment Station, Shizuoka (Japan); Hidaka, S [Saitama Agricultural Experiment Station, Saitama (Japan)

    1996-02-10

    It is well known that the concentration of nitrate nitrogen in the surface water decreases as it flows downward in rice paddies irrigated with water high in nitrate nitrogen concentration. The decrease is attributed to absorption by rice plants and algae adherent thereto and denitrification in the reduction layer well developed in the rice paddy surface soil. In paddy fields downstream of the Kushibiki plateau in the northwestern part of Saitama Prefecture, it is occasionally observed that nitrate nitrogen concentration in the ground water decreases as it flows down (farther from the plateau) not only in the flooded period but also in the non-flooded period. This suggests that in the said paddy field denitrification takes place not only in the rice paddy surface layer soil but also in the lower layer soil. Under the circumstances, the denitrification rate in the rice paddy lower layer soil was measured using the acetylene inhibition method under anaerobic and added nitrate conditions. A denitrification rate of 0.4-46ngN/g{sup -1} wet soil/h{sup -1} was obtained from a 40-150cm deep layer soil, smaller by the order of 1-2 than that in the surface layer soil. This suggests that the lower layer soil contributes to denitrification. 17 refs., 3 figs., 1 tab.

  11. Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

    Science.gov (United States)

    Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

    2015-06-16

    Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem.

  12. Irrigation with oxygen-nanobubble water can reduce methane emission and arsenic dissolution in a flooded rice paddy

    Science.gov (United States)

    Minamikawa, Kazunori; Takahashi, Masayoshi; Makino, Tomoyuki; Tago, Kanako; Hayatsu, Masahito

    2015-08-01

    A remarkable feature of nanobubbles (pot experiment and measuring redox-related variables. The NBs were introduced into control water (with properties similar to those of river water) using a commercially available generator. Rice (Oryza sativa L.) growth did not differ between plants irrigated with NB water and those irrigated with control water, but NB water significantly (p rice-growing season by 21%. The amounts of iron, manganese, and arsenic that leached into the drainage water before full rice heading were also reduced by the NB water. Regardless of the water type, weekly-measured CH4 flux was linearly correlated with the leached iron concentration during the rice-growing season (r = 0.74, p pots without rice plants, soil reduction was not enhanced, regardless of the water type. The results indicate that NB water reduced CH4 emission and arsenic dissolution through an oxidative shift of the redox conditions in the flooded soil. We propose the use of NB water as a tool for controlling redox conditions in flooded paddy soils.

  13. Irrigation with oxygen-nanobubble water can reduce methane emission and arsenic dissolution in a flooded rice paddy

    International Nuclear Information System (INIS)

    Minamikawa, Kazunori; Makino, Tomoyuki; Tago, Kanako; Hayatsu, Masahito; Takahashi, Masayoshi

    2015-01-01

    A remarkable feature of nanobubbles (<10 –6 m in diameter) is their long lifetime in water. Supplying oxygen-nanobubbles (NBs) to continuously flooded paddy soil may retard the development of reductive conditions, thereby reducing the emission of methane (CH 4 ), a potent greenhouse gas, and dissolution of arsenic, an environmental load. We tested this hypothesis by performing a pot experiment and measuring redox-related variables. The NBs were introduced into control water (with properties similar to those of river water) using a commercially available generator. Rice (Oryza sativa L.) growth did not differ between plants irrigated with NB water and those irrigated with control water, but NB water significantly (p < 0.05) reduced cumulative CH 4 emission during the rice-growing season by 21%. The amounts of iron, manganese, and arsenic that leached into the drainage water before full rice heading were also reduced by the NB water. Regardless of the water type, weekly-measured CH 4 flux was linearly correlated with the leached iron concentration during the rice-growing season (r = 0.74, p < 0.001). At the end of the experiment, the NB water significantly lowered the soil pH in the 0–5 cm layer, probably because of the raised redox potential. The population of methanogenic Archaea (mcrA copy number) in the 0–5 cm layer was significantly increased by the NB water, but we found no correlation between the mcrA copy number and the cumulative CH 4 emission (r = –0.08, p = 0.85). In pots without rice plants, soil reduction was not enhanced, regardless of the water type. The results indicate that NB water reduced CH 4 emission and arsenic dissolution through an oxidative shift of the redox conditions in the flooded soil. We propose the use of NB water as a tool for controlling redox conditions in flooded paddy soils. (letter)

  14. Release of cadmium in contaminated paddy soil amended with NPK fertilizer and lime under water management.

    Science.gov (United States)

    Han, Xiao-Qing; Xiao, Xi-Yuan; Guo, Zhao-Hui; Xie, Ye-Hua; Zhu, Hui-Wen; Peng, Chi; Liang, Yu-Qin

    2018-05-03

    Agricultural soils contaminated with cadmium (Cd) pose a risk to receiving surface water via drainage or runoff. A 90-day laboratory incubation experiment was conducted to investigate the release characteristics and transformation of Cd from contaminated paddy soil amended with agrochemical (NPK fertilizer) and lime (L) under water management regimes of continuous flooding (F) and drying-wetting cycles (DW). The result showed that the dissolved Cd concentrations in overlying water of the fertilizer treatment under flooding (NPK+F) and drying-wetting (NPK+DW) reached up to 81.0 μg/L and 276 μg/L, and were much higher than that from the corresponding controls without NPK fertilizer addition at the end of experiment. The Cd concentration showed significantly negative correlation with overlying water pH, but positive correlation with soil redox potential and concentrations of dissolved total nitrogen, sulfate and manganese in overlying water (P < 0.05), indicating that drying-wetting cycles and N fertilizer addition may enhance soil Cd release. The Cd concentrations in overlying water from all treatments except NPK+L+F treatment exceeded the Cd threshold limit of Chinese Environmental Quality Standards for Surface Water (10 μg/L Grade V) and poses potential risk to surface water quality. Meanwhile, the proportion of Cd in the acid-soluble fraction from all incubated soil except NPK+L+F treatment increased compared to before incubation. The results indicated that continuous flooding was a reasonable water management candidate coupled with lime addition for immobilizing soil Cd. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Substantial N2O emission during the initial period of the wheat season due to the conversion of winter-flooded paddy to rice-wheat rotation

    Science.gov (United States)

    Zhou, Wei; Lin, Shan; Wu, Lei; Zhao, Jingsong; Wang, Milan; Zhu, Bo; Mo, Yongliang; Hu, Ronggui; Chadwick, Dave; Shaaban, Muhammad

    2017-12-01

    Winter-flooded paddy is a typical rice-based cropping system to conserve water for the next rice growing season. Conversion of winter-flooded paddy to rice-wheat rotation has been widely adopted with the development of the water conservation infrastructure and the government's encouragement of winter agriculture in China in recent decades. However, the effects of this conversion on N2O emission are still not clear. Three winter-flooded paddy fields were studied in a split-plot design. One-half of each field was converted to rice-wheat rotation (RW), and the other half remained winter-flooded as rice-fallow (RF). Each plot of RW and RF was further divided into four subplots: three subplots for conventional N fertilizer application (RW-NC and RF-NC) and one for unfertilized treatment (RW-N0 and RF-N0). Conversion of RF-NC to RW-NC increased the N2O emission up to 6.6-fold in the first year and 4.4-fold in the second year. Moreover, N2O emissions for the entire wheat season were 1.74-3.74 kg N ha-1 and 0.24-0.31 kg N ha-1 from RW-NC and RW-N0, respectively, and accounted for 78%-94% and 78%-97% of the total annual amount. N2O emitted during the first 11-21 days of the wheat season from RW-NC was 1.48-3.28 kg N ha-1 and that from RW-N0 was 0.14-0.17 kg N ha-1, which contributed to 66%-82% and 45%-71% of the total annual amount, respectively. High N2O fluxes occurred when the soil water-filled pore space (WFPS) was in the range of 68%-72% and the ratio of available carbon to nitrogen in the soil was organic carbon (DOC) explained most of the variation of the N2O fluxes compared with the other measured environmental and soil factors. These findings suggest that the conversion of winter-flooded paddy to rice-wheat rotation increased N2O emissions that could be mitigated by controlling the soil moisture and ratio of available soil carbon to nitrogen.

  16. Formation of Microbial Mats and Salt in Radioactive Paddy Soils in Fukushima, Japan

    Directory of Open Access Journals (Sweden)

    Kazue Tazaki

    2015-12-01

    Full Text Available Coastal areas in Minami-soma City, Fukushima, Japan, were seriously damaged by radioactive contamination from the Fukushima Daiichi Nuclear Power Plant (FDNPP accident that caused multiple pollution by tsunami and radionuclide exposure, after the Great East Japan Earthquake, on 11 March 2011. Some areas will remain no-go zones because radiation levels remain high. In Minami-soma, only 26 percent of decontamination work had been finished by the end of July in 2015. Here, we report the characterization of microbial mats and salt found on flooded paddy fields at Karasuzaki, Minami-soma City, Fukushima Prefecture, Japan which have been heavily contaminated by radionuclides, especially by Cs (134Cs, 137Cs, 40K, Sr (89Sr, 90Sr, and 91 or 95Zr even though it is more than 30 km north of the FDNPP. We document the mineralogy, the chemistry, and the micro-morphology, using a combination of micro techniques. The microbial mats were found to consist of diatoms with mineralized halite and gypsum by using X-ray diffraction (XRD. Particular elements concentrated in microbial mats were detected using scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS and X-ray fluorescence (XRF. The objective of this contribution is to illustrate the ability of various diatoms associated with minerals and microorganisms which are capable of absorbing both radionuclides and stable isotopes from polluted paddy soils in extreme conditions. Ge semiconductor analysis of the microbial mats detected 134Cs, 137Cs, and 40K without 131I in 2012 and in 2013. Quantitative analysis associated with the elemental content maps by SEM-EDS indicated the possibility of absorption of radionuclide and stable isotope elements from polluted paddy soils in Fukushima Prefecture. In addition, radionuclides were detected in solar salts made of contaminated sea water collected from the Karasuzaki ocean bath, Minami-soma, Fukushima in 2015, showing high Zr content associated

  17. Fate of 14C-labelled diazinon in rice seedling and paddy soil

    International Nuclear Information System (INIS)

    Lee, Seong Kye; Kim, Kyoon; Park, Chang Kyu; Hwang, Eul Chul

    1985-01-01

    The fate of diazinon in the intact rice plants and submerged paddy soil has been investigated with (2- 14 C pyrimidine) diazinon. The labelled diazinon solution was applied to paddy water and distribution of radioactivities in the rice seedlings, paddy soil, volatile fraction and carbon dioxide has been ascertained at end the of incubation times of 0.5,1,4,6 and 9 days respectively. In addition, extract of plants and paddy soils were subjected to TLC separation for examination of possible transformation products of diazinon. The results may be summarized as follow; 1. Total recoveries of radiactivities were between 57.2∼73.6 per cent. 2. Radioactivity in rice seedlings increased with incubation periods reaching one tenth of treated radioactivity at the end of 9 day incubation. 3. Non-extractable radioactivity in paddy soil increased with incubation periods. 4. Radioactive volatile fraction increased in the presence of the rice seedlings. 5. Pyrimidinol was unique conversion product of diazinon in rice seedlings and paddy soils. 6. Pyrimidinol applied to paddy soil is readily absorbed by rice seedlings. (Author)

  18. Differential contributions of ammonia oxidizers and nitrite oxidizers to nitrification in four paddy soils

    Science.gov (United States)

    Wang, Baozhan; Zhao, Jun; Guo, Zhiying; Ma, Jing; Xu, Hua; Jia, Zhongjun

    2015-01-01

    Rice paddy fields are characterized by regular flooding and nitrogen fertilization, but the functional importance of aerobic ammonia oxidizers and nitrite oxidizers under unique agricultural management is poorly understood. In this study, we report the differential contributions of ammonia-oxidizing archaea (AOA), bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to nitrification in four paddy soils from different geographic regions (Zi-Yang (ZY), Jiang-Du (JD), Lei-Zhou (LZ) and Jia-Xing (JX)) that are representative of the rice ecosystems in China. In urea-amended microcosms, nitrification activity varied greatly with 11.9, 9.46, 3.03 and 1.43 μg NO3−-N g−1 dry weight of soil per day in the ZY, JD, LZ and JX soils, respectively, over the course of a 56-day incubation period. Real-time quantitative PCR of amoA genes and pyrosequencing of 16S rRNA genes revealed significant increases in the AOA population to various extents, suggesting that their relative contributions to ammonia oxidation activity decreased from ZY to JD to LZ. The opposite trend was observed for AOB, and the JX soil stimulated only the AOB populations. DNA-based stable-isotope probing further demonstrated that active AOA numerically outcompeted their bacterial counterparts by 37.0-, 10.5- and 1.91-fold in 13C-DNA from ZY, JD and LZ soils, respectively, whereas AOB, but not AOA, were labeled in the JX soil during active nitrification. NOB were labeled to a much greater extent than AOA and AOB, and the addition of acetylene completely abolished the assimilation of 13CO2 by nitrifying populations. Phylogenetic analysis suggested that archaeal ammonia oxidation was predominantly catalyzed by soil fosmid 29i4-related AOA within the soil group 1.1b lineage. Nitrosospira cluster 3-like AOB performed most bacterial ammonia oxidation in the ZY, LZ and JX soils, whereas the majority of the 13C-AOB in the JD soil was affiliated with the Nitrosomona communis lineage. The 13C-NOB was overwhelmingly

  19. Fe and Mn levels regulated by agricultural activities in alluvial groundwaters underneath a flooded paddy field

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kangjoo [School of Civil and Environmental Engineering, Kunsan National University, Jeonbuk 573-701 (Korea, Republic of)], E-mail: kangjoo@kunsan.ac.kr; Kim, Hyun-Jung; Choi, Byoung-Young; Kim, Seok-Hwi; Park, Ki-hoon [School of Civil and Environmental Engineering, Kunsan National University, Jeonbuk 573-701 (Korea, Republic of); Park, Eungyu [Department of Geology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Koh, Dong-Chan [Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Yun, Seong-Taek [Department of Earth and Environmental Sciences, Korea University, Seoul 136-701 (Korea, Republic of)

    2008-01-15

    Iron and Mn concentrations in fresh groundwaters of alluvial aquifers are generally high in reducing conditions reflecting low SO{sub 4} concentrations. The mass balance and isotopic approaches of this study demonstrate that reduction of SO{sub 4}, supplied from agricultural activities such as fertilization and irrigation, is important in lowering Fe and Mn levels in alluvial groundwaters underneath a paddy field. This study was performed to investigate the processes regulating Fe and Mn levels in groundwaters of a point bar area, which has been intensively used for flood cultivation. Four multilevel-groundwater samplers were installed to examine the relationship between geology and the vertical changes in water chemistry. The results show that Fe and Mn levels are regulated by the presence of NO{sub 3} at shallow depths and by SO{sub 4} reduction at the greater depths. Isotopic and mass balance analyses revealed that NO{sub 3} and SO{sub 4} in groundwater are mostly supplied from the paddy field, suggesting that the Fe-and Mn-rich zone of the study area is confined by the agricultural activities. For this reason, the geologic conditions controlling the infiltration of agrochemicals are also important for the occurrence of Fe/Mn-rich groundwaters in the paddy field area.

  20. Fe and Mn levels regulated by agricultural activities in alluvial groundwaters underneath a flooded paddy field

    International Nuclear Information System (INIS)

    Kim, Kangjoo; Kim, Hyun-Jung; Choi, Byoung-Young; Kim, Seok-Hwi; Park, Ki-hoon; Park, Eungyu; Koh, Dong-Chan; Yun, Seong-Taek

    2008-01-01

    Iron and Mn concentrations in fresh groundwaters of alluvial aquifers are generally high in reducing conditions reflecting low SO 4 concentrations. The mass balance and isotopic approaches of this study demonstrate that reduction of SO 4 , supplied from agricultural activities such as fertilization and irrigation, is important in lowering Fe and Mn levels in alluvial groundwaters underneath a paddy field. This study was performed to investigate the processes regulating Fe and Mn levels in groundwaters of a point bar area, which has been intensively used for flood cultivation. Four multilevel-groundwater samplers were installed to examine the relationship between geology and the vertical changes in water chemistry. The results show that Fe and Mn levels are regulated by the presence of NO 3 at shallow depths and by SO 4 reduction at the greater depths. Isotopic and mass balance analyses revealed that NO 3 and SO 4 in groundwater are mostly supplied from the paddy field, suggesting that the Fe-and Mn-rich zone of the study area is confined by the agricultural activities. For this reason, the geologic conditions controlling the infiltration of agrochemicals are also important for the occurrence of Fe/Mn-rich groundwaters in the paddy field area

  1. Effects of biochar on dechlorination of hexachlorobenzene and the bacterial community in paddy soil.

    Science.gov (United States)

    Song, Yang; Bian, Yongrong; Wang, Fang; Herzberger, Anna; Yang, Xinglun; Gu, Chenggang; Jiang, Xin

    2017-11-01

    Anaerobic reductive dechlorination is an important degradation pathway for chlorinated organic contaminants in paddy soil. This study investigated the effects of amending paddy soil with wheat straw biochar on both the dechlorination of hexachlorobenzene (HCB), a typical highly chlorinated contaminant, and on the structure of soil bacteria communities. Soil amendment of 0.1% biochar did not significantly affect the dechlorination of HCB in the soil. However, biochar amendment at higher application levels (5%) stimulated the dechlorination of HCB in the first month of anaerobic incubation and inhibited the dechlorination of HCB after that period. The stimulation effect may be ascribed to the graphite carbon and carbon-centered persistent radicals, which are redox active, in biochar. The inhibiting effect could be partly ascribed to the reduced bioavailability of HCB in biochar-amended soils. High-throughput sequencing revealed that the amendment of biochar changed the soil bacterial community structure but not the bacterial abundances and diversities. The relative abundance of Dehalococcoidaceae in the tested soils showed a significant relationship with the dechlorination percentages of HCB, indicating that Dehalococcoidaceae may be the main HCB-dechlorinating bacteria in the studied paddy soil. The results indicated that low application levels of biochar did not affect the dechlorination of HCB in the paddy soil, while high application levels of biochar mainly inhibited the dechlorination of HCB due to the reduced bioavailability of HCB and the reduced abundances of certain dechlorinating bacteria in the biochar-amended paddy soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Brus, D.J.; Guo, H.Y.; Chu, C.L.; Chiang, C.M.; Koopmans, G.F.

    2011-01-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal

  3. Soil microbial C:N ratio is a robust indicator of soil productivity for paddy fields

    Science.gov (United States)

    Li, Yong; Wu, Jinshui; Shen, Jianlin; Liu, Shoulong; Wang, Cong; Chen, Dan; Huang, Tieping; Zhang, Jiabao

    2016-10-01

    Maintaining good soil productivity in rice paddies is important for global food security. Numerous methods have been developed to evaluate paddy soil productivity (PSP), most based on soil physiochemical properties and relatively few on biological indices. Here, we used a long-term dataset from experiments on paddy fields at eight county sites and a short-term dataset from a single field experiment in southern China, and aimed at quantifying relationships between PSP and the ratios of carbon (C) to nutrients (N and P) in soil microbial biomass (SMB). In the long-term dataset, SMB variables generally showed stronger correlations with the relative PSP (rPSP) compared to soil chemical properties. Both correlation and variation partitioning analyses suggested that SMB N, P and C:N ratio were good predictors of rPSP. In the short-term dataset, we found a significant, negative correlation of annual rice yield with SMB C:N (r = -0.99), confirming SMB C:N as a robust indicator for PSP. In treatments of the short-term experiment, soil amendment with biochar lowered SMB C:N and improved PSP, while incorporation of rice straw increased SMB C:N and reduced PSP. We conclude that SMB C:N ratio does not only indicate PSP but also helps to identify management practices that improve PSP.

  4. Succession of bacterial community structure and diversity in a paddy soil oxygen gradient.

    Science.gov (United States)

    Noll, Matthias; Matthies, Diethart; Frenzel, Peter; Derakshani, Manigee; Liesack, Werner

    2005-03-01

    Cultivation-independent techniques were applied to assess the succession and phylogenetic composition of bacterial communities in a vertical oxygen gradient in flooded, unplanted paddy soil microcosms. Microsensor measurements showed that within 6 h of flooding, oxygen was depleted from 200 microM at the floodwater-soil interface to undetectable amounts at a depth of approximately 2 mm and below. The gradient was quite stable over time, although the oxygen depletion was less pronounced 84 days than 6 h after flooding. Community fingerprint patterns were obtained by terminal restriction fragment length polymorphism (T-RFLP) analysis from the oxic, transition, and anoxic zones of triplicate soil microcosms at 0, 1 and 6 h, and 1, 2, 7, 21, 30, 42, 84, and 168 days after flooding. Correspondence analyses revealed that T-RFLP patterns obtained using either community DNA or RNA were affected by time and oxygen zone, and that there was a significant interaction between the effects of time and oxygen zone. The temporal dynamics of bacterial populations were resolved more clearly using RNA than using DNA. At the RNA level, successional community dynamics were most pronounced from 1 h to 2 days and less pronounced from 2 to 21 days after flooding, for both oxic and anoxic zones. No effect of time or oxygen zone on the community dynamics was observed from 21 to 168 days after flooding. Dominant early successional populations were identified by cloning and comparative sequence analysis of environmental 16S rRNA and 16S rRNA genes as members of the Betaproteobacteria (oxic zone) and the clostridial cluster I (anoxic zone). Dominant late successional populations belonged to the Verrucomicrobia and Nitrospira (detected mainly in the oxic zone), and to the Myxococcales (detected mainly in the anoxic zone). In conclusion, the bacterial community developed through successional stages, leading at the RNA level to almost stable community patterns within 21 days after flooding. This

  5. Soil aggregate and organic carbon distribution at dry land soil and paddy soil: the role of different straws returning.

    Science.gov (United States)

    Huang, Rong; Lan, Muling; Liu, Jiang; Gao, Ming

    2017-12-01

    Agriculture wastes returning to soil is one of common ways to reuse crop straws in China. The returned straws are expected to improve the fertility and structural stability of soil during the degradation of straw it selves. The in situ effect of different straw (wheat, rice, maize, rape, and broad bean) applications for soil aggregate stability and soil organic carbon (SOC) distribution were studied at both dry land soil and paddy soil in this study. Wet sieving procedures were used to separate soil aggregate sizes. Aggregate stability indicators including mean weight diameter, geometric mean diameter, mean weight of specific surface area, and the fractal dimension were used to evaluate soil aggregate stability after the incubation of straws returning. Meanwhile, the variation and distribution of SOC in different-sized aggregates were further studied. Results showed that the application of straws, especially rape straw at dry land soil and rice straw at paddy soil, increased the fractions of macro-aggregate (> 0.25 mm) and micro-aggregate (0.25-0.053 mm). Suggesting the nutrients released from straw degradation promotes the growing of soil aggregates directly and indirectly. The application of different straws increased the SOC content at both soils and the SOC mainly distributed at  0.25 and 0.25-0.053 mm aggregates with dry land soil. Rape straw in dry land and rice straw in paddy field could stabilize soil aggregates and increasing SOC contents best.

  6. Development and Rainfed Paddy Soils Potency Derived from Lacustrine Material in Paguyaman, Gorontalo

    Directory of Open Access Journals (Sweden)

    Nurdin

    2011-09-01

    Full Text Available Rainfed paddy soils that are derived from lacustrine and include of E4 agroclimatic zone have many unique properties and potentially for paddy and corn plantations. This sreseach was aimed to: (1 study the soil development of rainfed paddy soils derived from lacustrine and (2 evaluate rainfed paddy soils potency for paddy and corn in Paguyaman. Soil samples were taken from three profiles according to toposequent, and they were analyzed in laboratory. Data were analyzed with descriptive-quantitative analysis. Furthermore, assessment on rainfed paddy soils potency was conducted with land suitability analysis using parametric approach. Results indicate that all pedon had evolved with B horizons structurization. However, pedon located on the summit slope was more developed and intensely weathered than those of the shoulder and foot slopes.The main pedogenesis in all pedons were through elluviation, illuviation, lessivage, pedoturbation, and gleization processes. The main factors of pedogenesis were climate, age (time and topography factors. Therefore, P1 pedons are classified as Ustic Endoaquerts, fine, smectitic, isohypertermic; P2 as Vertic Endoaquepts, fine, smectitic, isohypertermic; and P3 as Vertic Epiaquepts, fine, smectitic, isohypertermic. Based on the potentials of the land, the highest of land suitability class (LSC of land utilization type (LUT local paddy was highly suitable (S1, while the lowest one was not suitable with nutrient availability as the limiting factor (Nna. The highest LCS of paddy-corn LUT was marginally suitable with water availability as the limiting factor (S3wa, while the lower LSC was not suitable with nutrient availabily as the limiting factor (Nna.

  7. Downward carbon transport in a 2000-year rice paddy soil chronosequence traced by radiocarbon measurements

    Energy Technology Data Exchange (ETDEWEB)

    Braeuer, T., E-mail: tbraeuer@leibniz.uni-kiel.de [Leibniz-Laboratory, Christian-Albrechts-University, Kiel (Germany); Grootes, P.M.; Nadeau, M.-J.; Andersen, N. [Leibniz-Laboratory, Christian-Albrechts-University, Kiel (Germany)

    2013-01-15

    Paddy and non-paddy soils from a chronosequence of 50-2000 years of agricultural use, developed on former estuarine sediments of the Yangtze River, were sampled near Cixi, Zhejiang Province, China, in the framework of the Research Unit 'Biogeochemistry of paddy soil evolution' of the German Research Foundation (DFG). In addition samples of Yangtze River estuarine sediments were obtained. The parent sediment shows a fairly homogeneous composition with ca. 0.3% TOC and a {sup 14}C concentration of ca. 50 pMC. After being diked-in, gradients in soil organic carbon and {sup 14}C concentration develop under the influence of vegetation and cultivation. In the non-paddy soil, a {sup 14}C gradient with concentration decreasing with increasing depth from modern (>100 pMC) to original sediment values around 50 pMC is already established after 50 years and can also be observed in the older sites. In contrast, the 50 years old paddy soil shows organic carbon and {sup 14}C enrichment only in the A-horizon and a nearly constant TOC and {sup 14}C stock of original sediment below the plough pan. To test the basic approach that the soil profile development started on homogeneous sediment, an isotope and mass balance calculation was used. The results show a quite similar age composition of different sample sites. Paddy rice cultivation quickly leads to a dense plough pan, which seriously reduces, but not totally prevents, downward transport of organic matter. The equilibrium times for TOC and {sup 14}C in paddy soil profiles are short (decades) in the topsoil and in the order of centuries in the subsoil, underlining the dynamic character of soil organic carbon.

  8. Downward carbon transport in a 2000-year rice paddy soil chronosequence traced by radiocarbon measurements

    International Nuclear Information System (INIS)

    Bräuer, T.; Grootes, P.M.; Nadeau, M.-J.; Andersen, N.

    2013-01-01

    Paddy and non-paddy soils from a chronosequence of 50–2000 years of agricultural use, developed on former estuarine sediments of the Yangtze River, were sampled near Cixi, Zhejiang Province, China, in the framework of the Research Unit “Biogeochemistry of paddy soil evolution” of the German Research Foundation (DFG). In addition samples of Yangtze River estuarine sediments were obtained. The parent sediment shows a fairly homogeneous composition with ca. 0.3% TOC and a 14 C concentration of ca. 50 pMC. After being diked-in, gradients in soil organic carbon and 14 C concentration develop under the influence of vegetation and cultivation. In the non-paddy soil, a 14 C gradient with concentration decreasing with increasing depth from modern (>100 pMC) to original sediment values around 50 pMC is already established after 50 years and can also be observed in the older sites. In contrast, the 50 years old paddy soil shows organic carbon and 14 C enrichment only in the A-horizon and a nearly constant TOC and 14 C stock of original sediment below the plough pan. To test the basic approach that the soil profile development started on homogeneous sediment, an isotope and mass balance calculation was used. The results show a quite similar age composition of different sample sites. Paddy rice cultivation quickly leads to a dense plough pan, which seriously reduces, but not totally prevents, downward transport of organic matter. The equilibrium times for TOC and 14 C in paddy soil profiles are short (decades) in the topsoil and in the order of centuries in the subsoil, underlining the dynamic character of soil organic carbon.

  9. Mobilization of heavy metals from contaminated paddy soil by EDDS, EDTA, and elemental sulfur

    NARCIS (Netherlands)

    Wang, G.; Koopmans, G.F.; Song, J.; Temminghoff, E.J.M.; Luo, Y.; Zhao, Q.; Japenga, J.

    2007-01-01

    For enhanced phytoextraction, mobilization of heavy metals (HMs) from the soil solid phase to soil pore water is an important process. A pot incubation experiment mimicking field conditions was conducted to investigate the performance of three soil additives in mobilizing HMs from contaminated paddy

  10. Cadmium solubility in paddy soils: Effects of soil oxidation, metal sulfides and competitive ions

    Energy Technology Data Exchange (ETDEWEB)

    Livera, Jennifer de, E-mail: Jennifer.deLivera@adelaide.edu.au [Soil Science, School of Agriculture Food and Wine, Waite Research Institute, University of Adelaide, Adelaide, SA (Australia); McLaughlin, Mike J. [Soil Science, School of Agriculture Food and Wine, Waite Research Institute, University of Adelaide, Adelaide, SA (Australia); CSIRO Land and Water, Environmental Biogeochemistry Program, Sustainable Agriculture Flagship, Adelaide, SA (Australia); Hettiarachchi, Ganga M. [CSIRO Land and Water, Environmental Biogeochemistry Program, Sustainable Agriculture Flagship, Adelaide, SA (Australia); Department of Agronomy, Kansas state University, Manhattan, KS (United States); Kirby, Jason K. [CSIRO Land and Water, Environmental Biogeochemistry Program, Sustainable Agriculture Flagship, Adelaide, SA (Australia); CSIRO Land and Water, Environmental Biogeochemistry Program, Water for a Healthy Country Flagship, Adelaide, SA (Australia); Beak, Douglas G. [CSIRO Land and Water, Environmental Biogeochemistry Program, Sustainable Agriculture Flagship, Adelaide, SA (Australia)

    2011-03-15

    Cadmium (Cd) is a non-essential element for human nutrition and is an agricultural soil contaminant. Cadmium solubility in paddy soils affects Cd accumulation in the grain of rice. This is a human health risk, exacerbated by the fact that rice grains are deficient in iron (Fe) and zinc (Zn) for human nutrition. To find ways of limiting this potential risk, we investigated factors influencing Cd solubility relative to Fe and Zn during pre-harvest drainage of paddy soils, in which soil oxidation is accompanied by the grain-filling stage of rice growth. This was simulated in temperature-controlled 'reaction cell' experiments by first excluding oxygen to incubate soil suspensions anaerobically, then inducing aerobic conditions. In treatments without sulfur addition, the ratios of Cd:Fe and Cd:Zn in solution increased during the aerobic phase while Cd concentrations were unaffected and the Fe and Zn concentrations decreased. However, in treatments with added sulfur (as sulfate), up to 34 % of sulfur (S) was precipitated as sulfide minerals during the anaerobic phase and the Cd:Fe and Cd:Zn ratios in solution during the aerobic phase were lower than for treatments without S addition. When S was added, Cd solubility decreased whereas Fe and Zn were unaffected. When soil was spiked with Zn the Cd:Zn ratio was lower in solution during the aerobic phase, due to higher Zn concentrations. Decreased Cd:Fe and Cd:Zn ratios during the grain filling stage could potentially limit Cd enrichment in paddy rice grain due to competitive ion effects for root uptake. - Research Highlights: {yields} Cd:Fe and Cd:Zn ratios increase in paddy soil solution during oxidation. {yields} Cd:Fe and Cd:Zn ratios increase because Fe and Zn concentrations decrease. {yields} Cd concentrations do not change during oxidation. {yields} Cd:Fe and Cd:Zn ratios in solution decrease when Zn is added to soil. {yields} Metal sulfide precipitation lowers Cd:Fe and Cd:Zn ratios in soil solution.

  11. Phytoremediation of arsenic contaminated paddy soils with Pteris vittata markedly reduces arsenic uptake by rice

    International Nuclear Information System (INIS)

    Ye Wenling; Khan, M. Asaduzzaman; McGrath, Steve P.; Zhao Fangjie

    2011-01-01

    Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P. vittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P. vittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. - Highlights: → Pteris vittata removed 3.5-11.4% of the total As from five contaminated paddy soils. → P. vittata decreased phosphate-extractable and soil solution As to a greater extent. → P. vittata reduced As concentration in rice grain by 18-83%. → P. vittata decreased methylated As in rice grain more than inorganic As. - Phytoremediation with P. vittata significantly reduced arsenic uptake by rice from contaminated paddy soils.

  12. Speciation of heavy metals in paddy soils from selected areas in ...

    African Journals Online (AJOL)

    Jane

    2011-10-12

    Oct 12, 2011 ... regarding their origin and distribution in soils. Five sampling ... elements that originate in the phosphate rock. ... these areas to improve rice productivity and control pests. ... acid digest were determined by atomic absorption spectrometry ..... paddy soil using X-ray fluorescence, absorption and diffraction.

  13. Phytoremediation of arsenic contaminated paddy soils with Pteris vittata markedly reduces arsenic uptake by rice

    Energy Technology Data Exchange (ETDEWEB)

    Ye Wenling [Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Khan, M. Asaduzzaman [Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207 (Bangladesh); McGrath, Steve P. [Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom); Zhao Fangjie, E-mail: Fangjie.Zhao@bbsrc.ac.uk [Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ (United Kingdom)

    2011-12-15

    Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P. vittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P. vittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. - Highlights: > Pteris vittata removed 3.5-11.4% of the total As from five contaminated paddy soils. > P. vittata decreased phosphate-extractable and soil solution As to a greater extent. > P. vittata reduced As concentration in rice grain by 18-83%. > P. vittata decreased methylated As in rice grain more than inorganic As. - Phytoremediation with P. vittata significantly reduced arsenic uptake by rice from contaminated paddy soils.

  14. C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season

    Energy Technology Data Exchange (ETDEWEB)

    Pramanik, Prabhat, E-mail: prabhat2003@gmail.com; Haque, Md. Mozammel; Kim, Sang Yoon; Kim, Pil Joo, E-mail: pjkim@gnu.ac.kr

    2014-08-15

    Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH{sub 4}) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO{sub 3}–N concentrations in soil, which are precursors for the formation of nitrous oxide (N{sub 2}O). However, N{sub 2}O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N{sub 2}O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N{sub 2}O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N{sub 2}O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9 Mg ha{sup −1} and 27 Mg ha{sup −1} rates in rice paddy soil. Cover crop application significantly increased CH{sub 4} emission flux while decreased N{sub 2}O emissions during rice cultivation. The lowest N{sub 2}O emission was observed in 27 Mg ha{sup −1} cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (< 250 μm), and that proportionately increased the N{sub 2}O emission potentials of these soil aggregates. Fluxes of N{sub 2}O emissions in the fallow season were influenced by the N{sub 2}O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH{sub 4}, but N{sub 2}O should also be

  15. C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season

    International Nuclear Information System (INIS)

    Pramanik, Prabhat; Haque, Md. Mozammel; Kim, Sang Yoon; Kim, Pil Joo

    2014-01-01

    Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH 4 ) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO 3 –N concentrations in soil, which are precursors for the formation of nitrous oxide (N 2 O). However, N 2 O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N 2 O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N 2 O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N 2 O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9 Mg ha −1 and 27 Mg ha −1 rates in rice paddy soil. Cover crop application significantly increased CH 4 emission flux while decreased N 2 O emissions during rice cultivation. The lowest N 2 O emission was observed in 27 Mg ha −1 cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (< 250 μm), and that proportionately increased the N 2 O emission potentials of these soil aggregates. Fluxes of N 2 O emissions in the fallow season were influenced by the N 2 O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH 4 , but N 2 O should also be considered especially for fallow season to calculate total GWP. - Highlights:

  16. Roseomonas oryzae sp. nov., isolated from paddy rhizosphere soil.

    Science.gov (United States)

    Ramaprasad, E V V; Sasikala, Ch; Ramana, Ch V

    2015-10-01

    A non-motile, coccus-shaped, pale-pink-pigmented bacterium, designated strain JC288T, was isolated from a paddy rhizosphere soil collected from Western Ghats, Kankumbi, Karnataka, India. Cells were found to be Gram-stain-negative, and catalase- and oxidase-positive; the major fatty acids were C16 : 0, C16 : 1ω7c/C16 : 1ω6c, C18 : 1ω7c/C18 : 1ω6c and C18 : 1 2-OH. The predominant respiratory quinone was Q-10 and the genomic DNA G+C content was 67.5 mol%. Strain JC288T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, four unidentified aminolipids, three unidentified phospholipids, two unidentified lipids, an aminophospholipid and a glycolipid. Hydroxyspirilloxanthin was the major carotenoid of strain JC288T. 16S rRNA gene sequence comparisons indicated that strain JC288T represents a member of the genus Roseomonas within the family Acetobacteraceae of the phylum Proteobacteria. Strain JC288T shared the highest 16S rRNA gene sequence similarity with Roseomonas rhizosphaerae YW11T (97.3 %), Roseomonas aestuarii JC17T (97.1 %), Roseomonas cervicalis CIP 104027T (95.9 %) and other members of the genus Roseomonas ( < 95.5 %). The distinct genomic difference and morphological, physiological and chemotaxonomic differences from the previously described taxa support the classification of strain JC288T as a representative of a novel species of the genus Roseomonas, for which the name Roseomonas oryzae sp. nov. is proposed. The type strain is JC288T ( = KCTC 42542T = LMG 28711T).

  17. Effect of available phosphorus in paddy soils on phosphorus uptake of rice

    International Nuclear Information System (INIS)

    Liu Delin; Zhu Zhaomin

    1996-01-01

    Relation between available phosphorus in 6 types of paddy soil in Hunan Province and its uptake by rices was studied by 32 P tracing. The result indicated that the P uptake by rices varied with available P content in the paddy soils. When the content was high, the rice absorbed more P nutrient from the soil and decreased the P uptake from the P fertilizer, which showed a poor contribution of the P fertilizer to the rice yield increase, and vice versa. The recovery of the P fertilizer varied with the soil types. Ranked the first was in paddy soils derived from lacustrine deposite but little rice yield increased. While in paddy soils derived from limestone, the yield greatly increased although the recovery of P fertilizer was the lowest. Rice absorbed P nutrient during its whole growth duration. No matter the different uptake amount due to the P supply by the different soils, rice plant generally had the greatest P nutrient uptake from tillering stage to elongation stage, and along with the rise of the rices dry matter, amount of P uptake was gradually increased but the P content in unit dry matter was tended to decrease. (author). 5 refs., 3 figs., 6 tabs

  18. Pesticide-soil microflora interactions in flooded rice soils

    International Nuclear Information System (INIS)

    Sethunathan, N.; Siddaramappa, R.; Siddarame Gowda, T.K.; Rajaram, K.P.; Barik, S.; Rao, V.R.

    1976-01-01

    Isotope studies revealed that gamma and beta isomers of HCH (hexachlorocyclohexane) decomposed rapidly in nonsterile soils capable of attaining redox potentials of -40 to -100mV within 20 days after flooding. Degradation was slow, however, in soils low in organic matter and in soils with extremely low pH and positive potentials, even after several weeks of flooding. Under flooded conditions, endrin decomposed to six metabolites in most soils. There is evidence that biological hydrolysis of parathion is more widespread than hitherto believed, particularly under flooded soil conditions. Applications of benomyl (fungicide) to a simulated-oxidized zone of flooded soils favoured heterotrophic nitrification. (author)

  19. Electricity Generation in Microbial Fuel Cell (MFC) by Bacterium Isolated from Rice Paddy Field Soil

    Science.gov (United States)

    Fakhirruddin, Fakhriah; Amid, Azura; Salim, Wan Wardatul Amani Wan; Suhaida Azmi, Azlin

    2018-03-01

    Microbial fuel cell (MFC) is an alternative approach in generating renewable energy by utilising bacteria that will oxidize organic or inorganic substrates, producing electrons yielded as electrical energy. Different species of exoelectrogenic bacteria capable of generating significant amount of electricity in MFC has been identified, using various organic compounds for fuel. Soil sample taken from rice paddy field is proven to contain exoelectrogenic bacteria, thus electricity generation using mixed culture originally found in the soil, and pure culture isolated from the soil is studied. This research will isolate the exoelectrogenic bacterial species in the rice paddy field soil responsible for energy generation. Growth of bacteria isolated from the MFC is observed by measuring the optical density (OD), cell density weight (CDW) and viable cell count. Mixed bacterial species found in paddy field soil generates maximum power of 77.62 μW and 0.70 mA of current. In addition, the research also shows that the pure bacterium in rice paddy field soil can produce maximum power and current at 51.32 μW and 0.28 mA respectively.

  20. Composted Cattle Manure Increases Microbial Activity and Soil Fertility More Than Composted Swine Manure in a Submerged Rice Paddy

    Directory of Open Access Journals (Sweden)

    Suvendu Das

    2017-09-01

    Full Text Available Livestock waste composts with minimum inorganic fertilizer as a soil amendment in low-input intensive farming are a feasible agricultural practice to improve soil fertility and productivity and to mitigate soil degradation. The key benefits of the practice rely on the activities of soil microorganisms. However, the role of different livestock composts [composted cattle manure (CCM vs. composted swine manure (CSM] on soil microbes, their activities and the overall impact on soil fertility and productivity in a flooded paddy remains elusive. This study compares the effectiveness of CCM and CSM amendment on bacterial communities, activities, nutrient availability, and crop yield in a flooded rice cropping system. We used deep 16S amplicon sequencing and soil enzyme activities to decipher bacterial communities and activities, respectively. Both CCM and CSM amendment significantly increased soil pH, nutrient availability (C, N, and P, microbial biomass, soil enzyme activities indicative for C and N cycles, aboveground plant biomass and grain yield. And the increase in above-mentioned parameters was more prominent in the CCM treatment compared to the CSM treatment. The CCM amendment increased species richness and stimulated copiotrophic microbial groups (Alphaproteobacteria, Betaproteobacteria, and Firmicutes which are often involved in degradation of complex organic compounds. Moreover, some dominant species (e.g., Azospirillum zeae, Azospirillum halopraeferens, Azospirillum rugosum, Clostridium alkalicellulosi, Clostridium caenicola, Clostridium termitidis, Clostridium cellulolyticum, Magnetospirillum magnetotacticum, Pleomorphomonas oryzae, Variovorax boronicumulans, Pseudomonas xanthomarina, Pseudomonas stutzeri, and Bacillus niacini which have key roles in plant growth promotion and/or lignocellulose degradation were enhanced under CCM treatment compared to CSM treatment. Multivariate analysis revealed that soil pH and available carbon (C and

  1. Selenium inhibits sulfate-mediated methylmercury production in rice paddy soil.

    Science.gov (United States)

    Wang, Yong-Jie; Dang, Fei; Zhao, Jia-Ting; Zhong, Huan

    2016-06-01

    There is increasing interest in understanding factors controlling methylmercury (MeHg) production in mercury-contaminated rice paddy soil. Sulfate has been reported to affect MeHg biogeochemistry under anoxic conditions, and recent studies revealed that selenium (Se) could evidently reduce MeHg production in paddy soil. However, the controls of sulfate and Se on net MeHg production in paddy soil under fluctuating redox conditions remain largely unknown. Microcosm experiments were conducted to explore the effects of sulfate and Se on net MeHg production in rice paddy soil. Soil was added with 0-960 mg/kg sulfate, in the presence or absence of 3.0 mg/kg selenium (selenite or selenate), and incubated under anoxic (40 days) or suboxic conditions (5 days), simulating fluctuating redox conditions in rice paddy field. Sulfate addition moderately affected soil MeHg concentrations under anoxic conditions, while reoxidation resulted in evidently higher (18-40%) MeHg levels in sulfate amended soils than the control. The observed changes in net MeHg production were related to dynamics of sulfate and iron. However, Se could inhibit sulfate-mediated MeHg production in the soils: Se addition largely reduced net MeHg production in the soils (23-86%, compared to the control), despite of sulfate addition. Similarly, results of the pot experiments (i.e., rice cultivation in amended soils) indicated that soil MeHg levels were rather comparable in Se-amended soils during rice growth period, irrespective of added sulfate doses. The more important role of Se than sulfate in controlling MeHg production was explained by the formation of HgSe nanoparticles irrespective of the presence of sulfate, confirmed by TEM-EDX and XANES analysis. Our findings regarding the effects of sulfate and Se on net MeHg production in rice paddy soil together with the mechanistic explanation of the processes advance our understanding of MeHg dynamics and risk in soil-rice systems. Copyright © 2016 Elsevier

  2. Remediation of cadmium contamination in paddy soils by washing with chemicals: Selection of washing chemicals

    International Nuclear Information System (INIS)

    Makino, Tomoyuki; Sugahara, Kazuo; Sakurai, Yasuhiro; Takano, Hiroyuki; Kamiya, Takashi; Sasaki, Kouta; Itou, Tadashi; Sekiya, Naoki

    2006-01-01

    The efficiencies of neutral salts, strong acids, and chelates were tested for extracting cadmium (Cd) from three paddy soils. The higher the selectivity of the cations of the added neutral salts toward soil adsorption sites, the lower the pH in the extracts and the more soil Cd could be extracted. In addition, soil carbon and nitrogen contents and mineral composition were closely associated with the amount of Cd extracted. Calcium chloride and iron(III) chloride were selected as wash chemicals to restore Cd-contaminated paddy soils in situ. Washing with calcium chloride led to the formation of Cd chloride complexes, enhancing Cd extraction from the soils. The washing also substantially decreased soil levels of exchangeable and acid-soluble Cd, which are the major forms of bioavailable Cd for rice (Oryza sativa L.). The optimum conditions for in situ soil washing were also determined for calcium chloride. - Calcium chloride and iron(III) chloride were useful for the in situ washing of Cd-contaminated paddy soils

  3. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    Science.gov (United States)

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study.

  4. Assessing the pollution risk of soil Chromium based on loading capacity of paddy soil at a regional scale

    Science.gov (United States)

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2015-01-01

    The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of “loading capacity” (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale. PMID:26675587

  5. Assessing the pollution risk of soil Chromium based on loading capacity of paddy soil at a regional scale.

    Science.gov (United States)

    Qu, Mingkai; Li, Weidong; Zhang, Chuanrong; Huang, Biao; Zhao, Yongcun

    2015-12-17

    The accumulation of a trace metal in rice grain is not only affected by the total concentration of the soil trace metal, but also by crop variety and related soil properties, such as soil pH, soil organic matter (SOM) and so on. However, these factors were seldom considered in previous studies on mapping the pollution risk of trace metals in paddy soil at a regional scale. In this study, the spatial nonstationary relationships between rice-Cr and a set of perceived soil properties (soil-Cr, soil pH and SOM) were explored using geographically weighted regression; and the relationships were then used for calculating the critical threshold (CT) of soil-Cr concentration that may ensure the concentration of rice-Cr being below the permissible limit. The concept of "loading capacity" (LC) for Cr in paddy soil was then defined as the difference between the CT and the real concentration of Cr in paddy soil, so as to map the pollution risk of soil-Cr to rice grain and assess the risk areas in Jiaxing city, China. Compared with the information of the concentration of the total soil-Cr, such results are more valuable for spatial decision making in reducing the accumulation of rice-Cr at a regional scale.

  6. Enhancing Nitrogen Availability, Ammonium Adsorption-Desorption, and Soil pH Buffering Capacity using Composted Paddy Husk

    Science.gov (United States)

    Latifah, O.; Ahmed, O. H.; Abdul Majid, N. M.

    2017-12-01

    Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk.

  7. CHANGES IN SOIL CHEMICAL PROPERTIES OF ORGANIC PADDY FIELD WITH AZOLLA APPLICATION

    Directory of Open Access Journals (Sweden)

    Jauhari Syamsiyah

    2016-12-01

    Full Text Available The use of organic fertilizer is a way to improve soil fertility. Azolla can be used as organic fertilizer. This study aims to determine the effect of Azolla (Azolla mycrophylla. L on some soil chemical properties on organic paddy field. The field experiments used factorial complete randomized block design of three factors, namely Azolla (0 and 2 tons/ha, Manure (0 and 10 tons/ha and Rice Varieties (Mira1, Mentik Wangi and Merah Putih, with three times replication. Using Azolla on an organic paddy field does not significantly increase the levels of soil N, organic C, Cation Exchange Capacity and soil pH. However Azolla’s influence on soil available P is significant.

  8. Root distribution of paddy and wheat grown on differing soil and water conditions

    International Nuclear Information System (INIS)

    Jha, M.N.; Subbiah, B.V.

    1977-01-01

    Two varieties of paddy and one variety of wheat were grown on two soil texture types - paddy on silty clay loam and wheat on sandy loam. Wheat crop was grown on a well drained plot and given normally scheduled irrigation while paddy was given normal and restricted irrigation. The root distribution pattern of these crops was determined. Under normal irrigation, NP 130 showed greater proportion of roots in a soil zone of 16 cm depth and 16.5 cm lateral distance. In case of Padma, the trend was similar to NP 130. More roots were found in a soil zone of 8 cm depth and 22.5 cm lateral distance. Under restricted irrigation, NP 130 showed greater proportion upto 16 cm depth and 22.5 cm lateral distance. In case of Padma, larger proportion of roots was found to be in a soil zone of 8 cm depth and 16.5 cm lateral distance. The root distribution of wheat described almost cylindrical geometry with little overall lateral growth. Regardless of treatments, roots showed a tendency to describe a cylindrical geometry (of about 1.5 cm dia and 32 cm depth). Water stress does effect the root distribution pattern of crops. Other conditions remaining the same, the narrow root cylinder described by the crops of paddy and wheat could possibly be a genetically controlled behaviour. 32 P plant injection technique was used in the study. (author)

  9. Influence of rice straw amendment on mercury methylation and nitrification in paddy soils

    International Nuclear Information System (INIS)

    Liu, Yu-Rong; Dong, Ji-Xin; Han, Li-Li; Zheng, Yuan-Ming; He, Ji-Zheng

    2016-01-01

    Currently, rice straw return in place of burning is becoming more intensive in China than observed previously. However, little is known on the effect of returned rice straw on mercury (Hg) methylation and microbial activity in contaminated paddy fields. Here, we conduct a microcosm experiment to evaluate the effect of rice straw amendment on the Hg methylation and potential nitrification in two paddy soils with distinct Hg levels. Our results show that amended rice straw enhanced Hg methylation for relatively high Hg content soil, but not for low Hg soil, spiking the same additional fresh Hg. methylmercury (MeHg) concentration was significantly correlated to the dissolved organic carbon (DOC) content and relative abundance of dominant microbes associated with Hg methylation. Similarly, amended rice straw was found to only enhance the potential nitrification rate in soil with relatively high Hg content. These findings provide evidence that amended rice straw differentially modulates Hg methylation and nitrification in Hg contaminated soils possibly resulting from different characteristics in the soil microbial community. This highlights that caution should be taken when returning rice straw to contaminated paddy fields, as this practice may increase the risk of more MeHg production. Main finding: Rice straw amendment enhanced both Hg methylation and nitrification potential in the relatively high, but not low, Hg soil. - Highlights: • Rice straw enhanced Hg methylation in relatively high Hg content paddy soils. • Microbial community directly correlated to the Hg methylation. • Mercury methylation in soils depend on Hg bioavailability and microbial activities. • Hg input affects microbial community associated with decomposition of rice straw.

  10. Fate of {sup 14}C-labeled dissolved organic matter in paddy and upland soils in responding to moisture

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiangbi [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station for Karst Ecosystems, Huanjiang 547100 (China); Wang, Aihua [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125 (China); Li, Yang; Hu, Lening; Zheng, Hua; He, Xunyang [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station for Karst Ecosystems, Huanjiang 547100 (China); Ge, Tida; Wu, Jinshui [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125 (China); Kuzyakov, Yakov [Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science, University of Göttingen, 37077 Göttingen (Germany); Su, Yirong, E-mail: yrsu@isa.ac.cn [Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125 (China); Huanjiang Observation and Research Station for Karst Ecosystems, Huanjiang 547100 (China)

    2014-08-01

    Soil organic matter (SOM) content in paddy soils is higher than that in upland soils in tropical and subtropical China. The dissolved organic matter (DOM) concentration, however, is lower in paddy soils. We hypothesize that soil moisture strongly controls the fate of DOM, and thereby leads to differences between the two agricultural soils under contrasting management regimens. A 100-day incubation experiment was conducted to trace the fate and biodegradability of DOM in paddy and upland soils under three moisture levels: 45%, 75%, and 105% of the water holding capacity (WHC). {sup 14}C labeled DOM, extracted from the {sup 14}C labeled rice plant material, was incubated in paddy and upland soils, and the mineralization to {sup 14}CO{sub 2} and incorporation into microbial biomass were analyzed. Labile and refractory components of the initial {sup 14}C labeled DOM and their respective half-lives were calculated by a double exponential model. During incubation, the mineralization of the initial {sup 14}C labeled DOM in the paddy soils was more affected by moisture than in the upland soils. The amount of {sup 14}C incorporated into the microbial biomass (2.4–11.0% of the initial DOM-{sup 14}C activity) was less affected by moisture in the paddy soils than in the upland soils. At any of the moisture levels, 1) the mineralization of DOM to {sup 14}CO{sub 2} within 100 days was 1.2–2.1-fold higher in the paddy soils (41.9–60.0% of the initial DOM-{sup 14}C activity) than in the upland soils (28.7–35.7%), 2) {sup 14}C activity remaining in solution was significantly lower in the paddy soils than in the upland soils, and 3) {sup 14}C activity remaining in the same agricultural soil solution was not significantly different among the three moisture levels after 20 days. Therefore, moisture strongly controls DOM fate, but moisture was not the key factor in determining the lower DOM in the paddy soils than in the upland soils. The UV absorbance of DOM at 280 nm

  11. Metagenomic analysis revealed highly diverse microbial arsenic metabolism genes in paddy soils with low-arsenic contents

    International Nuclear Information System (INIS)

    Xiao, Ke-Qing; Li, Li-Guan; Ma, Li-Ping; Zhang, Si-Yu; Bao, Peng; Zhang, Tong; Zhu, Yong-Guan

    2016-01-01

    Microbe-mediated arsenic (As) metabolism plays a critical role in global As cycle, and As metabolism involves different types of genes encoding proteins facilitating its biotransformation and transportation processes. Here, we used metagenomic analysis based on high-throughput sequencing and constructed As metabolism protein databases to analyze As metabolism genes in five paddy soils with low-As contents. The results showed that highly diverse As metabolism genes were present in these paddy soils, with varied abundances and distribution for different types and subtypes of these genes. Arsenate reduction genes (ars) dominated in all soil samples, and significant correlation existed between the abundance of arr (arsenate respiration), aio (arsenite oxidation), and arsM (arsenite methylation) genes, indicating the co-existence and close-relation of different As resistance systems of microbes in wetland environments similar to these paddy soils after long-term evolution. Among all soil parameters, pH was an important factor controlling the distribution of As metabolism gene in five paddy soils (p = 0.018). To the best of our knowledge, this is the first study using high-throughput sequencing and metagenomics approach in characterizing As metabolism genes in the five paddy soil, showing their great potential in As biotransformation, and therefore in mitigating arsenic risk to humans. - Highlights: • Use metagenomics to analyze As metabolism genes in paddy soils with low-As content. • These genes were ubiquitous, abundant, and associated with diverse microbes. • pH as an important factor controlling their distribution in paddy soil. • Imply combinational effect of evolution and selection on As metabolism genes. - Metagenomics was used to analyze As metabolism genes in paddy soils with low-As contents. These genes were ubiquitous, abundant, and associated with diverse microbes.

  12. Do microorganism stoichiometric alterations affect carbon sequestration in paddy soil subjected to phosphorus input?

    Science.gov (United States)

    Zhang, ZhiJian; Li, HongYi; Hu, Jiao; Li, Xia; He, Qiang; Tian, GuangMing; Wang, Hang; Wang, ShunYao; Wang, Bei

    2015-04-01

    Ecological stoichiometry provides a powerful tool for integrating microbial biomass stoichiometry with ecosystem processes, opening far-reaching possibilities for linking microbial dynamics to soil carbon (C) metabolism in response to agricultural nutrient management. Despite its importance to crop yield, the role of phosphorus (P) with respect to ecological stoichiometry and soil C sequestration in paddy fields remains poorly understood, which limits our ability to predict nutrient-related soil C cycling. Here, we collected soil samples from a paddy field experiment after seven years of superphosphate application along a gradient of 0, 30, 60, and 90 (P-0 through P-90, respectively) kg.ha-1.yr-1 in order to evaluate the role of exogenous P on soil C sequestration through regulating microbial stoichiometry. P fertilization increased soil total organic C and labile organic C by 1-14% and 4-96%, respectively, while rice yield is a function of the activities of soil β-1,4-glucosidase (BG), acid phosphatase (AP), and the level of available soil P through a stepwise linear regression model. P input induced C limitation, as reflected by decreases in the ratios of C:P in soil and microbial biomass. An eco-enzymatic ratio indicating microbial investment in C vs. P acquisition, i.e., ln(BG): ln(AP), changed the ecological function of microbial C acquisition, and was stoichiometrically related to P input. This mechanism drove a shift in soil resource availability by increasing bacterial community richness and diversity, and stimulated soil C sequestration in the paddy field by enhancing C-degradation-related bacteria for the breakdown of plant-derived carbon sources. Therefore, the decline in the C:P stoichiometric ratio of soil microorganism biomass under P input was beneficial for soil C sequestration, which offered a "win-win" relationship for the maximum balance point between C sequestration and P availability for rice production in the face of climate change.

  13. [Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

    Science.gov (United States)

    Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

    2015-11-01

    The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions.

  14. Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

    Science.gov (United States)

    Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

    2016-01-01

    Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils. PMID:26739424

  15. Improvement of Soil Biology Characteristics at Paddy Field by System of Rice Intensification

    Directory of Open Access Journals (Sweden)

    Widyatmani Sih Dewi

    2015-07-01

    Full Text Available The aim of the research was to test the System of Rice Intensification (SRI method in improving the biological properties of paddy soil. The indicators of improvement were measured by the number of earthworm feces (cast, and the population of some microbial and nutrient content in the cast. The experiments were performed by comparing the three methods, namely: (1 SRI, (2 semi-conventional, and (3 conventional, using Randomized Completely Block Design. Each treatment was repeated nine times. The experiments were performed in the paddy fields belonging to farmers in Sukoharjo, Central Java. The result showed that the SRI (application of 1 tons ha-1 of vermicompost + 50% of inorganic fertilizer dosage tends to increase the number of earthworms cast. It is an indicator of earthworm activity in soil. Earthworms cast contains more phosphate solubilizing bacteria (12.98 x 1010cfu and N content (1.23% compared to its surrounding soil. There is a close functional relation between earthworms cast with total tiller number. SRI method is better than the other two methods to improve the biological characteristics of paddy soil that has the potential to maintain the sustainability of soil productivity.

  16. Increasing atmospheric deposition nitrogen and ammonium reduced microbial activity and changed the bacterial community composition of red paddy soil.

    Science.gov (United States)

    Zhou, Fengwu; Cui, Jian; Zhou, Jing; Yang, John; Li, Yong; Leng, Qiangmei; Wang, Yangqing; He, Dongyi; Song, Liyan; Gao, Min; Zeng, Jun; Chan, Andy

    2018-03-27

    Atmospheric deposition nitrogen (ADN) increases the N content in soil and subsequently impacts microbial activity of soil. However, the effects of ADN on paddy soil microbial activity have not been well characterized. In this study, we studied how red paddy soil microbial activity responses to different contents of ADN through a 10-months ADN simulation on well managed pot experiments. Results showed that all tested contents of ADN fluxes (27, 55, and 82kgNha -1 when its ratio of NH 4 + /NO 3 - -N (R N ) was 2:1) enhanced the soil enzyme activity and microbial biomass carbon and nitrogen and 27kgNha -1 ADN had maximum effects while comparing with the fertilizer treatment. Generally, increasing of both ADN flux and R N (1:2, 1:1 and 2:1 with the ADN flux of 55kgNha -1 ) had similar reduced effects on microbial activity. Furthermore, both ADN flux and R N significantly reduced soil bacterial alpha diversity (pADN flux and R N were the main drivers in shaping paddy soil bacteria community. Overall, the results have indicated that increasing ADN flux and ammonium reduced soil microbial activity and changed the soil bacterial community. The finding highlights how paddy soil microbial community response to ADN and provides information for N management in paddy soil. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Change of PAHs with evolution of paddy soils from prehistoric to present over the last six millennia in the Yangtze River Delta region, China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jin [School of Environmental and Resource Sciences, Zhejiang Agricultural and Forestry University, 88 North Huancheng Rd. of Lin' an, Hangzhou 311300 (China); Institute of Geosciences, Christian-Albrechts-University of Kiel, Ludewig-Meyn-Str. 10, 24118 Kiel (Germany); Cornelia, Mueller-Niggemann [Institute of Geosciences, Christian-Albrechts-University of Kiel, Ludewig-Meyn-Str. 10, 24118 Kiel (Germany); Wang, Minyan, E-mail: jz.zafu@gmail.com [Tianmu College of Zhejiang Agricultural and Forestry University, 252 Yijin Str.of Lin' an, Hangzhou 311300 (China); Cao, Zhihong [Institute of Soil Science, Chinese Academy of Sciences, 71 East Beijing Rd., Nanjing 210008 (China); Luo, Xiping, E-mail: luoxpzj@yahoo.com.cn [School of Environmental and Resource Sciences, Zhejiang Agricultural and Forestry University, 88 North Huancheng Rd. of Lin' an, Hangzhou 311300 (China); Wong, Minghung [School of Environmental and Resource Sciences, Zhejiang Agricultural and Forestry University, 88 North Huancheng Rd. of Lin' an, Hangzhou 311300 (China); Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, 224 Waterloo Rd., Kln., Hong Kong (China); Chen, Wei [Department of Ecology and Evolution, Frankfurt University, Max-Von-Laue Str. 13, 60438 Frankfurt am Main (Germany)

    2013-04-01

    To evaluate the influence of hydroponics management on soil organic components with evolution of paddy soil over the last six millennia, PAHs, as a biomarker, as well as total organic carbon content were used to explore changes of paddy soil organic carbon in two entirely buried ancient paddy soil profiles. The results showed that hydroponics management can cause organic carbon deposition in rice paddy. The changing of total PAH concentrations was not always in accordance with the changing of total organic carbon contents in layers of the buried ancient paddy soils. The PAHs in 6280 BP prehistoric paddy soil layer was 3-ring > 5-ring > 4-ring > 6-ring, while in layers of the present paddy soil and the prehistoric upland were 3-ring > 4-ring > 5-ring > 6-ring. The contribution of phenanthrene to total PAHs in two profiles and the increasing ratio of phenanthrene to alkylated PAHs from parent material/6280 BP prehistoric upland to 6280 BP paddy suggested substantial increase of the anthropogenic influence of hydroponics management on rice paddy soil. And in view of the {sup 14}C age and bioremains in the two profiles, it was only possible for PAHs to be derived from hydroponics management with evolution of the paddy soils form the Neolithic age. Cadalene could be used as an indicator for biological sources of PAHs released by rice plant residues, and benzo[g,h,i]fluoranthene and benzo[g,h,i]perylene for pyrogenic sources released by field vegetation fires. - Highlights: ► Soil hydroponics management can cause SOC deposition in rice paddy. ► PAHs in buried ancient paddy soil profiles were mainly derived from anthropogenic hydroponics management. ► PAH, as a biomarker, was not suitable for tracing SOC change with evolution of paddy soil from the Neolithic age.

  18. Change of PAHs with evolution of paddy soils from prehistoric to present over the last six millennia in the Yangtze River Delta region, China

    International Nuclear Information System (INIS)

    Zhang, Jin; Cornelia, Mueller-Niggemann; Wang, Minyan; Cao, Zhihong; Luo, Xiping; Wong, Minghung; Chen, Wei

    2013-01-01

    To evaluate the influence of hydroponics management on soil organic components with evolution of paddy soil over the last six millennia, PAHs, as a biomarker, as well as total organic carbon content were used to explore changes of paddy soil organic carbon in two entirely buried ancient paddy soil profiles. The results showed that hydroponics management can cause organic carbon deposition in rice paddy. The changing of total PAH concentrations was not always in accordance with the changing of total organic carbon contents in layers of the buried ancient paddy soils. The PAHs in 6280 BP prehistoric paddy soil layer was 3-ring > 5-ring > 4-ring > 6-ring, while in layers of the present paddy soil and the prehistoric upland were 3-ring > 4-ring > 5-ring > 6-ring. The contribution of phenanthrene to total PAHs in two profiles and the increasing ratio of phenanthrene to alkylated PAHs from parent material/6280 BP prehistoric upland to 6280 BP paddy suggested substantial increase of the anthropogenic influence of hydroponics management on rice paddy soil. And in view of the 14 C age and bioremains in the two profiles, it was only possible for PAHs to be derived from hydroponics management with evolution of the paddy soils form the Neolithic age. Cadalene could be used as an indicator for biological sources of PAHs released by rice plant residues, and benzo[g,h,i]fluoranthene and benzo[g,h,i]perylene for pyrogenic sources released by field vegetation fires. - Highlights: ► Soil hydroponics management can cause SOC deposition in rice paddy. ► PAHs in buried ancient paddy soil profiles were mainly derived from anthropogenic hydroponics management. ► PAH, as a biomarker, was not suitable for tracing SOC change with evolution of paddy soil from the Neolithic age

  19. Microbial characteristics of purple paddy soil in response to Pb pollution.

    Science.gov (United States)

    Jiang, Qiu-Ju; Zhang, Yue-Qiang; Zhang, La-Mei; Zhou, Xin-Bin; Shi, Xiao-Jun

    2014-05-01

    The study focused on the change of microbial characteristics affected by Plumbum pollution with purple paddy soil in an incubation experiment. The results showed that low concentration of Plumbum had little effect on most of microbial amounts, biological activity and enzymatic activity. However, denitrifying activity was inhibited severely, and inhibition rate was up to 98%. Medium and high concentration of Plumbum significantly reduced the amounts and activity of all microorganisms and enzymatic activity, which increased with incubation time. Negative correlations were found between Plumbum concentrations and microbial amounts, biological activity and enzymatic activities except fungi and actinomyces. Thus they can be used to indicate the Plumbum pollution levels to some extent. LD(50) of denitrifying bacteria (DB) and ED50 of denitrifying activity were 852mg/kg and 33.5mg/kg. Across all test soil microbes, denitrifying bacteria was most sensitive to Plumbum pollution in purple paddy soil. Value of early warning showed that anaerobic cellulose-decomposing bacteria (ACDB) and actinomyces were also sensitive to Plumbum pollution. We concluded that denitrifying activity, actinomyces, ACDB or DB can be chosen as predictor of Plumbum contamination in purple paddy soil.

  20. [Effect of carbon substrate concentration on N2, N2O, NO, CO2, and CH4 emissions from a paddy soil in anaerobic condition].

    Science.gov (United States)

    Chen, Nuo; Liao, Ting-ting; Wang, Rui; Zheng, Xun-hua; Hu, Rong-gui; Butterbach-Bahl, Klaus

    2014-09-01

    Understanding the effects of carbon and nitrogen substrates concentrations on the emissions of denitrification gases including nitrogen (N2) , nitrous oxide (N2O) and nitric oxide (NO), carbon dioxide (CO2) and methane (CH4) from anaerobic paddy soils is believed to be helpful for development of greenhouse gas mitigation strategies. Moreover, understanding the quantitative dependence of denitrification products compositions on carbon substrate concentration could provide some key parameters or parameterization scheme for developing process-oriented model(s) of nitrogen transformation. Using a silt loam soil collected from a paddy field, we investigated the influence of carbon substrate concentration on the emissions of the denitrification gases, CO2 and CH4 from anaerobically incubated soils by setting two treatments: control (CK) with initial soil nitrate and dissolved organic carbon (DOC) concentrations of ~ 50 mg.kg-1 and -28 mg kg-1 , respectively; and DOC added (C + ) with initial soil nitrate and DOC concentrations of ~50 mg.kg-1 and ~300 mg.kg-1 , respectively. The emissions of denitrification gases, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each treatment were dynamically measured, using the gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that CH4 emission was not observed in CK treatment while observed in C treatment. Aggregate emission of greenhouse gases for C + treatment was significantly higher comparing with the CK treatment (P emissions in total nitrogen gases emissions were approximately 9% , 35% and 56% for CK treatment, respectively; and approximately 31% , 50% and 19% for C+ treatment, respectively, with significant differences between these two treatments (P carbon substrate concentrations can significantly change the composition of nitrogen gas emissions. The results also implicated that organic fertilizer should not be applied to nitrate-rich paddy soils prior to

  1. ENZYME ACTIVITIES OF PADDY SOILS AND RELATIONSHIPS WITH THE SOIL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Rıdvan KIZILKAYA

    1998-03-01

    Full Text Available This study was carried out to determine the effect of soil properties on enzyme activities of paddy soils, the sample of which were taken from Üçpınar, Harız, Doğancı, Kaygusuz, Emenli, Sarıköy and Gelemenağarı villages where rice cultivation is an intensive agricultural system. In this study, soil properties having effects on urease, phosphatase, ß-glucosidase and catalase enzyme activities were setforth. Urease enzyme activities of soil samples varied from 24.12 to 39.03 mg N 100 g dry soil -1 . Significant correlations were determined between urease enzyme activities and organic matter (r = 0.89**, extractable Mn (r = 0.74**, exchangable K (r = 0.73** and total P content of soil (r = 0.81*. Acid phosphatase enzyme activity varied between 3.00-17.44 mg phenol 100 g dry soil -1 , alkaline phosphatase enzyme activity between 12.00-25.53 mg phenol 100 g dry soil-1 . Exchangable Mg (r = 0.71* and extractable Cu (r = 0.74* were found to have positive effect on acid phosphatase enzyme activity and pH (r = 0.73*, exchangable Ca (r = 0.74*, exchangable Mg (r = 0.71*, exchangable total basic cations (r = 0.79* and extractable Cu (r = 0.70* had positive effects on alkaline phosphatase enzyme activity, whereas total P (r = - 0.84** affected the activity negatively. ß-glucosidase enzyme activity was measured to vary between 1.12-3.64 mg salingen 100 g dry soil -1 . It was also observed that extractable Zn content of soil samples (r = - 0.97** had negative effect on ß-glucosidase activity, wheras total exchangable acidic cations (r = 0.70* affected the activity positively. Catalase enzyme activities of soils changed between 5.25 - 9.00 mg O2 5 g dry soil -1 . Significant correlations were found between catalase activities and fraction of soils and extractable Fe content. Positive correlations, however, were determined between catalase activities and clay fraction (r = 0.82* and salt content (r = 0.83** of samples.

  2. Polyphasic characterization of a PCP-to-phenol dechlorinating microbial community enriched from paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Naoko [EcoTopia Science Institute, Nagoya University Nagoya 464-8603 (Japan)]. E-mail: ysd75@esi.nagoya-u.ac.jp; Yoshida, Yukina [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Handa, Yuko [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Kim, Hyo-Keun [Korea Ginseng and Tobacco Research Institute, Taejon 305-345 (Korea, Republic of); Ichihara, Shigeyuki [Faculty of Agriculture, Meijo University, Nagoya 468-8502 (Japan); Katayama, Arata [EcoTopia Science Institute, Nagoya University Nagoya 464-8603 (Japan); Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)

    2007-08-01

    Dechlorination of PCP has been observed previously under anaerobic condition in paddy soil. However, there is poor information about the dechlorination pathway of PCP and the microbial community associated with the PCP dechlorination in paddy soil. In this study, an anaerobic microbial community dechlorinating PCP was enriched by serial transfers from a paddy soil using a medium containing PCP, lactate and the steam-sterilized paddy soil. The enriched microbial community dechlorinated PCP completely to phenol under the anaerobic condition by a dechlorinating pathway as follows; PCP {sup {yields}} 2,3,4,5-tetrachlorophenol {sup {yields}} 3,4,5-trichlorophenol {sup {yields}} 3,5-dichlorophenol {sup {yields}} 3-chlorophenol {sup {yields}} phenol. Intermediate products such as 3-chlorophenol were not accumulated, which were immediately dechlorinated to phenol. The enriched microbial community was characterized physiologically by testing the effects of electron donors and electron acceptors on the dechlorinating activity. The dechlorinating activity was promoted with lactate, pyruvate, and hydrogen as electron donors but not with acetate. Electron acceptors, nitrate and sulphate, inhibited the dechlorinating activity competitively but not iron (III). The microbial group associated with the anaerobic dechlorination was characterized by the effect of specific inhibitors on the PCP dechlorination. Effects of specific metabolic inhibitors and antibiotics indicated the involvement of Gram-positive spore-forming bacteria with the PCP dechlorinating activity, which was represented as bacteria of phylum Firmicutes. The structure of the microbial community was characterized by fluorescence in situ hybridization, quinone profiling, and PCR-DGGE (denaturing gel gradient electrophoresis). The combined results indicated the predominance of Clostridium species of phylum Firmicutes in the microbial community. Desulfitobacterium spp. known as anaerobic Gram-positive spore

  3. Polyphasic characterization of a PCP-to-phenol dechlorinating microbial community enriched from paddy soil

    International Nuclear Information System (INIS)

    Yoshida, Naoko; Yoshida, Yukina; Handa, Yuko; Kim, Hyo-Keun; Ichihara, Shigeyuki; Katayama, Arata

    2007-01-01

    Dechlorination of PCP has been observed previously under anaerobic condition in paddy soil. However, there is poor information about the dechlorination pathway of PCP and the microbial community associated with the PCP dechlorination in paddy soil. In this study, an anaerobic microbial community dechlorinating PCP was enriched by serial transfers from a paddy soil using a medium containing PCP, lactate and the steam-sterilized paddy soil. The enriched microbial community dechlorinated PCP completely to phenol under the anaerobic condition by a dechlorinating pathway as follows; PCP → 2,3,4,5-tetrachlorophenol → 3,4,5-trichlorophenol → 3,5-dichlorophenol → 3-chlorophenol → phenol. Intermediate products such as 3-chlorophenol were not accumulated, which were immediately dechlorinated to phenol. The enriched microbial community was characterized physiologically by testing the effects of electron donors and electron acceptors on the dechlorinating activity. The dechlorinating activity was promoted with lactate, pyruvate, and hydrogen as electron donors but not with acetate. Electron acceptors, nitrate and sulphate, inhibited the dechlorinating activity competitively but not iron (III). The microbial group associated with the anaerobic dechlorination was characterized by the effect of specific inhibitors on the PCP dechlorination. Effects of specific metabolic inhibitors and antibiotics indicated the involvement of Gram-positive spore-forming bacteria with the PCP dechlorinating activity, which was represented as bacteria of phylum Firmicutes. The structure of the microbial community was characterized by fluorescence in situ hybridization, quinone profiling, and PCR-DGGE (denaturing gel gradient electrophoresis). The combined results indicated the predominance of Clostridium species of phylum Firmicutes in the microbial community. Desulfitobacterium spp. known as anaerobic Gram-positive spore-forming bacteria dechlorinating PCP were not detected by PCR using a

  4. Remediation of Biological Organic Fertilizer and Biochar in Paddy Soil Contaminated by Cd and Pb

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    MA Tie-zheng

    2015-02-01

    Full Text Available The effect of application of biological organic fertilizer and biochar on the immobilized remediation of paddy soil contaminated by Cd and Pb was studied under the field experiment. The results showed that biological organic fertilizer and biochar increased the soil pH and soil nutrient contents, and reduced the soil available Cd and Pb concentrations significantly. The soil pH had significantly negative correla-tion with the soil available Cd and Pb contents. The application of biological organic fertilizer and biochar decreased Cd and Pb concentration in all parts of the rice plant, with Cd concentration in brown rice decrease by 22.00% and 18.34% and Pb decease in brown rice by 33.46% and 12.31%. The concentration of Cd and Pb in brown rice had significant positive correlation with the soil available Cd and Pb concentra-tions. It was observed that both biological organic fertilizer and biochar had a positive effect on the remediation of paddy soil contaminated by Cd and Pb.

  5. Variations in soil microbial community structure induced by the conversion from paddy fields to upland fields

    Science.gov (United States)

    Dai, X.

    2015-12-01

    Land-use conversion is an important factor influencing the carbon and nitrogen gas exchange between land and atmosphere, and soil microorganisms is main driver of soil carbon and nitrogen gas production. Understanding the effect of land-use conversion on soil microbial communities and its influencing factor is important for greenhouse gas emission reduction and soil organic carbon and nitrogen sequestration and stability. The influence of land use conversion on soil process was undergoing a dynamic change, but little research has been done to understand the effect on soil microbial communities during the initial years after land conversion. In the study, the influences of land-use conversion from double rice cropping (RR) to maize-maize (MM) and soybean-peanut (SP) double cropping systems on soil physical and chemical properties, and microbial community structure was studied after two years of the conversion in southern China. The results showed that land use conversion significantly changed soil properties, microbial communities and biomass. Soil pH significantly decreased by 0.50 and 0.52 after conversion to MM and SP, respectively. Soil TN and NH4-N also significantly decreased by 9%-15% and 60% after conversion to upland fields, respectively. The total PLFAs, bacterial, gram-positive bacterial (G+), gram-negative bacterial (G-) and actinomycetic PLFAs decreased significantly. The ng g-1 soil concentration of monounsaturated chain PLFAs 16:1ω7c and 18:1ω9t were significantly higher at paddy fields than at upland fields. No significant differences in soil properties, microbial communities and biomass were found between conversed MM and SP. Our results indicated that land use conversion, not crop type conversed had a significant effects on soil properties and microbial communities at the initial of land conversion. And soil pH was the key factor regulating the variations in soil microbial community structure after land use conversion from paddy to upland fields.

  6. Reducing CH{sub 4} and CO{sub 2} emissions from waterlogged paddy soil with biochar

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuxue; Yang, Min; Chen, Yingxu; Wu, Weixiang [Zhejiang Univ., Hangzhou (China). Inst. of Environmental Science and Technology; Wu, Yimin [Hangzhou No. 2 High School, Hangzhou (China); Wang, Hailong [Scion, Rotorua (New Zealand)

    2011-09-15

    Purpose: A potential means to diminish increasing levels of CO{sub 2} in the atmosphere is the use of pyrolysis to convert biomass into biochar, which stabilizes the carbon (C) that is then applied to soil. Before biochar can be used on a large scale, especially in agricultural soils, its effects on the soil system need to be assessed. This is especially important in rice paddy soils that release large amounts of greenhouse gases to the atmosphere. Materials and methods: In this study, the effects of biochar on CH{sub 4} and CO{sub 2} emissions from paddy soil with and without rice straw added as an additional C source were investigated. The biochars tested were prepared from bamboo chips or rice straw which yielded bamboo char (BC) and straw char (SC), respectively. BC and SC were applied to paddy soil to achieve low, medium, and high rates, based on C contents of the biochars. The biochar-amended soils were incubated under waterlogged conditions in the laboratory. Results and discussion: Adding rice straw significantly increased CH{sub 4} and CO{sub 2} emissions from the paddy soil. However, when soils were amended with biochar, CH{sub 4} emissions were reduced. CH{sub 4} emissions from the paddy soil amended with BC and SC at high rate were reduced by 51.1% and 91.2%, respectively, compared with those without biochar. Methanogenic activity in the paddy soil decreased with increasing rates of biochar, whereas no differences in denaturing gradient gel electrophoresis patterns were observed. CO{sub 2} emission from the waterlogged paddy soil was also reduced in the biochar treatments. Conclusions: Our results showed that SC was more effective than BC in reducing CH{sub 4} and CO{sub 2} emissions from paddy soils. The reduction of CH{sub 4} emissions from paddy soil with biochar amendment may result from the inhibition of methanogenic activity or a stimulation of methylotrophic activity during the incubation period. (orig.)

  7. Microbial community analysis in rice paddy soils irrigated by acid mine drainage contaminated water.

    Science.gov (United States)

    Sun, Min; Xiao, Tangfu; Ning, Zengping; Xiao, Enzong; Sun, Weimin

    2015-03-01

    Five rice paddy soils located in southwest China were selected for geochemical and microbial community analysis. These rice fields were irrigated with river water which was contaminated by Fe-S-rich acid mine drainage. Microbial communities were characterized by high-throughput sequencing, which showed 39 different phyla/groups in these samples. Among these phyla/groups, Proteobacteria was the most abundant phylum in all samples. Chloroflexi, Acidobacteria, Nitrospirae, and Bacteroidetes exhibited higher relative abundances than other phyla. A number of rare and candidate phyla were also detected. Moreover, canonical correspondence analysis suggested that pH, sulfate, and nitrate were significant factors that shaped the microbial community structure. In addition, a wide diversity of Fe- and S-related bacteria, such as GOUTA19, Shewanella, Geobacter, Desulfobacca, Thiobacillus, Desulfobacterium, and Anaeromyxobacter, might be responsible for biogeochemical Fe and S cycles in the tested rice paddy soils. Among the dominant genera, GOUTA19 and Shewanella were seldom detected in rice paddy soils.

  8. Anaerobic N mineralization in paddy soils in relation to inundation management, physicochemical soil fractions, mineralogy and soil properties

    Science.gov (United States)

    Sleutel, Steven; Kader, Mohammed Abdul; Ara Begum, Shamim; De Neve, Stefaan

    2013-04-01

    Anaerobic N mineralization measured from (saturated) repacked soil cores from 25 paddy fields in Bangladesh and was previously found to negatively related to soil N content on a relative basis. This suggests that other factors like soil organic matter (SOM) quality or abiotic factors instead control the anaerobic N mineralization process. We therefore assessed different physical and chemical fractions of SOM, management factors and various soil properties as predictors for the net anaerobic N mineralization. 1° First, we assessed routinely analyzed soil parameters (soil N and soil organic carbon, texture, pH, oxalate- and pyrophosphate-extractable Fe, Al, and Mn, fixed-NH4 content). We found no significant influences of neither soil mineralogy nor the annual length of inundation on soil N mineralization. The anaerobic N mineralization correlated positively with Na-pyrophosphate-extractable Fe and negatively with pH (both at Presistant OM fraction, followed by extraction of mineral bound OM with 10%HF thereby isolating the HF-resistant OM. None of the physicochemical SOM fractions were found useful predictors anaerobic N mineralization. The linkage between these chemical soil N fractions and N supplying processes actually occurring in the soil thus appears to be weak. Regardless, we hypothesize that variation in strength of N-mineral and N-OM linkages is likely to explain variation in bio-availability of organic N and proneness to mineralization. Yet, in order to separate kinetically different soil N fractions we then postulated that an alternative approach would be required, which instead isolates soil N fractions on the basis of bonding strength. In this respect bonding strength should be seen as opposite of proneness to dissolution of released N into water, the habitat of soil microorganisms mediating soil N mineralization. We hypothesize that soil N extracted by water at increasing temperatures would reflect such N fractions with increasing bonding strength, in

  9. Soil-to-Rice Transfer of {sup 99}Tc in Paddy Soils Contaminated in Two Different Ways

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yongho; Lim, Kwangmuk; Jun, In; Kim, Byungho; Keum, Dongkwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Rice is one of the most important food crops in the world. All isotopes of technetium (Tc) are radioactive, and the environmentally most important one is {sup 99}Tc because of its very long half-life (2.1x10{sup 5} years) and relatively high {sup 235}U-fission yield. Accordingly, it is one of the critical radionuclides in an environmental impact assessment for radioactive waste disposal. A significant amount of {sup 99}Tc can be released into the atmosphere in a severe reactor accident as was shown in the Chernobyl accident. It is a pure better emitter and thus internal exposure via food consumption may be a primary contributor to the {sup 99}Tc radiation dose to humans. Paddy rice fields can be contaminated with {sup 99}Tc in various ways. In the present study, greenhouse experiments were conducted to investigate the transfer of {sup 99}Tc from four paddy soils contaminated in two different ways. One was to simulate plowing the topsoil after a pre-transplanting deposition of {sup 99}Tc, whereas the other was to simulate a {sup 99}Tc deposition onto the surface water shortly after transplanting. Soil-to-rice transfer of {sup 99}Tc in paddy soils was experimentally investigated for two different scenarios of the paddy-field contamination. It was demonstrated that a post-transplanting deposition of {sup 99}Tc onto the surface water can lead to a much higher transfer than a pre-transplanting deposition followed by plowing. The surface-water concentrations of {sup 99}Tc following the post-transplanting deposition was markedly higher than those following the pre-transplanting deposition, possibly indicating a much higher plant-base uptake of {sup 99}Tc following the post-transplanting deposition. The present results can be referred to in a radiological impact assessment for the contamination of paddy fields with {sup 99}Tc by chronic or acute releases from nuclear facilities.

  10. The Short-Term Effects of Rice Straw Biochar, Nitrogen and Phosphorus Fertilizer on Rice Yield and Soil Properties in a Cold Waterlogged Paddy Field

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    Linlin Si

    2018-02-01

    Full Text Available Crop productivity in cold waterlogged paddy fields can be constrained by chronic flooding stress and low temperature. Farmers typically use chemical fertilizer to improve crop production, but this conventional fertilization is not very effective in a cold waterlogged paddy field. Biochar amendment has been proposed as a promising management approach to eliminating these obstacles. However, little is known about the performance of biochar when combined with N fertilizer and P fertilizer in cold waterlogged soils. The aim of this study was, therefore, to assess the main effects and interactive effects of rice straw biochar, N and P fertilizer on rice growth and soil properties in a cold waterlogged paddy field. The field treatments consisted of a factorial combination of two biochar levels (0 and 2.25 t ha−1, two N fertilizer levels (120.0 and 180.0 kg ha−1 and two P fertilizer levels (37.5 and 67.5 kg ha−1 which were arranged in a randomized block design, with three replicates. Results confirmed that biochar application caused a significant increase in the soil pH due to its liming effect, while this application resulted in a significant decrease in soil exchangeable cations, such as exchangeable Ca, Mg, Al and base cations. The interactive effect of N fertilizer, P fertilizer and biochar was significant for soil total N. Moreover, a negative effect of biochar on the internal K use efficiency suggested that K uptake into rice may benefit from biochar application. According to the partial Eta squared values, the combined application of N fertilizer and biochar was as effective as pure P fertilization at increasing straw P uptake. The addition of biochar to farmers’ fertilization practice treatment (180.0 kg N ha−1, 67.5 kg P2O5 ha−1 and 67.5 kg K2O ha−1 significantly increased rice yield, mainly owing to improvements in grains per panicle. However, notable effects of biochar on rice yield and biomass production were not detected

  11. Acid drainage from coal mining: Effect on paddy soil and productivity of rice.

    Science.gov (United States)

    Choudhury, Burhan U; Malang, Akbar; Webster, Richard; Mohapatra, Kamal P; Verma, Bibhash C; Kumar, Manoj; Das, Anup; Islam, Mokidul; Hazarika, Samarendra

    2017-04-01

    Overburden and acid drainage from coal mining is transforming productive agricultural lands to unproductive wasteland in some parts of Northeast India. We have investigated the adverse effects of acid mine drainage on the soil of rice paddy and productivity by comparing them with non-mined land and abandoned paddy fields of Jaintia Hills in Northeast India. Pot experiments with a local rice cultivar (Myngoi) as test crop evaluated biological productivity of the contaminated soil. Contamination from overburden and acid mine drainage acidified the soil by 0.5 pH units, increased the exchangeable Al 3+ content 2-fold and its saturation on clay complexes by 53%. Available sulfur and extractable heavy metals, namely Fe, Mn and Cu increased several-fold in excess of critical limits, while the availability of phosphorus, potassium and zinc contents diminished by 32-62%. The grain yield of rice was 62% less from fields contaminated with acid mine drainage than from fields that have not suffered. Similarly, the amounts of vegetation, i.e. shoots and roots, in pots filled with soil from fields that received acid mine drainage were 59-68% less than from uncontaminated land (average shoot weight: 7.9±2.12gpot -1 ; average root weight: 3.40±1.15gpot -1 ). Paddy fields recovered some of their productivity 4years after mining ceased. Step-wise multiple regression analysis affirmed that shoot weight in the pots and grain yield in field were significantly (p<0.01) and positively influenced by the soil's pH and its contents of K, N and Zn, while concentration of S in excess of threshold limits in contaminated soil significantly (p<0.01) reduced the weight of shoots in the pots and grain yield in the field. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Heavy metal contamination and risk assessment in water, paddy soil, and rice around an electroplating plant.

    Science.gov (United States)

    Liu, Jie; Zhang, Xue-Hong; Tran, Henry; Wang, Dun-Qiu; Zhu, Yi-Nian

    2011-11-01

    The objective of this paper is to assess the impact of long-term electroplating industrial activities on heavy metal contamination in agricultural soils and potential health risks for local residents. Water, soil, and rice samples were collected from sites upstream (control) and downstream of the electroplating wastewater outlet. The concentrations of heavy metals were determined by an atomic absorption spectrophotometer. Fractionation and risk assessment code (RAC) were used to evaluate the environmental risks of heavy metals in soils. The health risk index (HRI) and hazard index (HI) were calculated to assess potential health risks to local populations through rice consumption. Hazardous levels of Cu, Cr, and Ni were observed in water and paddy soils at sites near the plant. According to the RAC analysis, the soils showed a high risk for Ni and a medium risk for Cu and Cr at certain sites. The rice samples were primarily contaminated with Ni, followed by Cr and Cu. HRI values >1 were not found for any heavy metal. However, HI values for adults and children were 2.075 and 1.808, respectively. Water, paddy soil, and rice from the studied area have been contaminated by Cu, Cr, and Ni. The contamination of these elements is related to the electroplating wastewater. Although no single metal poses health risks for local residents through rice consumption, the combination of several metals may threaten the health of local residents. Cu and Ni are the key components contributing to the potential health risks.

  13. Does soil compaction increase floods? A review

    Science.gov (United States)

    Alaoui, Abdallah; Rogger, Magdalena; Peth, Stephan; Blöschl, Günter

    2018-02-01

    Europe has experienced a series of major floods in the past years which suggests that flood magnitudes may have increased. Land degradation due to soil compaction from crop farming or grazing intensification is one of the potential drivers of this increase. A literature review suggests that most of the experimental evidence was generated at plot and hillslope scales. At larger scales, most studies are based on models. There are three ways in which soil compaction affects floods at the catchment scale: (i) through an increase in the area affected by soil compaction; (ii) by exacerbating the effects of changes in rainfall, especially for highly degraded soils; and (iii) when soil compaction coincides with soils characterized by a fine texture and a low infiltration capacity. We suggest that future research should focus on better synthesising past research on soil compaction and runoff, tailored field experiments to obtain a mechanistic understanding of the coupled mechanical and hydraulic processes, new mapping methods of soil compaction that combine mechanical and remote sensing approaches, and an effort to bridge all disciplines relevant to soil compaction effects on floods.

  14. Irrigation management and phosphorus addition alter the abundance of carbon dioxide-fixing autotrophs in phosphorus-limited paddy soil.

    Science.gov (United States)

    Wu, Xiaohong; Ge, Tida; Yan, Wende; Zhou, Juan; Wei, Xiaomeng; Chen, Liang; Chen, Xiangbi; Nannipieri, Paolo; Wu, Jinshui

    2017-12-01

    In this study, we assessed the interactive effects of phosphorus (P) application and irrigation methods on the abundances of marker genes (cbbL, cbbM, accA and aclB) of CO2-fixing autotrophs. We conducted rice-microcosm experiments using a P-limited paddy soil, with and without the addition of P fertiliser (P-treated-pot (P) versus control pot (CK)), and using two irrigation methods, namely alternate wetting and drying (AWD) and continuous flooding (CF). The abundances of bacterial 16S rRNA, archaeal 16S rRNA, cbbL, cbbM, accA and aclB genes in the rhizosphere soil (RS) and bulk soil (BS) were quantified. The application of P significantly altered the soil properties and stimulated the abundances of Bacteria, Archaea and CO2-fixation genes under CF treatment, but negatively influenced the abundances of Bacteria and marker genes of CO2-fixing autotrophs in BS soils under AWD treatment. The response of CO2-fixing autotrophs to P fertiliser depended on the irrigation management method. The redundancy analysis revealed that 54% of the variation in the functional marker gene abundances could be explained by the irrigation method, P fertiliser and the Olsen-P content; however, the rhizosphere effect did not have any significant influence. P fertiliser application under CF was more beneficial in improving the abundance of CO2-fixing autotrophs compared to the AWD treatment; thus, it is an ideal irrigation management method to increase soil carbon fixation. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Phytoremediation of arsenic contaminated paddy soils with Pteris vittata markedly reduces arsenic uptake by rice.

    Science.gov (United States)

    Ye, Wen-Ling; Khan, M Asaduzzaman; McGrath, Steve P; Zhao, Fang-Jie

    2011-12-01

    Arsenic (As) accumulation in food crops such as rice is of major concern. To investigate whether phytoremediation can reduce As uptake by rice, the As hyperaccumulator Pteris vittata was grown in five contaminated paddy soils in a pot experiment. Over a 9-month period P. vittata removed 3.5-11.4% of the total soil As, and decreased phosphate-extractable As and soil pore water As by 11-38% and 18-77%, respectively. Rice grown following P. vittata had significantly lower As concentrations in straw and grain, being 17-82% and 22-58% of those in the control, respectively. Phytoremediation also resulted in significant changes in As speciation in rice grain by greatly decreasing the concentration of dimethylarsinic acid (DMA). In two soils the concentration of inorganic As in rice grain was decreased by 50-58%. The results demonstrate an effective stripping of bioavailable As from contaminated paddy soils thus reducing As uptake by rice. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Distribution of Pb and Zn and their chemical specieisations in the paddy soils from the Kochani field (Macedonia)

    International Nuclear Information System (INIS)

    Rogan, Nastja; Todor, Serafimovski; Tasev, Goran; Dolenec, Tadej; Dolenec, Matej

    2009-01-01

    The distribution and chemical specifications of Pb and Zn in the paddy soils of Kochani Field, Macedonia, were investigated using a sequential extraction procedure. This study was carried out in order to develop an understanding of the metal contamination found in the area which is due to historical and recent mining operations around Kochani Field. The paddy soil sample from location VII-2 in the vicinity of Zletovo mine in the western part of Kochani Field was found to contain highly elevated concentrations of Pb and Zn which are under reduction conditions very unstable and mobile. According to the total Pb and Zn concentrations, their mobility characteristics and the index of geo accumulation for all studied soil samples, it is observable that the paddy soil sample from location VII-2 represents a potential environmental risk.

  17. Stabilization by hydrophobic protection as a molecular mechanism for organic carbon sequestration in maize-amended rice paddy soils.

    Science.gov (United States)

    Song, X Y; Spaccini, R; Pan, G; Piccolo, A

    2013-08-01

    The hydrophobic components of soil organic matter (SOM) are reckoned to play an important role in the stabilization of soil organic carbon (SOC). The contribution of hydrophobic substances to SOC sequestration was evaluated in four different paddy soils in the South of China, following a 6-month incubation experiment with maize straw amendments. Soil samples included: a well developed paddy soil (TP) derived from clayey lacustrine deposits in the Tai Lake plain of Jiangsu; an acid clayey paddy soil (RP) derived from red earth in the rolling red soil area of Jiangxi; a weakly developed neutral paddy soil (PP) formed on Jurassic purple shale from Chongq; and a calcic Fluvisol (MS) derived from riverine sediments from a wetland along the Yangtze valley of Anhui, China. The SOC molecular composition after 30 and 180 days of incubation, was determined by off-line thermochemolysis followed by gas chromatography-mass spectrometry analysis. Lignin, lipids and carbohydrates were the predominant thermochemolysis products released from the treated soils. A selective preservation of hydrophobic OM, including lignin and lipids, was shown in maize amended soils with prolonged incubation. The decomposition of lignin and lipids was significantly slower in the TP and RP soils characterized by a larger content of extractable iron oxyhydrates (Fed) and lower pH. The overall increase in hydrophobic substances in maize incubated samples was correlated, positively, with total content of clay and Fed, and, negatively, with soil pH. Moreover, yields of both lignin and lipid components showed a significant relationship with SOC increase after incubation. These findings showed that the larger the lipid and lignin content of SOM, the greater was the stability of SOC, thereby suggesting that OM hydrophobic components may have an essential role in controlling the processes of OC sequestration in paddy soils of South China. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Total mercury and methylmercury concentrations over a gradient of contamination in earthworms living in rice paddy soil.

    Science.gov (United States)

    Abeysinghe, Kasun S; Yang, Xiao-Dong; Goodale, Eben; Anderson, Christopher W N; Bishop, Kevin; Cao, Axiang; Feng, Xinbin; Liu, Shengjie; Mammides, Christos; Meng, Bo; Quan, Rui-Chang; Sun, Jing; Qiu, Guangle

    2017-05-01

    Mercury (Hg) deposited from emissions or from local contamination, can have serious health effects on humans and wildlife. Traditionally, Hg has been seen as a threat to aquatic wildlife, because of its conversion in suboxic conditions into bioavailable methylmercury (MeHg), but it can also threaten contaminated terrestrial ecosystems. In Asia, rice paddies in particular may be sensitive ecosystems. Earthworms are soil-dwelling organisms that have been used as indicators of Hg bioavailability; however, the MeHg concentrations they accumulate in rice paddy environments are not well known. Earthworm and soil samples were collected from rice paddies at progressive distances from abandoned mercury mines in Guizhou, China, and at control sites without a history of Hg mining. Total Hg (THg) and MeHg concentrations declined in soil and earthworms as distance increased from the mines, but the percentage of THg that was MeHg, and the bioaccumulation factors in earthworms, increased over this gradient. This escalation in methylation and the incursion of MeHg into earthworms may be influenced by more acidic soil conditions and higher organic content further from the mines. In areas where the source of Hg is deposition, especially in water-logged and acidic rice paddy soil, earthworms may biomagnify MeHg more than was previously reported. It is emphasized that rice paddy environments affected by acidifying deposition may be widely dispersed throughout Asia. Environ Toxicol Chem 2017;36:1202-1210. © 2016 SETAC. © 2016 SETAC.

  19. Rapid Measurement of Soil Carbon in Rice Paddy Field of Lombok Island Indonesia Using Near Infrared Technology

    Science.gov (United States)

    Kusumo, B. H.; Sukartono, S.; Bustan, B.

    2018-02-01

    Measuring soil organic carbon (C) using conventional analysis is tedious procedure, time consuming and expensive. It is needed simple procedure which is cheap and saves time. Near infrared technology offers rapid procedure as it works based on the soil spectral reflectance and without any chemicals. The aim of this research is to test whether this technology able to rapidly measure soil organic C in rice paddy field. Soil samples were collected from rice paddy field of Lombok Island Indonesia, and the coordinates of the samples were recorded. Parts of the samples were analysed using conventional analysis (Walkley and Black) and some other parts were scanned using near infrared spectroscopy (NIRS) for soil spectral collection. Partial Least Square Regression (PLSR) Models were developed using data of soil C analysed using conventional analysis and data from soil spectral reflectance. The models were moderately successful to measure soil C in rice paddy field of Lombok Island. This shows that the NIR technology can be further used to monitor the C change in rice paddy soil.

  20. Evaluation of potential effects of soil available phosphorus on soil arsenic availability and paddy rice inorganic arsenic content.

    Science.gov (United States)

    Jiang, Wei; Hou, Qingye; Yang, Zhongfang; Zhong, Cong; Zheng, Guodong; Yang, Zhiqiang; Li, Jie

    2014-05-01

    The transfer of arsenic from paddy field to rice is a major exposure route of the highly toxic element to humans. The aim of our study is to explore the effects of soil available phosphorus on As uptake by rice, and identify the effects of soil properties on arsenic transfer from soil to rice under actual field conditions. 56 pairs of topsoil and rice samples were collected. The relevant parameters in soil and the inorganic arsenic in rice grains were analyzed, and then all the results were treated by statistical methods. Results show that the main factors influencing the uptake by rice grain include soil pH and available phosphorus. The eventual impact of phosphorus is identified as the suppression of As uptake by rice grains. The competition for transporters from soil to roots between arsenic and phosphorus in rhizosphere soil has been a dominant feature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Atsushi, E-mail: na_4_ka_triplochiton@kpu.ac.jp [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan); Ogasawara, Sho [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan); Sano, Oki; Ito, Toyoaki [Field Science Center, Graduate School of Agricultural Science, Tohoku University, Naruko-Onsen 232-3, Osaki, Miyagi 989-6711 (Japan); Yanai, Junta [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan)

    2014-01-01

    Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the {sup 137}Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, {sup 137}Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the {sup 137}Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg{sup −1}, and ranged from 2.4 mol kg{sup −1} to 19.4 mol kg{sup −1}. The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the {sup 137}Cs retention ability of the soil clays, but also could be used to predict the {sup 137}Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. - Highlights: • RIP was measured for 97 paddy soils from Fukushima to assess {sup 137}Cs retention ability. • The dominant clay mineral was smectite, but this did not control RIP. • RIP was positively correlated with native K content. • Micaceous minerals were found to control the {sup 137}Cs retention

  2. [Study on mechanism of SOM stabilization of paddy soils under long-term fertilizations].

    Science.gov (United States)

    Luo, Lu; Zhou, Ping; Tong, Cheng-Li; Shi, Hui; Wu, Jin-Shui; Huang, Tie-Ping

    2013-02-01

    Fourier transform infrared spectroscopy (FTIR) was applied to study the structure of soil organic matter (SOM) of paddy soils under long-term different fertilization treatments. The aim was to clarify the different distribution of SOM between different fertilization methods and between topsoil and subsoil, and to explore the stability mechanism of SOM under different fertilization treatments. The results showed that the content of topsoil organic carbon (SOC) was the highest under organic-inorganic fertilizations, with the increment of SOC by 18.5%, 12.9% and 18.4% under high organic manure (HOM), low organic manure (LOM) and straw returning (STW) respectively compared with no fertilization treatment (CK). The long-term fertilizations also changed the chemical structure of SOM. As compared with CK, different fertilization treatments increased the functional group absorbing intensity of chemical resistance compounds (aliphatic, aromaticity), carbohydrate and organo-silicon compounds, which was the most distinctive under treatments of HOM, LOM and STW. For example, the absorbing intensity of alkyl was 0.30, 0.25 and 0.29 under HOM, LOM and STW, respectively. These values were increased by 87% , 56% and 81% as compared with that under CK treatment. The functional group absorbing intensity of SOM in the topsoil was stronger than that in the subsoil, with the most distinctive difference under HOM, LOM and STW treatments. The present research indicated that the enhanced chemical resistance of functional group of SOM may contribute to the high contents of SOC in the paddy soils under long-term organic-inorganic fertilizations, which also suggested a chemical stabilization mechanism of SOM in the paddy soils.

  3. Phylogenetic diversity of dissimilatory ferric iron reducers in paddy soil of Hunan, South China

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xin-Jun [State Key Lab. of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, BJ (China); Graduate Univ., Chinese Academy of Sciences, BJ (China); Yang Jing; Chen Xue-Ping; Sun Guo-Xin [State Key Lab. of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, BJ (China); Zhu Yong-Guan [State Key Lab. of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, BJ (China); Key Lab. of Urban Environment and Health, Inst. of Urban Environment, Chinese Academy of Sciences, Xiamen (China)

    2009-12-15

    Purpose: Dissimilatory iron-reducing bacteria have been described by both culture-dependent and -independent methods in various environments, including freshwater, marine sediments, natural wetlands, and contaminated aquifers. However, little is known about iron-reducing microbial communities in paddy soils. The goal of this study was to characterize iron-reducing microbial communities in paddy soil. Moreover, the effect of dissolved and solid-phase iron (III) species on the iron-reducing microbial communities was also investigated by enrichment cultures. Methods: Ferric citrate and ferrihydrite were used respectively to set up enrichment cultures of dissimilatory ironreducing microorganisms using 1% inoculum of soil samples, and the iron reduction was measured. Moreover, bacterial DNA was extracted and 16S rRNA genes were PCR-amplified, and subsequently analyzed by the clone library and terminal restriction fragment length polymorphism (T-RFLP). Results: Phylogenetic analysis of 16S rRNA gene sequences extracted from the enrichment cultures revealed that Bradyrhizobium, Bacteroides, Clostridium and Ralstonia species were the dominant bacteria in the ferric citrate enrichment. However, members of the genera Clostridium, Bacteroides, and Geobacter were the dominant micro-organisms in the ferrihydrite enrichment. Analysis of enrichment cultures by T-RFLP strongly supported the cloning and sequencing results. Conclusions: The present study demonstrated that dissimilatory iron-reducing consortia in As-contaminated paddy soil are phylogenetically diverse. Moreover, iron (III) sources as a key factor have a strong effect on the iron (III)-reducing microbial community structure and relative abundance in the enrichments. In addition, Geobacter species are selectively enriched by ferrihydrite enrichment cultures. (orig.)

  4. Remediation mechanisms of mercapto-grafted palygorskite for cadmium pollutant in paddy soil.

    Science.gov (United States)

    Liang, Xuefeng; Qin, Xu; Huang, Qingqing; Huang, Rong; Yin, Xiuling; Cai, Yanming; Wang, Lin; Sun, Yuebing; Xu, Yingming

    2017-10-01

    The immobilization agent was the key factor that determined the success of remediation of heavy metal polluted soil. In this study, mercapto-grafted palygorskite (MP) as a novel and efficient immobilization agent was utilized for the remediation of Cd-polluted paddy soil in pot trials, and the remediation mechanisms were investigated in the aspect of soil chemistry and plant physiology with different rice cultivars as model plants. Mercapto-grafted palygorskite at applied doses of 0.1-0.3% could reduce Cd contents of brown rice and straws of different cultivars significantly. Both reduced DTPA-extractable Cd contents in rhizosphere and non-rhizosphere soil and decreasing Cd contents in iron plaques on rice root surfaces confirmed that MP was an efficient immobilization agent for Cd pollutant in paddy soil. In the aspect of soil chemistry, the pH values of rhizosphere and non-rhizosphere soils had no statistical changes in the MP treatment groups, but their zeta potentials decreased obviously, indicating that MP could enhance the fixation or sorption of Cd on soil compositions. In the aspect of antioxidant system, MP could increase POD activity of rice roots significantly to alleviate the stress of Cd to roots, and resulted in the decrease of T-AOC, SOD, and CAT activities of rice roots of the selected cultivars. MP had no inhabitation or enhancement effects on TSH of rice roots but enhance the contents of MTs and NPT to binding Cd to complete detoxification process. MP as a novel and efficient immobilization agent could complete the remediation effects through soil chemistry and plant physiological mechanisms.

  5. Evaluation of soil characteristics potentially affecting arsenic concentration in paddy rice (Oryza sativa L.)

    International Nuclear Information System (INIS)

    Bogdan, Katja; Schenk, Manfred K.

    2009-01-01

    Paddy rice may contribute considerably to the human intake of As. The knowledge of soil characteristics affecting the As content of the rice plant enables the development of agricultural measures for controlling As uptake. During field surveys in 2004 and 2006, plant samples from 68 fields (Italy, Po-area) revealed markedly differing As concentration in polished rice. The soil factors total As (aquaregia) , pH, grain size fractions, total C, plant available P (CAL) , poorly crystalline Fe (oxal.) and plant available Si (Na-acetate) content that potentially affect As content of rice were determined. A multiple linear regression analysis showed a significant positive influence of the total As (aquaregia) and plant available P (CAL) content and a negative influence of the poorly crystalline Fe (oxal.) content of the soil on the As content in polished rice and rice straw. Si concentration in rice straw varied widely and was negatively related to As content in straw and polished rice. - Field selection for total As, poorly crystalline Fe and plant available P in soil might contribute to control As content of paddy rice.

  6. Phospholipid fatty acid patterns of microbial communities in paddy soil under different fertilizer treatments

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qi-chun; WANG Guang-huo; YAO Huai-ying

    2007-01-01

    The microbial communities under irrigated rice cropping with different fertilizer treatments, including control (CK), PK, NK, NP, NPK fertilization, were investigated using phospholipid fatty acid (PLFA) profile method. The results of this study revealed that the fertilizer practice had an impact on the community structure of specific microbial groups. The principal components analysis (PCA) showed that proportion of the actinomycete PLFAs (10Me 18:0 and 10Me 16:0) were the lowest in the PK treatment and the highest in the NPK treatment, which means that soil nitrogen status affected the diversity of actinomycetes, whereas nitrogen cycling was related to the actinomycets. Under CK treatment, the ratio of Gram-positive to Gram-negative bacteria was lower compared with that in fertilizer addition treatments, indicating that fertilizer application stimulated Gram-positive bacterial population in paddy soil. The fatty acid 18:2ω6, 9, which is considered to be predominantly of fungal origin, was at low level in all the treatments. The ratio of cy19:0 to 18:1ω7, which has been proposed as an indicator of stress conditions, decreased in PK treatment. Changes of soil microbial community under different fertilizer treatments of paddy soil were detected in this study; however, the causes that lead to changes in the microbial community still needs further study.

  7. Effect of simulated tillage on microbial autotrophic CO2 fixation in paddy and upland soils

    Science.gov (United States)

    Ge, Tida; Wu, Xiaohong; Liu, Qiong; Zhu, Zhenke; Yuan, Hongzhao; Wang, Wei; Whiteley, A. S.; Wu, Jinshui

    2016-01-01

    Tillage is a common agricultural practice affecting soil structure and biogeochemistry. To evaluate how tillage affects soil microbial CO2 fixation, we incubated and continuously labelled samples from two paddy soils and two upland soils subjected to simulated conventional tillage (CT) and no-tillage (NT) treatments. Results showed that CO2 fixation (14C-SOC) in CT soils was significantly higher than in NT soils. We also observed a significant, soil type- and depth-dependent effect of tillage on the incorporation rates of labelled C to the labile carbon pool. Concentrations of labelled C in the carbon pool significantly decreased with soil depth, irrespective of tillage. Additionally, quantitative PCR assays revealed that for most soils, total bacteria and cbbL-carrying bacteria were less abundant in CT versus NT treatments, and tended to decrease in abundance with increasing depth. However, specific CO2 fixation activity was significantly higher in CT than in NT soils, suggesting that the abundance of cbbL-containing bacteria may not always reflect their functional activity. This study highlights the positive effect of tillage on soil microbial CO2 fixation, and the results can be readily applied to the development of sustainable agricultural management. PMID:26795428

  8. [Influence of paddy rice-upland crop rotation of cold-waterlogged paddy field on crops produc- tion and soil characteristics].

    Science.gov (United States)

    Wang, Fei; Li, Qing-hua; Lin, Cheng; He, Chun-mei; Zhong, Shao-jie; Li, Yu; Lin, Xin-jian; Huang, Jian-cheng

    2015-05-01

    Two consecutive years (4-crop) experiments were conducted to study the influence of different paddy rice-upland crop rotation in cold-waterlogged paddy field on the growth of crops and soil characteristics. The result showed that compared with the rice-winter fallow (CK) pattern, the two-year average yield of paddy rice under four rotation modes, including rape-rice (R-R), spring corn-rice (C-R), Chinese milk vetch-rice (M-R) and bean-rice (B-R), were increased by 5.3%-26.7%, with significant difference observed in C-R and R-R patterns. Except for M-R pattern, the annual average total economic benefits were improved by 79.0%-392.4% in all rotation pattern compared with the CK, and the ration of output/input was enhanced by 0.06-0.72 unit, with the most significant effect found in the C-R pattern. Likewise, compared with the CK, the contents of chlorophyll and carotenoid, and net photosynthetic rate (Pn) of rice plant were all increased during the full-tillering stage of rice in all rotation patterns. The rusty lines and rusty spots of soils were more obvious compared with the CK during the rice harvest, particularly in R-R, C-R and B-R patterns. The ratio of water-stable soil macro aggregates of plough layer of soil (> 2 mm) decreased at different levels in all rotation patterns while the ratios of middle aggregate (0.25-2 mm, expect for M-R) and micro aggregate of soil (< 0.25 mm) were opposite. There was a decreasing trend for soil active reducing agents in all rotation patterns, whereas the available nutrient increased. The amounts of soil bacteria in C-R and B-R patterns, fungi in B-R rotation pattern, cellulose bacteria in R-R, C-R and B-R patterns and N-fixing bacteria in B-R pattern were improved by 285.7%-403.0%, 221.7%, 64.6-92.2% and 162.2%, respectively. Moreover, the differences in all microorganisms were significant. Thus, based on the experimental results of cold-waterlogged paddy field, it was concluded that changing from single cropping rice system

  9. In situ measurement of some soil properties in paddy soil using visible and near-infrared spectroscopy.

    Directory of Open Access Journals (Sweden)

    Ji Wenjun

    Full Text Available In situ measurements with visible and near-infrared spectroscopy (vis-NIR provide an efficient way for acquiring soil information of paddy soils in the short time gap between the harvest and following rotation. The aim of this study was to evaluate its feasibility to predict a series of soil properties including organic matter (OM, organic carbon (OC, total nitrogen (TN, available nitrogen (AN, available phosphorus (AP, available potassium (AK and pH of paddy soils in Zhejiang province, China. Firstly, the linear partial least squares regression (PLSR was performed on the in situ spectra and the predictions were compared to those with laboratory-based recorded spectra. Then, the non-linear least-square support vector machine (LS-SVM algorithm was carried out aiming to extract more useful information from the in situ spectra and improve predictions. Results show that in terms of OC, OM, TN, AN and pH, (i the predictions were worse using in situ spectra compared to laboratory-based spectra with PLSR algorithm (ii the prediction accuracy using LS-SVM (R2>0.75, RPD>1.90 was obviously improved with in situ vis-NIR spectra compared to PLSR algorithm, and comparable or even better than results generated using laboratory-based spectra with PLSR; (iii in terms of AP and AK, poor predictions were obtained with in situ spectra (R2<0.5, RPD<1.50 either using PLSR or LS-SVM. The results highlight the use of LS-SVM for in situ vis-NIR spectroscopic estimation of soil properties of paddy soils.

  10. The key microorganisms for anaerobic degradation of pentachlorophenol in paddy soil as revealed by stable isotope probing

    International Nuclear Information System (INIS)

    Tong, Hui; Liu, Chengshuai; Li, Fangbai; Luo, Chunling; Chen, Manjia; Hu, Min

    2015-01-01

    Highlights: • SIP suggested that Dechloromonas can mineralize PCP in soil. • Methanosaeta and Methanocella acquired PCP-derived carbon. • Lactate enhanced microbial degradation of PCP in soil. - Abstract: Pentachlorophenol (PCP) is a common residual persistent pesticide in paddy soil and has resulted in harmful effect on soil ecosystem. The anaerobic microbial transformation of PCP, therefore, has been received much attentions, especially the functional microbial communities for the reductive transformation. However, the key functional microorganisms for PCP mineralization in the paddy soil still remain unknown. In this work, DNA-based stable isotope probing (SIP) was applied to explore the key microorganisms responsible for PCP mineralization in paddy soil. The SIP results indicated that the dominant bacteria responsible for PCP biodegradation belonged to the genus Dechloromonas of the class β-Proteobacteria. In addition, the increased production of 13 CH 4 and 13 CO 2 indicated that the addition of lactate enhanced the rate of biodegradation and mineralization of PCP. Two archaea classified as the genera of Methanosaeta and Methanocella of class Methanobacteria were enriched in the heavy fraction when with lactate, whereas no archaea was detected in the absence of lactate. These findings provide direct evidence for the species of bacteria and archaea responsible for anaerobic PCP or its breakdown products mineralization and reveal a new insight into the microorganisms linked with PCP degradation in paddy soil

  11. The key microorganisms for anaerobic degradation of pentachlorophenol in paddy soil as revealed by stable isotope probing

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Hui [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Chengshuai [State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550009 (China); Li, Fangbai, E-mail: cefbli@soil.gd.cn [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Luo, Chunling [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chen, Manjia; Hu, Min [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China)

    2015-11-15

    Highlights: • SIP suggested that Dechloromonas can mineralize PCP in soil. • Methanosaeta and Methanocella acquired PCP-derived carbon. • Lactate enhanced microbial degradation of PCP in soil. - Abstract: Pentachlorophenol (PCP) is a common residual persistent pesticide in paddy soil and has resulted in harmful effect on soil ecosystem. The anaerobic microbial transformation of PCP, therefore, has been received much attentions, especially the functional microbial communities for the reductive transformation. However, the key functional microorganisms for PCP mineralization in the paddy soil still remain unknown. In this work, DNA-based stable isotope probing (SIP) was applied to explore the key microorganisms responsible for PCP mineralization in paddy soil. The SIP results indicated that the dominant bacteria responsible for PCP biodegradation belonged to the genus Dechloromonas of the class β-Proteobacteria. In addition, the increased production of {sup 13}CH{sub 4} and {sup 13}CO{sub 2} indicated that the addition of lactate enhanced the rate of biodegradation and mineralization of PCP. Two archaea classified as the genera of Methanosaeta and Methanocella of class Methanobacteria were enriched in the heavy fraction when with lactate, whereas no archaea was detected in the absence of lactate. These findings provide direct evidence for the species of bacteria and archaea responsible for anaerobic PCP or its breakdown products mineralization and reveal a new insight into the microorganisms linked with PCP degradation in paddy soil.

  12. Arsenic mobilization and speciation during iron plaque decomposition in a paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hai; Chen, Zheng; Sun, Guoxin [Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences; Zhu, Yongguan [Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences; Chinese Academy of Sciences, Xiamen (China). Key Lab. of Urban Environment and Health; Yin, Xixiang [Chinese Academy of Sciences, Xiamen (China). Key Lab. of Urban Environment and Health; Chinese Academy of Sciences, Beijing (China). Research Center for Eco-environmental Sciences

    2012-03-15

    Little information is available concerning the mobilization and speciation of arsenic (As) in paddy soils during iron plaque decomposition. It is important to investigate these processes since they affect As bioavailability and contaminate surface and ground water systems. A microcosm experiment was conducted to investigate the reductive dissolution of iron plaque and subsequent As mobilization under NaN{sub 3} sterilized (abiotic treatments) and non-sterilized (biotic treatments) paddy soil conditions. In the biotic treatment, As and iron (Fe) were quickly released into the soil solution, with more than 76.1% of total arsenic (T{sub As}) on the roots lost in 27 days. In the abiotic treatment, both iron plaque decomposition and As release were significantly slower, with only 39.4% of T{sub As} on the roots lost in 85 days. A part of arsenate reduction reaction occurred before and may also occur after release from roots in both abiotic and biotic treatments. Bacterial abundance, quantified by real-time PCR, varied significantly between treatments. Terminal restriction fragment length polymorphism combined with principal component analysis (PCA) revealed that microbial community structures were also different between treatments. The changes in microbial factors (bacterial abundance and microbial diversity and activities) significantly affected iron plaque decomposition, As mobilization, and speciation processes. Iron plaque reductive dissolution was likely the major factor leading to As release. Most As released was trapped in the solid phase during the incubation period. (orig.)

  13. Eco-toxicity and metal contamination of paddy soil in an e-wastes recycling area

    International Nuclear Information System (INIS)

    Zhang Junhui; Hang Min

    2009-01-01

    Paddy soil samples taken from different sites in an old primitive electronic-waste (e-waste) processing region were examined for eco-toxicity and metal contamination. Using the environmental quality standard for soils (China, Grade II) as reference, soil samples of two sites were weakly contaminated with trace metal, but site G was heavily contaminated with Cd (6.37 mg kg -1 ), and weakly contaminated with Cu (256.36 mg kg -1 ) and Zn (209.85 mg kg -1 ). Zn appeared to be strongly bound in the residual fraction (72.24-77.86%), no matter the soil was metal contaminated or not. However, more than 9% Cd and 16% Cu was present in the non-residual fraction in the metal contaminated soils than in the uncontaminated soil, especially for site G and site F. Compared with that of the control soil, the micronucleus rates of site G and site F soil treatments increased by 2.7-fold and 1.7-fold, respectively. Low germination rates were observed in site C (50%) and site G (50%) soil extraction treated rice seeds. The shortest root length (0.2377 cm) was observed in site G soil treated groups, which is only 37.57% of that of the control soil treated groups. All of the micronucleus ratio of Vicia faba root cells, rice germination rate and root length after treatment of soil extraction indicate the eco-toxicity in site F and G soils although the three indexes are different in sensitivity to soil metal contamination.

  14. Analysis of Eh Condition and Evolutional Trend of Paddy Soils in a Toposequence

    Directory of Open Access Journals (Sweden)

    javad seyedmohammadi

    2017-02-01

    Full Text Available Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant effects on soil fertility. Eh, rH and pH are important indexes that are used to investigate oxidation and reduction condition in submerged soils and have abundant effects on activity and sorption rate of nutrients. Decrease of Eh and rH in poorly drainage of paddy soils affects availability and solubility of nutrient. Different Fe forms are used for analysis of soils evolution trend and submerging influences on changes of Fe forms. The aim of the present study was conducted to investigate the effect of redox potential changes on soil characteristics and analysis of soils evolutional trend in different physiographic units. Materials and Methods: The study area with 40000ha (at the east of Rasht city is located between 49° 31' to 49° 45' E longitude and 37° 7' to 37° 27' N latitude in North of Guilan Province, Northern Iran, in the southern coast of the Caspian sea with different water table depth. The climate of the region is very humid with the mean annual precipitation of 1293.6 mm. The mean annual temperature is 15.8°C. The soil moisture and temperature regimes are Aquic, Udicand Thermic, respectively. The parent materials are derived from river sediments. The soils formed on the plateaues and upper terraces, river alluvial plain and lowland physiographic units were classified as Inceptisols and the soils formed on coastal plain physiographic unit as Entisols. Air-dried soil samples were crushed and passed through a 2mm sieve. Particle-size distribution, organic carbon and cation exchange capacity were determined by hydrometric, wet oxidation and ammonium acetate methods, respectively. Eh by Eh electrode, total iron, free iron and amorphous

  15. Response of methane production via propionate oxidation to carboxylated multiwalled carbon nanotubes in paddy soil enrichments

    Directory of Open Access Journals (Sweden)

    Jianchao Zhang

    2018-01-01

    Full Text Available Carboxylated multiwalled carbon nanotubes (MWCNTs-COOH have become a growing concern in terms of their fate and toxicity in aqueous environments. Methane (CH4 is a major product of organic matter degradation in waterlogged environments. In this study, we determined the effect of MWCNTs-COOH on the production of CH4 from propionate oxidation in paddy soil enrichments. The results showed that the methanogenesis from propionate degradation was accelerated in the presence of MWCNTs-COOH. In addition, the rates of CH4 production and propionate degradation increased with increasing concentrations of MWCNTs-COOH. Scanning electron microscopy (SEM observations showed that the cells were intact and maintained their structure in the presence of MWCNTs-COOH. In addition, SEM and fluorescence in situ hybridization (FISH images revealed that the cells were in direct contact with the MWCNTs and formed cell-MWCNTs aggregates that contained both bacteria and archaea. On the other hand, nontoxic magnetite nanoparticles (Fe3O4 had similar effects on the CH4 production and cell integrity as the MWCNTs-COOH. Compared with no nanomaterial addition, the relative abundances of Geobacter and Methanosarcina species increased in the presence of MWCNTs-COOH. This study suggests that MWCNTs-COOH exerted positive rather than cytotoxic effects on the syntrophic oxidation of propionate in paddy soil enrichments and affected the bacterial and archaeal community structure at the test concentrations. These findings provide novel insight into the consequences of nanomaterial release into anoxic natural environments.

  16. Soil-to-Rice Seeds Transfer Factors of Radioiodine and Technetium for Paddy Fields around the Radioactive-Waste Disposal Site in Gyeongju

    International Nuclear Information System (INIS)

    Choi, Yong Ho; Lim, Kwang Muk; Jun, In; Park, Doo Won; Keum, Dong Kwon; Han, Moon Hee

    2010-01-01

    Radiotracer experiments were performed over two years using pot cultures in a greenhouse to investigate soil-torice seeds transfer factors of radioiodine and technetium for paddy fields around the radioactive-waste disposal site in Gyeongju. Before transplanting rice seedlings, the top about 20 cm soils were thoroughly mixed with 125 I (2007) and 99 Tc (2008), and the pots were irrigated to simulate flooded rice fields. Transfer factors were determined as the ratios of the radionuclide concentrations in dry rice seeds (brown rice) to those in dry soils. Transfer factors of radioiodine and technetium were in the ranges of 1.1 x 10 -3 ∼ 6.4 x 10 -3 (three soils) and 5.4 x 10 -4 ∼ 2.5 x 10 -3 (four soils), respectively, for different soils. It seems that the differences in the clay content among soils played a more important role for such variations than those in the organic matter content and pH. As the representative values of radioiodine and technetium transfer factors for rice seeds, 2.9 x 10 -3 and 1.1 x 10 -3 , respectively, were proposed. In order to obtain more highly representative values in the future, investigations for the sites of interest need to be carried out continuously

  17. Microbial utilization of rice straw and its derived biochar in a paddy soil

    International Nuclear Information System (INIS)

    Pan, Fuxia; Li, Yaying; Chapman, Stephen James; Khan, Sardar; Yao, Huaiying

    2016-01-01

    The application of straw and biochar to soil has received great attention because of their potential benefits such as fertility improvement and carbon (C) sequestration. The abiotic effects of these materials on C and nitrogen (N) cycling in the soil ecosystem have been previously investigated, however, the effects of straw or its derived biochar on the soil microbial community structure and function are not well understood. For this purpose, a short-term incubation experiment was conducted using 13 C-labeled rice straw and its derived biochar ( 13 C-labeled biochar) to deepen our understanding about soil microbial community dynamics and function in C sequestration and greenhouse gas emission in the acidic paddy soil amended with these materials. Regarding microbial function, biochar and straw applications increased CO 2 emission in the initial stage of incubation and reached the highest level (0.52 and 3.96 mg C kg −1 soil h −1 ) at 1 d and 3 d after incubation, respectively. Straw amendment significantly (p < 0.01) increased respiration rate, total phospholipid fatty acids (PLFAs) and 13 C-PLFA as compared to biochar amendment and the control. The amount and percent of Gram positive bacteria, fungi and actinomycetes were also significantly (p < 0.05) higher in 13 C-labeled straw amended soil than the 13 C-labeled biochar amended soil. According to the 13 C data, 23 different PLFAs were derived from straw amended paddy soil, while only 17 PLFAs were derived from biochar amendments. The profile of 13 C-PLFAs derived from straw amendment was significantly (p < 0.01) different from biochar amendment. The PLFAs 18:1ω7c and cy17:0 (indicators of Gram negative bacteria) showed high relative abundances in the biochar amendment, while 10Me18:0, i17:0 and 18:2ω6,9c (indicators of actinomycetes, Gram positive bacteria and fungi, respectively) showed high relative abundance in the straw amendments. Our results suggest that the function, size and structure of the

  18. Microbial utilization of rice straw and its derived biochar in a paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Fuxia [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Ningbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo 315800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Yaying [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Ningbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo 315800 (China); Chapman, Stephen James [The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Khan, Sardar [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Department of Environmental Science, University of Peshawar (Pakistan); Yao, Huaiying, E-mail: hyyao@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Ningbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo 315800 (China)

    2016-07-15

    The application of straw and biochar to soil has received great attention because of their potential benefits such as fertility improvement and carbon (C) sequestration. The abiotic effects of these materials on C and nitrogen (N) cycling in the soil ecosystem have been previously investigated, however, the effects of straw or its derived biochar on the soil microbial community structure and function are not well understood. For this purpose, a short-term incubation experiment was conducted using {sup 13}C-labeled rice straw and its derived biochar ({sup 13}C-labeled biochar) to deepen our understanding about soil microbial community dynamics and function in C sequestration and greenhouse gas emission in the acidic paddy soil amended with these materials. Regarding microbial function, biochar and straw applications increased CO{sub 2} emission in the initial stage of incubation and reached the highest level (0.52 and 3.96 mg C kg{sup −1} soil h{sup −1}) at 1 d and 3 d after incubation, respectively. Straw amendment significantly (p < 0.01) increased respiration rate, total phospholipid fatty acids (PLFAs) and {sup 13}C-PLFA as compared to biochar amendment and the control. The amount and percent of Gram positive bacteria, fungi and actinomycetes were also significantly (p < 0.05) higher in {sup 13}C-labeled straw amended soil than the {sup 13}C-labeled biochar amended soil. According to the {sup 13}C data, 23 different PLFAs were derived from straw amended paddy soil, while only 17 PLFAs were derived from biochar amendments. The profile of {sup 13}C-PLFAs derived from straw amendment was significantly (p < 0.01) different from biochar amendment. The PLFAs 18:1ω7c and cy17:0 (indicators of Gram negative bacteria) showed high relative abundances in the biochar amendment, while 10Me18:0, i17:0 and 18:2ω6,9c (indicators of actinomycetes, Gram positive bacteria and fungi, respectively) showed high relative abundance in the straw amendments. Our results suggest

  19. Simulating water and nitrogen loss from an irrigated paddy field under continuously flooded condition with Hydrus-1D model.

    Science.gov (United States)

    Yang, Rui; Tong, Juxiu; Hu, Bill X; Li, Jiayun; Wei, Wenshuo

    2017-06-01

    Agricultural non-point source pollution is a major factor in surface water and groundwater pollution, especially for nitrogen (N) pollution. In this paper, an experiment was conducted in a direct-seeded paddy field under traditional continuously flooded irrigation (CFI). The water movement and N transport and transformation were simulated via the Hydrus-1D model, and the model was calibrated using field measurements. The model had a total water balance error of 0.236 cm and a relative error (error/input total water) of 0.23%. For the solute transport model, the N balance error and relative error (error/input total N) were 0.36 kg ha -1 and 0.40%, respectively. The study results indicate that the plow pan plays a crucial role in vertical water movement in paddy fields. Water flow was mainly lost through surface runoff and underground drainage, with proportions to total input water of 32.33 and 42.58%, respectively. The water productivity in the study was 0.36 kg m -3 . The simulated N concentration results revealed that ammonia was the main form in rice uptake (95% of total N uptake), and its concentration was much larger than for nitrate under CFI. Denitrification and volatilization were the main losses, with proportions to total consumption of 23.18 and 14.49%, respectively. Leaching (10.28%) and surface runoff loss (2.05%) were the main losses of N pushed out of the system by water. Hydrus-1D simulation was an effective method to predict water flow and N concentrations in the three different forms. The study provides results that could be used to guide water and fertilization management and field results for numerical studies of water flow and N transport and transformation in the future.

  20. Geofractionation of heavy metals and application of indices for pollution prediction in paddy field soil of Tumpat, Malaysia.

    Science.gov (United States)

    Sow, Ai Yin; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir

    2013-12-01

    The present study investigates the concentration of Pb, Cd, Ni, Zn, and Cu in the paddy field soils collected from Tumpat, Kelantan. Soil samples were treated with sequential extraction to distinguish the anthropogenic and lithogenic origin of Pb, Cd, Ni, Zn, and Cu. ELFE and oxidizable-organic fractions were detected as the lowest accumulation of Pb, Cd, Ni, Zn, and Cu. Therefore, all the heavy metals examined were concentrated, particularly in resistant fraction, indicating that those heavy metals occurred and accumulated in an unavailable form. The utilization of agrochemical fertilizers and pesticides might not elevate the levels of heavy metals in the paddy field soils. In comparison, the enrichment factor and geoaccumulation index for Pb, Cd, Ni, Zn, and Cu suggest that these heavy metals have the potential to cause environmental risk, although they present abundance in resistant fraction. Therefore, a complete study should be conducted based on the paddy cycle, which in turn could provide a clear picture of heavy metals distribution in the paddy field soils.

  1. Assessment of toxicity of heavy metal contaminated soils toward Collembola in paddy fields supported by laboratory tests

    DEFF Research Database (Denmark)

    Liu, Manping; Xu, Jie; Krogh, Paul Henning

    2018-01-01

    Effects on soil Collembola of Cu, Zn, Pb, and Cd pollution from Cu smelters over 40 years were investigated in paddy fields from an area of Eastern China. We compared the field effects to those observed in single-species laboratory tests employing the hemiedaphic collembolan Folsomia candida and ...

  2. Radiotracer experiments on the desorption of iodine from paddy soil with and without rice plants

    International Nuclear Information System (INIS)

    Muramatsu, Yasuyuki; Uchida, Shigeo; Yoshida, Satoshi

    1991-01-01

    In order to assess the behavior of radioiodine in rice fields, we have performed laboratory experiments, using 125 I tracer, on the desorption phenomena of iodine from soil during rice cultivation. Most of the 125 I added to the soil was adsorbed by the soil solid phase at the beginning of the experiment. However, the iodine started to desorb into the soil solution with the growth of rice plants. The highest desorption rate of iodine was found around the flowering period, i.e. nearly 30% of the 125 I was desorbed from Ando soil into the soil solution. In contrast to this, no particular increase in the iodine desorption was observed from the uncultivated flooded soil. It was suggested that rice plants had some influence upon iodine desorption from soil and the desorption also depended on the soil types. (author)

  3. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    Science.gov (United States)

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles.

  4. Mapping spatial variability of soil salinity in a coastal paddy field based on electromagnetic sensors.

    Directory of Open Access Journals (Sweden)

    Yan Guo

    Full Text Available In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9 allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v as well as other EMI instruments (e.g. DUALEM-421 can be incorporated to conduct Quasi-3D inversions for deeper soil profiles.

  5. Mapping Spatial Variability of Soil Salinity in a Coastal Paddy Field Based on Electromagnetic Sensors

    Science.gov (United States)

    Guo, Yan; Huang, Jingyi; Shi, Zhou; Li, Hongyi

    2015-01-01

    In coastal China, there is an urgent need to increase land area for agricultural production and urban development, where there is a rapid growing population. One solution is land reclamation from coastal tidelands, but soil salinization is problematic. As such, it is very important to characterize and map the within-field variability of soil salinity in space and time. Conventional methods are often time-consuming, expensive, labor-intensive, and unpractical. Fortunately, proximal sensing has become an important technology in characterizing within-field spatial variability. In this study, we employed the EM38 to study spatial variability of soil salinity in a coastal paddy field. Significant correlation relationship between ECa and EC1:5 (i.e. r >0.9) allowed us to use EM38 data to characterize the spatial variability of soil salinity. Geostatistical methods were used to determine the horizontal spatio-temporal variability of soil salinity over three consecutive years. The study found that the distribution of salinity was heterogeneous and the leaching of salts was more significant in the edges of the study field. By inverting the EM38 data using a Quasi-3D inversion algorithm, the vertical spatio-temporal variability of soil salinity was determined and the leaching of salts over time was easily identified. The methodology of this study can be used as guidance for researchers interested in understanding soil salinity development as well as land managers aiming for effective soil salinity monitoring and management practices. In order to better characterize the variations in soil salinity to a deeper soil profile, the deeper mode of EM38 (i.e., EM38v) as well as other EMI instruments (e.g. DUALEM-421) can be incorporated to conduct Quasi-3D inversions for deeper soil profiles. PMID:26020969

  6. Remediation of cadmium-contaminated paddy soils by washing with calcium chloride: Verification of on-site washing

    International Nuclear Information System (INIS)

    Makino, Tomoyuki; Kamiya, Takashi; Takano, Hiroyuki; Itou, Tadashi; Sekiya, Naoki; Sasaki, Kouta; Maejima, Yuji; Sugahara, Kazuo

    2007-01-01

    We developed a new, three-step soil-wash method to remediate Cd-contaminated paddy fields. The method comprises (1) chemically washing the field soil with a CaCl 2 solution; (2) washing the treated soil with water to eliminate residual Cd and CaCl 2 ; and (3) on-site treatment of wastewater using a portable wastewater treatment system. Cd concentrations in the treated water were below Japan's environmental quality standard (0.01 mg Cd L -1 ), and the removal of Cd from the exchangeable fraction was 55% and from the acid-soluble fraction 15%. While soil fertility properties were affected by the soil washing, adverse effects were not crucial and could be corrected. The washing had no affect on rice growth, and reduced the average Cd concentration in rice grains by about two-thirds compared to a control plot. These results confirmed the effectiveness of the soil-wash method in remediating Cd-contaminated paddy fields. - In situ soil washing in a paddy field using an on-site wastewater treatment system resulted in an effective decrease of Cd in soil and rice grains without affecting rice yield

  7. Soil CO2 venting as one of the mechanisms for tolerance of Zn deficiency by rice in flooded soils.

    Science.gov (United States)

    Affholder, Marie-Cecile; Weiss, Dominik J; Wissuwa, Matthias; Johnson-Beebout, Sarah E; Kirk, Guy J D

    2017-12-01

    We sought to explain rice (Oryza sativa) genotype differences in tolerance of zinc (Zn) deficiency in flooded paddy soils and the counter-intuitive observation, made in earlier field experiments, that Zn uptake per plant increases with increasing planting density. We grew tolerant and intolerant genotypes in a Zn-deficient flooded soil at high and low planting densities and found (a) plant Zn concentrations and growth increased with planting density and more so in the tolerant genotype, whereas the concentrations of other nutrients decreased, indicating a specific effect on Zn uptake; (b) the effects of planting density and genotype on Zn uptake could only be explained if the plants induced changes in the soil to make Zn more soluble; and (c) the genotype and planting density effects were both associated with decreases in dissolved CO 2 in the rhizosphere soil solution and resulting increases in pH. We suggest that the increases in pH caused solubilization of soil Zn by dissolution of alkali-soluble, Zn-complexing organic ligands from soil organic matter. We conclude that differences in venting of soil CO 2 through root aerenchyma were responsible for the genotype and planting density effects. © 2017 John Wiley & Sons Ltd.

  8. Reverse-transcriptional gene expression of anammox and ammonia-oxidizing archaea and bacteria in soybean and rice paddy soils of Northeast China.

    Science.gov (United States)

    Wang, Jing; Dong, Hailiang; Wang, Weidong; Gu, Ji-Dong

    2014-03-01

    The relative gene expression of hydrazine oxidoreductase encoding gene (hzo) for anaerobic ammonium oxidizing bacteria (anammox) and ammonia monooxygenase encoding gene (amoA) for both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in Sanjiang Plain soybean and rice paddy soils of Northeast China was investigated by using real-time reverse-transcriptional quantitative PCR. Metabolically active populations of anammox, AOA, and AOB in rice paddy soils were evident by the presence and successful quantification of hzo mRNA and amoA mRNA genes. The expression ratio of amoA gene for both AOA and AOB varied between soybean soils and different rice paddy soils while the expression of hzo gene for anammox was detectable only in rice paddy soils by showing a diverse relative expression ratio in each soil sample. Gene expression of both archaeal and bacterial amoA genes in rice paddy soils differed among the three sampling depths, but that of hzo was not. Both archaeal and bacterial amoA genes showed an increase trend of expression level with continuation of rice paddy cultivation, but the low expression ratio of hzo gene indicated a relatively small contribution of anammox in overall removal of inorganic nitrogen through N2 even under anoxic and high nitrogen input in agriculture. Bacterial amoA gene from two soybean fields and three rice paddy fields were also analyzed for community composition by denaturing gradient gel electrophoresis fingerprint. Community shift was observed between soybean and paddy fields and within each of them. The consistent occurrence of three bands 5, 6, and 7 in all samples showed their high adaptability for both arid cultivation and continuous rice paddy cultivation. Our data suggest that AOA and AOB are playing a more important role in nitrogen transformation in agricultural soils in oxic or anoxic environment and anammox bacteria may also contribute but in a less extent to N transformation in these agricultural soils

  9. Surfactant flooding of diesel-contaminated soils

    International Nuclear Information System (INIS)

    Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.A.

    1991-01-01

    At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

  10. Interactions between selected PAHs and the microbial community in rhizosphere of a paddy soil.

    Science.gov (United States)

    Su, Yu H; Yang, Xue Y

    2009-01-15

    This study investigated the interaction of three polycyclic aromatic hydrocarbons (PAHs), i.e., naphthalene (NAP), phenanthrene (PHN), and pyrene (PYR), with the microbial community in the rhizosphere of a paddy soil and the influence of the rice (Oryza sativa) rhizosphere on the microbial community structure. A range of initial NAP, PHN and PYR levels in soil (50-200, 18-72, and 6.6-26.6 mg kg(-1), respectively) were prepared and the soil samples were then aged for 4 months (to yield PAH concentrations at 1.02-1.42, 1.32-4.77, and 2.98-18.5 mg kg(-)(1), respectively) before the soil samples were planted with rice seedlings. The microbial phospholipid-fatty-acid (PLFA) patterns in PAH-contaminated soils were analyzed to elucidate the changes of the microbial biomass and community composition. Results indicated that at the applied concentrations the PAHs were not toxic to rice seedlings, as evidenced by no growth inhibition during the 8-week planting period. However, the microbial biomass, as revealed by PLFAs, decreased significantly with increasing PAH concentration in both rhizospheric and non-rhizospheric soils. The PAHs in soils were obviously toxic to microorganisms, and the toxicity of PHN was greater than PYR due likely to the higher PHN bioavailability. Total PLFAs in rhizospheric soils were profoundly higher than those in non-rhizospheric soils, suggesting that the inhibitive effect of PAHs on microbial activities was alleviated by the rice roots. The principal component analysis (PCA) of the PLFA signatures revealed pronounced changes in PLFA pattern in rhizospheric and non-rhizospheric soils with or without spiked PAHs. Using the PLFA patterns as a biomarker, it was found that Gram-positive bacteria were more sensitive to PAHs than Gram-negative bacteria, and the rhizosphere of rice roots stimulated the growth of aerobic bacteria.

  11. Long-term fertilisation causes excess supply and loss of phosphorus in purple paddy soil.

    Science.gov (United States)

    Zhang, Yue-Qiang; Wen, Ming-Xia; Li, Xue-Ping; Shi, Xiao-Jun

    2014-04-01

    Phosphorus (P) loss from cropland is accelerating the eutrophication of waters around the world such as the Three Gorges Reservoir (TGR) in China. We investigated whether purple paddy soil under long-term P applications was a major source of P efflux to the TGR. Substantial surplus P in the plough layer (0-20 cm) was evident after 15-year P applications. Available P (Olsen-P) in the plough layer ranged from 1.9 to 42.4 mg kg(-1) and some of which will exceed the threshold of 30 mg kg(-1) for environmental concern within 7 years of P application (inorganic NPK with or without organic fertiliser). Between 30 and 70% of Olsen-P was leached out of the 0-30 cm soil layer. Surplus P resulted in high P concentrations in the surface water during the rice cropping season, and these concentrations exceeded those in most waters of the TGR and exceeded the critical level for eutrophication (0.1 mg L(-1)) during the first 10 days after rice planting. Furthermore, total P in run-off due to rainfall events exceeded the level for eutrophication, with a total loss of 43.2-147.9 g P ha(-1) depending on the fertilisation. Current agronomic P management in purple paddy soil is environmentally unsustainable in terms of the adverse impact on surface water quality. Integrated P management practices are urgently required to optimise crop yield while minimising P loss in order to protect surface water quality in the TGR region. © 2013 Society of Chemical Industry.

  12. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    Energy Technology Data Exchange (ETDEWEB)

    Roemkens, P.F.A.M., E-mail: paul.romkens@wur.nl [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Brus, D.J. [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Guo, H.Y.; Chu, C.L.; Chiang, C.M. [Taiwan Agricultural Research Institute (TARI), Wufong, Taiwan (China); Koopmans, G.F. [Soil Science Center, Alterra, WageningenUR. P.O. Box 47, 6700AA Wageningen (Netherlands); Department of Soil Quality, Wageningen University, WageningenUR. P.O. Box 47, 6700AA, Wageningen (Netherlands)

    2011-08-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal content, pH, and CEC or soil Cd and Zn extracted by 0.01 M CaCl{sub 2} as explanatory variables. The models were validated against a set of 2300 data points not used in the calibration. These models were then used inversely to derive soil quality standards for Japonica and Indica rice cultivars based on the food quality standards for rice. To account for model uncertainty, strict soil quality standards were derived considering a maximum probability that rice exceeds the food quality standard equal to 10 or 5%. Model derived soil standards based on Aqua Regia ranged from less than 0.3 mg kg{sup -1} for Indica at pH 4.5 to more than 6 mg kg{sup -1} for Japonica-type cultivars in clay soils at pH 7. Based on the CaCl{sub 2} extract, standards ranged from 0.03 mg kg{sup -1} Cd for Indica cultivars to 0.1 mg kg{sup -1} Cd for Japonica cultivars. For both Japonica and Indica-type cultivars, the soil quality standards must be reduced by a factor of 2 to 3 to obtain the strict standards. The strong impact of pH and CEC on soil quality standards implies that it is essential to correct for soil type when deriving national or local standards. Validation on the remaining 2300 samples indicated that both types of models were able to accurately predict (> 92%) whether rice grown on a specific soil will meet the food quality standard used in Taiwan. - Research highlights: {yields} Cadmium uptake by Japonica and Indica rice varieties depends on soil pH and CEC. {yields} Food safety based soil standards range from 0.3 (Indica) to 6 mg kg{sup -1} (Japonica). {yields} Model uncertainty leads to strict soil standards of less than 0.1 mg kg{sup -1} for Indica. {yields} Soil pH and CEC should be

  13. Impact of model uncertainty on soil quality standards for cadmium in rice paddy fields

    International Nuclear Information System (INIS)

    Roemkens, P.F.A.M.; Brus, D.J.; Guo, H.Y.; Chu, C.L.; Chiang, C.M.; Koopmans, G.F.

    2011-01-01

    At present, soil quality standards used for agriculture do not consider the influence of pH and CEC on the uptake of pollutants by crops. A database with 750 selected paired samples of cadmium (Cd) in soil and paddy rice was used to calibrate soil to plant transfer models using the soil metal content, pH, and CEC or soil Cd and Zn extracted by 0.01 M CaCl 2 as explanatory variables. The models were validated against a set of 2300 data points not used in the calibration. These models were then used inversely to derive soil quality standards for Japonica and Indica rice cultivars based on the food quality standards for rice. To account for model uncertainty, strict soil quality standards were derived considering a maximum probability that rice exceeds the food quality standard equal to 10 or 5%. Model derived soil standards based on Aqua Regia ranged from less than 0.3 mg kg -1 for Indica at pH 4.5 to more than 6 mg kg -1 for Japonica-type cultivars in clay soils at pH 7. Based on the CaCl 2 extract, standards ranged from 0.03 mg kg -1 Cd for Indica cultivars to 0.1 mg kg -1 Cd for Japonica cultivars. For both Japonica and Indica-type cultivars, the soil quality standards must be reduced by a factor of 2 to 3 to obtain the strict standards. The strong impact of pH and CEC on soil quality standards implies that it is essential to correct for soil type when deriving national or local standards. Validation on the remaining 2300 samples indicated that both types of models were able to accurately predict (> 92%) whether rice grown on a specific soil will meet the food quality standard used in Taiwan. - Research highlights: → Cadmium uptake by Japonica and Indica rice varieties depends on soil pH and CEC. → Food safety based soil standards range from 0.3 (Indica) to 6 mg kg -1 (Japonica). → Model uncertainty leads to strict soil standards of less than 0.1 mg kg -1 for Indica. → Soil pH and CEC should be considered to obtain meaningful standards for agriculture.

  14. Mass balance and long-term fate of PCDD/Fs in a lagoon sediment and paddy soil, Niigata, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Mizuki [National Institute for Agro-Environmental Science, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)], E-mail: mizukis@affrc.go.jp; Seike, Nobuyasu [National Institute for Agro-Environmental Science, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)], E-mail: seike@niaes.affrc.go.jp; Kobayashi, Jun [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)], E-mail: kobayashi.jun@nies.go.jp; Kajihara, Hideo [National Institute of Advanced Industrial Science and Technology, 16-1 Tsukuba, Ibaraki 305-8569 (Japan)], E-mail: kajihara.hideo@aist.go.jp; Takahashi, Yukio [Academic Assembly Institute of Science and Technology, Niigata University, 2-8050 Ikarashi, Niigata City 950-2181 (Japan)], E-mail: yukitak@eng.niigata-u.ac.jp

    2008-12-15

    Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in a sediment core and in samples of surface sediment and paddy soil collected from the Toyano lagoon and Kameda basin in Niigata, Japan, were analyzed to elucidate the temporal trends of their concentrations in the lagoon sediment and the relationship between the sediment and the paddy soil. The mass balance of these pollutants was also estimated to determine their long-term fate in surface waters. An analysis by chemical mass balance identified the agrochemicals pentachlorophenol and 2,4,6-trichlorophenyl 4-nitrophenyl ether as the major sources of PCDD/Fs. On the basis of the findings regarding the mass balance in the Kameda basin over the last 40 years, we estimate that more than half the input of PCDD/Fs to the Kameda basin has disappeared. We suggest that the PCDD/Fs that flowed out from the paddy fields have been transferred to the lower basin. - The long-term mass balance of PCDD/Fs in sediments from paddy soil is elucidated.

  15. Monitoring of water movement in paddy field's soil using a bromide tracer

    International Nuclear Information System (INIS)

    Asiah Ahmad; Kouichi Yuita

    1994-01-01

    Water movement in soils at the lower course and the middle course of Sakawa River's paddy field was monitored over an 8 week period using a bromide tracer. The water of soil samples taken one day after bromide application contained high concentrations of bromide at 50 to 60 cm soil depth at lower course. The bromide was concentrated promarily within 20 to 80 cm depth. No downward movement below 80 cm depth was detected six weeks afetr the application. This might indicate the high water table of this area. On the other hand, bromide concentrations were high at 50 cm depth in water of the soils sample taken one day after application from the middle course of Sakawa River plot. However, the concentrations were nearly at background level in all samples taken from the middle course of sakawa River 3 weeks after application. The evidence from bromide's movement shows that water readily penetrate the soils at the middle course of Sakawa River. The downward movement was faster compared to that at lower course

  16. [Effect of composting organic fertilizer supplies on hexachlorobenzene dechlorination in paddy soils].

    Science.gov (United States)

    Liu, Cui-Ying; Jiang, Xin

    2013-04-01

    A rice pot experiment was conducted in two soils, Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An). Three treatments including control and additions of 1% or 2% composting organic fertilizer were designed for each soil. The objective of this research was to evaluate the reductive dechlorination of hexachlorobenzene (HCB) as affected by organic fertilizer supplies in planted paddy soils, and to analyze the relationship between methane production and HCB dechlorination. The results showed that the HCB residues were decreased by 28.6%-30.1% of the initial amounts in Ac, and 47.3% -61.0% in An after 18 weeks of experiment. The amount of HCB and its metabolite uptake by rice plants was only a few thousandths of the initial HCB amount in soils. The main product of HCB dechlorination was pentachlorobenzene (PeCB). The rates of HCB dechlorination in An were higher than those in Ac, which was mainly attributed to the higher pH and dissolved organic carbon (DOC) content of An. The applications of both 1% and 2% composting organic fertilizer showed significant inhibition on PeCB production after the 6th and 10th week in Ac and An, respectively. In both tested soils, no significant difference of PeCB production rates was observed between the applications of 1% and 2% composting organic fertilizer. The role of methanogenic bacteria in HCB dechlorination was condition-dependent.

  17. Biochar amendment reduces paddy soil nitrogen leaching but increases net global warming potential in Ningxia irrigation, China.

    Science.gov (United States)

    Wang, Yongsheng; Liu, Yansui; Liu, Ruliang; Zhang, Aiping; Yang, Shiqi; Liu, Hongyuan; Zhou, Yang; Yang, Zhengli

    2017-05-09

    The efficacy of biochar as an environmentally friendly agent for non-point source and climate change mitigation remains uncertain. Our goal was to test the impact of biochar amendment on paddy rice nitrogen (N) uptake, soil N leaching, and soil CH 4 and N 2 O fluxes in northwest China. Biochar was applied at four rates (0, 4.5, 9 and13.5 t ha -1 yr -1 ). Biochar amendment significantly increased rice N uptake, soil total N concentration and the abundance of soil ammonia-oxidizing archaea (AOA), but it significantly reduced the soil NO 3 - -N concentration and soil bulk density. Biochar significantly reduced NO 3 - -N and NH 4 + -N leaching. The C2 and C3 treatments significantly increased the soil CH 4 flux and reduced the soil N 2 O flux, leading to significantly increased net global warming potential (GWP). Soil NO 3 - -N rather than NH 4 + -N was the key integrator of the soil CH 4 and N 2 O fluxes. Our results indicate that a shift in abundance of the AOA community and increased rice N uptake are closely linked to the reduced soil NO 3 - -N concentration under biochar amendment. Furthermore, soil NO 3 - -N availability plays an important role in regulating soil inorganic N leaching and net GWP in rice paddies in northwest China.

  18. County-Scale Spatial Variability of Macronutrient Availability Ratios in Paddy Soils

    Directory of Open Access Journals (Sweden)

    Mingkai Qu

    2014-01-01

    Full Text Available Macronutrients (N, P, and K are essential to plants but also can be harmful to the environment when their available concentrations in soil are excessive. Availability ratios (available concentration/total concentration of macronutrients may reflect their transforming potential between fixed and available forms in soil. Understanding their spatial distributions and impact factors can be, therefore, helpful to applying specific measures to modify the availability of macronutrients for agricultural and environmental management purposes. In this study, 636 topsoil samples (0–15 cm were collected from paddy fields in Shayang County, Central China, for measuring soil properties. Factors influencing macronutrient availability ratios were investigated, and total and available concentrations of macronutrients were mapped using geostatistical method. Spatial distribution maps of macronutrient availability ratios were further derived. Results show that (1 availability of macronutrients is controlled by multiple factors, and (2 macronutrient availability ratios are spatially varied and may not always have spatial patterns identical to those of their corresponding total and available concentrations. These results are more useful than traditional soil macronutrient average content data for guiding site-specific field management for agricultural production and environmental protection.

  19. Biochar amendment immobilizes lead in rice paddy soils and reduces its phytoavailability

    Science.gov (United States)

    Li, Honghong; Liu, Yuting; Chen, Yanhui; Wang, Shanli; Wang, Mingkuang; Xie, Tuanhui; Wang, Guo

    2016-08-01

    This study aimed to determine effects of rice straw biochar on Pb sequestration in a soil-rice system. Pot experiments were conducted with rice plants in Pb-contaminated paddy soils that had been amended with 0, 2.5, and 5% (w/w) biochar. Compared to the control treatment, amendment with 5% biochar resulted in 54 and 94% decreases in the acid soluble and CaCl2-extractable Pb, respectively, in soils containing rice plants at the maturity stage. The amount of Fe-plaque on root surfaces and the Pb concentrations of the Fe-plaque were also reduced in biochar amended soils. Furthermore, lead species in rice roots were determined using Pb L3-edge X-ray absorption near edge structure (XANES), and although Pb-ferrihydrite complexes dominated Pb inventories, increasing amounts of organic complexes like Pb-pectins and Pb-cysteine were found in roots from the 5% biochar treatments. Such organic complexes might impede Pb translocation from root to shoot and subsequently reduce Pb accumulation in rice with biochar amendment.

  20. Risk assessment and vertical distribution of thallium in paddy soils and uptake in rice plants irrigated with acid mine drainage.

    Science.gov (United States)

    Huang, Xuexia; Li, Ning; Wu, Qihang; Long, Jianyou; Luo, Dinggui; Zhang, Ping; Yao, Yan; Huang, Xiaowu; Li, Dongmei; Lu, Yayin; Liang, Jianfeng

    2016-12-01

    The objective of this paper is to assess the influence of irritating paddy fields with acid mine drainage containing thallium (Tl) to rice plant-soil system and potential health risks for local residents. Vertical distribution of Tl, pH, organic matter (OM), and cation exchange capacity (CEC) in 24 paddy soil profiles around Yunfu pyrite mine area was investigated. Rice plant samples were collected from the corresponding soil sampling site. The results showed that Tl concentrations in paddy soils at 0-60 cm depth range from 3.07 to 9.42 mg kg -1 , with a mean of 5.74 mg kg -1 , which were significantly higher than the background value of soil in China (0.58 mg kg -1 ). On the whole, Tl contents in paddy soil profiles increased quickly with soil depth from 0 to 30 cm and decreased slowly with soil depth from 30 to 60 cm. The soil Tl content was significant negatively correlated with soil pH. The mean content of Tl in the root, stem, leaf, and rice was 4.36, 1.83, 2.74, and 1.42 mg kg -1 , respectively, which exceeded the proposed permissible limits for foods and feedstuffs in Germany. The Tl content in various tissues of the rice plants followed the order root > leaf > stem (rice), which suggested that most Tl taken up by rice plants retained in the root, and a little migrated to the leaf, stem, and rice. Correlation analysis showed that Tl content in root was significant positively correlated with Tl content in leaf and rice. The ranges of hazard quotient (HQ) values were 4.08∼24.50 and 3.84∼22.38 for males and females, respectively. Males have higher health risk than females in the same age group. In childhood age groups (2 to <21 years) and adult age groups (21 to <70 years), the highest health risk level was observed in the 11 to 16 age group and 21 to 50 age group, respectively. The findings indicated that regular irrigation with Tl-bearing acid mine drainage led to considerable contamination of Tl in paddy soil and rice plant. Local government

  1. Adaptation of ammonia-oxidizing microorganisms to environment shift of paddy field soil.

    Science.gov (United States)

    Ke, Xiubin; Lu, Yahai

    2012-04-01

    Adaptation of microorganisms to the environment is a central theme in microbial ecology. The objective of this study was to investigate the response of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) to a soil medium shift. We employed two rice field soils collected from Beijing and Hangzhou, China. These soils contained distinct AOB communities dominated by Nitrosomonas in Beijing rice soil and Nitrosospira in Hangzhou rice soil. Three mixtures were generated by mixing equal quantities of Beijing soil and Hangzhou soil (BH), Beijing soil with sterilized Hangzhou soil (BSH), and Hangzhou soil with sterilized Beijing soil (HSB). Pure and mixed soils were permanently flooded, and the surface-layer soil where ammonia oxidation occurred was collected to determine the response of AOB and AOA to the soil medium shift. AOB populations increased during the incubation, and the rates were initially faster in Beijing soil than in Hangzhou soil. Nitrosospira (cluster 3a) and Nitrosomonas (communis cluster) increased with time in correspondence with ammonia oxidation in the Hangzhou and Beijing soils, respectively. The 'BH' mixture exhibited a shift from Nitrosomonas at day 0 to Nitrosospira at days 21 and 60 when ammonia oxidation became most active. In 'HSB' and 'BSH' mixtures, Nitrosospira showed greater stimulation than Nitrosomonas, both with and without N amendment. These results suggest that Nitrosospira spp. were better adapted to soil environment shifts than Nitrosomonas. Analysis of the AOA community revealed that the composition of AOA community was not responsive to the soil environment shifts or to nitrogen amendment. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  2. Stratification of Diversity and Activity of Methanogenic and Methanotrophic Microorganisms in a Nitrogen-Fertilized Italian Paddy Soil

    Directory of Open Access Journals (Sweden)

    Annika Vaksmaa

    2017-11-01

    Full Text Available Paddy fields are important ecosystems, as rice is the primary food source for about half of the world’s population. Paddy fields are impacted by nitrogen fertilization and are a major anthropogenic source of methane. Microbial diversity and methane metabolism were investigated in the upper 60 cm of a paddy soil by qPCR, 16S rRNA gene amplicon sequencing and anoxic 13C-CH4 turnover with a suite of electron acceptors. The bacterial community consisted mainly of Acidobacteria, Chloroflexi, Proteobacteria, Planctomycetes, and Actinobacteria. Among archaea, Euryarchaeota and Bathyarchaeota dominated over Thaumarchaeota in the upper 30 cm of the soil. Bathyarchaeota constituted up to 45% of the total archaeal reads in the top 5 cm. In the methanogenic community, Methanosaeta were generally more abundant than the versatile Methanosarcina. The measured maximum methane production rate was 444 nmol gdwh-1, and the maximum rates of nitrate-, nitrite-, and iron-dependent anaerobic oxidation of methane (AOM were 57 nmol, 55 nmol, and 56 nmol gdwh-1, respectively, at different depths. qPCR revealed a higher abundance of ‘Candidatus Methanoperedens nitroreducens’ than methanotrophic NC10 phylum bacteria at all depths, except at 60 cm. These results demonstrate that there is substantial potential for AOM in fertilized paddy fields, with ‘Candidatus Methanoperedens nitroreducens’ archaea as a potential important contributor.

  3. Adsorption and desorption of Cu2+ on paddy soil aggregates pretreated with different levels of phosphate.

    Science.gov (United States)

    Dai, Jun; Wang, Wenqin; Wu, Wenchen; Gao, Jianbo; Dong, Changxun

    2017-05-01

    Interactions between anions and cations are important for understanding the behaviors of chemical pollutants and their potential risks in the environment. Here we prepared soil aggregates of a yellow paddy soil from the Taihu Lake region, and investigated the effects of phosphate (P) pretreatment on adsorption-desorption of Cu 2+ of soil aggregates, free iron oxyhydrates-removed soil aggregates, goethite, and kaolinite with batch adsorption method. The results showed that Cu 2+ adsorption was reduced on the aggregates pretreated with low concentrations of P, and promoted with high concentrations of P, showing a V-shaped change. Compared with the untreated aggregates, the adsorption capacity of Cu 2+ was reduced when P application rates were lower than 260, 220, 130 and 110mg/kg for coarse, clay, silt and fine sand fractions, respectively. On the contrary, the adsorption capacity of Cu 2+ was higher on P-pretreated soil aggregates than on the control ones when P application rates were greater than those values. However, the desorption of Cu 2+ was enhanced at low levels of P, but suppressed at high levels of P, displaying an inverted V-shaped change over P adsorption. The Cu 2+ adsorption by the aggregate particles with and without P pretreatments was well described by the Freundlich equation. Similar results were obtained on P-pretreated goethite. However, such P effects on Cu 2+ adsorption-desorption were not observed on kaolinite and free iron oxyhydrates-removed soil aggregates. The present results indicate that goethite is one of the main soil substances responsible for the P-induced promotion and inhibition of Cu 2+ adsorption. Copyright © 2016. Published by Elsevier B.V.

  4. Downward migration of radiocesium in an abandoned paddy soil after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Takahashi, Junko; Wakabayashi, Shokichi; Tamura, Kenji; Onda, Yuichi

    2018-02-01

    After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, continuous monitoring of the detailed vertical distribution of radiocesium in soil is required to evaluate the fate of radiocesium and establish strategies for remediation and management of the contaminated land. It is especially important to investigate paddy soil because little knowledge has been accumulated for paddy soil and wetland rice is a major staple in Japan. Therefore, we monitored the vertical distribution of 137 Cs in abandoned paddy soil in a planned evacuation zone from June 2011 to March 2016. The decontamination works (i.e., 5 cm of surface soil removal and re-covering with uncontaminated soil) were conducted by the government in 2015. As a result of monitoring, the 137 Cs gradually migrated downward with time and the 137 Cs concentration in the 0-10 cm soil was almost homogenous in October 2014, although it was non-cultivated. The liner relationship was obtained between the median depth, which is the thickness of a soil layer containing half of the total 137 Cs inventory, and the time after the accident, indicating the migration rate was constant (1.3 cm y -1 ) before the decontamination works. After the decontamination works, the 137 Cs concentration in the uppermost surface layer was reduced by 90%, however the total 137 Cs inventory was reduced by only 50-70%. It was shown that the efficiency of 137 Cs removal by the decontamination works decrease linearly over time in fields like the studied paddy, in which the homogenization of 137 Cs concentration occurred. Conversely, the downward migration of 137 Cs to subsurface layers deeper than 10 cm (i.e., plowpan layer) with low permeability rarely occurred. It is expected that these unique trends in distribution and migration of 137 Cs would be found in abandoned paddy soils with properties similar to the studied soil, sandy loam but poorly drained because of the low permeable plowpan layer, although further validation is

  5. Increased microbial functional diversity under long-term organic and integrated fertilization in a paddy soil.

    Science.gov (United States)

    Ding, Long-Jun; Su, Jian-Qiang; Sun, Guo-Xin; Wu, Jin-Shui; Wei, Wen-Xue

    2018-02-01

    Microbes play key roles in diverse biogeochemical processes including nutrient cycling. However, responses of soil microbial community and functional genes to long-term integrated fertilization (chemical combined with organic fertilization) remain unclear. Here, we used pyrosequencing and a microarray-based GeoChip to explore the shifts of microbial community and functional genes in a paddy soil which received over 21-year fertilization with various regimes, including control (no fertilizer), rice straw (R), rice straw plus chemical fertilizer nitrogen (NR), N and phosphorus (NPR), NP and potassium (NPKR), and reduced rice straw plus reduced NPK (L-NPKR). Significant shifts of the overall soil bacterial composition only occurred in the NPKR and L-NPKR treatments, with enrichment of certain groups including Bradyrhizobiaceae and Rhodospirillaceae families that benefit higher productivity. All fertilization treatments significantly altered the soil microbial functional structure with increased diversity and abundances of genes for carbon and nitrogen cycling, in which NPKR and L-NPKR exhibited the strongest effect, while R exhibited the least. Functional gene structure and abundance were significantly correlated with corresponding soil enzymatic activities and rice yield, respectively, suggesting that the structural shift of the microbial functional community under fertilization might promote soil nutrient turnover and thereby affect yield. Overall, this study indicates that the combined application of rice straw and balanced chemical fertilizers was more pronounced in shifting the bacterial composition and improving the functional diversity toward higher productivity, providing a microbial point of view on applying a cost-effective integrated fertilization regime with rice straw plus reduced chemical fertilizers for sustainable nutrient management.

  6. Microbial Community and Functional Structure Significantly Varied among Distinct Types of Paddy Soils But Responded Differently along Gradients of Soil Depth Layers

    Directory of Open Access Journals (Sweden)

    Ren Bai

    2017-05-01

    Full Text Available Paddy rice fields occupy broad agricultural area in China and cover diverse soil types. Microbial community in paddy soils is of great interest since many microorganisms are involved in soil functional processes. In the present study, Illumina Mi-Seq sequencing and functional gene array (GeoChip 4.2 techniques were combined to investigate soil microbial communities and functional gene patterns across the three soil types including an Inceptisol (Binhai, an Oxisol (Leizhou, and an Ultisol (Taoyuan along four profile depths (up to 70 cm in depth in mesocosm incubation columns. Detrended correspondence analysis revealed that distinctly differentiation in microbial community existed among soil types and profile depths, while the manifest variance in functional structure was only observed among soil types and two rice growth stages, but not across profile depths. Along the profile depth within each soil type, Acidobacteria, Chloroflexi, and Firmicutes increased whereas Cyanobacteria, β-proteobacteria, and Verrucomicrobia declined, suggesting their specific ecophysiological properties. Compared to bacterial community, the archaeal community showed a more contrasting pattern with the predominant groups within phyla Euryarchaeota, Thaumarchaeota, and Crenarchaeota largely varying among soil types and depths. Phylogenetic molecular ecological network (pMEN analysis further indicated that the pattern of bacterial and archaeal communities interactions changed with soil depth and the highest modularity of microbial community occurred in top soils, implying a relatively higher system resistance to environmental change compared to communities in deeper soil layers. Meanwhile, microbial communities had higher connectivity in deeper soils in comparison with upper soils, suggesting less microbial interaction in surface soils. Structure equation models were developed and the models indicated that pH was the most representative characteristics of soil type and

  7. Microbial Community and Functional Structure Significantly Varied among Distinct Types of Paddy Soils But Responded Differently along Gradients of Soil Depth Layers.

    Science.gov (United States)

    Bai, Ren; Wang, Jun-Tao; Deng, Ye; He, Ji-Zheng; Feng, Kai; Zhang, Li-Mei

    2017-01-01

    Paddy rice fields occupy broad agricultural area in China and cover diverse soil types. Microbial community in paddy soils is of great interest since many microorganisms are involved in soil functional processes. In the present study, Illumina Mi-Seq sequencing and functional gene array (GeoChip 4.2) techniques were combined to investigate soil microbial communities and functional gene patterns across the three soil types including an Inceptisol (Binhai), an Oxisol (Leizhou), and an Ultisol (Taoyuan) along four profile depths (up to 70 cm in depth) in mesocosm incubation columns. Detrended correspondence analysis revealed that distinctly differentiation in microbial community existed among soil types and profile depths, while the manifest variance in functional structure was only observed among soil types and two rice growth stages, but not across profile depths. Along the profile depth within each soil type, Acidobacteria , Chloroflexi , and Firmicutes increased whereas Cyanobacteria , β -proteobacteria , and Verrucomicrobia declined, suggesting their specific ecophysiological properties. Compared to bacterial community, the archaeal community showed a more contrasting pattern with the predominant groups within phyla Euryarchaeota , Thaumarchaeota , and Crenarchaeota largely varying among soil types and depths. Phylogenetic molecular ecological network (pMEN) analysis further indicated that the pattern of bacterial and archaeal communities interactions changed with soil depth and the highest modularity of microbial community occurred in top soils, implying a relatively higher system resistance to environmental change compared to communities in deeper soil layers. Meanwhile, microbial communities had higher connectivity in deeper soils in comparison with upper soils, suggesting less microbial interaction in surface soils. Structure equation models were developed and the models indicated that pH was the most representative characteristics of soil type and

  8. CYANOBACTERIA FOR MITIGATING METHANE EMISSION FROM SUBMERGED PADDY FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Upasana Mishra; Shalini Anand [Department of Environmental Studies, Inderprastha Engineering College, Sahibabad, Ghaziabad (India)

    2008-09-30

    Atmospheric methane, a potent greenhouse gas with high absorption potential for infrared radiation, is responsible for one forth of the total anticipated warming. It is forming a major part of green house gases, next after carbon dioxide. Its concentration has been increasing alarmingly on an average at the rate of one percent per year. Atmospheric methane, originating mainly from biogenic sources such as paddy fields, natural wetlands and landfills, accounts for 15-20% of the world's total anthropogenic methane emission. With intensification of rice cultivation in coming future, methane emissions from paddy fields are anticipated to increase. India's share in world's rice production is next after to China and likewise total methane emission from paddy fields also. Methane oxidation through planktophytes, particularly microalgae which are autotrophic and abundant in rice rhizospheres, hold promise in controlling methane emission from submerged paddy fields. The present study is focused on the role of nitrogen fixing, heterocystous cyanobacteria and Azolla (a water fern harboring a cyanobacterium Anabaena azollae) as biological sink for headspace concentration of methane in flooded soils. In this laboratory study, soil samples containing five potent nitrogen fixer cyanobacterial strains from paddy fields, were examined for their methane reducing potential. Soil sample without cyanobacterial strain was tested and taken as control. Anabaena sp. was found most effective in inhibiting methane concentration by 5-6 folds over the control. Moist soil cores treated with chemical nitrogen, urea, in combination with cyanobacteria mixture, Azolla microphylla or cyanobacteria mixture plus Azolla microphylla exhibited significance reduction in the headspace concentration of methane than the soil cores treated with urea alone. Contrary to other reports, this study also demonstrates that methane oxidation in soil core samples from paddy fields was stimulated by

  9. Concentrations of major and trace elements in polished rice and paddy soils collected in Aomori, Japan

    International Nuclear Information System (INIS)

    Tsukada, H.; Hasegawa, H.; Takeda, A.; Hisamatsu, S.

    2005-01-01

    Rice is a staple food in most Asian countries including Japan, and it is important to evaluate the intake of elements through polished rice ingestion in daily life. Rice grain samples and surface paddy soil samples were collected from 20 sites throughout Aomori Prefecture, Japan. Rice grains were threshed and then polished to 90% of the total weight of brown rice. The polished rice samples for the determination of the neutron activation analysis (NAA) were dried at 50 degree C and those of the inductively coupled plasma-mass spectrometer (ICP-MS) were ashed at a temperature below 450 degree C to avoid loss of alkali metals. The soil samples were dried at 50 degree C and were pulverized with an agate ball mill. The concentrations of As, Cl and I in the polished rice and As, Cl, I, Ti and Zr in the soils were determined by the NAA. The concentrations of 22 elements in the polished rice and 28 elements in the soils were determined by the ICP-MS. The mean concentrations of essential elements in the polished rice such as K, Mg, Cl, Ca, Zn, Mn, Fe, Cu and Mo were 720, 270, 160, 54, 16, 9.7, 2.3, 21 and 0.47 mg kg -1 dry weight, respectively, and the range of each element was within one order of magnitude. However, the ranges of most trace elements in the polished rice including Al, Ni, Ba, Cd, Pb, Cr, I, Ag and Cs were more than one order of magnitude. The mean concentrations of non-essential elements in the polished rice were as follows: Na, 11; Al, 3.9; Rb, 1.2; Ni, 0.11; As, Sr, Ba, Cd, V and Pb, 0.1-0.01; Cr, I, Co, Ag, Se and Cs, O.Ol-0.001 mg kg -1 dry weight. The concentration ranges of elements, except for I, in the paddy soils were within one order of magnitude. The mean concentrations of elements in the soils were as follows: Al, Fe, Ca and Na, 100000-10000; Mg, K and Ti, 10000-1000; Mn, Ba, Cl, Zr, Sr and Zn, 1000-100; V, Ce, Cr, Rb, Cu, Pb, Sc, La, As and Ni, 100-10; Co, Th, Cs, I, U, Mo and Se, 10-1; Sb, Cd and Ag, 1-0.1 mg kg -1 . The mean concentrations of

  10. Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil.

    Science.gov (United States)

    Ok, Yong Sik; Usman, Adel R A; Lee, Sang Soo; Abd El-Azeem, Samy A M; Choi, Bongsu; Hashimoto, Yohey; Yang, Jae E

    2011-10-01

    Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer+rapeseed residue (N70+R), 30% mineral N fertilizer+rapeseed residue (N30+R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70+R and N30+R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Organic fertilizer application increases the soil respiration and net ecosystem carbon dioxide absorption of paddy fields under water-saving irrigation.

    Science.gov (United States)

    Yang, Shihong; Xiao, Ya Nan; Xu, Junzeng

    2018-04-01

    Quantifying carbon sequestration in paddy soil is necessary to understand the effect of agricultural practices on carbon cycles. The objective of this study was to assess the effect of organic fertilizer addition (MF) on the soil respiration and net ecosystem carbon dioxide (CO 2 ) absorption of paddy fields under water-saving irrigation (CI) in the Taihu Lake Region of China during the 2014 and 2015 rice-growing seasons. Compared with the traditional fertilizer and water management (FC), the joint regulation of CI and MF (CM) significantly increased the rice yields and irrigation water use efficiencies of paddy fields by 4.02~5.08 and 83.54~109.97% (p < 0.05). The effects of organic fertilizer addition on soil respiration and net ecosystem CO 2 absorption rates showed inter-annual differences. CM paddy fields showed a higher soil respiration and net CO 2 absorption rates during some periods of the rice growth stage in the first year and during most periods of the rice growth stage in the second year. These fields also had significantly higher total CO 2 emission through soil respiration (total R soil ) and total net CO 2 absorption compared with FC paddy fields (p < 0.05). The total R soil and net ecosystem CO 2 absorption of CM paddy fields were 67.39~91.55 and 129.41~113.75 mol m -2 , which were 27.66~135.52 and 12.96~31.66% higher than those of FC paddy fields. The interaction between water and fertilizer management had significant effects on total net ecosystem CO 2 absorption. The frequent alternate wet-dry cycles of CI paddy fields increased the soil respiration and reduced the net CO 2 absorption. Organic fertilizer promoted the soil respiration of paddy soil but also increased its net CO 2 absorption and organic carbon content. Therefore, the joint regulation of water-saving irrigation and organic fertilizer is an effective measure for maintaining yield, increasing irrigation water use efficiency, mitigating CO 2 emission, and promoting paddy

  12. Interactive effects of straw-derived biochar and N fertilization on soil C storage and rice productivity in rice paddies of Northeast China

    International Nuclear Information System (INIS)

    Sui, Yanghui; Gao, Jiping; Liu, Caihong; Zhang, Wenzhong; Lan, Yu; Li, Shuhang; Meng, Jun; Xu, Zhengjin; Tang, Liang

    2016-01-01

    Impacts of biochar on greenhouse gas emissions and C sequestration in agricultural soils have been considered as the key to mitigate climate change. There is limited knowledge regarding the effects of rice straw-derived biochar and interaction with N fertilization on soil C sequestration and rice productivity in fertile paddy fields. A 2-year (2013 and 2014) consecutive field trial was performed using straw treatment (5.05 t ha −1 ) and biochar amendment (0, 1.78, 14.8 and 29.6 t ha −1 ) with or without urea application in a rice paddy in Northeast China. A super high yielding rice variety (Oryza sativa L. subsp. Japonica cv. ‘Shennong 265’) was cultivated with permanent flooding. Results showed that biochar amendments significantly decreased CH 4 emissions relative to straw treatment irrespective of N fertilization, especially in N-fertilized soils with 1.78 t ha −1 biochar. There were no differences in CO 2 emissions with respect to biochar amendments, except for 14.8 t ha −1 biochar with N fertilization. Straw treatment had the highest global warming potential over a 100-year time frame, which was nearly 1.5 times that of 14.8 t ha −1 biochar amendment without N fertilization. Biochar addition increased total soil C by up to 5.75 mg g −1 and 11.69 mg g −1 (with 14.8 and 29.6 t ha −1 biochar, respectively), whereas straw incorporation increased this value by only 3.92 mg g −1 . The aboveground biomass of rice in biochar-amended soils increased to varying degrees compared with that in straw-treated soils. However, biochar application had no effects on rice yield, regardless of N fertilization. This study indicated that transforming straw to biochar was more stabilized and more suitable to mitigate greenhouse gas emissions and increase C storage in agriculture soils in Northeast China. - Highlights: • Rice straw-derived biochar significantly reduced CH 4 emission. • Rice straw-derived biochar interacted with the effects of N fertilizers on

  13. Interactive effects of straw-derived biochar and N fertilization on soil C storage and rice productivity in rice paddies of Northeast China

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Yanghui [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China); Gao, Jiping [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China); Liaoning Biochar Engineering & Technology Research Center, Shenyang Agricultural University, Dongling Rd, Shenyang 110866 (China); Liu, Caihong; Zhang, Wenzhong [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China); Lan, Yu [Liaoning Biochar Engineering & Technology Research Center, Shenyang Agricultural University, Dongling Rd, Shenyang 110866 (China); Li, Shuhang [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China); Meng, Jun [Liaoning Biochar Engineering & Technology Research Center, Shenyang Agricultural University, Dongling Rd, Shenyang 110866 (China); Xu, Zhengjin, E-mail: xuzhengjin@126.com [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China); Tang, Liang, E-mail: tl_rice@126.com [Rice Research Institute, Shenyang Agricultural University, Shenyang 110866 (China)

    2016-02-15

    Impacts of biochar on greenhouse gas emissions and C sequestration in agricultural soils have been considered as the key to mitigate climate change. There is limited knowledge regarding the effects of rice straw-derived biochar and interaction with N fertilization on soil C sequestration and rice productivity in fertile paddy fields. A 2-year (2013 and 2014) consecutive field trial was performed using straw treatment (5.05 t ha{sup −1}) and biochar amendment (0, 1.78, 14.8 and 29.6 t ha{sup −1}) with or without urea application in a rice paddy in Northeast China. A super high yielding rice variety (Oryza sativa L. subsp. Japonica cv. ‘Shennong 265’) was cultivated with permanent flooding. Results showed that biochar amendments significantly decreased CH{sub 4} emissions relative to straw treatment irrespective of N fertilization, especially in N-fertilized soils with 1.78 t ha{sup −1} biochar. There were no differences in CO{sub 2} emissions with respect to biochar amendments, except for 14.8 t ha{sup −1} biochar with N fertilization. Straw treatment had the highest global warming potential over a 100-year time frame, which was nearly 1.5 times that of 14.8 t ha{sup −1} biochar amendment without N fertilization. Biochar addition increased total soil C by up to 5.75 mg g{sup −1} and 11.69 mg g{sup −1} (with 14.8 and 29.6 t ha{sup −1} biochar, respectively), whereas straw incorporation increased this value by only 3.92 mg g{sup −1}. The aboveground biomass of rice in biochar-amended soils increased to varying degrees compared with that in straw-treated soils. However, biochar application had no effects on rice yield, regardless of N fertilization. This study indicated that transforming straw to biochar was more stabilized and more suitable to mitigate greenhouse gas emissions and increase C storage in agriculture soils in Northeast China. - Highlights: • Rice straw-derived biochar significantly reduced CH{sub 4} emission. • Rice straw

  14. Enrichment of anaerobic nitrate-dependent methanotrophic ?Candidatus Methanoperedens nitroreducens? archaea from an Italian paddy field soil

    OpenAIRE

    Vaksmaa, Annika; Guerrero-Cruz, Simon; van Alen, Theo A.; Cremers, Geert; Ettwig, Katharina F.; L?ke, Claudia; Jetten, Mike S. M.

    2017-01-01

    Paddy fields are a significant source of methane and contribute up to 20% of total methane emissions from wetland ecosystems. These inundated, anoxic soils featuring abundant nitrogen compounds and methane are an ideal niche for nitrate-dependent anaerobic methanotrophs. After 2?years of enrichment with a continuous supply of methane and nitrate as the sole electron donor and acceptor, a stable enrichment dominated by ?Candidatus Methanoperedens nitroreducens? archaea and ?Candidatus Methylom...

  15. Investigation of Hg uptake and transport between paddy soil and rice seeds combining Hg isotopic composition and speciation

    OpenAIRE

    C. Feng; Z. Pedrero; P. Li; B. Du; X. Feng; M. Monperrus; E. Tessier; S. Berail; D. Amouroux

    2016-01-01

    Abstract Human consumption of rice constitutes a potential toxicological risk in mercury (Hg) polluted areas such as Hg mining regions in China. It is recognized to be an important source of Hg for the local human diet considering the efficient bioaccumulation of methylmercury (MeHg) in rice seed. To assess Hg sources and uptake pathways to the rice plants, Hg speciation and isotopic composition were investigated in rice seeds and their corresponding paddy soils from different locations withi...

  16. Modelling cadmium contamination in paddy soils under long-term remediation measures: Model development and stochastic simulations.

    Science.gov (United States)

    Peng, Chi; Wang, Meie; Chen, Weiping

    2016-09-01

    A pollutant accumulation model (PAM) based on the mass balance theory was developed to simulate long-term changes of heavy metal concentrations in soil. When combined with Monte Carlo simulation, the model can predict the probability distributions of heavy metals in a soil-water-plant system with fluctuating environmental parameters and inputs from multiple pathways. The model was used for evaluating different remediation measures to deal with Cd contamination of paddy soils in Youxian county (Hunan province), China, under five scenarios, namely the default scenario (A), not returning paddy straw to the soil (B), reducing the deposition of Cd (C), liming (D), and integrating several remediation measures (E). The model predicted that the Cd contents of soil can lowered significantly by (B) and those of the plants by (D). However, in the long run, (D) will increase soil Cd. The concentrations of Cd in both soils and rice grains can be effectively reduced by (E), although it will take decades of effort. The history of Cd pollution and the major causes of Cd accumulation in soil were studied by means of sensitivity analysis and retrospective simulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Identification of qSOR1, a major rice QTL involved in soil-surface rooting in paddy fields.

    Science.gov (United States)

    Uga, Yusaku; Hanzawa, Eiko; Nagai, Shinsei; Sasaki, Kazuhiro; Yano, Masahiro; Sato, Tadashi

    2012-01-01

    Specific Indonesian lowland rice (Oryza sativa L.) cultivars elongate thick primary roots on the soil surface of paddy fields. To clarify the genetic factors controlling soil-surface rooting, we performed quantitative trait locus (QTL) analyses using 124 recombinant inbred lines (RILs) derived from a cross between Gemdjah Beton, an Indonesian lowland rice cultivar with soil-surface roots, and Sasanishiki, a Japanese lowland rice cultivar without soil-surface roots. These cultivars and the RILs were tested for soil-surface rooting in a paddy field. We identified four regions of chromosomes 3, 4, 6, and 7 that were associated with soil-surface rooting in the field. Among them, one major QTL was located on the long arm of chromosome 7. This QTL explained 32.5-53.6% of the total phenotypic variance across three field evaluations. To perform fine mapping of this QTL, we measured the basal root growth angle of crown roots at the seedling stage in seven BC(2)F(3) recombinant lines grown in small cups in a greenhouse. The QTL was mapped between markers RM21941 and RM21976, which delimit an 812-kb interval in the reference cultivar Nipponbare. We have designated this QTL qSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1).

  18. Residence half-time of {sup 137}Cs in the top-soils of Japanese paddy and upland fields

    Energy Technology Data Exchange (ETDEWEB)

    Komamura, Misako [National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan); Tsumura, Akito; Kodaira, Kiyoshi

    1999-03-01

    A series of top-soil samples of 14 paddy fields and 10 upland fields in Japan, were annually collected during more than 30 years, to be examined in the contents of {sup 137}Cs. The data, which were obtained by the use of a gamma spectrometric system, received some statistical treatments to distinguish the annual decline of {sup 137}Cs contents from deviations. Then the authors calculated `residence half-time of {sup 137}Cs` within top-soil, and `eluviation rate of {sup 137}Cs` from top to the sub-layer of the soil. The following nationwide results were obtained irrespective of paddy or upland field: (1) The `apparent residence half-time` was estimated as 16 - 17 years. This consists of both effects of eluviation and nuclear disintegration. (2) The true residence half-time` was reported as 41 - 42 years. This depends on the eluviation speed of {sup 137}Cs exclusively, because the influence of nuclear disintegration has been compensated. (3) The eluviation rate of {sup 137}Cs from top-soil down to the sub-soil was 1.6 - 1.7% per year. (4) The ratio of distribution of {sup 137}Cs between top-soil and the sub-soil was estimated to be 6:4 as average at the date of 1996. (author)

  19. Effect of Flooding and the nosZ Gene in Bradyrhizobia on Bradyrhizobial Community Structure in the Soil.

    Science.gov (United States)

    Saeki, Yuichi; Nakamura, Misato; Mason, Maria Luisa T; Yano, Tsubasa; Shiro, Sokichi; Sameshima-Saito, Reiko; Itakura, Manabu; Minamisawa, Kiwamu; Yamamoto, Akihiro

    2017-06-24

    We investigated the effects of the water status (flooded or non-flooded) and presence of the nosZ gene in bradyrhizobia on the bradyrhizobial community structure in a factorial experiment that examined three temperature levels (20°C, 25°C, and 30°C) and two soil types (andosol and gray lowland soil) using microcosm incubations. All microcosms were inoculated with Bradyrhizobium japonicum USDA6 T , B. japonicum USDA123, and B. elkanii USDA76 T , which do not possess the nosZ gene, and then half received B. diazoefficiens USDA110 T wt (wt for the wild-type) and the other half received B. diazoefficiens USDA110ΔnosZ. USDA110 T wt possesses the nosZ gene, which encodes N 2 O reductase; 110ΔnosZ, a mutant variant, does not. Changes in the community structure after 30- and 60-d incubations were investigated by denaturing-gradient gel electrophoresis and an image analysis. USDA6 T and 76 T strains slightly increased in non-flooded soil regardless of which USDA110 T strain was present. In flooded microcosms with the USDA110 T wt strain, USDA110 T wt became dominant, whereas in microcosms with the USDA110ΔnosZ, a similar change in the community structure occurred to that in non-flooded microcosms. These results suggest that possession of the nosZ gene confers a competitive advantage to B. diazoefficiens USDA110 T in flooded soil. We herein demonstrated that the dominance of B. diazoefficiens USDA110 T wt within the soil bradyrhizobial population may be enhanced by periods of flooding or waterlogging systems such as paddy-soybean rotations because it appears to have the ability to thrive in moderately anaerobic soil.

  20. Temporal dynamics of the compositions and activities of soil microbial communities post-application of the insecticide chlorantraniliprole in paddy soils.

    Science.gov (United States)

    Wu, Meng; Liu, Jia; Li, Weitao; Liu, Ming; Jiang, Chunyu; Li, Zhongpei

    2017-10-01

    Chlorantraniliprole (CAP) is a newly developed insecticide widely used in rice fields in China. There has been few studies evaluating the toxicological effects of CAP on soil-associated microbes. An 85-day microcosm experiment was performed to reveal the dissipation dynamics of CAP in three types of paddy soils in subtropical China. The effects of CAP on microbial activities (microbial biomass carbon-MBC, basal soil respiration-BSR, microbial metabolic quotient-qCO 2 , acid phosphatase and sucrose invertase activities) in the soils were periodically evaluated. Microbial phospholipid fatty acid (PLFA) analysis was used to evaluate the change of soil microbial community composition on day 14 and 50 of the experiment. CAP residues were extracted using the quick, easy, cheap, effective, rugged, and safe (QuChERS) method and quantification was measured by high performance liquid chromatography (HPLC). The half-lives (DT 50 ) of CAP were in the range of 41.0-53.0 days in the three soils. The results showed that CAP did not impart negative effects on MBC during the incubation. CAP inhibited BSR, qCO 2 , acid phosphatase and sucrose invertase activities in the first 14 days of incubation in all the soils. After day 14, the soil microbial parameters of CAP-treated soils became statistically at par with their controls. Principal component analysis (PCA) determining abundance of biomarker PLFAs indicated that the application of CAP significantly changed the compositions of microbial communities in all three paddy soils on day 14 but the compositions of soil microbial communities recovered by day 50. This study indicates that CAP does not ultimately impair microbial activities and microbial compositions of these three paddy soil types. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Influence of gypsum amendment on methane emission from paddy rice soil affected by saline irrigation water

    Directory of Open Access Journals (Sweden)

    Ei Ei eTheint

    2016-01-01

    Full Text Available To investigate the influence of gypsum application on methane (CH4 emission from paddy rice soil affected by saline irrigation water, two pot experiments with the rice cultivation were conducted. In pot experiment (I, salinity levels 30 mMNaCl (S30 and 90 mMNaCl (S90, that showed maximum and minimum CH4 production in an incubation experiment, respectively, were selected and studied without and with application of 1 Mg gypsum ha-1(G1. In pot experiment (II, CH4 emission was investigated under different rates of gypsum application: 1 (G1, 2.5 (G2.5 and 5 (G5 Mg gypsum ha-1 under a non-saline and saline condition of 25 mMNaCl (S25. In experiment (I, the smallest CH4 emission was observed in S90. Methane emission in S30 was not significantly different with the non-saline control. The addition of gypsum showed significant lower CH4 emission in saline and non-saline treatments compared with non-saline control. In experiment (II, the CH4 emissions in the saline treatments were not significantly different to the non-saline treatments except S25-G5. However, our work has shown that gypsum can lower CH4 emissions under saline and non-saline conditions. Thus, gypsum can be used as a CH4 mitigation option in non-saline as well as in saline conditions.

  2. Growth and Cd uptake by rice (Oryza sativa) in acidic and Cd-contaminated paddy soils amended with steel slag.

    Science.gov (United States)

    He, Huaidong; Tam, Nora F Y; Yao, Aijun; Qiu, Rongliang; Li, Wai Chin; Ye, Zhihong

    2017-12-01

    Contamination of rice (Oryza sativa) by Cd is of great concern. Steel slag could be used to amend Cd-contaminated soils and make them safe for cereal production. This work was conducted to study the effects of steel slag on Cd uptake and growth of rice plants in acidic and Cd-contaminated paddy soils and to determine the possible mechanisms behind these effects. Pot (rhizobag) experiments were conducted using rice plants grown on two acidic and Cd-contaminated paddy soils with or without steel slag amendment. Steel slag amendment significantly increased grain yield by 36-45% and root catalase activity, and decreased Cd concentrations in brown rice by 66-77% compared with the control, in both soils. Steel slag amendment also markedly decreased extractable soil Cd, Cd concentrations in pore-water and Cd translocation from roots to above-ground parts. It also significantly increased soil pH, extractable Si and Ca in soils and Ca concentrations in roots. Significant positive correlations were found between extractable soil Cd and Cd concentrations in rice tissues, but it was negatively correlated with soil pH and extractable Si. Calcium in root tissues significantly and negatively correlated with Cd translocation factors from roots to straw. Overall, steel slag amendment not only significantly promoted rice growth but decreased Cd accumulation in brown rice. These benefits appear to be related to improvements in soil conditions (e.g. increasing pH, extractable Si and Ca), a reduction in extractable soil Cd, and suppression of Cd translocation from roots to above-ground parts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Mitigating yield-scaled greenhouse gas emissions through combined application of soil amendments: A comparative study between temperate and subtropical rice paddy soils.

    Science.gov (United States)

    Ali, Muhammad Aslam; Kim, P J; Inubushi, K

    2015-10-01

    Effects of different soil amendments were investigated on methane (CH4) and nitrous oxide (N2O) emissions, global warming potential (GWP) and yield scaled GWPs in paddy soils of Republic of Korea, Japan and Bangladesh. The experimental treatments were NPK only, NPK+fly ash, NPK+silicate slag, NPK+phosphogypsum(PG), NPK+blast furnace slag (BFS), NPK+revolving furnace slag (RFS), NPK+silicate slag (50%)+RFS (50%), NPK+biochar, NPK+biochar+Azolla-cyanobacteria, NPK+silicate slag+Azolla-cyanobacteria, NPK+phosphogypsum (PG)+Azolla-cyanobacteria. The maximum decrease in cumulative seasonal CH4 emissions was recorded 29.7% and 32.6% with Azolla-cyanobacteria plus phospho-gypsum amendments in paddy soils of Japan and Bangladesh respectively, followed by 22.4% and 26.8% reduction with silicate slag plus Azolla-cyanobacteria application. Biochar amendments in paddy soils of Japan and Bangladesh decreased seasonal cumulative N2O emissions by 31.8% and 20.0% respectively, followed by 26.3% and 25.0% reduction with biochar plus Azolla-cyanobacteria amendments. Although seasonal cumulative CH4 emissions were significantly increased by 9.5-14.0% with biochar amendments, however, global warming potentials were decreased by 8.0-12.0% with cyanobacterial inoculation plus biochar amendments. The maximum decrease in GWP was calculated 22.0-30.0% with Azolla-cyanobacteria plus silicate slag amendments. The evolution of greenhouse gases per unit grain yield (yield scaled GWP) was highest in the NPK treatment, which was decreased by 43-50% from the silicate slag and phosphogypsum amendments along with Azolla-cyanobacteria inoculated rice planted soils. Conclusively, it is recommended to incorporate Azolla-cyanobacteria with inorganic and organic amendments for reducing GWP and yield scaled GWP from the rice planted paddy soils of temperate and subtropical countries. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Toward optimal soil organic carbon sequestration with effects of agricultural management practices and climate change in Tai-Lake paddy soils of China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liming; Zhuang, Qianlai; He, Yujie; Liu, Yaling; Yu, Dongsheng; Zhao, Quanying; Shi, Xuezheng; Xing, Shihe; Wang, Guangxiang

    2016-08-01

    Understanding the impacts of climate change and agricultural management practices on soil organic carbon (SOC) dynamics is critical for implementing optimal farming practices and maintaining agricultural productivity. This study examines the influence of climate and agricultural management on carbon sequestration potentials in Tai-Lake Paddy soils of China using the DeNitrification-DeComposition (DNDC) model, with a high-resolution soil database (1:50,000). Model simulations considered the effects of no tillage, increasing manure application, increasing/decreasing of N-fertilizer application and crop residues, water management, and climatic shifts in temperature and precipitation. We found that the carbon sequestration potential for the 2.32 Mha paddy soils of the Tai-Lake region varied from 4.71 to 44.31 Tg C during the period 2001-2019, with an annual average SOC changes ranged from 107 to 1005 kg C ha-1 yr-1. The sequestration potential significantly increased with increasing application of N-fertilizer, manure, conservation tillage, and crop residues. To increase soil C sequestration in this region, no-tillage and increasing of crop residue return to soils and manure application are recommended. Our analysis of climate impacts on SOC sequestration suggests that the rice paddies in this region will continue to be a carbon sink under future warming conditions. In addition, because the region’s annual precipitation (>1200 mm) is high, we also recommend reducing irrigation water use for these rice paddies to conserve freshwater in the Tai-Lake region.

  5. Mitigating yield-scaled greenhouse gas emissions through combined application of soil amendments: A comparative study between temperate and subtropical rice paddy soils

    International Nuclear Information System (INIS)

    Ali, Muhammad Aslam; Kim, P.J.; Inubushi, K.

    2015-01-01

    Effects of different soil amendments were investigated on methane (CH 4 ) and nitrous oxide (N 2 O) emissions, global warming potential (GWP) and yield scaled GWPs in paddy soils of Republic of Korea, Japan and Bangladesh. The experimental treatments were NPK only, NPK + fly ash, NPK + silicate slag, NPK + phosphogypsum(PG), NPK + blast furnace slag (BFS), NPK + revolving furnace slag (RFS), NPK + silicate slag (50%) + RFS (50%), NPK + biochar, NPK + biochar + Azolla-cyanobacteria, NPK + silicate slag + Azolla-cyanobacteria, NPK + phosphogypsum (PG) + Azolla-cyanobacteria. The maximum decrease in cumulative seasonal CH 4 emissions was recorded 29.7% and 32.6% with Azolla-cyanobacteria plus phospho-gypsum amendments in paddy soils of Japan and Bangladesh respectively, followed by 22.4% and 26.8% reduction with silicate slag plus Azolla-cyanobacteria application. Biochar amendments in paddy soils of Japan and Bangladesh decreased seasonal cumulative N 2 O emissions by 31.8% and 20.0% respectively, followed by 26.3% and 25.0% reduction with biochar plus Azolla-cyanobacteria amendments. Although seasonal cumulative CH 4 emissions were significantly increased by 9.5–14.0% with biochar amendments, however, global warming potentials were decreased by 8.0–12.0% with cyanobacterial inoculation plus biochar amendments. The maximum decrease in GWP was calculated 22.0–30.0% with Azolla-cyanobacteria plus silicate slag amendments. The evolution of greenhouse gases per unit grain yield (yield scaled GWP) was highest in the NPK treatment, which was decreased by 43–50% from the silicate slag and phosphogypsum amendments along with Azolla-cyanobacteria inoculated rice planted soils. Conclusively, it is recommended to incorporate Azolla-cyanobacteria with inorganic and organic amendments for reducing GWP and yield scaled GWP from the rice planted paddy soils of temperate and subtropical countries. - Highlights: • Azolla-cyanobacteria with organic and inorganic amendments

  6. Mitigating yield-scaled greenhouse gas emissions through combined application of soil amendments: A comparative study between temperate and subtropical rice paddy soils

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Muhammad Aslam, E-mail: litonaslam@yahoo.com [Dept. of Environmental Science, Bangladesh Agricultural University, Mymensingh 2202 (Bangladesh); Dept. of Agricultural Chemistry, Gyeongsang National University, Jinju (Korea, Republic of); Division of Environmental Horticulture, Chiba University, Matsudo, Chiba 271-8510 (Japan); Kim, P.J., E-mail: pjkim@nongae.gsnu.ac.kr [Dept. of Agricultural Chemistry, Gyeongsang National University, Jinju (Korea, Republic of); Inubushi, K. [Division of Environmental Horticulture, Chiba University, Matsudo, Chiba 271-8510 (Japan)

    2015-10-01

    Effects of different soil amendments were investigated on methane (CH{sub 4}) and nitrous oxide (N{sub 2}O) emissions, global warming potential (GWP) and yield scaled GWPs in paddy soils of Republic of Korea, Japan and Bangladesh. The experimental treatments were NPK only, NPK + fly ash, NPK + silicate slag, NPK + phosphogypsum(PG), NPK + blast furnace slag (BFS), NPK + revolving furnace slag (RFS), NPK + silicate slag (50%) + RFS (50%), NPK + biochar, NPK + biochar + Azolla-cyanobacteria, NPK + silicate slag + Azolla-cyanobacteria, NPK + phosphogypsum (PG) + Azolla-cyanobacteria. The maximum decrease in cumulative seasonal CH{sub 4} emissions was recorded 29.7% and 32.6% with Azolla-cyanobacteria plus phospho-gypsum amendments in paddy soils of Japan and Bangladesh respectively, followed by 22.4% and 26.8% reduction with silicate slag plus Azolla-cyanobacteria application. Biochar amendments in paddy soils of Japan and Bangladesh decreased seasonal cumulative N{sub 2}O emissions by 31.8% and 20.0% respectively, followed by 26.3% and 25.0% reduction with biochar plus Azolla-cyanobacteria amendments. Although seasonal cumulative CH{sub 4} emissions were significantly increased by 9.5–14.0% with biochar amendments, however, global warming potentials were decreased by 8.0–12.0% with cyanobacterial inoculation plus biochar amendments. The maximum decrease in GWP was calculated 22.0–30.0% with Azolla-cyanobacteria plus silicate slag amendments. The evolution of greenhouse gases per unit grain yield (yield scaled GWP) was highest in the NPK treatment, which was decreased by 43–50% from the silicate slag and phosphogypsum amendments along with Azolla-cyanobacteria inoculated rice planted soils. Conclusively, it is recommended to incorporate Azolla-cyanobacteria with inorganic and organic amendments for reducing GWP and yield scaled GWP from the rice planted paddy soils of temperate and subtropical countries. - Highlights: • Azolla-cyanobacteria with organic and

  7. Assessment of heavy metals (Cd and Pb) and micronutrients (Cu, Mn, and Zn) of paddy (Oryza sativa L.) field surface soil and water in a predominantly paddy-cultivated area at Puducherry (Pondicherry, India), and effects of the agricultural runoff on the elemental concentrations of a receiving rivulet.

    Science.gov (United States)

    Reddy, M Vikram; Satpathy, Deepmala; Dhiviya, K Shyamala

    2013-08-01

    The concentrations of toxic heavy metals-Cd and Pb and micronutrients-Cu, Mn, and Zn were assessed in the surface soil and water of three different stages of paddy (Oryza sativa L.) fields, the stage I-the first stage in the field soon after transplantation of the paddy seedlings, holding adequate amount of water on soil surface, stage II-the middle stage with paddy plants of stem of about 40 cm length, with sufficient amount of water on the soil surface, and stage III-the final stage with fully grown rice plants and very little amount of water in the field at Bahour, a predominantly paddy cultivating area in Puducherry located on the southeast Coast of India. Comparison of the heavy metal and micronutrient concentrations of the soil and water across the three stages of paddy field showed their concentrations were significantly higher in soil compared with that of water (p soil. The elemental concentrations in paddy soil as well as water was in the ranking order of Cd > Mn > Zn > Cu > Pb indicating concentration of Cd was maximum and Pb was minimum. The elemental concentrations in both soil and water across the three stages showed a ranking order of stage II > stage III > stage I. The runoff from the paddy fields has affected the elemental concentrations of the water and sediment of an adjacent receiving rivulet.

  8. Impacts of soil incorporation of pre-incubated silica-rich rice residue on soil biogeochemistry and greenhouse gas fluxes under flooding and drying.

    Science.gov (United States)

    Gutekunst, Madison Y; Vargas, Rodrigo; Seyfferth, Angelia L

    2017-09-01

    Incorporation of silica-rich rice husk residue into flooded paddy soil decreases arsenic uptake by rice. However, the impact of this practice on soil greenhouse gas (GHG) emissions and elemental cycling is unresolved particularly as amended soils experience recurrent flooding and drying cycles. We evaluated the impact of pre-incubated silica-rich rice residue incorporation to soils on pore water chemistry and soil GHG fluxes (i.e., CO 2 , CH 4 , N 2 O) over a flooding and drying cycle typical of flooded rice cultivation. Soils pre-incubated with rice husk had 4-fold higher pore water Si than control and 2-fold higher than soils pre-incubated with rice straw, whereas the pore water As and Fe concentrations in soils amended with pre-incubated straw and husk were unexpectedly similar (maximum ~0.85μM and ~450μM levels, respectively). Pre-incubation of residues did not affect Si but did affect the pore water levels of As and Fe compared to previous studies using fresh residues where straw amended soils had higher As and Fe in pore water. The global warming potential (GWP) of soil GHG emissions decreased in the order straw (612±76g CO 2 -eqm -2 )>husk (367±42gCO 2 -eqm -2 )>ashed husk=ashed straw (251±26 and 278±28gCO 2 -eqm -2 )>control (186±23gCO 2 -eqm -2 ). The GWP increase due to pre-incubated straw amendment was due to: a) larger N 2 O fluxes during re-flooding; b) smaller contributions from larger CH 4 fluxes during flooded periods; and c) higher CH 4 and CO 2 fluxes at the onset of drainage. In contrast, the GWP of the husk amendment was dominated by CO 2 and CH 4 emissions during flooded and drainage periods, while ashed amendments increased CO 2 emissions particularly during drainage. This experiment shows that ashed residues and husk addition minimizes GWP of flooded soils and enhances pore water Si compared to straw addition even after pre-incubation. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Evaluating cadmium bioavailability in contaminated rice paddy soils and assessing potential for contaminant immobilisation with biochar.

    Science.gov (United States)

    Kosolsaksakul, Peerapat; Oliver, Ian W; Graham, Margaret C

    2018-06-01

    Cadmium (Cd) contaminated soils from the Mae Sot district in northwest Thailand, a region in which rice Cd concentrations often exceed health limits (0.4 mg/kg) set by the World Health Organisation, were examined for isotopically exchangeable Cd (Cd E values using a 111 Cd spike) to determine how this rates as a predictor of rice grain Cd in comparison with soil total Cd and solution extractable Cd (using the commonly applied BCR scheme and, in an attempt to distinguish carbonate bound forms, the Tessier soil sequential extraction scheme reagents). Step 1 of the BCR scheme (0.11 M CH 3 COOH) and step 1 of the Tessier scheme (1M MgCl 2 ) showed the highest R 2 values in regressions with rice Cd (91% and 90%, respectively), but all predictors were strongly linked to rice Cd (p soil, of the six tested, was an exception to this, where all predictors over-estimated grain Cd by a factor of 2.5-5.7, suggesting that rice grain Cd had been restricted here by the differing flooding regime and subsequent changes to redox conditions. E values and Tessier step 1 extractions were closely related, indicating that these measurements access similar pools of soil Cd. Separately, the isotopic exchangeability (representing bioavailability) of Cd was also assessed in two soils amended with rice husk and miscanthus biochars (0, 1, 5, 10, 15 and 20% w/w) in order to assess the utility of the biochars as a soil amendment for immobilising Cd in situ. One soil showed significant reductions in Cd E value at 5% rice husk biochar addition and at 15% miscanthus biochar addition however, based on the E value-rice grain Cd regression relationship previously established, the E values in the amended soils still predicted for a rice Cd concentration above the health limit. In the second soil, neither of the biochars successfully reduced the Cd E value. This indicates that further work is needed to customise biochar properties to suit specific soil and contaminant situations if they are to be

  10. Nitrogen fertilizer fate after introducing maize into a continuous paddy rice cropping system

    Science.gov (United States)

    Thiemann, Irabella; He, Yao; Siemens, Jan; Brüggemann, Nicolas; Lehndorf, Eva; Amelung, Wulf

    2017-04-01

    After introducing upland crops into permanent flooded cropping systems, soil conditions temporally change from anaerobic to aerobic, which profoundly impacts nitrogen (N) dynamics. In the framework of the DFG research unit 1701 ICON we applied a single 15N-urea pulse in a field experiment in the Philippines with three different crop rotations: continuous paddy rice, paddy rice-dry rice, and paddy rice-maize. Subsequently, we traced the fate of the labelled urea in bulk soil, rhizosphere, roots, biomass and microbial residues (amino sugars) within the following two years. 15N recovery in the first 5 cm of bulk soil was highest in the first dry season of continuous paddy rice cropping (37.8 % of applied 15N) and lowest in the paddy rice-maize rotation (19.2 %). While an accumulation over time could be observed in bulk soil in 5-20 cm depth of the continuous paddy rice system, the recoveries decreased over time within the following two years in the other cropping systems. Highest 15N-recovery in shoots and roots were found in the continuous paddy rice system in the first dry season (27.3 % in shoots, 3.2 % in roots) as well as in the following wet season (4.2 % in shoots, 0.3 % in roots). Lowest recoveries in biomass were found for the paddy rice-dry rice rotation. Long-term fixation of 15N in microbial biomass residues was observed in all cropping systems (2-3 % in the 3rd dry season). The results indicate that the introduction of maize into a continuous paddy rice cropping system can reduce the fertilizer N use efficiency especially in the first year, most likely due to nitrate leaching and gaseous losses to the atmosphere.

  11. Seasonal variation of carbon dioxide and methane exchange between rice paddy fields and atmosphere in Japan

    Science.gov (United States)

    Kokubo, R.

    2017-12-01

    Rice paddy fields spread throughout Asia and play an important role in terms of regulating greenhouse gases on the ground. Rice paddies have the potential to either increase or decrease the net balance of greenhouse gases in the atmosphere. In the rice growth period, rice paddy fields are sources of CH4, whereas they generally act as a sink of CO2. However, the behavior of greenhouse gases during fallow periods has not been well understood. A field experiment was conducted at a rice paddy field in Fuchu, central Japan in 2014. We evaluated CO2 and CH4 fluxes in the rice paddy field using the eddy covariance method. Except for 20 days after transplanting (DAT), temporal CO2 fluxes showed negative values during a rice growth period whereas they showed positive values throughout a fallow period. The positive CO2 fluxes at 2 emissions by respiration of rice plants and soil microorganisms than CO2 uptake by photosynthesis of rice plants. In the middle of the growing season at around DAT=50, CO2 emission became dominant again because flooded water was temporarily drained in the rice paddy field. Seasonal CH4 fluxes during a growth period were regulated by water management and plant growth stages. During a fallow period, however, the field was kept a non-flooded condition that resulted in an aerobic soil condition and thus very low CH4 emission.

  12. Influence of Heavy Metals and PCBs Pollution on the Enzyme Activity and Microbial Community of Paddy Soils around an E-Waste Recycling Workshop

    Directory of Open Access Journals (Sweden)

    Xianjin Tang

    2014-03-01

    Full Text Available Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m. The concentration of Cd (2.16 mg·kg−1 and Cu (69.2 mg·kg−1 were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg−1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

  13. Influence of heavy metals and PCBs pollution on the enzyme activity and microbial community of paddy soils around an e-waste recycling workshop.

    Science.gov (United States)

    Tang, Xianjin; Hashmi, Muhammad Z; Long, Dongyan; Chen, Litao; Khan, Muhammad I; Shen, Chaofeng

    2014-03-14

    Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m). The concentration of Cd (2.16 mg·kg-1) and Cu (69.2 mg·kg-1) were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg-1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

  14. Influence of Heavy Metals and PCBs Pollution on the Enzyme Activity and Microbial Community of Paddy Soils around an E-Waste Recycling Workshop

    Science.gov (United States)

    Tang, Xianjin; Hashmi, Muhammad Z.; Long, Dongyan; Chen, Litao; Khan, Muhammad I.; Shen, Chaofeng

    2014-01-01

    Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m). The concentration of Cd (2.16 mg·kg−1) and Cu (69.2 mg·kg−1) were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg−1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination. PMID:24637907

  15. Transport and retention of biochar nanoparticles in a paddy soil under environmentally-relevant solution chemistry conditions.

    Science.gov (United States)

    Chen, Ming; Wang, Dengjun; Yang, Fan; Xu, Xiaoyun; Xu, Nan; Cao, Xinde

    2017-11-01

    Land application of biochar has been increasingly recommended as a powerful strategy for carbon sequestration and soil remediation. However, the biochar particles, especially those in the nanoscale range, may migrate or carry the inherent contaminants along the soil profile, posing a potential risk to the groundwater. This study investigated the transport and retention of wood chip-derived biochar nanoparticles (NPs) in water-saturated columns packed with a paddy soil. The environmentally-relevant soil solution chemistry including ionic strength (0.10-50 mM), electrolyte type (NaCl and CaCl 2 ), and natural organic matter (0-10 mg L -1 humic acid) were tested to elucidate their effects on the biochar NPs transport. Higher mobility of biochar NPs was observed in the soil at lower ionic strengths, with CaCl 2 electrolyte being more effective than NaCl in decreasing biochar NPs transport. The retained biochar NPs in NaCl was re-entrained (∼57.7%) upon lowering transient pore-water ionic strength, indicating that biochar NPs were reversibly retained in the secondary minimum. In contrast, negligible re-entrainment of biochar NPs occurred in CaCl 2 due to the primary minimum and/or particle aggregation. Humic acid increased the mobility of biochar NPs, likely due to enhanced electrosteric repulsive interactions. The transport behaviors of biochar NPs can be well interpreted by a two-site kinetic retention model that assumes reversible retention for one site, and irreversible retention for the other site. Our findings indicated that the transport of wood chip biochar NPs is significant in the paddy soil, highlighting the importance of understanding the mobility of biochar NPs in natural soils for accurately assessing their environmental impacts. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Fate of free amino acids in paddy and upland soils by using 13C and 15N tracer techniques

    International Nuclear Information System (INIS)

    Yamamuro, Shigekazu; Ueno, Hideto; Takahashi, Shigeru

    1999-01-01

    Direct and indirect (=through decomposition) uptakes of free amino acids (FAA) by rice and tomato plants were investigated by using 13 C- and 15 N-labeled aspartic and glutamic acids, serine, leusine and ammonium as tracers. 1) One week after the surface application of amino acid-N or NH 4 -N to paddy soil, the amounts of ammonium remaining in the soil, assimilated ammonium, denitrificated ammonium and amounts taken up by plants were similar. 2) From 5.5 to 7.7% of the FAA applied was absorbed directly by rice plants, and from 42.5 to 47.2% of that was indirectly absorbed as ammonium after decomposition. It is suggested that the FAA degraded to ammonium around 2 or 3 d and the 1- 13 C absorption rates of the FAA (RCH(NH 2 ) 13 COOH) were high in proportion to the number of carbon atoms of the R side-chain. 3) The absorption rate of N derived from the FAA by tomato plants was lower than that by rice plants, namely, from 0.4 to 1.9% in direct-uptake and from 16.0 to 29.8% in indirect-uptake. Percentage of direct-uptake of the FAA in upland soil was much lower than that in the paddy field. (author)

  17. Instrumental neutron activation analysis to determine inorganic elements in paddy soil and rice and evaluate bioconcentration factors in rice

    Directory of Open Access Journals (Sweden)

    Prapamon Seeprasert

    2017-06-01

    Full Text Available Increased anthropogenic activity, especially in thriving industries and mining activity, has led to the accumulation of inorganic elements in the soil. This study applied neutron activation analysis for the determination of inorganic element concentrations in paddy soils and quantified the nutrient value of paddy rice cultivated on various agricultural sites throughout Thailand. The determination accuracy of the elements—U, As, Sb, W, Mn, K, La, Cr, Hf, Cs, Sc, Fe, Co, Cd and Zn was assessed using National Institute of Standards and Technology standard reference materials; the results were satisfactory, showing low relative error. High analytical precision was also observed. Cadmium was selected to check the linearity of the calibration curve against a Cd standard. For a calibration curve in the range 1–9 μg, a correlation coefficient of 0.997 was found. Trace amounts of U, As, Sb, W, Mn, K, La, Cr, Hf, Cs, Sc, Fe, Co, Zn and Cd were also found in the soil samples. However, the Co, Cd, and Zn concentrations were especially high in agricultural sites in Tak province. The elemental concentrations in rice followed the order K > Zn > Mn. The data obtained are of potential benefit for the development of trace element supplementation in food.

  18. Metabolism of 14C-lindane in flooded alluvial soil

    International Nuclear Information System (INIS)

    Siddaramappa, R.; Sethunathan, N.

    1975-01-01

    The effect of rice straw on the persistence of uniformly ring labelled 14 C-lindane in an alluvial soil was investigated under flooded conditions. The residues in the soil were extracted with chloroform-diethyl ether and the radioactivity was measured by liquid scintillation. The radioactivity in the solvent phase decreased more rapidly in amended soil than in unamended soil. Radioautograph of thin layer chromatograms of solvent phase indicated that lindane was readily converted to a breakdown product in both amended and unamended soils. This breakdown product was also formed in both autoclaved and nonautoclaved soils. Rice straw amendment enhanced further decomposition of lindane and its breakdown product. Heat treatment retarded further decomposition of lindane and its breakdown product whereas they were rapidly decomposed in nonautoclaved soil. These studies indicated that in flooded alluvial soil tested, lindane was initially decomposed by a chemical reaction and soil microorganisms appeared to attack the products of the chemical reaction. (author)

  19. Isolation and identification of soil fungi isolates from forest soil for flooded soil recovery

    Science.gov (United States)

    Hazwani Aziz, Nor; Zainol, Norazwina

    2018-04-01

    Soil fungi have been evaluated for their ability in increasing and recovering nitrogen, phosphorus and potassium content in flooded soil and in promoting the growth of the host plant. Host plant was cultivated in a mixture of fertile forest soil (nutrient-rich soil) and simulated flooded soil (nutrient-poor soil) in an optimized soil condition for two weeks. The soil sample was harvested every day until two weeks of planting and was tested for nitrogen, phosphorus and potassium concentration. Soil fungi were isolated by using dilution plating technique and was identified by Biolog’s Microbial Systems. The concentration of nitrogen, phosphorus, and potassium was found to be increasing after two weeks by two to three times approximately from the initial concentration recorded. Two fungi species were identified with probability more than 90% namely Aspergillus aculeatus and Paecilomyces lilacinus. Both identified fungi were found to be beneficial in enhancing plant growth and increasing the availability of nutrient content in the soil and thus recovering the nutrient content in the flooded soil.

  20. Phases and rates of iron and magnetism changes during paddy soil development on calcareous marine sediment and acid Quaternary red-clay.

    Science.gov (United States)

    Huang, Laiming; Jia, Xiaoxu; Shao, Ming'an; Chen, Liumei; Han, Guangzhong; Zhang, Ganlin

    2018-01-11

    Dynamic changes in Fe oxides and magnetic properties during natural pedogenesis are well documented, but variations and controls of Fe and magnetism changes during anthropedogenesis of paddy soils strongly affected by human activities remain poorly understood. We investigated temporal changes in different Fe pools and magnetic parameters in soil profiles from two contrasting paddy soil chronosequences developed on calcareous marine sediment and acid Quaternary red clay in Southern China to understand the directions, phases and rates of Fe and magnetism evolution in Anthrosols. Results showed that paddy soil evolution under the influence of artificial submergence and drainage caused changes in soil moisture regimes and redox conditions with both time and depth that controlled Fe transport and redistribution, leading to increasing profile differentiation of Fe oxides, rapid decrease of magnetic parameters, and formation of diagnostic horizons and features, irrespective of the different parent materials. However, the initial parent material characteristics (pH, Fe content and composition, weathering degree and landscape positions) exerted a strong influence on the rates and trajectories of Fe oxides evolution as well as the phases and rates of magnetism changes. This influence diminished with time as prolonged rice cultivation drove paddy soil evolving to common pedogenic features.

  1. Estimating CH4 emission from paddy managed soils in southern guinea savanna zone of Nigeria using an integrated approach

    Science.gov (United States)

    Akpeokhai, Agatha; Menz, Gunter; Thonfeld, Frank; Akinluyi, Francis

    2016-04-01

    ESTIMATING CH4 EMISSION FROM PADDY MANAGED SOILS IN SOUTHERN GUINEA SAVANNA ZONE OF NIGERIA USING AN INTEGRATED APPROACH Akpeokhai Agatha 1, Menz Gunter 1, Thonfeld Frank 1, Akinluyi Francis 2 1 Remote Sensing Research Group (RSRG), Geography Institute, University of Bonn, Germany. 2 Department Remote Sensing and Geo-Science Information System, School of Earth and Mineral Science, Federal University of Technology, Akure Nigeria. Methane is one of the most important greenhouse gases as it has the second greatest climate forcing potential. Paddy fields have been identified to be sources of methane and Nigerian paddies are not left out. In Nigeria, the guinea savanna region is regarded as the bread basket of the nation and this area is one of the major rice producing regions in Nigeria. Its location in the food basket region of the country makes this part a very important study site. However, since Nigerian paddies contribute to methane emission by how much do these paddies contribute to the emissions? Also, so far, there limited studies on methane from rice fields in West Africa thus making this study a very important start off point. To answer this huge question, methane emission will be estimated using an integrated approach in the North Central part of Nigeria. Land use change cultivated to rice was analysed using Remote sensing techniques to determine the changes in land cultivated to rice. Methane emission from these identified rice fields will be estimated using the IPCC Tier 1 set of equations. First relevant indices (Normalized Differential Moisture Index, Normalized Differential Wetness Index and Rice Growth Vegetation Index) were generated to aid classification of rice fields using LANDSAT data from the USGS. Next the LANDSAT datasets were analyzed for land use change cultivated to rice from 1990 to 2014 to generate rice field maps. ERDAS Imagine, ARCGIS and ENVI tools were used to meet these spatial needs. Methane emissions from this region will be

  2. Rice uptake and leaching of {sup 99}Tc in different paddy soils contaminated according to two contrasting scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Ho; Lim, Kwang Muk; Jun, In; Kim, Byung Ho; Keum, Dong Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    Four different paddy soils collected around the Gyeongju nuclear site were treated with {sup 99}TcO{sub 4}{sup -1} solution under the assumption of two contrasting contamination scenarios. Scenario I (SN-I) is for a pre-transplanting deposition of {sup 99}Tc followed by plowing, whereas SN-II is for its deposition onto the water surface shortly after transplanting. Rice plants were grown in lysimeters in a greenhouse. Plant uptake of {sup 99}Tc was quantified with the TF{sub area} (m{sup 2}·kg{sup -1}-dry). The SN-II values for straws and brown rice, having been generally higher than the SN-I values, were within the ranges of 6.9x10{sup -3}⁓4.1x10{sup -2} and 5.2x10{sup -6}⁓7.3x10{sup -5}, respectively. Sorption onto clay seems to have decreased {sup 99}Tc uptake in SN-I, whereas it may have had an insignificant effect in SN-II. A phenomenon characteristic of submerged paddy soil, i.e., the development of a thin oxic surface layer may have greatly affected the rice uptake of SN-II {sup 99}Tc. The surface-water concentrations of {sup 99}Tc were much higher in SN-II than in SN-I. For the percolating water, however, the opposite was generally true. At most 1.3% of the applied {sup 99}Tc were leached through such percolation. The use of empirical deposition time-dependent TF{sub area} values was considered desirable in assessing the radiological impact of a growing-season deposition of {sup 99}Tc onto paddy fields.

  3. Risk Assessment of Heavy Metals Contamination in Paddy Soil, Plants, and Grains (Oryza sativa L.) at the East Coast of India

    Science.gov (United States)

    Satpathy, Deepmala; Reddy, M. Vikram; Dhal, Soumya Prakash

    2014-01-01

    Heavy metals known to be accumulated in plants adversely affect human health. This study aims to assess the effects of agrochemicals especially chemical fertilizers applied in paddy fields, which release potential toxic heavy metals into soil. Those heavy metals get accumulated in different parts of paddy plant (Oryza sativa L.) including the grains. Concentrations of nonessential toxic heavy metals (Cd, Cr, and Pb) and the micronutrients (Cu, Mn, and Zn) were measured in the paddy field soil and plant parts. Mn and Cd are found to be accumulated more in shoot than in root. The metal transfer factors from soil to rice plant were significant for Pb, Cd, Cu, Cr, Mn, and Zn. The ranking order of bioaccumulation factor (BAF) for heavy metals was Zn > Mn > Cd > Cu > Cr > Pb indicating that the accumulation of micronutrients was more than that of nonessential toxic heavy metals. The concentrations of heavy metals were found to be higher in paddy field soils than that of the nearby control soil but below permissible limits. The higher Health Index (HI) values of rice consuming adults (1.561) and children (1.360) suggest their adverse health effects in the near future. PMID:24995308

  4. Heavy metals in paddy fields in Taiwan: chemical behavior in soil and uptake by brown rice

    NARCIS (Netherlands)

    Chu, C.L.; Romkens, P.F.A.M.; Guo, H.Y.

    2009-01-01

    Levels of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were measured in 19 individual paddy fields in Taiwan. Total, reactive, and available metal levels were measured using Aqua Regia, 0.43 N HNO3, 0.1 M HCl, 0.05 M EDTA and 0.01 M CaCl2. Total metal levels ranged

  5. Speciation of heavy metals in paddy soils from selected areas in ...

    African Journals Online (AJOL)

    A site in Langkawi, where organic paddy farming is practised was used as the ... four heavy metal fractions namely the easily leachable and ion exchange (ELFE), ... high in organic carbon (6.54 to 8.71%) and slightly acidic (pH 4.92 to 5.12).

  6. Hexachlorobenzene dechlorination as affected by organic fertilizer and urea applications in two rice planted paddy soils in a pot experiment

    International Nuclear Information System (INIS)

    Liu, C.Y.; Jiang, X.; Yang, X.L.; Song, Y.

    2010-01-01

    Reductive dechlorination is a crucial pathway for HCB degradation, the applications of organic materials and nitrogen can alter microbial activity and redox potential of soils, thus probably influence HCB dechlorination. To evaluate hexachlorobenzene (HCB) dechlorination as affected by organic fertilizer (OF) and urea applications in planted paddy soils, a pot experiment was conducted in two types of soils, Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An). After 18 weeks of experiment, HCB residues decreased by 28.2-37.5% of the initial amounts in Ac, and 42.1-70.9% in An. The amounts of HCB metabolites showed that dechlorination rates in An were higher than in Ac, which was mainly attributed to the higher pH and dissolved organic carbon (DOC) content of An. Both in Ac and An, the additions of 1% and 2% OF had negative effect on HCB dechlorination, which was probably because excessive nitrogen in OF decreased degraders' activity and the degradation of organic carbon in OF accepted electrons. The application of 0.03% urea could enhance HCB dechlorination rates slightly, while 0.06% urea accelerated HCB dechlorination significantly both in Ac and An. It could be assumed that urea served as an electron donor and stimulated degraders to dechlorinate HCB. In addition, the methanogenic bacteria were involved in dechlorination process, and reductive dechlorination in planted paddy soil might be impeded for the aerenchyma and O 2 supply into the rhizosphere. Results indicated that soil types, rice root system, methanogenic bacteria, OF and urea applications all had great effects on dechlorination process.

  7. Evaluation of radioactive decontamination effect for paddy soil contaminated by the Fukushima Daiichi Nuclear Power Plant accident

    International Nuclear Information System (INIS)

    Imaizumi, Masayuki; Yoshimoto, Shuhei; Ishida, Satoshi; Okushima, Shuji; Yuuki, Youichi; Hirata, Ryoji

    2016-01-01

    The National Institute for Rural Engineering performed decontamination of radioactivity at the experimental sites in Iitate Village where paddy fields were contaminated by the Fukushima Daiichi nuclear power plant accident in March 2011 by means of three methods as follows; (1) topsoil removal using soil hardener, (2) removal of soil after paddling with water draining suspended contaminated soil by pumping without manual assistance, and (3) removal of soil after paddling with water draining suspended contaminated soil by pumping with manual assistance. The three methods were evaluated using decontamination factors (DFs) that were determined by applying a variant of inverse analysis using the calculation system for the estimation of decontamination effects (CDE). Input data were provided by surveys using a low-level balloon and a radio-controlled helicopter. The DF values of the three methods were determined on the basis of the Euclidean distances between the simulated and measured dose rates after decontamination. The resulting DFs were > 60 for topsoil removal using soil hardener, 1.4 for slurry pumping, and 2.2 for manually assisted slurry pumping. The area decontaminated by the soil hardening method may have been fully decontaminated, because the distribution of measured dose rates was consistent with the distribution of dose rates calculated for a fully decontaminated area within 20 m in radius. (author)

  8. Effects of flooding on phosphorus and iron mobilization in highly weathered soils: Short-term effects and mechanisms

    Science.gov (United States)

    Maranguit, Deejay

    2017-04-01

    The strong affinity of phosphorus (P) to iron (Fe) oxides and hydroxides in highly weathered tropical soils limits P availability and therefore plant productivity. In flooded soils, however, P fixed by Fe oxides and hydroxides can be released and transformed to a more available form because of Fe3+ reduction to Fe2+. These P dynamics in flooded soils are well documented for rice paddies. Such effects are much less studied in other land-use types under the influence of seasonal flooding, especially in the tropics during heavy monsoon rains. The aim of this study was to investigate the mobilization of P during flooding leading to anaerobic conditions in topsoil and subsoil horizons depending on land-use type. Samples were collected in highly weathered soils from four replicate sites under natural rainforest, jungle rubber, rubber and oil palm plantations in Sumatra, Indonesia. Topsoil and subsoil were taken to ensure a wide range of soil organic matter (SOM) and P contents. Soils were incubated under anaerobic, flooded conditions at 30 ± 1 oC for 60 days. Our results confirmed the hypothesis that soil flooding mobilizes P and increases P availability. Two distinct and opposite phases, however, were observed upon flooding. During the first three weeks of flooding, the dissolved P (DP) concentration peaked, simultaneously with a peak of dissolved Fe2+ (DFe2+) and dissolved organic carbon (DOC) in the soil solution. After three weeks, P availability in soils decreased, although Fe-P and available P did not reach initial, pre-flooding levels. Accordingly, Fe dissolution and P mobilization were reversible processes. Furthermore, land-use type influenced the impacts of flooding on P and Fe forms mainly in the topsoil, where P dissolution and availability were generally higher under forest and, to a lesser extent, under jungle rubber. A positive correlation between DOC and DFe2+ (R2 = 0.42) in topsoil indicates that the intensity of microbially-mediated Fe3+ reduction is

  9. Evaluation of Heavy Metal Exposure to Soil and Paddy Plant around the Closed Municipal Solid Waste Landfill: Case Study at Gunung Tugel Landfill, Banyumas-Central Java

    Science.gov (United States)

    Kasam; Rahmawati, Suphia; Mulya Iresha, Fajri; Wacano, Dhandhun; Farida Fauziah, Ida; Afif Amrullah, Muhammad

    2018-01-01

    This work was focused on assessing the exposure of heavy metal from closed municipal solid waste (MSW) landfill on soil and paddy plants. This study aimed to determine heavy metal content whether at the soil in the around Gunung Tugel landfill included and accumulated in the paddy plant tissues. The investigated metals include chromium (Cr), copper (Cu), cadmium (Cd), iron (Fe), and zinc (Zn). The samples were acid-digested before the desired elements were measured using Atomic Absorption Spectrophotometry (AAS). The results are presented as distribution map of the landfill area based on the total heavy metals content distribution in the soil and paddy plants. The samples shown that the concentrations of heavy metals around Gunung Tugel landfill are 6.27-34.71 mg/kg, 0.17-0.42 mg/kg, 28.29-48.69 mg/kg, 18,997.26-32,572.29 mg/kg, 342.74-834.49 mg/kg, 136.10-290.14 mg/kg at the top soil and 0.00-1.70 mg/kg, 0.00-0.26 mg/kg, 0.79-10.46 mg/kg, 13.88-61.46 mg/kg, 18.79-50.56 mg/kg, 87.27-273.22 mg/kg at the paddy for Cr, Cd, Cu, Fe, Mn, and Zn respectively. According to the results, The Gunung Tugel landfill is not a direct source of heavy metal pollution at paddy plant in the landfill area, but through surface water and soil media. Rainfall around landfill is quite high ie more 2000 mm/year of rainfall and soil permeability is 1.0 cm/sec.

  10. Efficiency evaluation for remediating paddy soil contaminated with cadmium and arsenic using water management, variety screening and foliage dressing technologies.

    Science.gov (United States)

    Liao, Guojian; Wu, Qianhua; Feng, Renwei; Guo, Junkang; Wang, Ruigang; Xu, Yingming; Ding, Yongzhen; Fan, Zhilian; Mo, Liangyu

    2016-04-01

    Paddy soils in many regions of China have been seriously polluted by multiple heavy metals or metalloids, such as arsenic (As), cadmium (Cd) and lead (Pb). In order to ensure the safety of food and take full advantage of the limited farmland resources of China, exploring an effective technology to repair contaminated soils is urgent and necessary. In this study, three technologies were employed, including variety screening, water management and foliage dressing, to assess their abilities to reduce the accumulation of Cd and As in the grains of different rice varieties, and meanwhile monitor the related yields. The results of variety screening under insufficient field drying condition showed that the As and Cd contents in the grains of only four varieties [Fengliangyouxiang 1 (P6), Zhongzheyou 8 (P7), Guangliangyou 1128 (P10), Y-liangyou 696 (P11)] did not exceed their individual national standard. P6 gained a relatively high grain yield but accumulated less As and Cd in the grains despite of the relatively high As and Cd concentrations in the rhizosphere soil. However, long-playing field drying in water management trial significantly increased Cd but decreased As content in the grains of all tested three varieties including P6, suggesting an important role of water supply in controlling the accumulation of grain As and Cd. Selenium (Se) showed a stronger ability than silicon (Si) to reduce As and Cd accumulation in the grains of Fengliangyou 4 (P2) and Teyou 524 (P13), and keep the yields. The results of this study suggest that combined application of water management and foliage dressing may be an efficient way to control As and Cd accumulation in the grains of paddy rice exposing to As- and Cd-contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Stabilization of lead (Pb) and zinc (Zn) in contaminated rice paddy soil using starfish: A preliminary study.

    Science.gov (United States)

    Moon, Deok Hyun; Hwang, Inseong; Koutsospyros, Agamemnon; Cheong, Kyung Hoon; Ok, Yong Sik; Ji, Won Hyun; Park, Jeong-Hun

    2018-05-01

    Lead (Pb) and zinc (Zn) contaminated rice paddy soil was stabilized using natural (NSF) and calcined starfish (CSF). Contaminated soil was treated with NSF in the range of 0-10 wt% and CSF in the range of 0-5 wt% and cured for 28 days. Toxicity characteristic leaching procedure (TCLP) test was used to evaluate effectiveness of starfish treatment. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses were conducted to investigate the mechanism responsible for effective immobilization of Pb and Zn. Experimental results suggest that NSF and CSF treatments effectively immobilize Pb and Zn in treated rice paddy soil. TCLP levels for Pb and Zn were reduced with increasing NSF and CSF dosage. Comparison of the two treatment methods reveals that CSF treatment is more effective than NSF treatment. Leachability of the two metals is reduced approximately 58% for Pb and 51% for Zn, upon 10 wt% NSF treatment. More pronounced leachability reductions, 93% for Pb and 76% for Zn, are achieved upon treatment with 5 wt% CSF. Sequential extraction results reveal that NSF and CSF treatments of contaminated soil generated decrease in exchangeable/weak acid Pb and Zn soluble fractions, and increase of residual Pb and Zn fractions. Results for the SEM-EDX sample treated with 5 wt% CSF indicate that effective Pb and Zn immobilization is most probably associated with calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs). Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Uptake of radionuclides and stable elements from paddy soil to rice: a review

    International Nuclear Information System (INIS)

    Uchida, S.; Tagami, K.; Shang, Z.R.; Choi, Y.H.

    2009-01-01

    The critical paths for radionuclides and the critical foods in Asian countries differ from those in Western countries because agricultural products and diets are different. Consequently, safety assessments for Asian countries must consider rice as a critical food. As most rice is produced under flooded conditions, the uptake of radionuclides by rice is affected by soil conditions. In this report, we summarize radionuclide and stable element soil-to-plant transfer factors (TFs) for rice. Field observation results for fallout 137 Cs and stable Cs TFs indicated that while fallout 137 Cs had higher TF than stable Cs over several decades, the GM (geometric mean) values were similar with the GM of TF value for 137 Cs being 3.6 x 10 -3 and that for stable Cs being 2.5 x 10 -3 . Although there are some limitations to the use of TF for stable elements under some circumstances, these values can be used to evaluate long-term transfer of long-lived radionuclides in the environment. The compiled data showed that TF values were higher in brown rice than in white rice because distribution patterns for elements were different in the bran and white parts of rice grains.

  13. Heavy metal pollution decreases microbial abundance, diversity and activity within particle-size fractions of a paddy soil.

    Science.gov (United States)

    Chen, Junhui; He, Feng; Zhang, Xuhui; Sun, Xuan; Zheng, Jufeng; Zheng, Jinwei

    2014-01-01

    Chemical and microbial characterisations of particle-size fractions (PSFs) from a rice paddy soil subjected to long-term heavy metal pollution (P) and nonpolluted (NP) soil were performed to investigate whether the distribution of heavy metals (Cd, Cu, Pb and Zn) regulates microbial community activity, abundance and diversity at the microenvironment scale. The soils were physically fractionated into coarse sand, fine sand, silt and clay fractions. Long-term heavy metal pollution notably decreased soil basal respiration (a measurement of the total activity of the soil microbial community) and microbial biomass carbon (MBC) across the fractions by 3-45% and 21-53%, respectively. The coarse sand fraction was more affected by pollution than the clay fraction and displayed a significantly lower MBC content and respiration and dehydrogenase activity compared with the nonpolluted soils. The abundances and diversities of bacteria were less affected within the PSFs under pollution. However, significant decreases in the abundances and diversities of fungi were noted, which may have strongly contributed to the decrease in MBC. Sequencing of denaturing gradient gel electrophoresis bands revealed that the groups Acidobacteria, Ascomycota and Chytridiomycota were clearly inhibited under pollution. Our findings suggest that long-term heavy metal pollution decreased the microbial biomass, activity and diversity in PSFs, particularly in the large-size fractions. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  14. Sewage sludge biochar influence upon rice (Oryza sativa L) yield, metal bioaccumulation and greenhouse gas emissions from acidic paddy soil.

    Science.gov (United States)

    Khan, Sardar; Chao, Cai; Waqas, Muhammad; Arp, Hans Peter H; Zhu, Yong-Guan

    2013-08-06

    Biochar addition to soil has been proposed to improve plant growth by increasing soil fertility, minimizing bioaccumulation of toxic metal(liod)s and mitigating climate change. Sewage sludge (SS) is an attractive, though potentially problematic, feedstock of biochar. It is attractive because of its large abundance; however, it contains elevated concentrations of metal(loid)s and other contaminants. The pyrolysis of SS to biochar (SSBC) may be a way to reduce the availability of these contaminants to the soil and plants. Using rice plant pot experiments, we investigated the influence of SSBC upon biomass yield, bioaccumulation of nutrients, and metal(loid)s, and green housegas (GHG) emissions. SSBC amendments increased soil pH, total nitrogen, soil organic carbon and available nutrients and decreased bioavailable As, Cr, Co, Ni, and Pb (but not Cd, Cu, and Zn). Regarding rice plant properties, SSBC amendments significantly (P ≤ 0.01) increased shoot biomass (71.3-92.2%), grain yield (148.8-175.1%), and the bioaccumulation of phosphorus and sodium, though decreased the bioaccumulation of nitrogen (except in grain) and potassium. Amendments of SSBC significantly (P ≤ 0.05) reduced the bioaccumulation of As, Cr, Co, Cu, Ni, and Pb, but increased that of Cd and Zn, though not above limits set by Chinese regulations. Finally regarding GHG emissions, SSBC significantly (P rice paddy soil but the actual associated benefits will depend on site-specific conditions and source of SS; long-term effects remain a further unknown.

  15. Evaluation of the mobility and pollution index of selected essential/toxic metals in paddy soil by sequential extraction method.

    Science.gov (United States)

    Hasan, Maria; Kausar, Dilshad; Akhter, Gulraiz; Shah, Munir H

    2018-01-01

    Comparative distribution and mobility of selected essential and toxic metals in the paddy soil from district Sargodha, Pakistan was evaluated by the modified Community Bureau of Reference (mBCR) sequential extraction procedure. Most of the soil samples showed slightly alkaline nature while the soil texture was predominantly silty loam in nature. The metal contents were quantified in the exchangeable, reducible, oxidisable and residual fractions of the soil by flame atomic absorption spectrophotometry and the metal data were subjected to the statistical analyses in order to evaluate the mutual relationships among the metals in each fraction. Among the metals, Ca, Sr and Mn were found to be more mobile in the soil. A number of significant correlations between different metal pairs were noted in various fractions. Contamination factor, geoaccumulation index and enrichment factor revealed extremely severe enrichment/contamination for Cd; moderate to significant enrichment/contamination for Ni, Zn, Co and Pb while Cr, Sr, Cu and Mn revealed minimal to moderate contamination and accumulation in the soil. Multivariate cluster analysis showed significant anthropogenic intrusions of the metals in various fractions. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Feasibility Study of Soil Quality Survey using Visible and Near Infrared Spectroscopy in Rice Paddy Fields in China

    Directory of Open Access Journals (Sweden)

    Hongyi Li

    2014-06-01

    Full Text Available Survey and monitoring of soil quality are needed to prevent soil degradation and are important for sustainable farming and food production. Conventional soil survey involves intensive soil sampling and laboratory analysis, which are time consuming and expensive. Visible and near infrared spectroscopy of soil has proved to be accurate, cheap and robust and has huge potential for survey of soil quality. To test its potential, 327 soil samples were taken from long-term paddy rice fields in four provinces in south of China and covered a wide range of soil types and texture. The samples were air-dried, ground and passed through a 2 mm sieve. They were then scanned by an ASD vis–NIR spectrometer with wavelength range from 350 to 2500 nm. Organic matter (OM, pH, total nitrogen (TN and available nitrogen (N_av were also measured on soil samples to build calibration models and also to validate the models’ accuracy. On the basis of the ratio of prediction deviation (RPD, which is standard deviation (SD of prediction divided by the root mean square error of prediction (RMSEP, the accuracy of leave-one-out cross-validation of soil N_av model was classified very good (RPD=1.96 and soil OM and TN was good (RPD=1.78 and RPD=1.81, respectively. However, the model accuracy of pH was poor due to non-direct soil spectral response for soil pH in vis–NIR spectroscopy. The independent validation results showed excellent accuracy for soil N_av (RPD=3.26, good accuracy for OM and TN (RPD=1.76 and RPD=1.78 and relative poor accuracy for soil pH (RPD=1.27. This feasibility study is encouraging for the application of vis–NIR surveys of soil quality accuracy at regional and national scales; it found good to excellent accuracy for some important soil properties in quality survey.

  17. Affects of mining activities on Cd pollution to the paddy soils and rice grain in Hunan province, Central South China.

    Science.gov (United States)

    Du, Yan; Hu, Xue-Feng; Wu, Xiao-Hong; Shu, Ying; Jiang, Ying; Yan, Xiao-Juan

    2013-12-01

    Located in Central South China, Hunan province is rich in mineral resources. To study the influence of mining on Cd pollution to local agricultural eco-system, the paddy soils and rice grain of Y county in northern Hunan province were intensively monitored. The results were as follows: (1) Total Cd (T-Cd) content in the soils of the county ranges from 0.13 to 6.02 mg kg(-1), with a mean of 0.64 mg kg(-1), of which 57.5% exceed the allowable limit specified by the China Soil Environmental Quality Standards. T-Cd in the soils varies largely, with the coefficient of variation reaching 146.4%. The spatial distribution of T-Cd in the soils quite matches with that of mining and industries. The content of HCl-extractable Cd (HCl-Cd) in the soils ranges from 0.02 to 2.17 mg kg(-1), with a mean of 0.24 mg kg(-1). A significant positive correlation exists between T-Cd and HCl-Cd in the soils (r = 0.770, ρ soils (r = 0.091, ρ > 0.05), which suggests that the amount of Cd accumulating in the rice is more affected by its availability in the soils, rather than the total content. (4) The dietary intake of Cd via rice consumption in Y county is estimated to be 179.9 μg day(-1) person(-1) on average, which is far beyond the allowable limit specified by FAO/WHO and the target hazard quotients of Cd much higher than 1, suggesting the high risk on human health from Cd exposure.

  18. Effect of Elevated CO2 Concentration, Elevated Temperature and No Nitrogen Fertilization on Methanogenic Archaeal and Methane-Oxidizing Bacterial Community Structures in Paddy Soil.

    Science.gov (United States)

    Liu, Dongyan; Tago, Kanako; Hayatsu, Masahito; Tokida, Takeshi; Sakai, Hidemitsu; Nakamura, Hirofumi; Usui, Yasuhiro; Hasegawa, Toshihiro; Asakawa, Susumu

    2016-09-29

    Elevated concentrations of atmospheric CO2 ([CO2]) enhance the production and emission of methane in paddy fields. In the present study, the effects of elevated [CO2], elevated temperature (ET), and no nitrogen fertilization (LN) on methanogenic archaeal and methane-oxidizing bacterial community structures in a free-air CO2 enrichment (FACE) experimental paddy field were investigated by PCR-DGGE and real-time quantitative PCR. Soil samples were collected from the upper and lower soil layers at the rice panicle initiation (PI) and mid-ripening (MR) stages. The composition of the methanogenic archaeal community in the upper and lower soil layers was not markedly affected by the elevated [CO2], ET, or LN condition. The abundance of the methanogenic archaeal community in the upper and lower soil layers was also not affected by elevated [CO2] or ET, but was significantly increased at the rice PI stage and significantly decreased by LN in the lower soil layer. In contrast, the composition of the methane-oxidizing bacterial community was affected by rice-growing stages in the upper soil layer. The abundance of methane-oxidizing bacteria was significantly decreased by elevated [CO2] and LN in both soil layers at the rice MR stage and by ET in the upper soil layer. The ratio of mcrA/pmoA genes correlated with methane emission from ambient and FACE paddy plots at the PI stage. These results indicate that the decrease observed in the abundance of methane-oxidizing bacteria was related to increased methane emission from the paddy field under the elevated [CO2], ET, and LN conditions.

  19. Nitrate isotopes illuminate the black box of paddy soil biogeochemistry: water and carbon management control nitrogen sources and sinks

    Science.gov (United States)

    Wells, N. S.; Clough, T. J.; Johnson-Beebout, S. E.; Buresh, R. J.

    2010-12-01

    Accurate prediction of the available nitrogen (N) pool in submerged paddy soils is needed in order to produce rice, one of the world’s most essential crops, in an economically and environmentally sustainable manner. By applying emerging nitrate dual-isotope (δ15N- δ18O- NO3-) techniques to paddy systems, we were able to obtain a unique process-level quantification of the synergistic impacts of carbon (C) and water management on N availability. Soil and water samples were collected from fallow experimental plots, with or without organic C amendments, that were maintained under 1 of 3 different hydrologic regimens: continuously submerged, water excluded, or alternate wetting and drying. In continuously submerged soils the δ15N-NO3- : δ18O-NO3- signal of denitrification was not present, indicating that there was no N attenuation. Biological nitrogen fixation (BNF) was the dominant factor in defining the available N pool under these conditions, with δ15N-NO3- approaching atmospheric levels as size of the pool increased. Using an isotope-based pool-mixing model, it was calculated that 10±2 µg N g-1 soil were contributed by BNF during the fallow. A lack of BNF combined with removal via denitrification (δ15N-NO3- : δ18O-NO3- = 1) caused relatively lower available N levels in dried and alternate wetting-drying soils during this period. Magnitude and net impact of denitrification was defined by the extent of drying and C availability, with rice straw C additions driving tighter coupling of nitrification and denitrification (δ15N:δ18O <1). However, despite high rates of attenuation during wetting events, soils that had been completely dried and received straw amendments ultimately retained a significantly larger available N pool due to enhanced input from soil organic matter. These findings underline the necessity of, and validate a new means for, accurate quantification micro-scale biogeochemical interactions for developing farm-scale management practices that

  20. Response of hydrolytic enzyme activities and nitrogen mineralization to fertilizer and organic matter application in subtropical paddy soils

    Science.gov (United States)

    Kader, Mohammed Abdul; Yeasmin, Sabina; Akter, Masuda; Sleutel, Steven

    2016-04-01

    Driving controllers of nitrogen (N) mineralization in paddy soils, especially under anaerobic soil conditions, remain elusive. The influence of exogenous organic matter (OM) and fertilizer application on the activities of five relevant enzymes (β-glucosaminidase, β-glucosidase, L-glutaminase, urease and arylamidase) was measured in two long-term field experiments. One 18-years field experiment was established on a weathered terrace soil with a rice-wheat crop rotation at the Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU) having five OM treatments combined with two mineral N fertilizer levels. Another 30-years experiment was established on a young floodplain soil with rice-rice crop rotation at the Bangladesh Agricultural University (BAU) having eight mineral fertilizer treatments combined with organic manure. At BSMRAU, N fertilizer and OM amendments significantly increased all enzyme activities, suggesting them to be primarily determined by substrate availability. At BAU, non-responsiveness of β-glucosidase activity suggested little effect of the studied fertilizer and OM amendments on general soil microbial activity. Notwithstanding probably equal microbial demand for N, β-glucosaminidase and L-glutaminase activities differed significantly among the treatments (P>0.05) and followed strikingly opposite trends and correlations with soil organic N mineralization. So enzymatic pathways to acquire N differed by treatment at BAU, indicating differences in soil N quality and bio-availability. L-glutaminase activity was significantly positively correlated to the aerobic and anaerobic N mineralization rates at both field experiments. Combined with negative correlations between β-glucosaminidase activity and N mineralization rates, it appears that terminal amino acid NH2 hydrolysis was a rate-limiting step for soil N mineralization at BAU. Future investigations with joint quantification of polyphenol accumulation and binding of N, alongside an

  1. Effects of Crop Straw Returning with Lime on Activity of Cu, Zn, Pb and Cd in Paddy Soil

    Directory of Open Access Journals (Sweden)

    NI Zhong-ying

    2017-05-01

    Full Text Available Crop straw returning is an important measure for increasing soil carbon fixation and soil fertility in China, but it also may result in some risk of raising activity of heavy metals in the soil. In order to understand the effects of different sources of crop straw on heavy metals activity in soil with different pollution levels, and to take appropriate measures to prevent the activation of heavy metals in the soil, both pot and field experiments were carried out to study the effects of crop straw returning with lime on activity of Cu, Zn, Pb and Cd in paddy soil. The experiments were carried out in the soils with both light and heavy pollution of heavy metals. In the pot experiment, three straws, including rice straw with heavy pollution of heavy metals, rice straw with light pollution of heavy metals, and rape straw with light pollution of heavy metals, were tested. Two dosages of lime(0 kg·hm-2 and 750 kg·hm-2were applied. Field experiment had three treatments, ie., control without application of straw and lime, straw returning and straw returning + lime. Soil available heavy metals, accumulation of heavy metals in rice grain, and chemical forms of soil heavy metals were dynamical monitored. The results showed that crop straw returning increased significantly the concentrations of dissolved organic carbon and water soluble heavy metals in paddy soils at the early stage of experiment (in first 20 days. The increase in water soluble heavy metals in the soil with heavy pollution of heavy metals was most obvious as compared with the control treatment. After 60th day of the experiment, the effects of straw returning on the activity of heavy metals in the soil decreased gradually with the time, and became no obvious. The concentrations of water soluble heavy metals in the soil treated with rape straw was generally lower than that of rice straw, while those in the soil treated with heavy pollution of rice straw was higher than low pollution of rice

  2. Cadmium availability in rice paddy fields from a mining area: The effects of soil properties highlighting iron fractions and pH value.

    Science.gov (United States)

    Yu, Huan-Yun; Liu, Chuanping; Zhu, Jishu; Li, Fangbai; Deng, Dong-Mei; Wang, Qi; Liu, Chengshuai

    2016-02-01

    Cadmium (Cd) availability can be significantly affected by soil properties. The effect of pH value on Cd availability has been confirmed. Paddy soils in South China generally contain high contents of iron (Fe). Thus, it is hypothesized that Fe fractions, in addition to pH value, may play an important role in the Cd bioavailability in paddy soil and this requires further investigation. In this study, 73 paired soil and rice plant samples were collected from paddy fields those were contaminated by acid mine drainage containing Cd. The contents of Fe in the amorphous and DCB-extractable Fe oxides were significantly and negatively correlated with the Cd content in rice grain or straw (excluding DCB-extractable Fe vs Cd in straw). In addition, the concentration of HCl-extractable Fe(II) derived from Fe(III) reduction was positively correlated with the Cd content in rice grain or straw. These results suggest that soil Fe redox could affect the availability of Cd in rice plant. Contribution assessment of soil properties to Cd accumulation in rice grain based on random forest (RF) and stochastic gradient boosting (SGB) showed that pH value should be the most important factor and the content of Fe in the amorphous Fe oxides should be the second most important factor in affecting Cd content in rice grain. Overall, compared with the studies from temperate regions, such as Europe and northern China, Fe oxide exhibited its unique role in the bioavailability of Cd in the reddish paddy soil from our study area. The exploration of practical remediation strategies for Cd from the perspective of Fe oxide may be promising. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Impact of a commercial glyphosate formulation on adsorption of Cd(II) and Pb(II) ions on paddy soil.

    Science.gov (United States)

    Divisekara, T; Navaratne, A N; Abeysekara, A S K

    2018-05-01

    Use of glyphosate as a weedicide on rice cultivation has been a controversial issue in Sri Lanka, due to the hypothesis that the metal complexes of commercial glyphosate is one of the causative factors of Chronic Kidney Disease of unknown aetiology (CKDu) prevalent in some parts of Sri Lanka. The effect of commercial glyphosate on the adsorption and desorption of Cd(II) and Pb(II) ions on selective paddy soil studied using batch experiments, over a wide concentration range, indicates that the Langmuir adsorption isotherm model is obeyed at low initial metal ion concentrations while the Freundlich adsorption isotherm model obeys at high metal ion concentrations in the presence and absence of glyphosate. For all cases, adsorption of both Cd(II) and Pb(II) ions obeys pseudo second order kinetics, suggesting that initial adsorption is a chemisorption process. In the presence of glyphosate formulation, the extent of adsorption of Cd(II) and Pb(II) ions on soil is decreased, while their desorption is increased at high concentrations of glyphosate. Low concentrations of glyphosate formulation do not significantly affect the desorption of metal ions from soil. Reduction of adsorption leads to enhance the concentration of Cd(II) and Pb(II) ions in the aqueous phase when in contact with soil. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Impacts of Steel-Slag-Based Silicate Fertilizer on Soil Acidity and Silicon Availability and Metals-Immobilization in a Paddy Soil.

    Directory of Open Access Journals (Sweden)

    Dongfeng Ning

    Full Text Available Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd and lead (Pb was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant-availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system.

  5. Evaluation of methane emissions from Taiwanese paddies

    International Nuclear Information System (INIS)

    Liu, C.-W.; Wu, C.-Y.

    2004-01-01

    The main greenhouse gases are carbon dioxide, methane and nitrous oxide. Methane is the most important because the warming effect of methane is 21 times greater than that of carbon dioxide. Methane emitted from rice paddy fields is a major source of atmospheric methane. In this work, a methane emission model (MEM), which integrates climate change, plant growth and degradation of soil organic matter, was applied to estimate the emission of methane from rice paddy fields in Taiwan. The estimated results indicate that much methane is emitted during the effective tillering and booting stages in the first crop season and during the transplanting stage in the second crop season in a year. Sensitivity analysis reveals that the temperature is the most important parameter that governs the methane emission rate. The order of the strengths of the effects of the other parameters is soil pH, soil water depth (SWD) and soil organic matter content. The masses of methane emitted from rice paddy fields of Taiwan in the first and second crop seasons are 28,507 and 350,231 tons, respectively. The amount of methane emitted during the second crop season is 12.5 times higher than that emitted in the first crop season. With a 12% reduction in planted area during the second crop season, methane emission could be reduced by 21%. In addition, removal of rice straw left from the first crop season and increasing the depth of flooding to 25 cm are also strategies that could help reduce annual emission by up to 18%

  6. The dynamics of arsenic in four paddy fields in the Bengal delta

    International Nuclear Information System (INIS)

    Stroud, Jacqueline L.; Norton, Gareth J.; Islam, M. Rafiqul; Dasgupta, Tapash; White, Rodger P.; Price, Adam H.; Meharg, Andrew A.; McGrath, Steve P.; Zhao Fangjie

    2011-01-01

    Irrigation with arsenic contaminated groundwater in the Bengal Delta may lead to As accumulation in the soil and rice grain. The dynamics of As concentration and speciation in paddy fields during dry season (boro) rice cultivation were investigated at 4 sites in Bangladesh and West Bengal, India. Three sites which were irrigated with high As groundwater had elevated As concentrations in the soils, showing a significant gradient from the irrigation inlet across the field. Arsenic concentration and speciation in soil pore water varied temporally and spatially; higher As concentrations were associated with an increasing percentage of arsenite, indicating a reductive mobilization. Concentrations of As in rice grain varied by 2-7 fold within individual fields and were poorly related with the soil As concentration. A field site employing alternating flooded-dry irrigation produced the lowest range of grain As concentration, suggesting a lower soil As availability caused by periodic aerobic conditions. - Research highlights: → Irrigation with As-contaminated groundwater resulted in a gradient of As concentration in the soil. → Arsenic concentration in paddy standing water decreased as arsenite was oxidised to arsenate. → Soil pore water As increased with the %arsenite, suggesting reductive mobilisation. → Alternative flooded-dry conditions led to lowest range of As concentration in rice grain. - Spatial variations of arsenic concentrations in paddy soil and waters do not correlate to within-field variations of arsenic concentrations in rice grain.

  7. Effects of soil flooding on photosynthesis and growth of Zea mays L ...

    African Journals Online (AJOL)

    Soil flooding is one of the major abiotic stresses that repress maize (Zea mays L.) growth and yield, and other environmental factors often influence soil flooding stress. This paper reports an experimental test of the hypothesis that light intensity can influence the responses of maize seedlings to soil flooding.

  8. Electro-kinetic remediation coupled with phytoremediation to remove lead, arsenic and cesium from contaminated paddy soil.

    Science.gov (United States)

    Mao, Xinyu; Han, Fengxiang X; Shao, Xiaohou; Guo, Kai; McComb, Jacqueline; Arslan, Zikri; Zhang, Zhanyu

    2016-03-01

    The objectives of this study were to investigate distribution and solubility of Pb, Cs and As in soils under electrokinetic field and examine the processes of coupled electrokinetic phytoremediation of polluted soils. The elevated bioavailability and bioaccumulation of Pb, As and Cs in paddy soil under an electro-kinetic field (EKF) were studied. The results show that the EKF treatment is effective on lowering soil pH to around 1.5 near the anode which is beneficial for the dissolution of metal(loid)s, thus increasing their overall solubility. The acidification in the anode soil efficiently increased the water soluble (SOL) and exchangeable (EXC) Pb, As and Cs, implying enhanced solubility and elevated overall potential bioavailability in the anode region while lower solubility in the cathode areas. Bioaccumulations of Pb, As and Cs were largely determined by the nature of elements, loading levels and EKF treatment. The native Pb in soil usually is not bioavailable. However, EKF treatment tends to transfer Pb to the SOL and EXC fractions improving the phytoextraction efficiency. Similarly, EKF transferred more EXC As and Cs to the SOL fraction significantly increasing their bioaccumulation in plant roots and shoots. Pb and As were accumulated more in plant roots than in shoots while Cs was accumulated more in shoots due to its similarity of chemical properties to potassium. Indian mustard, spinach and cabbage are good accumulators for Cs. Translocation of Pb, As and Cs from plant roots to shoots were enhanced by EKF. However, this study indicated the overall low phytoextraction efficiency of these plants. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. The exchangeable cations in soils flooded with sea water

    NARCIS (Netherlands)

    Molen, van der W.H.

    1958-01-01

    The changes in the exchangeable cations of soils flooded with sea-water were extensively studied in the Netherlands after the inundations of 1940, 1945 and 1953. A synopsis of the results was given, both from a theoretical and a practical viewpoint.

    Current formulae for ion-exchange tested in the

  10. Highly stable rice-straw-derived charcoal in 3700-year-old ancient paddy soil: evidence for an effective pathway toward carbon sequestration.

    Science.gov (United States)

    Wu, Mengxiong; Yang, Min; Han, Xingguo; Zhong, Ting; Zheng, Yunfei; Ding, Pin; Wu, Weixiang

    2016-01-01

    Recalcitrant charcoal application is predicted to decelerate global warming through creating a long-term carbon sink in soil. Although many studies have showed high stability of charcoal derived from woody materials, few have focused on the dynamics of straw-derived charcoal in natural environment on a long timescale to evaluate its potential for agricultural carbon sequestration. Here, we examined straw-derived charcoal in an ancient paddy soil dated from ~3700 calendar year before present (cal. year BP). Analytical results showed that soil organic matter consisted of more than 25% of charcoal in charcoal-rich layer. Similarities in morphology and molecular structure between the ancient and the fresh rice-straw-derived charcoal indicated that ancient charcoal was derived from rice straw. The lower carbon content, higher oxygen content, and obvious carbonyl of the ancient charcoal compared with fresh rice straw charcoal implied that oxidation occurred in the scale of thousands years. However, the dominant aromatic C of ancient charcoal indicated that rice-straw-derived charcoal was highly stable in the buried paddy soil due to its intrinsic chemical structures and the physical protection of ancient paddy wetland. Therefore, it may suggest that straw charcoal application is a potential pathway for C sequestration considering its longevity.

  11. Improved isolation of cadmium from paddy soil by novel technology based on pore water drainage with graphite-contained electro-kinetic geosynthetics.

    Science.gov (United States)

    Tang, Xianqiang; Li, Qingyun; Wang, Zhenhua; Hu, Yanping; Hu, Yuan; Scholz, Miklas

    2018-03-10

    Novel soil remediation equipment based on electro-kinetic geosynthetics (EKG) was developed for in situ isolation of metals from paddy soil. Two mutually independent field plot experiments A and B (with and without electric current applied) were conducted. After saturation using ferric chloride (FeCl 3 ) and calcium chloride (CaCl 2 ), soil water drainage capacity, soil cadmium (Cd) removal performance, energy consumption as well as soil residual of iron (Fe) and chloride (Cl) were assessed. Cadmium dissolved in the soil matrix and resulted in a 100% increase of diethylenetriamine-pentaacetic acid (DTPA) extracted phyto-available Cd. The total soil Cd content reductions were 15.20% and 26.58% for groups A and B, respectively, and electric field applications resulted in a 74.87% increase of soil total Cd removal. The electric energy consumption was only 2.17 kWh/m 3 for group B. Drainage by gravity contributed to > 90% of the overall soil dewatering capacity. Compared to conventional electro-kinetic technology, excellent and fast soil water drainage resulted in negligible hydrogen ion (H + ) and hydroxide ion (OH - ) accumulation at nearby electrode zones, which addressed the challenge of anode corrosion and cathode precipitation of soil metals. External addition of FeCl 3 and CaCl 2 caused soil Fe and Cl residuals and led to 4.33-7.59% and 139-172% acceptable augments in soil total Fe and Cl content, correspondingly, if compared to original untreated soils. Therefore, the novel soil remediation equipment developed based on EKG can be regarded as a promising new in situ technology for thoroughly isolating metals from large-scale paddy soil fields.

  12. The specific role of fungal community structure on soil aggregation and carbon sequestration: results from long-term field study in a paddy soil

    Science.gov (United States)

    Murugan, Rajasekaran; Kumar, Sanjay

    2015-04-01

    Soil aggregate stability is a crucial soil property that affects soil biota, biogeochemical processes and C sequestration. The relationship between soil aggregate stability and soil C cycling is well known but the influence of specific fungal community structure on this relationship is largely unknown in paddy soils. The aim of the present study was to evaluate the long-term fertilisation (mineral fertiliser-MIN; farmyard manure-FYM; groundnut oil cake-GOC) effects on soil fungal community shifts associated with soil aggregates under rice-monoculture (RRR) and rice-legume-rice (RLR) systems. Fungal and bacterial communities were characterized using phospholipid fatty acids, and glucosamine and muramic acid were used as biomarkers for fungal and bacterial residues, respectively. Microbial biomass C and N, fungal biomass and residues were significantly higher in the organic fertiliser treatments than in the MIN treatment, for all aggregate sizes under both crop rotation systems. In general, fungal/bacterial biomass ratio and fungal residue C/bacterial residue C ratio were significantly higher in macroaggregate fractions (> 2000 and 250-2000 μm) than in microaggregate fractions (53-250 and crop rotation systems, the long-term application of FYM and GOC led to increased accumulation of saprotrophic fungi (SF) in aggregate fractions > 2000 μm. In contrast, we found that arbuscular mycorrhizal fungi (AMF) was surprisingly higher in aggregate fractions > 2000 μm than in aggregate fraction 250-2000 μm under MIN treatment. The RLR system showed significantly higher AMF biomass and fungal residue C/ bacterial residue C ratio in both macroaggregate fractions compared to the RRR system. The strong relationships between SF, AMF and water stable aggregates shows the specific contribution of fungi community on soil aggregate stability. Our results highlight the fact that changes within fungal community structure play an important role in shaping the soil aggregate stability

  13. Effect of levels of P, FYM and PSB on mobilization of soil phosphorus using isotope technique in paddy

    International Nuclear Information System (INIS)

    Khatik, S.K.; Deshmukh, K.K.; Sharma, G.D.; Dwivedi, B.S.

    2004-01-01

    A greenhouse experiment was conducted using paddy (variety IR-36) as a test crop, receiving graded doses of P to study the effect of added P through SSP (labelled 32 P) alone and in combination with FYM and biofertilizer on uptake pattern, mobilization. Olsen's P and different inorganic P fractions. The results showed that the amount of Olsen's extractable P decreased with increasing cropping period up to harvest and the highest value was recorded in treatment receiving SSP- 32 P + FYM + PSB. Almost similar results were observed in P uptake pattern. The highest values 34.68. 29.91 and 28.36 of the per cent P derived from fertilizer (Pdff) and the lowest values of 65.31, 70.08 and 71.65 for the per cent P derived from soil (Pdff) were registered in SSP + FYM +PSB at tillering, flowering and harvest stages, indicating that combined use of FYM and bio-fertilizer helped in better utilization of native reserve phosphorus. It was also found that maximum amount of applied P was transformed to Ca-P and minimum into saloid-P in all the plant growth stages. Different fractions of transformed P in the soil followed the order Ca-P > Fe-P > Al-P > Occluded-P > saloid-P. Maximum response to added P was obtained in SSP + FYM + PSB treatment and minimum was noticed in control at all the growth stages of plant. (author)

  14. Field investigation to assess nutrient emission from paddy field to surface water in river catchment

    Science.gov (United States)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2015-04-01

    In order to maintain good river environment, it is remarkably important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. Our former research dealing with nutrient emission analysis in the Tone River basin area in Japan, in addition to urban and industrial waste water, nutrient emission from agricultural activity is dominant pollution source into the river system. Japanese style agriculture produces large amount of rice and paddy field occupies large areas in Japanese river basin areas. While paddy field can deteriorate river water quality by outflow of fertilizer, it is also suggested that paddy field has water purification function. As we carried out investigation in the Tone River Basin area, data were obtained which dissolved nitrogen concentration is lower in discharging water from paddy field than inflowing water into the field. Regarding to nutrient emission impact from paddy field, sufficient data are required to discuss quantitatively seasonal change of material behavior including flooding season and dry season, difference of climate condition, soil type, and rice species, to evaluate year round comprehensive impact from paddy field to the river system. In this research, field survey in paddy field and data collection relating rice production were carried out as a preliminary investigation to assess how Japanese style paddy field contributes year round on surface water quality. Study sites are three paddy fields located in upper reach of the Tone River basin area. The fields are flooded from June to September. In 2014, field investigations were carried out three times in flooding period and twice in dry period. To understand characteristics of each paddy field and seasonal tendency accompanying weather of agricultural event, short term investigations were conducted and we prepare for further long term investigation. Each study site has irrigation water inflow and outflow. Two sites have tile drainage system under the field and

  15. Stratification of Diversity and Activity of Methanogenic and Methanotrophic Microorganisms in a Nitrogen-Fertilized Italian Paddy Soil

    NARCIS (Netherlands)

    Vaksmaa, A.; Alen, T. van; Ettwig, K.F.; Valè, G.; Jetten, M.S.M.; Lüke, C.

    2017-01-01

    Paddy fields are important ecosystems, as rice is the primary food source for about half of the world’s population. Paddy fields are impacted by nitrogen fertilization and are a major anthropogenic source of methane. Microbial diversity and methane metabolism were investigated in the upper 60cm of a

  16. Heavy metal pollution and ecological risk assessment of the paddy soils near a zinc-lead mining area in Hunan.

    Science.gov (United States)

    Lu, Sijin; Wang, Yeyao; Teng, Yanguo; Yu, Xuan

    2015-10-01

    Soil pollution by Cd, Hg, As, Pb, Cr, Cu, and Zn was characterized in the area of the mining and smelting of metal ores at Guiyang, northeast of Hunan Province. A total of 150 topsoil (0-20 cm) samples were collected in May 2012 with a nominal density of one sample per 4 km(2). High concentrations of heavy metals especially, Cd, Zn, and Pb were found in many of the samples taken from surrounding paddy soil, indicating a certain extent of spreading of heavy metal pollution. Sequential extraction technique and risk assessment code (RAC) were used to study the mobility of chemical forms of heavy metals in the soils and their ecological risk. The results reveal that Cd represents a high ecological risk due to its highest percentage of the exchangeable and carbonate fractions. The metals of Zn and Cu pose a medium risk, and the rest of the metals represent a low environmental risk. The range of the potential ecological risk of soil calculated by risk index (RI) was 123.5~2791.2 and revealed a considerable-high ecological risk in study area especially in the neighboring and surrounding the mining activities area. Additionally, cluster analyses suggested that metals such as Pb, As, Hg, Zn, and Cd could be from the same sources probably related to the acidic drainage and wind transport of dust. Cluster analysis also clearly distinguishes the samples with similar characteristics according to their spatial distribution. The results could be used during the ecological risk screening stage, in conjunction with total concentrations and metal fractionation values to better estimate ecological risk.

  17. A Preliminary Study of the Application of Electromagnetic Conductivity Meter on Soil Properties of Paddy Cultivation Areas at Wue Village, Jantho, Aceh Besar District, Indonesia

    Directory of Open Access Journals (Sweden)

    . Marwan

    2015-01-01

    Full Text Available Conventional soil sampling is time consuming and requires meticulous laboratory analysis. Hence, mapping of soil apparent in respect to electrical conductivity (ECa has been developed to identify areas of contrasting soil properties. Such ECa values are represent measures of soil properties. The sensor system, GF Instrument model CMD-4 were used to analyze soil physical properties. This system consists of three important parts, ECa sensor, data logger and Global Positioning System (DGPS receiver. This research was aimed to evaluate the relationships between ECa and soil properties as well as the yield of rice (paddy in paddy’s farming fields. One study site was chosen. The sensor was pulled through a plotted area of 0.25 km2. The distribution map of ECa was developed to identify the contrast of ECa. More than 100 ECa of data points were collected in 3-hour for the large plot. The data was later transferred to a notebook computer for generation of ECa maps using Surfer 11 software. According to the data analyses, field and ECa showed positive correlation. The average values of ECa are significantly different between hilly area and drainage canal area signifying differences in soil structure. Soil ECa could provide a measure of the spatial differences associated with soil physical and chemical properties, which for paddy soil may be a measure of soil suitability for crop growth and its productivity. This sensor can measure the soil ECa through the field quickly for detailed features of the soil and can be operated by just one worker. The ECa map provides some ideas for future soil management

  18. Arsenic mobility and bioavailability in paddy soil under iron compound amendments at different growth stages of rice.

    Science.gov (United States)

    Yu, Huan-Yun; Wang, Xiangqin; Li, Fangbai; Li, Bin; Liu, Chuanping; Wang, Qi; Lei, Jing

    2017-05-01

    Iron (Fe)-based solids can reduce arsenic (As) mobility and bioavailability in soils, which has been well recognized. However, to our knowledge, there are few studies on As uptake at different growth stages of rice under Fe compound amendments. In addition, the formation of Fe plaques at different growth stages of rice has also been rarely reported. Therefore, the present study was undertaken to investigate As mobility and bioavailability in paddy soil under Fe compound amendments throughout the whole growth stage of rice plants. Amendments of poorly crystalline Fe oxides (PC-Fe), FeCl 2 +NaNO 3 and FeCl 2 reduced grain As by 54% ± 3.0%, 52% ± 3.0% and 46% ± 17%, respectively, compared with that of the non-amended control. The filling stage was suggested to be the key stage to take measures to reduce As uptake. At this stage, all soil amendments significantly reduced As accumulation in rice plants. At the maturation stage, PC-Fe amendment significantly reduced mobile pools and increased immobile pools of soil As. Besides, PC-Fe treatment promoted the transformation of Fe fractions from dissolved Fe to adsorbed, poorly crystalline and free Fe oxides. Moreover, significant positive correlations between soil Fe fractions and As fractions were found. Accordingly, we hypothesized that Fe compound amendments might affect the concentration distribution of Fe fractions first and then affect As fractionation in soil and its bioavailability to rice plants indirectly. The formation of Fe plaques varied with growth stages and different treatments. Significantly negative correlations between mobile pools of As and Fe or As in Fe plaques indicated that Fe plaques could immobilize mobile As in soils and thus affect As bioavailability. Overall, the effect of the soil amendments on reduction of As uptake varied with growth stages and different treatments, and further research on the key stage for reducing As uptake is still required. Copyright © 2017 Elsevier Ltd. All

  19. An Approach to Flooding Inundation Combining the Streamflow Prediction Tool (SPT) and Downscaled Soil Moisture

    Science.gov (United States)

    Cotterman, K. A.; Follum, M. L.; Pradhan, N. R.; Niemann, J. D.

    2017-12-01

    Flooding impacts numerous aspects of society, from localized flash floods to continental-scale flood events. Many numerical flood models focus solely on riverine flooding, with some capable of capturing both localized and continental-scale flood events. However, these models neglect flooding away from channels that are related to excessive ponding, typically found in areas with flat terrain and poorly draining soils. In order to obtain a holistic view of flooding, we combine flood results from the Streamflow Prediction Tool (SPT), a riverine flood model, with soil moisture downscaling techniques to determine if a better representation of flooding is obtained. This allows for a more holistic understanding of potential flood prone areas, increasing the opportunity for more accurate warnings and evacuations during flooding conditions. Thirty-five years of near-global historical streamflow is reconstructed with continental-scale flow routing of runoff from global land surface models. Elevation data was also obtained worldwide, to establish a relationship between topographic attributes and soil moisture patterns. Derived soil moisture data is validated against observed soil moisture, increasing confidence in the ability to accurately capture soil moisture patterns. Potential flooding situations can be examined worldwide, with this study focusing on the United States, Central America, and the Philippines.

  20. Simulating the Effects of Agricultural Management on Water Quality Dynamics in Rice Paddies for Sustainable Rice Production—Model Development and Validation

    Directory of Open Access Journals (Sweden)

    Soon-Kun Choi

    2017-11-01

    Full Text Available The Agricultural Policy/Environmental eXtender (APEX model is widely used for evaluating agricultural conservation efforts and their effects on soil and water. A key component of APEX application in Korea is simulating the water quality impacts of rice paddies because rice agriculture claims the largest cropland area in the country. In this study, a computational module called APEX-Paddy (National Academy of Agricultural Sciences, Wanju, Korea is developed to simulate water quality with considering pertinent paddy management practices, such as puddling and flood irrigation management. Data collected at two experimental paddy sites in Korea were used to calibrate and validate the model. Results indicate that APEX-Paddy performs well in predicting runoff discharge rate and nitrogen yield while the original APEX highly overestimates runoff rates and nitrogen yields on large storm events. With APEX-Paddy, simulated and observed flow and mineral nitrogen yield (QN are found to be highly correlated after calibration (Nash & Sutcliffe Efficiency (NSE = 0.87 and Percent Bias (PBIAS = −14.6% for flow; NSE = 0.68 and PBIAS = 2.1% for QN. Consequently, the APEX-Paddy showed a greater accuracy in flow and QN prediction than the original APEX modeling practice using the SCS-CN (Soil Conservation Service-Curve Number method.

  1. Different Recovery Processes of Soil Ammonia Oxidizers from Flooding Disturbance.

    Science.gov (United States)

    Ye, Fei; Ma, Mao-Hua; Op den Camp, Huub J M; Chatzinotas, Antonis; Li, Lei; Lv, Ming-Quan; Wu, Sheng-Jun; Wang, Yu

    2018-04-11

    Understanding how microorganisms respond to environmental disturbance is one of the key focuses in microbial ecology. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are responsible for ammonia oxidation which is a crucial step in the nitrogen cycle. Although the physiology, distribution, and activity of AOA and AOB in soil have been extensively investigated, their recovery from a natural disturbance remains largely unknown. To assess the recovery capacities, including resistance and resilience, of AOA and AOB, soil samples were taken from a reservoir riparian zone which experienced periodically water flooding. The samples were classified into three groups (flooding, recovery, and control) for a high-throughput sequencing and quantitative PCR analysis. We used a relative quantitative index of both the resistance (RS) and resilience (RL) to assess the variation of gene abundance, alpha-diversity, and community composition. The AOA generally demonstrated a better recovery capability after the flooding disturbance compared to AOB. In particular, AOA were more resilient after the flooding disturbance. Taxa within the AOA and AOB showed different RS and RL values, with the most abundant taxa showing in general the highest RS indices. Soil NH 4 + and Fe 2+ /Fe 3+ were the main variables controlling the key taxa of AOA and AOB and probably influenced the resistance and resilience properties of AOA and AOB communities. The distinct mechanisms of AOA and AOB in maintaining community stability against the flooding disturbance might be linked to the different life-history strategies: the AOA community was more likely to represent r-strategists in contrast to the AOB community following a K-life strategy. Our results indicated that the AOA may play a vital role in ammonia oxidation in a fluctuating habitat and contribute to the stability of riparian ecosystem.

  2. Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils

    Directory of Open Access Journals (Sweden)

    Juan Tian

    2017-07-01

    Full Text Available In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP, soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss.

  3. Distribution, and uptake by rice plants of 15N-labeled ammonium applied in mudballs in paddy soils

    International Nuclear Information System (INIS)

    Ventura, Wilbur; Yoshida, Tomio

    1978-01-01

    A 1974 field experiment determined the distribution, and uptake by rice plants, of ammonium fertilizer at 60 kg N/ha applied in mudballs into the reduced layer of paddy soil. The fertilizer-carrying mudballs were placed at the center of four hills. At the center of the plot, one 15 N-labeled mudball was applied and the 15 N content of the plants surrounding the site of placement were determined. For comparison, labeled ammonium fertilizer was basally incorporated with the entire puddled layer and a topdress application was made 39 days before heading. There was little movement of the ammonium nitrogen horizontally from the site of placement so that the distribution of 15 N was restricted to the four adjacent plant hills. The distribution of incorporated ammonium fertilizer with the puddled layer was likewise restricted to the four adjacent rice plants but topdressing, with the unavoidable disturbance of the floodwater, resulted to a wide distribution of the 15 N-labeled fertilizer. In all the methods of application, there was an uneven uptake of 15 N among four plants adjacent to the site of placement. An increase of at least 10% in the efficiency of ammonium fertilizer was obtained by the deep placement of ammoniated mudballs as compared to the common practice of incorporating the fertilizer with the puddled soil layer. Topdressing at 39 days before heading, however, was as efficient as mudballs applied at the same stage of growth. There was no significant increase in grain yield by deep placement of fertilizer because of the high initial nitrogen content of the soil. (author)

  4. Factors affecting variation in CH4 emission from paddy soils grown with different rice cultivars: A pot experiment

    Science.gov (United States)

    Watanabe, Akira; Kimura, Makoto

    1998-08-01

    The growth of rice plants greatly influences CH4 emission from paddy fields through the supply of organic materials such as root exudates and sloughed tissues, the release of oxygen to the root environment, and the transfer of CH4 from the rhizosphere into the atmosphere through the aerenchyma. In the present pot experiments, the effects of the release of water-soluble organic substances from roots, the air space in roots, and the CH4-oxidizing capacity of roots on intervarietal differences in CH4 emission were examined using three Japonica type cultivars (Norin 25, Nipponbare, and Aoinokaze), which differ in morphological properties. The CH4 emission rates varied among the cultivars from mid-July (tillering stage) to the beginning of September (heading stage).Total CH4 emission throughout the rice growth period was largest for Norin 25, followed by Nipponbare, and Aoinokaze. In August, the rate of release of water-soluble organic substances from roots was largest for Norin 25. The air space in roots was also largest in Norin 25 and least in Aoinokaze. The stable carbon isotopic ratios (δ13C) of CH4 in roots were 3-10‰ higher than those in soil in August. The difference in δ13C values of CH4 between roots and soil was largest for Aoinokaze and smallest for Norin 25. In September, the difference in δ13C values of CH4 between roots and soil became small (2-3‰). These findings suggest that the proportion of CH4 oxidation in the rhizosphere was largest in the cultivar which emitted the smallest amount of CH4 and that the proportion became smaller with continued plant growth.

  5. The effect of iron plaque on uptake and translocation of norfloxacin in rice seedlings grown in paddy soil.

    Science.gov (United States)

    Yan, Dafang; Ma, Wei; Song, Xiaojing; Bao, Yanyu

    2017-03-01

    Although the role of iron plaque on rice root surface has been investigated in recent years, its effect on antibiotic uptake remains uncertain. In the study, pot experiment was conducted to investigate the effect of iron plaque on uptake and translocation of norfloxacin (adding 10 and 50 mg·kg -1 treatments) in rice seedlings grown in paddy soil. Iron plaque was induced by adding different amounts of Fe(II) in soil. The results showed that the presence of norfloxacin can decrease the amount of iron plaque induced. After rice with iron plaque induced, norfloxacin was mainly accumulated in iron plaque on root surface, followed by inside root, but its translocation from root to other rice tissues is not observed. Iron plaque played the role of a barrier for norfloxacin uptake into rice roots under high norfloxacin concentration of 50 mg·kg -1 , however not that under low concentration of 10 mg·kg -1 . And the barrier function was the most strongest with adding Fe(II) of 30 mg·kg -1 as combined action of iron plaque and rhizosphere effect. Fluorescence microscope analysis showed that norfloxacin mainly distributed in the outside of root cell, which showed its translocation as apoplastic pathway in rice. Comparing with non-rhizosphere, more norfloxacin was accumulated in rhizosphere soil. Maybe, strong root oxidization (high Eh values) induced more iron oxide formation in rhizosphere and on root surface, which led to norfloxacin's mobility towards to rhizosphere through its strong adsorption of iron oxides and then promoted its uptake by rice on root surface.

  6. Fractionation and solubility of cadmium in paddy soils amended with porous hydrated calcium silicate.

    Science.gov (United States)

    Zhao, Xiu-Lan; Masaihiko, Saigusa

    2007-01-01

    Previous studies have shown that porous hydrated calcium silicate (PS) is very effective in decreasing cadmium (Cd) content in brown rice. However, it is unclear whether the PS influences cadmium transformation in soil. The present study examined the effect of PS on pH, cadmium transformation and cadmium solubility in Andosol and Alluvial soil, and also compared its effects with CaCO3, acidic porous hydrated calcium silicate (APS) and silica gel. Soil cadmium was operationally fractionationed into exchangeable (Exch), bound to carbonates (Carb), bound to iron and manganese oxides (FeMnO(x)), bound to organic matters (OM) and residual (Res) fraction. Application of PS and CaCO3 at hig rates enhanced soil pH, while APS and silica gel did not obviously change soil pH. PS and CaCO3 also increased the FeMnO(x)-Cd in Andosol and Carb-Cd in Alluvial soil, thus reducing the Exch-Cd in the tested soils. However, PS was less effective than CaCO3 at the same application rate. Cadmium fractions in the two soils were not changed by the treatments of APS and silica gel. There were no obvious differences in the solubility of cadmium in soils treated with PS, APS, silica gel and CaCO3 except Andosol treated 2.0% CaCO3 at the same pH of soil-CaCl2 suspensions. These findings suggested that the decrease of cadmium availability in soil was mainly attributed to the increase of soil pH caused by PS.

  7. Open-pit coal-mining effects on rice paddy soil composition and metal bioavailability to Oryza sativa L. plants in Cam Pha, northeastern Vietnam.

    Science.gov (United States)

    Martinez, Raul E; Marquez, J Eduardo; Hòa, Hoàng Thị Bích; Gieré, Reto

    2013-11-01

    This study quantified Cd, Pb, and Cu content, and the soil-plant transfer factors of these elements in rice paddies within Cam Pha, Quang Ninh province, northeastern Vietnam. The rice paddies are located at a distance of 2 km from the large Coc Sau open-pit coal mine. Electron microprobe analysis combined with backscattered electron imaging and energy-dispersive spectroscopy revealed a relatively high proportion of carbon particles rimmed by an iron sulfide mineral (probably pyrite) in the quartz-clay matrix of rice paddy soils at 20-30 cm depth. Bulk chemical analysis of these soils revealed the presence of Cd, Cu, and Pb at concentrations of 0.146±0.004, 23.3±0.1, and 23.5±0.1 mg/kg which exceeded calculated background concentrations of 0.006±0.004, 1.9±0.5, and 2.4±1.5 mg/kg respectively at one of the sites. Metals and metalloids in Cam Pha rice paddy soils, including As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn, were found in concentrations ranging from 0.2±0.1 to 140±3 mg/kg, which were in close agreement with toxic metal contents in mine tailings and Coc Sau coal samples, suggesting mining operations as a major cause of paddy soil contamination. Native and model Oryza sativa L. rice plants were grown in the laboratory in a growth medium to which up to 1.5 mg/kg of paddy soil from Cam Pha was added to investigate the effects on plant growth. A decrease in growth by up to 60% with respect to a control sample was found for model plants, whereas a decrease of only 10% was observed for native (Nep cai hoa vang variety) rice plants. This result suggests an adaptation of native Cam Pha rice plants to toxic metals in the agricultural lands. The Cd, Cu, and Pb contents of the native rice plants from Cam Pha paddies exceeded permitted levels in foods. Cadmium and Pb were highest in the rice plant roots with concentrations of 0.84±0.02 and 7.7±0.3 mg/kg, suggesting an intake of these metals into the rice plant as shown, for example, by Cd and Pb concentrations of 0

  8. Contrasting effects of elevated CO2 and warming on temperature sensitivity of soil organic matter decomposition in a Chinese paddy field.

    Science.gov (United States)

    Chen, Zhaozhi; Wang, Bingyu; Wang, Jinyang; Pan, Genxing; Xiong, Zhengqin

    2015-10-01

    Climate changes including elevated CO2 and temperature have been known to affect soil carbon (C) storage, while the effects of climate changes on the temperature sensitivity of soil organic matter (SOM) are unclear. A 365-day laboratory incubation was used to investigate the temperature sensitivity for decomposition of labile (Q 10-L) and recalcitrant (Q 10-R) SOMs by comparing the time required to decompose a given amount of C at 25 and 35 °C. Soils were collected from a paddy field that was subjected to four treatments: ambient CO2 and temperature, elevated CO2 (500 μmol/mol), enhanced temperature (+2 °C), and their combination. The results showed that the temperature sensitivity of SOM decomposition increased with increasing SOM recalcitrance in this paddy soil (Q 10-L = 2.21 ± 0.16 vs. Q 10-R = 2.78 ± 0.42; mean ± SD). Elevated CO2 and enhanced temperature showed contrasting effects on the temperature sensitivity of SOM decomposition. Elevated CO2 stimulated Q 10-R but had no effect on Q 10-L; in contrast, enhanced temperature increased Q 10-L but had no effect on Q 10-R. Furthermore, the elevated CO2 combined with enhanced temperature treatment significantly increased Q 10-L and Q 10-R by 18.9 and 10.2 %, respectively, compared to the ambient conditions. Results suggested that the responses of SOM to temperature, especially for the recalcitrant SOM pool, were altered by climate changes. The greatly enhanced temperature sensitivity of SOM decomposition by elevated CO2 and temperature indicates that more CO2 will be released to the atmosphere and losses of soil C may be even greater than that previously expected in paddy field.

  9. Effects of tillage and nitrogen fertilizers on CH4 and CO2 emissions and soil organic carbon in paddy fields of central China.

    Directory of Open Access Journals (Sweden)

    Li Cheng-Fang

    Full Text Available Quantifying carbon (C sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT and no-tillage (NT] and the application of nitrogen (N fertilizer (0 and 210 kg N ha(-1 on fluxes of CH(4 and CO(2, and soil organic C (SOC sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH(4 emissions by 13%-66% and SOC by 21%-94% irrespective of soil sampling depths, but had no effect on CO(2 emissions in either year. Tillage significantly affected CH(4 and CO(2 emissions, where NT significantly decreased CH(4 emissions by 10%-36% but increased CO(2 emissions by 22%-40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%-48% in the 0-5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0-20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered.

  10. Potential of VIS-NIR-SWIR Spectroscopy from the Chinese Soil Spectral Library for Assessment of Nitrogen Fertilization Rates in the Paddy-Rice Region, China

    Directory of Open Access Journals (Sweden)

    Shuo Li

    2015-05-01

    Full Text Available To meet growing food demand with limited land and reduced environmental impact, soil testing and formulated fertilization methods have been widely adopted around the world. However, conventional technology for investigating nitrogen fertilization rates (NFR is time consuming and expensive. Here, we evaluated the use of visible near-infrared shortwave-infrared (VIS-NIR-SWIR: 400–2500 nm spectroscopy for the assessment of NFR to provide necessary information for fast, cost-effective and precise fertilization rating. Over 2000 samples were collected from paddy-rice fields in 10 Chinese provinces; samples were added to the Chinese Soil Spectral Library (CSSL. Two kinds of modeling strategies for NFR, quantitative estimation of soil N prior to classification and qualitative by classification, were employed using partial least squares regression (PLSR, locally weighted regression (LWR, and support vector machine discriminant analogy (SVMDA. Overall, both LWR and SVMDA had moderate accuracies with Cohen’s kappa coefficients of 0.47 and 0.48, respectively, while PLSR had fair accuracy (0.37. We conclude that VIS-NIR-SWIR spectroscopy coupled with the CSSL appears to be a viable, rapid means for the assessment of NFR in paddy-rice soil. Based on qualitative classification of soil spectral data only, it is recommended that the SVMDA be adopted for rapid implementation.

  11. Effects of tillage and nitrogen fertilizers on CH4 and CO2 emissions and soil organic carbon in paddy fields of central China.

    Science.gov (United States)

    Cheng-Fang, Li; Dan-Na, Zhou; Zhi-Kui, Kou; Zhi-Sheng, Zhang; Jin-Ping, Wang; Ming-Li, Cai; Cou-Gui, Cao

    2012-01-01

    Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha(-1)) on fluxes of CH(4) and CO(2), and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH(4) emissions by 13%-66% and SOC by 21%-94% irrespective of soil sampling depths, but had no effect on CO(2) emissions in either year. Tillage significantly affected CH(4) and CO(2) emissions, where NT significantly decreased CH(4) emissions by 10%-36% but increased CO(2) emissions by 22%-40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%-48% in the 0-5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0-20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered.

  12. Tungsten (W) bioavailability in paddy rice soils and its accumulation in rice (Oryza sativa).

    Science.gov (United States)

    James, Blessing; Zhang, Weili; Sun, Pei; Wu, Mingyan; Li, Hong Hong; Khaliq, Muhammad Athar; Jayasuriya, Pathmamali; James, Swithin; Wang, Guo

    2017-12-01

    The aim of this study was to investigate the accumulation characteristics of tungsten (W) by different indica rice cultivars from the soil and to assess the potential risks to human health via dietary intake of W in rice consumption. A total of 153 rice (ear) samples of 15 cultivars and the corresponding surface soil samples were collected from 7 cities in Fujian Province of southeastern China. The available soil W were extracted using H 2 C 2 O 4 ·2H 2 O-(NH 4 ) 2 C 2 O 4 ·H 2 O at pH 3.3). Results showed that the total soil W ranged from 2.03 mg kg -1 to 15.34 mg kg -1  and available soil W ranged from 0.03 mg kg -1 to 1.61 mg kg -1 . The W concentration in brown rice varied from 7 μg kg -1 to 283 μg kg -1 and was significantly correlated with the available soil W. The highest mean TF avail (transfer factor based on available soil W) was 0.91 for Te-you 627 (hybrid, indica rice), whereas the lowest was 0.08 for Yi-you 673 (hybrid, indica rice). The TF avail decreased with the increase in available soil W, clay content, and cation exchange capacity. The consumption of the brown rice produced from the investigated areas in some cultivars by the present study may cause risks to human health.

  13. Dynamics of pH, Ferrum and Mangan, and Phosphorus on Newly Opened Paddy Soil having High Soil Organic Matter on Rice Growth

    Directory of Open Access Journals (Sweden)

    Sukristyonubowo

    2012-01-01

    Full Text Available Research had been carried out at the Research and Soil Testing Laboratory and Greenhouse of Soil ResearchInstitute, Bogor using newly opened paddy soil from Pesisir Selatan districts, West Sumatra (one year old. Totaltreatments tested were 12 which were combination of farmer rate, NPK recommendation (½×; ¾×; 1½×, strawcompost (½×; ¾×; 1½×, and dolomite. The trial was conducted using a completely randomized design with threereplications. This research had been prepared in two units, one unit for observing plant response to nutrientmanagement and another unit for incubation trial with the same treatment placed in the greenhouse. Rice cultivarused was IR-42 in accordance to the preferred varieties of local farmers. The sampling method for measuring thesolubility of Fe2+ and Mn2+, as well as the availability of PO43- was by centrifuge 50 g mud samples from theincubation pots then separated clear extract using filter paper. The observation results on dynamics of pH, Fe2+,Mn2+ and PO4-3 mainly occured in 1 to 14 days after submerging (incubation. After 14 days soil reaction had reachedthermodynamic sequence of oxidation-reduction processes, the PO43- more available and pH of the soil reached thepeak. The optimum dose of NPK fertilizer obtained 0.875 NPK or equal to 175 kg of urea, 87.5 kg of SP-36 and 87.5 kgKCl ha-1. The highest number of hills achieved from straw compost treatment 1½ organic matter (OM or 3 tons withan increase of 20%. Application of ameliorant dolomite increased the number of tillers about 2-3%, but insignificantlydifferent with no dolomite treatment.

  14. Dynamics of N-NH4 +, N-NO3 -, and total soil nitrogen in paddy field with azolla and biochar

    Science.gov (United States)

    Dewi, W. S.; Wahyuningsih, G. I.; Syamsiyah, J.; Mujiyo

    2018-03-01

    Nitrogen (N) is one of macronutrients which is dynamic in the soil and becomes constraint factor for rice crops. The addition of nitrogen fertilizers and its absorption in paddy field causes the dynamics of nitrogen, thus declines of N absorption efficiency. The aim of this research is to know influence Azolla, biochar and different varieties application on N-NH4 +, N-NO3 -, and total soil N in paddy field. This research was conducted in a screen house located in Jumantono Laboratory, Faculty of Agriculture, Universitas Sebelas Maret (UNS) with altitude 170 m asl from April to June 2016. Treatment factors that were examined consisted of azolla (0 and 10 tons/ha), biochar (0 and 2 tons/ha), and rice varieties (Cisadane, Memberamo, Ciherang, IR64). The results of this research showed that there was no interaction between azolla, biochar and varieties. Nevertheless, azolla treatment with dose of 10 tons/ha increased soil NH4 + content (41 days after planting, DAP) by 13.4% but tend to decrease at 70 and 90 DAP. Biochar treatment with dose of 2 ton/ha increases NO3 - soil content (70 DAP) by 1.7% but decreases total N soil by 5.8% (41 DAP) and 4.7% (90 DAP). Different rice varieties generated different soil NH4 + content (41 DAP) and rice root volume. Cisadane variety can increase soil NH4 + content (41 DAP) by 52.08% and root volume by 51.80% (90 DAP) compared with Ciherang variety. Organic rice field management with azolla and biochar affects the availability of N in the soil and increase N absorption efficiency through its role in increasing rice root volume.

  15. Conventional methanotrophs are responsible for atmospheric methane oxidation in paddy soils

    NARCIS (Netherlands)

    Cai, Yuanfeng; Yan, Zheng; Bodelier, P.L.E.; Conrad, R.; Jia, Zhongjun

    2016-01-01

    Soils serve as the biological sink of the potent greenhouse gas methane with exceptionally low concentrations of ~1.84 p.p.m.v. in the atmosphere. The as-yet-uncultivated methane-consuming bacteria have long been proposed to be responsible for this ‘high-affinity’ methane oxidation (HAMO). Here we

  16. The 'Brazilian Test' as an indicator of workability for paddy soils in Vietnam

    NARCIS (Netherlands)

    Hoogmoed, W.B.; Nguyen, V.L.

    2006-01-01

    Farmers in Mekong delta prefer to till their soil in dry conditions when possible. They claim that crops establish and yield better when the field have been ploughed when dry compared to the wet preparation by puddling. Experiments were carried out to investigate the optimum workabilty range for the

  17. Effect of nitrogen fertilizer and/or rice straw amendment on methanogenic archaeal communities and methane production from a rice paddy soil.

    Science.gov (United States)

    Bao, Qiongli; Huang, Yizong; Wang, Fenghua; Nie, Sanan; Nicol, Graeme W; Yao, Huaiying; Ding, Longjun

    2016-07-01

    Nitrogen fertilization and returning straw to paddy soil are important factors that regulate CH4 production. To evaluate the effect of rice straw and/or nitrate amendment on methanogens, a paddy soil was anaerobically incubated for 40 days. The results indicated that while straw addition increased CH4 production and the abundances of mcrA genes and their transcripts, nitrate amendment showed inhibitory effects on them. The terminal restriction fragment length polymorphism (T-RFLP) analysis based on mcrA gene revealed that straw addition obviously changed methanogenic community structure. Based on mcrA gene level, straw-alone addition stimulated Methanosarcinaceaes at the early stage of incubation (first 11 days), but nitrate showed inhibitory effect. The relative abundance of Methanobacteriaceae was also stimulated by straw addition during the first 11 days. Furthermore, Methanosaetaceae were enriched by nitrate-alone addition after 11 days, while Methanocellaceae were enriched by nitrate addition especially within the first 5 days. The transcriptional methanogenic community indicated more dynamic and complicated responses to straw and/or nitrate addition. Based on mcrA transcript level, nitrate addition alone resulted in the increase of Methanocellaceae and the shift from Methanosarcinaceae to Methanosaetaceae during the first 5 days of incubation. Straw treatments increased the relative abundance of Methanobacteriaceae after 11 days. These results demonstrate that nitrate addition influences methanogens which are transcriptionally and functionally active and can alleviate CH4 production associated with straw amendment in paddy soil incubations, presumably through competition for common substrates between nitrate-utilizing organisms and methanogens.

  18. Soil organic carbon (SOC) accumulation in rice paddies under long-term agro-ecosystem experiments in southern China - VI. Changes in microbial community structure and respiratory activity

    Science.gov (United States)

    Liu, D.; Liu, X.; Liu, Y.; Li, L.; Pan, G.; Crowley, D.; Tippkötter, R.

    2011-02-01

    Biological stabilization within accumulated soil organic carbon (SOC) has not been well understood, while its role in physical and chemical protection as well as of chemical recalcitrance had been addressed in Chinese rice paddies. In this study, topsoil samples were collected and respiratory activity measured in situ following rice harvest under different fertilization treatments of three long-term experimental sites across southern China in 2009. The SOC contents, microbial biomass carbon (SMBC) and nitrogen (SMBN) were analysed using chemical digestion and microbial community structure assessment via clony dilute plate counting methods. While SOC contents were consistently higher under compound chemical fertilization (Comp-Fert) or combined organic and inorganic fertilization (Comb-Fert) compared to N fertilization only (N-Fert), there was significantly higher fungal-bacterial ratio under Comb-Fert than under N-Fert and Comp-Fert. When subtracting the background effect under no fertilization treatment (Non-Fert), the increase both in SMBC and SMBN under fertilization treatment was found very significantly correlated to the increase in SOC over controls across the sites. Also, the ratio of culturable fungal to bacterial population numbers (F/B ratio) was well correlated with soil organic carbon contents in all samples across the sites studied. SOC accumulation favoured a build-up the microbial community with increasing fungal dominance in the rice paddies under fertilization treatments. While soil respiration rates were high under Comb-Fert as a result of enhanced microbial community build-up, the specific soil respiratory activity based on microbial biomass carbon was found in a significantly negatively correlation with the SOC contents for overall samples. Thus, a fungal-dominated microbial community seemed to slow SOC turnover, thereby favouring SOC accumulation under Comp-Fert or under Comb-Fert in the rice paddies. Therefore, the biological stabilization

  19. Carbon degradation in agricultural soils flooded with seawater after managed coastal realignment

    Science.gov (United States)

    Sjøgaard, Kamilla S.; Treusch, Alexander H.; Valdemarsen, Thomas B.

    2017-09-01

    Permanent flooding of low-lying coastal areas is a growing threat due to climate change and related sea-level rise. An increasingly common solution to protect coastal areas lying below sea level is intentional flooding by "managed coastal realignment". However, the biogeochemical implications of flooding agricultural soils with seawater are still not well understood. We conducted a 1-year mesocosm experiment to investigate microbial carbon degradation processes in soils flooded with seawater. Agricultural soils were sampled on the northern coast of the island Fyn (Denmark) at Gyldensteen Strand, an area that was subsequently flooded in a coastal realignment project. We found rapid carbon degradation to TCO2 1 day after experimental flooding and onwards and microbial sulfate reduction established quickly as an important mineralization pathway. Nevertheless, no free sulfide was observed as it precipitated as Fe-S compounds with Fe acting as a natural buffer, preventing toxic effects of free sulfide in soils flooded with seawater. Organic carbon degradation decreased significantly after 6 months, indicating that most of the soil organic carbon was refractory towards microbial degradation under the anoxic conditions created in the soil after flooding. During the experiment only 6-7 % of the initial soil organic carbon pools were degraded. On this basis we suggest that most of the organic carbon present in coastal soils exposed to flooding through sea-level rise or managed coastal realignment will be permanently preserved.

  20. Phosphorus status and microbial community of paddy soil with the growth of annual ryegrass (Lolium multiflorum Lam.) under different phosphorus fertilizer treatments*

    Science.gov (United States)

    Guo, Hai-chao; Wang, Guang-huo

    2009-01-01

    Annual ryegrass (Lolium multiflorum Lam.) was grown in paddy soil in pots under different phosphorus (P) fertilizer treatments to investigate changes of P fractions and microbial community of the soil. The treatments included Kunyang phosphate rock (KPR) applications at 50 mg P/kg (KPR50) and 250 mg P/kg (KPR250), mono-calcium phosphate (MCP) application at 50 mg P/kg (MCP50), and the control without P application. The results showed that KPR50, KPR250, and MCP50 applications significantly increased the dry weight of the ryegrass by 13%, 38%, and 55%, and increased P uptake by 19%, 135%, and 324%, respectively. Compared with MCP50, the relative effectiveness of KPR50 and KPR250 treatments in ryegrass production was about 23% and 68%, respectively. After one season of ryegrass growth, the KPR50, KPR250, and MCP50 applications increased soil-available P by 13.4%, 26.8%, and 55.2%, respectively. More than 80% of the applied KPR-P remained as HCl-P fraction in the soil. Phospholipid fatty acid (PLFA) analysis showed that the total and bacterial PLFAs were significantly higher in the soils with KPR250 and MCP50 treatments compared with KPR50 and control. The latter had no significant difference in the total or bacterial PLFAs. The KPR50, KPR250, and MCP50 treatments increased fungal PLFA by 69%, 103%, and 69%, respectively. Both the principal component analysis and the cluster analysis of the PLFA data suggest that P treatments altered the microbial community composition of the soils, and that P availability might be an important contributor to the changes in the microbial community structure during the ryegrass growth in the paddy soils. PMID:19817001

  1. Long-term Fertilization Structures Bacterial and Archaeal Communities along Soil Depth Gradient in a Paddy Soil

    Directory of Open Access Journals (Sweden)

    Yunfu Gu

    2017-08-01

    Full Text Available Soil microbes provide important ecosystem services. Though the effects of changes in nutrient availability due to fertilization on the soil microbial communities in the topsoil (tilled layer, 0–20 cm have been extensively explored, the effects on communities and their associations with soil nutrients in the subsoil (below 20 cm which is rarely impacted by tillage are still unclear. 16S rRNA gene amplicon sequencing was used to investigate bacterial and archaeal communities in a Pup-Calric-Entisol soil treated for 32 years with chemical fertilizer (CF and CF combined with farmyard manure (CFM, and to reveal links between soil properties and specific bacterial and archaeal taxa in both the top- and subsoil. The results showed that both CF and CFM treatments increased soil organic carbon (SOC, soil moisture (MO and total nitrogen (TN while decreased the nitrate_N content through the profile. Fertilizer applications also increased Olsen phosphorus (OP content in most soil layers. Microbial communities in the topsoil were significantly different from those in subsoil. Compared to the CF treatment, taxa such as Nitrososphaera, Nitrospira, and several members of Acidobacteria in topsoil and Subdivision 3 genera incertae sedis, Leptolinea, and Bellilinea in subsoil were substantially more abundant in CFM. A co-occurrence based network analysis demonstrated that SOC and OP were the most important soil parameters that positively correlated with specific bacterial and archaeal taxa in topsoil and subsoil, respectively. Hydrogenophaga was identified as the keystone genus in the topsoil, while genera Phenylobacterium and Steroidobacter were identified as the keystone taxa in subsoil. The taxa identified above are involved in the decomposition of complex organic compounds and soil carbon, nitrogen, and phosphorus transformations. This study revealed that the spatial variability of soil properties due to long-term fertilization strongly shapes the bacterial

  2. Uptake of C-14 tagged acetate by rice in a paddy soil-to-rice plant system

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Nobuyoshi; Tagami, Keiko; Uchida, Shigeo [Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)

    2014-07-01

    Geological disposal of Transuranic (TRU) waste is planned to avoid radiation exposure to the public. One of the dominant nuclides contributing to the dose from TRU waste is C-14, which is long-lived and has very poor sorption properties on natural geological media. Therefore, there are some concerns regarding possible migration of C-14 to the living environments. For the public health safety, it is necessary to clarify pathways of C-14 to human beings in the environment. Intake of C-14 from food source is one of important pathways. In the present study, we examined transfer of C-14 to various parts of rice plant in a paddy soil-to-rice plant system. Rice seedlings in Wagner pots (n=12) were grown for about two months from 7 May 2012 under natural light. The grown plants were moved to a closed chamber on 5 July 2012. The rice plants were grown without water supply from 5 July 2012, and then one liter of C-14 tagged acetate (1.85 MBq) was supplied to the rice plants in the spiked group (n=8) just once on 9 July 2012. For the rice plants in the control group (n=4), uncontaminated water was supplied. These rice plants were air-dried after a harvest on 23 August 2012 and divided into four parts: white rice, bran, rice husk, and the stem and leaf part. The activities of C-14 in the divided parts and air-dried soil samples were determined with a liquid scintillation counting system. Radiocarbon was detected even in the rice plants of the control group. However, the C-14 activity in the soil of the control group was less than the detection limit (1.0 Bq/g). The C-14 activities for the control group decreased in the order of rice husk, bran, white rice, and the stem and leaf part. The detection of C-14 in the control group may be caused by the release of C-14 tagged carbon dioxide from the spiked group. That is, C-14 tagged acetate was converted to carbon dioxide by microbial activity in the spiked group, and then some of the released carbon dioxide was assimilated into

  3. [Runoff Pollution Experiments of Paddy Fields Under Different Irrigation Patterns].

    Science.gov (United States)

    Zhou, Jing-wen; Su, Bao-lin; Huang, Ning-bo; Guan, Yu-tang; Zhao, Kun

    2016-03-15

    To study runoff and non-point source pollution of paddy fields and to provide a scientific basis for agricultural water management of paddy fields, paddy plots in the Jintan City and the Liyang City were chosen for experiments on non-point source pollution, and flood irrigation and intermittent irrigation patterns were adopted in this research. The surface water level and rainfall were observed during the growing season of paddies, and the runoff amount from paddy plots and loads of total nitrogen (TN) and total phosphorus (TP) were calculated by different methods. The results showed that only five rain events of totally 27 rainfalls and one artificially drainage formed non-point source pollution from flood irrigated paddy plot, which resulted in a TN export coefficient of 49.4 kg · hm⁻² and a TP export coefficient of 1.0 kg · hm⁻². No any runoff event occurred from the paddy plot with intermittent irrigation even in the case of maximum rainfall of 95.1 mm. Runoff from paddy fields was affected by water demands of paddies and irrigation or drainage management, which was directly correlated to surface water level, rainfall amount and the lowest ridge height of outlets. Compared with the flood irrigation, intermittent irrigation could significantly reduce non-point source pollution caused by rainfall or artificial drainage.

  4. Effects of organic matter fraction and compositional changes on distribution of cadmium and zinc in long-term polluted paddy soils

    International Nuclear Information System (INIS)

    Zhou, Tong; Wu, Longhua; Luo, Yongming; Christie, Peter

    2018-01-01

    Soil particulate organic matter (POM) has rapid turnover and metal enrichment, but the interactions between organic matter (OM) and metals have not been well studied. The present study aimed to investigate changes in the OM concentration and composition of the POM fraction and their corresponding effects on metal distribution and extractability in long-term polluted paddy soils. Soil 2000–53 μm POM size fractions had higher contents of C–H and C=O bonds, C–H/C=O ratios and concentrations of fulvic acid (FA), humic acid (HA), cadmium (Cd) and zinc (Zn) than the bulk soils. Cadmium and Zn stocks in soil POM fractions were 24.5–27.9% and 7.12–16.7%, respectively, and were more readily EDTA-extractable. Compared with the control soil, the 2000–250 μm POM size fractions had higher organic carbon concentrations and C/N ratios in the polluted soils. However, there were no significant differences in the contents in C–H and C=O bonds or C–H/C=O ratios of POM fractions among the control, slightly and highly polluted soils. In accordance with the lower contents of C=O bonds and FA and HA concentrations, the Cd and Zn concentrations in 250–53 μm POM size fractions were lower than those in 2000–250 μm POM size fractions. Enrichment of Cd in POM fractions increased with increasing soil pollution level. These results support the view that changes in the OM concentration and the size and composition of POM fractions play a key role in determining the distribution of Cd and Zn in paddy soils. - Highlights: • The OC and FA contents and C/N in POM (2000–250 μm) increased in polluted soil. • Enrichment of Cd and Zn decreased with decreasing POM size. • No significant change in content of C=O group in POM was observed in polluted soil. • Changes in the size and composition of soil POM affected the Cd and Zn distribution. - Interactions between soil organic matter and metals.

  5. Noviherbaspirillum denitrificans sp. nov., a denitrifying bacterium isolated from rice paddy soil and Noviherbaspirillum autotrophicum sp. nov., a denitrifying, facultatively autotrophic bacterium isolated from rice paddy soil and proposal to reclassify Herbaspirillum massiliense as Noviherbaspirillum massiliense comb. nov.

    Science.gov (United States)

    Ishii, Satoshi; Ashida, Naoaki; Ohno, Hiroki; Segawa, Takahiro; Yabe, Shuhei; Otsuka, Shigeto; Yokota, Akira; Senoo, Keishi

    2017-06-01

    Thirty-nine denitrifying bacterial strains closely related to one another, represented by strains TSA40T and TSA66T, were isolated from rice paddy soils. Strains TSA40T and TSA66T were Gram-stain-negative, slightly curved rod-shaped, and motile by means of polar flagella. They were able to reduce nitrate, nitrite and nitrous oxide, but unable to fix atmospheric N2. While strain TSA66T was able to grow autotrophically by H2-dependent denitrification, strain TSA40T could not. Phylogenetic analysis suggested that they belong to the family Oxalobacteraceae, the order Burkholderiales in the class Betaproteobacteria. Major components in the fatty acids (C16 : 0, C17 : 0 cyclo, C18 : 1ω7c and summed feature 3) and quinone (Q-8) also supported the affiliation of strains TSA40T and TSA66T to the family Oxalobacteraceae. Based on 16S rRNA gene sequence comparisons, strains TSA40T and TSA66T showed the greatest degree of similarity to Herbaspirillum massiliense JC206T, Noviherbaspirillum malthae CC-AFH3T, Noviherbaspirillum humi U15T, Herbaspirillum seropedicae Z67T and Paucimonas lemoignei LMG 2207T, and lower similarities to the members of other genera. Average nucleotide identity values between the genomes of strain TSA40T, TSA66T and H. massiliense JC206T were 75-77 %, which was lower than the threshold value for species discrimination (95-96 %). Based on the 16S rRNA gene sequence analysis in combination with physiological, chemotaxonomic and genomic properties, strains TSA40T (=JCM 17722T=ATCC TSD-69T) and TSA66T (=JCM 17723T=DSM 25787T) are the type strains of two novel species within the genus Noviherbaspirillum, for which the names Noviherbaspirillum denitrificans sp. nov. and Noviherbaspirillum autotrophicum sp. nov. are proposed, respectively. We also propose the reclassification of Herbaspirillum massiliense as Noviherbaspirillum massiliense comb. nov.

  6. Survival and bioturbation effects of common marine macrofauna in coastal soils newly flooded with seawater

    DEFF Research Database (Denmark)

    Valdemarsen, Thomas Bruun; Quintana, Cintia Organo; Thorsen, Sandra Walløe

    Low-lying coastal soils are at risk of being permanently flooded due to global sea level rise, but how will these areas develop as habitat for marine species? We conducted an experiment to evaluate the habitat quality of flooded soils for common marine polychaetes (Marenzelleria viridis, Nereis d...

  7. Biochar application mode influences nitrogen leaching and NH3 volatilization losses in a rice paddy soil irrigated with N-rich wastewater.

    Science.gov (United States)

    Sun, Haijun; Min, Ju; Zhang, Hailin; Feng, Yanfang; Lu, Kouping; Shi, Weiming; Yu, Min; Li, Xuewen

    2017-07-11

    Impacts of biochar application mode on nitrogen (N) leaching, ammonia (NH 3 ) volatilization, rice grain yield and N use efficiency (NUE) are not well understood. Therefore, a field experiment was conducted to evaluate those impacts in a rice paddy soil received 225 kg N ha -1 from either urea or N-rich wastewater. One treatment received 10 t ha -1 biochar with the basal fertilization, and the other received same total amount of biochar but split applied with the three split N applications with same ratio as N fertilizer split ratio (40%, 30% and 30%). Results showed that N leaching loads were 4.20-6.22 kg ha -1 . Biochar one-time application reduced N leaching by 23.1%, and biochar split application further reduced N leaching by 32.4%. Total NH 3 volatilization loss was 15.5-24.5 kg ha -1 . Biochar one-time application did not influence the NH 3 volatilization, but biochar split application stimulated the cumulative NH 3 volatilization by 57.7%. Both biochar treatments had no influence on NUE and rice grain yield. In conclusion, biochar application mode indeed influences the N leaching and NH 3 volatilization in rice paddy soils, and biochar one-time application should be recommended for reducing N leaching without increasing NH 3 volatilization.

  8. Quantitative Estimation of Soil Carbon Sequestration in Three Land Use Types (Orchard, Paddy Rice and Forest in a Part of Ramsar Lands, Northern Iran

    Directory of Open Access Journals (Sweden)

    zakieh pahlavan yali

    2017-02-01

    Full Text Available Introduction: The increasing Greenhouse Gases in atmosphere is the main cause of climate and ecosystems changes. The most important greenhouse gas is CO2 that causes global warming or the greenhouse effect. One of the known solutions that reduces atmospheric carbon and helps to improve the situation, is carbon sequestration in vegetation cover and soil. Carbon sequestration refers to the change in atmospheric CO2 into organic carbon compounds by plants and capture it for a certain time . However, the ecosystems with different vegetation have Impressive Influence on soil carbon sequestration (SCS. Soil as the main component of these ecosystems is a world-wide indicator which has been known to play an important role in global balance of carbon sequestration. Furthermore, carbon sequestration can be a standard world trade and becomes guaranteed. Costs of transfer of CO2 (carbon transfer From the atmosphere into the soil based on the negative effects of increased CO2 on Weather is always increasing, This issue can be faced by developing countries to create a new industry, especially when conservation and restoration of rangeland to follow. This research was regarded due to estimation of SCS in three land use types (orchard, paddy rice and forest in a Part of Ramsar Lands, Northern Iran. Materials and Methods: Ramsar city with an area of about 729/7 km2 is located in the western part of Mazandaran province. Its height above sea level is 20 meters. Ramsar city is situated in a temperate and humid climate. Land area covered by forest, orchard and paddy rice. After field inspection of the area, detailed topographic maps of the specified zone on the study were also tested. In each of the three land types, 500 hectares in the every growing and totally 1,500 hectares as study area were selected .For evaluation the sequestration of carbon in different vegetation systems,15 soil profile selected and sampling from depth of 0 to 100 centimetres of each profile

  9. Separate effects of flooding and anaerobiosis on soil greenhouse gas emissions and redox sensitive biogeochemistry

    Science.gov (United States)

    Gavin McNicol; Whendee L. Silver

    2014-01-01

    Soils are large sources of atmospheric greenhouse gases, and both the magnitude and composition of soil gas emissions are strongly controlled by redox conditions. Though the effect of redox dynamics on greenhouse gas emissions has been well studied in flooded soils, less research has focused on redox dynamics without total soil inundation. For the latter, all that is...

  10. Accumulation of methylmercury in rice and flooded soil in experiments with an enriched isotopic Hg(II) tracer

    Science.gov (United States)

    Strickman, R. J.; Mitchell, C. P. J.

    2015-12-01

    Methylmercury (MeHg) is a neurotoxin produced in anoxic aquatic sediments. Numerous factors, including the presence of aquatic plants, alter the biogeochemistry of sediments, affecting the rate at which microorganisms transform bioavailable inorganic Hg (IHg) to MeHg. Methylmercury produced in flooded paddy soils and its transfer into rice has become an important dietary consideration. An improved understanding of how MeHg reaches the grain and the extent to which rice alters MeHg production in rhizosphere sediments could help to inform rice cultivation practices. We conducted a controlled greenhouse experiment with thirty rice plants grown in individual, flooded pots amended with enriched 200Hg. Unvegetated controls were maintained under identical conditions. At three plant growth stages (vegetative growth, flowering, and grain maturity), ten plants were sacrificed and samples collected from soil, roots, straw, panicle, and grain of vegetated and unvegetated pots, and assessed for MeHg and THg concentrations. We observed consistent ratios between ambient and tracer MeHg between soils (0.36 ±0.04 — 0.44 ± 0.09) and plant compartments (0.23 ± 0.07 -0.34 ± 0.05) indicating that plant MeHg contamination originates in the soil rather than in planta methylation. The majority of this MeHg was absorbed between the tillering (4.48 ± 2.38 ng/plant) and flowering (8.43 ± 5.12 ng/pl) phases, with a subsequent decline at maturity (2.87 ± 1.23 ng/pl) only partly explained by translocation to the developing grain, indicating that MeHg was demethylated in planta. In contrast, IHg was absorbed from both soil and air, as evidenced by the higher ambient IHg concentrations compared to tracer (3.76 ± 1.19 vs. 0.27 ± 0.40 ng/g). Surprisingly, MeHg accumulation was significantly (p= 0.042-- 0.003) lower in vegetated vs. unvegetated sediments at flowering (1.41 ± 0.26 vs. 1.57 ± 0.23) and maturity (1.27 ± 0.22 vs. 1.71 ± 0.25), suggesting that plant exudates bound Hg

  11. Short-chain chlorinated paraffins in soil, paddy seeds (Oryza sativa) and snails (Ampullariidae) in an e-waste dismantling area in China: Homologue group pattern, spatial distribution and risk assessment.

    Science.gov (United States)

    Yuan, Bo; Fu, Jianjie; Wang, Yawei; Jiang, Guibin

    2017-01-01

    Short-chain chlorinated paraffins (SCCPs) in multi-environmental matrices are studied in Taizhou, Zhejiang Province, China, which is a notorious e-waste dismantling area. The investigated matrices consist of paddy field soil, paddy seeds (Oryza sativa, separated into hulls and rice unpolished) and apple snails (Ampullariidae, inhabiting the paddy fields). The sampling area covered a 65-km radius around the contamination center. C 10 and C 11 are the two predominant homologue groups in the area, accounting for about 35.7% and 33.0% of total SCCPs, respectively. SCCPs in snails and hulls are generally higher than in soil samples (30.4-530 ng/g dw), and SCCPs in hulls are approximate five times higher than in corresponding rice samples (4.90-55.1 ng/g dw). Homologue pattern analysis indicates that paddy seeds (both hull and rice) tend to accumulate relatively high volatile SCCP homologues, especially the ones with shorter carbon chain length, while snails tend to accumulate relatively high lipophilic homologues, especially the ones with more substituted chlorines. SCCPs in both paddy seeds and snails are linearly related to those in the soil. The e-waste dismantling area, which covers a radius of approximate 20 km, shows higher pollution levels for SCCPs according to their spatial distribution in four matrices. The preliminary assessment indicates that SCCP levels in local soils pose no significant ecological risk for soil dwelling organisms, but higher risks from dietary exposure of SCCPs are suspected for people living in e-waste dismantling area. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Biochar affects soil organic matter cycling and microbial functions but does not alter microbial community structure in a paddy soil.

    Science.gov (United States)

    Tian, Jing; Wang, Jingyuan; Dippold, Michaela; Gao, Yang; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2016-06-15

    The application of biochar (BC) in conjunction with mineral fertilizers is one of the most promising management practices recommended to improve soil quality. However, the interactive mechanisms of BC and mineral fertilizer addition affecting microbial communities and functions associated with soil organic matter (SOM) cycling are poorly understood. We investigated the SOM in physical and chemical fractions, microbial community structure (using phospholipid fatty acid analysis, PLFA) and functions (by analyzing enzymes involved in C and N cycling and Biolog) in a 6-year field experiment with BC and NPK amendment. BC application increased total soil C and particulate organic C for 47.4-50.4% and 63.7-74.6%, respectively. The effects of BC on the microbial community and C-cycling enzymes were dependent on fertilization. Addition of BC alone did not change the microbial community compared with the control, but altered the microbial community structure in conjunction with NPK fertilization. SOM fractions accounted for 55% of the variance in the PLFA-related microbial community structure. The particulate organic N explained the largest variation in the microbial community structure. Microbial metabolic activity strongly increased after BC addition, particularly the utilization of amino acids and amines due to an increase in the activity of proteolytic (l-leucine aminopeptidase) enzymes. These results indicate that microorganisms start to mine N from the SOM to compensate for high C:N ratios after BC application, which consequently accelerate cycling of stable N. Concluding, BC in combination with NPK fertilizer application strongly affected microbial community composition and functions, which consequently influenced SOM cycling. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Tenax extraction for exploring rate-limiting factors in methyl-β-cyclodextrin enhanced anaerobic biodegradation of PAHs under denitrifying conditions in a red paddy soil

    International Nuclear Information System (INIS)

    Sun, Mingming; Ye, Mao; Hu, Feng; Li, Huixin; Teng, Ying; Luo, Yongming; Jiang, Xin; Kengara, Fredrick Orori

    2014-01-01

    Highlights: • Enhanced anaerobic bioremediation of a red paddy soil polluted with PAHs. • 1% (w/w) methyl-β-cyclodextrin (MCD) and 20 mM nitrate addition acted as solubility-enhancing agent and electron acceptor respectively. • Tenax extraction and a first-three-compartment modeling were applicable to explore the rate-limiting factors in the biodegradation. • Lack of PAH-degraders hindered biodegradation in control and MCD addition treatments. • Inadequate bioaccessible PAHs was vital rate-limiting factor in nitrate addition treatments. -- Abstract: The effectiveness of anaerobic bioremediation systems for PAH-contaminated soil may be constrained by low contaminants bioaccessibility due to limited aqueous solubility and lack of suitable electron acceptors. Information on what is the rate-limiting factor in bioremediation process is of vital importance in the decision in what measures can be taken to assist the biodegradation efficacy. In the present study, four different microcosms were set to study the effect of methyl-β-cyclodextrin (MCD) and nitrate addition (N) on PAHs biodegradation under anaerobic conditions in a red paddy soil. Meanwhile, sequential Tenax extraction combined with a first-three-compartment model was employed to evaluate the rate-limiting factors in MCD enhanced anaerobic biodegradation of PAHs. Microcosms with both 1% (w/w) MCD and 20 mM N addition produced maximum biodegradation of total PAHs of up to 61.7%. It appears rate-limiting factors vary with microcosms: low activity of degrading microorganisms is the vital rate-limiting factor for control and MCD addition treatments (CK and M treatments); and lack of bioaccessible PAHs is the main rate-limiting factor for nitrate addition treatments (N and MN treatments). These results have practical implications for site risk assessment and cleanup strategies

  14. Tenax extraction for exploring rate-limiting factors in methyl-β-cyclodextrin enhanced anaerobic biodegradation of PAHs under denitrifying conditions in a red paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Mingming, E-mail: sunmingming@njau.edu.cn [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Key Laboratory of Soil Environmental and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Ye, Mao [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Hu, Feng, E-mail: fenghu@njau.edu.cn [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Li, Huixin [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Teng, Ying [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Luo, Yongming [Yantai Institute of Costal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Jiang, Xin [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Kengara, Fredrick Orori [Department of Chemistry, Maseno University, Private Bag, Maseno 40105 (Kenya)

    2014-01-15

    Highlights: • Enhanced anaerobic bioremediation of a red paddy soil polluted with PAHs. • 1% (w/w) methyl-β-cyclodextrin (MCD) and 20 mM nitrate addition acted as solubility-enhancing agent and electron acceptor respectively. • Tenax extraction and a first-three-compartment modeling were applicable to explore the rate-limiting factors in the biodegradation. • Lack of PAH-degraders hindered biodegradation in control and MCD addition treatments. • Inadequate bioaccessible PAHs was vital rate-limiting factor in nitrate addition treatments. -- Abstract: The effectiveness of anaerobic bioremediation systems for PAH-contaminated soil may be constrained by low contaminants bioaccessibility due to limited aqueous solubility and lack of suitable electron acceptors. Information on what is the rate-limiting factor in bioremediation process is of vital importance in the decision in what measures can be taken to assist the biodegradation efficacy. In the present study, four different microcosms were set to study the effect of methyl-β-cyclodextrin (MCD) and nitrate addition (N) on PAHs biodegradation under anaerobic conditions in a red paddy soil. Meanwhile, sequential Tenax extraction combined with a first-three-compartment model was employed to evaluate the rate-limiting factors in MCD enhanced anaerobic biodegradation of PAHs. Microcosms with both 1% (w/w) MCD and 20 mM N addition produced maximum biodegradation of total PAHs of up to 61.7%. It appears rate-limiting factors vary with microcosms: low activity of degrading microorganisms is the vital rate-limiting factor for control and MCD addition treatments (CK and M treatments); and lack of bioaccessible PAHs is the main rate-limiting factor for nitrate addition treatments (N and MN treatments). These results have practical implications for site risk assessment and cleanup strategies.

  15. [Aluminum dissolution and changes of pH in soil solution during sorption of copper by aggregates of paddy soil].

    Science.gov (United States)

    Xu, Hai-Bo; Zhao, Dao-Yuan; Qin, Chao; Li, Yu-Jiao; Dong, Chang-Xun

    2014-01-01

    Size fractions of soil aggregates in Lake Tai region were collected by the low-energy ultrasonic dispersion and the freeze-desiccation methods. The dissolution of aluminum and changes of pH in soil solution during sorption of Cu2+ and changes of the dissolution of aluminum at different pH in the solution of Cu2+ by aggregates were studied by the equilibrium sorption method. The results showed that in the process of Cu2+ sorption by aggregates, the aluminum was dissoluted and the pH decreased. The elution amount of aluminum and the decrease of pH changed with the sorption of Cu2+, both increasing with the increase of Cu2+ sorption. Under the same conditions, the dissolution of aluminum and the decrease of pH were in the order of coarse silt fraction > silt fraction > sand fraction > clay fraction, which was negatively correlated with the amount of iron oxide, aluminum and organic matter. It suggested that iron oxide, aluminum and organic matters had inhibitory and buffering effect on the aluminum dissolution and the decrease of pH during the sorption of Cu2+.

  16. Fenton process-affected transformation of roxarsone in paddy rice soils: Effects on plant growth and arsenic accumulation in rice grain.

    Science.gov (United States)

    Qin, Junhao; Li, Huashou; Lin, Chuxia

    2016-08-01

    Batch and greenhouse experiments were conducted to examine the effects of Fenton process on transformation of roxarsone in soils and its resulting impacts on the growth of and As uptake by a rice plant cultivar. The results show that addition of Fenton reagent markedly accelerated the degradation of roxarsone and produced arsenite, which was otherwise absent in the soil without added Fenton reagent. Methylation of arsenate was also enhanced by Fenton process in the earlier part of the experiment due to abundant supply of arsenate from Roxarsone degradation. Overall, addition of Fenton reagent resulted in the predominant presence of arsenate in the soils. Fenton process significantly improved the growth of rice in the maturity stage of the first crop, The concentration of methylated As species in the rice plant tissues among the different growth stages was highly variable. Addition of Fenton reagent into the soils led to reduced uptake of soil-borne As by the rice plants and this had a significant effect on reducing the accumulation of As in rice grains. The findings have implications for understanding As biogeochemistry in paddy rice field receiving rainwater-borne H2O2 and for development of mitigation strategies to reduce accumulation of As in rice grains. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Scaling the flood regime with the soil hydraulic properties of the catchment

    Science.gov (United States)

    Peña Rojas, Luis Eduardo; Francés García, Félix; Barrios Peña, Miguel

    2015-04-01

    The spatial land cover distribution and soil type affect the hydraulic properties of soils, facilitating or retarding the infiltration rate and the response of a catchment during flooding events. This research analyzes: 1) the effect of land cover use in different time periods as a source of annual maximum flood records nonstationarity; 2) the scalability of the relationship between soil hydraulic properties of the catchment (initial abstractions, upper soil capillary storage and vertical and horizontal hydraulic conductivity) and the flood regime. The study was conducted in Combeima River basin in Colombia - South America and it was modelled the changes in the land uses registered in 1991, 2000, 2002 and 2007, using distributed hydrological modelling and nonparametric tests. The results showed that changes in land use affect hydraulic properties of soil and it has influence on the magnitude of flood peaks. What is a new finding is that this behavior is scalable with the soil hydraulic properties of the catchment flood moments have a simple scaling behavior and the peaks flow increases with higher values of capillary soil storage, whereas higher values, the peaks decreased. Finally it was applied Generalized Extreme Values and it was found scalable behavior in the parameters of the probability distribution function. The results allowed us to find a relationship between soil hydraulic properties and the behavior of flood regime in the basin studied.

  18. [Characteristics of N2, N2O, NO, CO2 and CH4 Emissions in Anaerobic Condition from Sandy Loam Paddy Soil].

    Science.gov (United States)

    Cao, Na; Wang, Rui; Liao, Ting-ting; Chen, Nuo; Zheng, Xun-hua; Yao, Zhi-sheng; Zhang, Hai; Butterbach-Bahl, Klaus

    2015-09-01

    Understanding the characteristics of the production of nitrogen gases (N2, N2O and NO), CO2 and CH4 in anaerobic paddy soils is not only a prerequisite for an improved mechanistic understanding of key microbial processes involved in the production of atmospheric greenhouse gases (GHG), but might also provide the basis for designing greenhouse gas mitigation strategies. Moreover, quantifying the composition fractions of denitrification gaseous products is of key importance for improving parameterization schemes of microbial processes in process-oriented models which are increasingly used for assessing soil GHG emissions at site and national scales. In our experiments we investigated two sandy loam soils from two paddy fields. The initial concentrations of soil nitrate and dissolved organic carbon (DOC) were set at approximately 50 mg.kg-1 and mg.kg-1, respectively, by adding a mixture solution of KNO3 and glucose. The emissions of N2, N2O NO, CO2 and CH4, as well as concentrations of carbon and nitrogen substrates for each soil sample were measured simultaneously, using a gas-flow-soil-core technique and a paralleling substrate monitoring system. The results showed that the accumulative emissions of N2, N2O and NO of the two soil samples for the entire incubation period were 6 - 8, 20, and 15 - 18 mg.kg-1, respectively. By measuring the cumulative emissions of denitrification gases (N, = N2 + N2O + NO) we were able to explain 95% to 98% of observed changes in s1ifr nilrate concentrations. The mass fractions of N2, N2O and NO emissions to Nt were approximately 15% -19%, 47% -49%, and 34% -36%, respectively. Thus, in our experiments N2O and NO were the main products of denitrification for the entire incubation period. However, as the temporal courses of hourly or daily production of the denitrification gases showed, NO production dominated and peaked firstly, and then N2O, before finally N2 became the dominant product. Our results show the high temporal dynamic of

  19. Conditions Leading to High CO2 (>5 kPa) in Waterlogged–Flooded Soils and Possible Effects on Root Growth and Metabolism

    Science.gov (United States)

    GREENWAY, HANK; ARMSTRONG, WILLIAM; COLMER, TIMOTHY D.

    2006-01-01

    • Aims Soil waterlogging impedes gas exchange with the atmosphere, resulting in low PO2 and often high PCO2. Conditions conducive to development of high PCO2 (5–70 kPa) during soil waterlogging and flooding are discussed. The scant information on responses of roots to high PCO2 in terms of growth and metabolism is reviewed. • Scope PCO2 at 15–70 kPa has been reported for flooded paddy-field soils; however, even 15 kPa PCO2 may not always be reached, e.g. when soil pH is above 7. Increases of PCO2 in soils following waterlogging will develop much more slowly than decreases in PO2; in soil from rice paddies in pots without plants, maxima in PCO2 were reached after 2–3 weeks. There are no reliable data on PCO2 in roots when in waterlogged or flooded soils. In rhizomes and internodes, PCO2 sometimes reached 10 kPa, inferring even higher partial pressures in the roots, as a CO2 diffusion gradient will exist from the roots to the rhizomes and shoots. Preliminary modelling predicts that when PCO2 is higher in a soil than in roots, PCO2 in the roots would remain well below the PCO2 in the soil, particularly when there is ventilation via a well-developed gas-space continuum from the roots to the atmosphere. The few available results on the effects of PCO2 at > 5 kPa on growth have nearly all involved sudden increases to 10–100 kPa PCO2; consequently, the results cannot be extrapolated with certainty to the much more gradual increases of PCO2 in waterlogged soils. Nevertheless, rice in an anaerobic nutrient solution was tolerant to 50 kPa CO2 being suddenly imposed. By contrast, PCO2 at 25 kPa retarded germination of some maize genotypes by 50 %. With regard to metabolism, assuming that the usual pH of the cytoplasm of 7·5 was maintained, every increase of 10 kPa CO2 would result in an increase of 75–90 mm HCO3− in the cytoplasm. pH maintenance would depend on the biochemical and biophysical pH stats (i.e. regulatory systems

  20. Effects of water-saving irrigation on emissions of greenhouse gases and prokaryotic communities in rice paddy soil.

    Science.gov (United States)

    Ahn, Jae-Hyung; Choi, Min-Young; Kim, Byung-Yong; Lee, Jong-Sik; Song, Jaekyeong; Kim, Gun-Yeob; Weon, Hang-Yeon

    2014-08-01

    The effects of water-saving irrigation on emissions of greenhouse gases and soil prokaryotic communities were investigated in an experimental rice field. The water layer was kept at 1-2 cm in the water-saving (WS) irrigation treatment and at 6 cm in the continuous flooding (CF) irrigation treatment. WS irrigation decreased CH(4) emissions by 78 % and increased N(2)O emissions by 533 %, resulting in 78 % reduction of global warming potential compared to the CF irrigation. WS irrigation did not affect the abundance or phylogenetic distribution of bacterial/archaeal 16S rRNA genes and the abundance of bacterial/archaeal 16S rRNAs. The transcript abundance of CH(4) emission-related genes generally followed CH(4) emission patterns, but the difference in abundance between mcrA transcripts and amoA/pmoA transcripts best described the differences in CH(4) emissions between the two irrigation practices. WS irrigation increased the relative abundance of 16S rRNAs and functional gene transcripts associated with Anaeromyxobacter and Methylocystis spp., suggesting that their activities might be important in emissions of the greenhouse gases. The N(2)O emission patterns were not reflected in the abundance of N(2)O emission-related genes and transcripts. We showed that the alternative irrigation practice was effective for mitigating greenhouse gas emissions from rice fields and that it did not affect the overall size and structure of the soil prokaryotic community but did affect the activity of some groups.

  1. Physiological and biochemical responses of Salix integra Thunb. under copper stress as affected by soil flooding.

    Science.gov (United States)

    Cao, Yini; Ma, Chuanxin; Chen, Guangcai; Zhang, Jianfeng; Xing, Baoshan

    2017-06-01

    To explore the joint effect of copper (Cu) and flooding on Salix integra Thunb. (S. integra), the physiological and biochemical parameters of the seedlings grown in Cu amended soil (50, 150, 450 mg kg -1 ) with or without the flooding for 60 days were evaluated. The results suggested that the flooding significantly inhibited the root growth in terms of root length and root tips. The Cu exposures of 50 and 150 mg kg -1 notably enhanced the root growth as compared to the control. Majority of Cu was accumulated in S. integra roots, while flooding significantly reduced the Cu content, except the 150 mg kg -1 Cu treatment, but the iron (Fe) and manganese (Mn) content on the root surface were both markedly increased relative to non-flooded control. The malonaldehyde (MDA) and glutathione (GSH) contents in leaves showed a dose-response upon Cu exposure. Soil flooding enhanced the GSH level, which displayed 4.50-49.59% increases compared to its respective non-flooded treatment, while no difference was evident on MDA contents between the flooding and the non-flooded treatments. Both superoxide dismutase (SOD) and peroxidase (POD) activities were boosted while the catalase (CAT) was suppressed with increasing Cu exposure dose, and soil flooding reduced the POD and CAT activities. The elevated Cu level caused the evident increases of root calcium (Ca), potassium (K), and sulfur (S) concentrations and decreases of root phosphorus (P), sodium (Na), and zinc (Zn) concentrations. Soil flooding increased the concentrations of Fe, S, Na, Ca, and magnesium (Mg) in S. integra root. Taken together, our results suggested S. integra has high tolerance to the joint stress from Cu and flooding. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients

    International Nuclear Information System (INIS)

    Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

    2013-01-01

    The transfer coefficient (TF) from soil to rice plants of 134 Cs and 137 Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure 134 Cs and 137 Cs radioactivity at 5-cm intervals. 134 Cs and 137 Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the 134 Cs and 137 Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 ± 0.10 in the field where the 40 K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019–0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10–0.16, 0.013–0.017 and 0.005–0.013, respectively. - Highlights: ► We investigated the transfer coefficient of 134 Cs and 137 Cs from soil to rice plants in Minami-Soma City due to the Fukushima accident in 2011. ► The rice ears, straws, roots, chaff, brown rice, polished rice, rice bran and soil samples have been measured by Ge-detector. ► Transfer coefficient of chaff, rice bran, brown rice, and polished rice is estimated as 0.049, ranging from 0.10 to 0.16, 0.013 to 0.017, and 0.005 to 0.013, respectively.

  3. Rice straw incorporated just before soil flooding increases acetic acid formation and decreases available nitrogen

    Directory of Open Access Journals (Sweden)

    Ronaldir Knoblauch

    2014-02-01

    Full Text Available Incorporation of rice straw into the soil just before flooding for water-seeded rice can immobilize mineral nitrogen (N and lead to the production of acetic acid harmful to the rice seedlings, which negatively affects grain yield. This study aimed to evaluate the formation of organic acids and variation in pH and to quantify the mineral N concentration in the soil as a function of different times of incorporation of rice straw or of ashes from burning the straw before flooding. The experiment was carried out in a greenhouse using an Inceptisol (Typic Haplaquept soil. The treatments were as follows: control (no straw or ash; incorporation of ashes from previous straw burning; rice straw incorporated to drained soil 60 days before flooding; straw incorporated 30 days before flooding; straw incorporated 15 days before flooding and straw incorporated on the day of flooding. Experimental units were plastic buckets with 6.0 kg of soil. The buckets remained flooded throughout the trial period without rice plants. Soil samples were collected every seven days, beginning one day before flooding until the 13th week of flooding for determination of mineral N- ammonium (NH4+ and nitrate (NO3-. Soil solution pH and concentration of organic acids (acetic, propionic and butyric were determined. All NO3- there was before flooding was lost in approximately two weeks of flooding, in all treatments. There was sigmoidal behavior for NH4+ formation in all treatments, i.e., ammonium ion concentration began to rise shortly after soil flooding, slightly decreased and then went up again. On the 91st day of flooding, the NH4+ concentrations in soil was 56 mg kg-1 in the control treatment, 72 mg kg-1 for the 60-day treatment, 73 mg kg-1 for the 30-day treatment and 53 mg kg-1 for the ash incorporation treatment. These ammonium concentrations correspond to 84, 108, 110 and 80 kg ha-1 of N-NH4+, respectively. When the straw was incorporated on the day of flooding or 15 days

  4. Effects of soil flooding on photosynthesis and growth of Zea mays L ...

    African Journals Online (AJOL)

    user

    2012-04-12

    Apr 12, 2012 ... most important responses of plants to soil flooding which could be caused by ... by monitoring stomata morphometric, intercellular CO2 (Ci) and stomata ..... absorb water and nutrients, then decrease root growth rate and dry ...

  5. Mapping paddy rice planting area in rice-wetland coexistent areas through analysis of Landsat 8 OLI and MODIS images.

    Science.gov (United States)

    Zhou, Yuting; Xiao, Xiangming; Qin, Yuanwei; Dong, Jinwei; Zhang, Geli; Kou, Weili; Jin, Cui; Wang, Jie; Li, Xiangping

    2016-04-01

    Accurate and up-to-date information on the spatial distribution of paddy rice fields is necessary for the studies of trace gas emissions, water source management, and food security. The phenology-based paddy rice mapping algorithm, which identifies the unique flooding stage of paddy rice, has been widely used. However, identification and mapping of paddy rice in rice-wetland coexistent areas is still a challenging task. In this study, we found that the flooding/transplanting periods of paddy rice and natural wetlands were different. The natural wetlands flood earlier and have a shorter duration than paddy rice in the Panjin Plain, a temperate region in China. We used this asynchronous flooding stage to extract the paddy rice planting area from the rice-wetland coexistent area. MODIS Land Surface Temperature (LST) data was used to derive the temperature-defined plant growing season. Landsat 8 OLI imagery was used to detect the flooding signal and then paddy rice was extracted using the difference in flooding stages between paddy rice and natural wetlands. The resultant paddy rice map was evaluated with in-situ ground-truth data and Google Earth images. The estimated overall accuracy and Kappa coefficient were 95% and 0.90, respectively. The spatial pattern of OLI-derived paddy rice map agrees well with the paddy rice layer from the National Land Cover Dataset from 2010 (NLCD-2010). The differences between Rice Landsat and Rice NLCD are in the range of ±20% for most 1-km grid cell. The results of this study demonstrate the potential of the phenology-based paddy rice mapping algorithm, via integrating MODIS and Landsat 8 OLI images, to map paddy rice fields in complex landscapes of paddy rice and natural wetland in the temperate region.

  6. Cadmium, lead, and arsenic contamination in paddy soils of a mining area and their exposure effects on human HEPG2 and keratinocyte cell-lines.

    Science.gov (United States)

    Xue, Shengguo; Shi, Lizheng; Wu, Chuan; Wu, Hui; Qin, Yanyan; Pan, Weisong; Hartley, William; Cui, Mengqian

    2017-07-01

    A mining district in south China shows significant metal(loid) contamination in paddy fields. In the soils, average Pb, Cd and As concentrations were 460.1, 11.7 and 35.1mgkg -1 respectively, which were higher than the environmental quality standard for agricultural soils in China (GB15618-1995) and UK Clea Soil Guideline Value. The average contents of Pb, Cd and As in rice were 5.24, 1.1 and 0.7mgkg -1 respectively, which were about 25, 4.5 or 2.5 times greater than the limit values of the maximum safe contaminant concentration standard in food of China (GB 2762-2012), and about 25, 10 or 1 times greater than the limit values of FAO/WHO standard. The elevated contents of Pb, Cd and As detected in soils around the factories, indicated that their spatial distribution was influenced by anthropogenic activity, while greater concentrations of Cd in rice appeared in the northwest region of the factories, indicating that the spatial distribution of heavy metals was also affected by natural factors. As human exposure around mining districts is mainly through oral intake of food and dermal contact, the effects of these metals on the viability and MT protein of HepG2 and KERTr cells were investigated. The cell viability decreased with increasing metal concentrations. Co-exposure to heavy metals (Pb+Cd) increased the metals (Pb or Cd)-mediated MT protein induction in both human HepG2 and KERTr cells. Increased levels of MT protein will lead to greater risk of carcinogenic manifestations, and it is likely that chronic exposure to metals may increase the risk to human health. Nevertheless, when co-exposure to two or more metals occur (such as As+Pb), they may have an antagonistic effect thus reducing the toxic effects of each other. Metal contaminations in paddy soils and rice were influenced by anthropogenic activity; metal co-exposure induced MT protein in human cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. The effect of flooding on soil proportion and plant growth. 2. Its effect on the changes in soil proportion

    International Nuclear Information System (INIS)

    Sisworo, E.L.

    1975-01-01

    An experiment has been carried out to study changes in soil proportion as affected by flooding. Barley plants were used as indicators. Black polyethylene columns were used as plant containers, and were filled with sandy loam Begbroke soil. Several parameters were used in the experiment, namely concentrations of oxygen carbon dioxide, ethylene, hydrogen sulfide, and organic acids. Oxygen concentration dropped to about 2% one day after flooding, while the concentration of carbon dioxide, ethylene and organic acids turned out to be slowly increased with the extension of flooding time. No hydrogen sulfide was detectable as affected by various flooding periods. Different concentrations of oxygen, carbon dioxide, and ethylene were observed between the top and the lower layers of soil. (author)

  8. Floods

    Science.gov (United States)

    Floods are common in the United States. Weather such as heavy rain, thunderstorms, hurricanes, or tsunamis can ... is breached, or when a dam breaks. Flash floods, which can develop quickly, often have a dangerous ...

  9. Variable response of three Trifolium repens ecotypes to soil flooding by seawater.

    Science.gov (United States)

    White, Anissia C; Colmer, Timothy D; Cawthray, Greg R; Hanley, Mick E

    2014-08-01

    Despite concerns about the impact of rising sea levels and storm surge events on coastal ecosystems, there is remarkably little information on the response of terrestrial coastal plant species to seawater inundation. The aim of this study was to elucidate responses of a glycophyte (white clover, Trifolium repens) to short-duration soil flooding by seawater and recovery following leaching of salts. Using plants cultivated from parent ecotypes collected from a natural soil salinity gradient, the impact of short-duration seawater soil flooding (8 or 24 h) on short-term changes in leaf salt ion and organic solute concentrations was examined, together with longer term impacts on plant growth (stolon elongation) and flowering. There was substantial Cl(-) and Na(+) accumulation in leaves, especially for plants subjected to 24 h soil flooding with seawater, but no consistent variation linked to parent plant provenance. Proline and sucrose concentrations also increased in plants following seawater flooding of the soil. Plant growth and flowering were reduced by longer soil immersion times (seawater flooding followed by drainage and freshwater inputs), but plants originating from more saline soil responded less negatively than those from lower salinity soil. The accumulation of proline and sucrose indicates a potential for solute accumulation as a response to the osmotic imbalance caused by salt ions, while variation in growth and flowering responses between ecotypes points to a natural adaptive capacity for tolerance of short-duration seawater soil flooding in T. repens. Consequently, it is suggested that selection for tolerant ecotypes is possible should the predicted increase in frequency of storm surge flooding events occur. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Degradation of 14C - DDT in soils under moist and flooded conditions with rice straw and green manure amendments

    International Nuclear Information System (INIS)

    Dubey, S.; Dubey, P.S.; Kale, S.P.; Murthy, N.B.K.

    2001-01-01

    Degradation of 14 C - DDT in moist and flooded soils was studied with rice straw and green manure amendments for 100 days. The mineralization of DDT was not significantly influenced by any of the treatments. Rice straw and green manure in flooded soil brought about decrease in extractable 14 C - residues with concomitant increase in soil bound residues. DDT has a very short residence in flooded soils though radiocarbon was more in extractable residues. DDD is the major degradation product in flooded soils. (author)

  11. Responses of an Agricultural Soil Microbiome to Flooding with Seawater after Managed Coastal Realignment

    Directory of Open Access Journals (Sweden)

    Kamilla S. Sjøgaard

    2018-01-01

    Full Text Available Coastal areas have become more prone to flooding with seawater due to climate-change-induced sea-level rise and intensified storm surges. One way to cope with this issue is by “managed coastal realignment”, where low-lying coastal areas are no longer protected and instead flooded with seawater. How flooding with seawater impacts soil microbiomes and the biogeochemical cycling of elements is poorly understood. To address this, we conducted a microcosm experiment using soil cores collected at the nature restoration project site Gyldensteen Strand (Denmark, which were flooded with seawater and monitored over six months. Throughout the experiment, biogeochemical analyses, microbial community fingerprinting and the quantification of marker genes documented clear shifts in microbiome composition and activity. The flooding with seawater initially resulted in accelerated heterotrophic activity that entailed high ammonium production and net removal of nitrogen from the system, also demonstrated by a concurrent increase in the abundances of marker genes for ammonium oxidation and denitrification. Due to the depletion of labile soil organic matter, microbial activity decreased after approximately four months. The event of flooding caused the largest shifts in microbiome composition with the availability of labile organic matter subsequently being the most important driver for the succession in microbiome composition in soils flooded with seawater.

  12. Effect of systemic herbicides on N2-fixing and phosphate solubilizing microorganisms in relation to availability of nitrogen and phosphorus in paddy soils of West Bengal.

    Science.gov (United States)

    Das, Amal Chandra; Debnath, Anjan

    2006-11-01

    A field experiment has been conducted with four systemic herbicides viz., butachlor [N-(butoxymethyl)-2-chloro-2',6'-diethyl-acetanilide], fluchloralin [N-(2-chloroethyl)-(2,6-dinitro-N-propyl-4-trifluoromethyl) aniline], oxadiazon [5-terbutyl-3-(2,4-dichloro-5-isopro poxyphenyl)-1,3,4-oxadiazol-2-one] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenyl)-4-(trifluoromethyl) benzene] at their recommended field rates (2.0, 1.5, 0.4 and 0.12kga.i.ha(-1), respectively) to investigate their effects on growth and activities of aerobic non-symbiotic N(2)-fixing bacteria and phosphate solubilizing microorganisms in relation to availability of nitrogen and phosphorus in the rhizosphere soils as well as yield of the rice crop (Oryza sativa L cv. IR-36). Application of herbicides, in general, highly stimulated the population and activities of the target microorganisms, which resulted in a greater amount of atmospheric nitrogen fixation and phosphate solubilization in the rhizosphere soils of the test crop. The greater microbial activities subsequently augmented the mineralization and availability of nitrogen and phosphorus in the soil solution, which in turn increased the yield of the crop. Among the herbicides, oxyfluorfen was most stimulative followed by fluchloralin and oxadiazon in augmenting the microbial activities in soil. Butachlor also accentuated the mineralization and availability of nitrogen due to higher incitement of non-symbiotic N(2)-fixing bacteria in paddy soil. The grain and straw yields of the crop were also significantly increased due to the application of oxyfluorfen (20.2% and 21%) followed by fluchloralin (13.1% and 15.4%) and butachlor (9.1% and 10.2%), respectively.

  13. [Effect of Long-term Fertilizer Application on the Stability of Organic Carbon in Particle Size Fractions of a Paddy Soil in Zhejiang Province, China].

    Science.gov (United States)

    Mao, Xia-li; Lu, Kou-ping; Sun, Tao; Zhang, Xiao-kai; He, Li-zhi; Wang, Hai-long

    2015-05-01

    Effects of chemical fertilizers and organic manure on the soil organic carbon (SOC) content in particle size fractions of paddy soil were investigated in a 17-year long-term fertilization field experiment in Zhejiang Province, China. The inherent chemical composition of silt- and clay-associated SOC was evaluated with solid-state 13C-NMR spectroscopy. Compared to CK (no fertilizer treatment), NPKRS (NPK fertilizers plus rice straw) , NPKOM (NPK fertilizers plus organic manure) , NPK (NPK fertilizers) and OM (organic manure alone) treatments significantly (P fertilizers alone, combined application of organic amendments and NPK fertilizers facilitated the storage of newly sequestered SOC in silt- and clay-sized fractions, which could be more conducive to the stability of SOC. Based on 13C-NMR spectra, both silt and clay fractions were composed of Alkyl-C, O-alkyl-C, Aromatic-C and carbonyl-C. Changes in the relative proportion of different C species were observed between silt and clay fractions: the clay fraction had relatively more Alkyl-C, carbonyl-C and less O-alkyl-C, Aromatic-C than those in the silt fraction. This might be ascribed to the fact that the organic matter complexed with clay was dominated by microbial products, whereas the silt appeared to be rich in aromatic residues derived from plants. The spectra also showed that the relative proportion of different C species was modified by fertilization practices. In comparison with organic amendments alone, the relative proportion of Alkyl-C was decreased by 9.1%-11.9% and 13.7%-19.9% under combined application of organic amendments and chemical fertilizers, for silt and clay, respectively, and that of O-alkyl-C was increased by 2.9%-6.3% and 13.4%-22.1%, respectively. These results indicated that NPKOM and NPKRS treatments reduced the decomposition rate of SOC. The aromaticity, hydrophobicity and, hence, chemical recalcitrance of silt- and clay-associated SOC in the NPK fertilizer treatments were lower than

  14. Change of microelemental composition of flood-plain soils under the increase of the anthropogenic impact

    International Nuclear Information System (INIS)

    Dmitrakov, L.M.; Dmitrakova, L.K.

    2008-01-01

    Change of technogenic pressure and pedotechnogenic concentration were research for some heavy metals (Mn, Pb, Zn, Cu, Ni, Cr, Cd). They describe the general character of element into the soil and the risk of disturbance of geochemical equilibrium in flood-plain soils and depend on regional technogenic loads and combinations of sources of microelements emission.

  15. [Effects of silicon supply on rice growth and methane emission from paddy soil under elevated UV-B radiation].

    Science.gov (United States)

    Meng, Yan; Lou, Yun-sheng; Wu, Lei; Cui, He-yang; Wang, Wei-qing

    2015-01-01

    A pot experiment was conducted to investigate the effects of silicon supply on rice growth and methane (CH4) emission in paddy field under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B (ambient, A) and elevated UV-B radiation (elevated by 20%, E) ; with four silicon supply levels, i.e., Si0 (control, without silicon), Si2 (as sodium silicate, 100 kg SiO2 . hm-2), Si2 (as sodium silicate, 200 kg SiO2 hm-2) and Si3 (as slag fertilizer, 200 kg SiO2 . hm-2). The results indicated that, silicon supply obviously alleviated the depressive effect of elevated UV-B radiation on rice growth, and increased the tiller numbers, chlorophyll content, and shoot and root dry masses. Silicon supply promoted rice growth, which increased with the silicon supply level (sodium silicate). Slag fertilizer was better than*sodium silicate in promoting rice growth. CH4 flux and accumulated CH4emission were obviously increased by elevated UV-B radiation, but significantly decreased by silicon application. CH4 emission was reduced with increasing the silicon supply level. Under the same silicon supply level, slag fertilizer was better than sodium silicate in inhibiting CH4 flux and accumulated CH4 emission. This research suggested that fertilizing slag in rice production was helpful not only in utilizing industrial wastes, but also in significantly mitigating CH4 emissions in rice paddy under elevated UV-B radiation.

  16. Runoff and degradation of aerially applied dinotefuran in paddy fields and river.

    Science.gov (United States)

    Yokoyama, Sayako; Ito, Masataka; Nagasawa, Shunsuke; Morohashi, Masayuki; Ohno, Masaki; Todate, Yukitaka; Kose, Tomohiro; Kawata, Kuniaki

    2015-06-01

    Variation, run-off and degradation characteristics of the insecticide dinotefuran, (EZ)-(RS)-1-methyl-2-nitro-3-(tetrahydro-3-furyl-methyl)guanidine, in water and soil from two paddy fields after aerial application was investigated as well as in river water. Maximum concentrations of dinotefuran were 290 and 720 µg/L in the two paddy waters, 25 and 28 µg/kg dry in the two paddy soils, and 10 µg/L in the river water. Runoff ratios of dinotefuran from the paddy fields were calculated as 14%-41%. Mean half-lives of dinotefuran were 5.4 days in the paddy water and 12 days in the paddy soil. Results obtained in this study are important for the evaluation of the actual behavior of dinotefuran in paddy fields and rivers.

  17. Determination of soil degradation from flooding for estimating ecosystem services in Slovakia

    Science.gov (United States)

    Hlavcova, Kamila; Szolgay, Jan; Karabova, Beata; Kohnova, Silvia

    2015-04-01

    Floods as natural hazards are related to soil health, land-use and land management. They not only represent threats on their own, but can also be triggered, controlled and amplified by interactions with other soil threats and soil degradation processes. Among the many direct impacts of flooding on soil health, including soil texture, structure, changes in the soil's chemical properties, deterioration of soil aggregation and water holding capacity, etc., are soil erosion, mudflows, depositions of sediment and debris. Flooding is initiated by a combination of predispositive and triggering factors and apart from climate drivers it is related to the physiographic conditions of the land, state of the soil, land use and land management. Due to the diversity and complexity of their potential interactions, diverse methodologies and approaches are needed for describing a particular type of event in a specific environment, especially in ungauged sites. In engineering studies and also in many rainfall-runoff models, the SCS-CN method has remained widely applied for soil and land use-based estimations of direct runoff and flooding potential. The SCS-CN method is an empirical rainfall-runoff model developed by the USDA Natural Resources Conservation Service (formerly called the Soil Conservation Service or SCS). The runoff curve number (CN) is based on the hydrological soil characteristics, land use, land management and antecedent saturation conditions of soil. Since the method and curve numbers were derived on the basis of an empirical analysis of rainfall-runoff events from small catchments and hillslope plots monitored by the USDA, the use of the method for the conditions of Slovakia raises uncertainty and can cause inaccurate results in determining direct runoff. The objective of the study presented (also within the framework of the EU-FP7 RECARE Project) was to develop the SCS - CN methodology for the flood conditions in Slovakia (and especially for the RECARE pilot site

  18. Effects of Crop Straw Returning with Lime on Activity of Cu, Zn, Pb and Cd in Paddy Soil

    OpenAIRE

    NI Zhong-ying; SHEN Qian; ZHANG Ming-kui

    2017-01-01

    Crop straw returning is an important measure for increasing soil carbon fixation and soil fertility in China, but it also may result in some risk of raising activity of heavy metals in the soil. In order to understand the effects of different sources of crop straw on heavy metals activity in soil with different pollution levels, and to take appropriate measures to prevent the activation of heavy metals in the soil, both pot and field experiments were carried out to study the effects of crop s...

  19. Simultaneous alleviation of cadmium and arsenic accumulation in rice by applying zero-valent iron and biochar to contaminated paddy soils.

    Science.gov (United States)

    Qiao, Jiang-Tao; Liu, Tong-Xu; Wang, Xiang-Qin; Li, Fang-Bai; Lv, Ya-Hui; Cui, Jiang-Hu; Zeng, Xiao-Duo; Yuan, Yu-Zhen; Liu, Chuan-Ping

    2018-03-01

    The fates of cadmium (Cd) and arsenic (As) in paddy fields are generally opposite; thus, the inconsistent transformation of Cd and As poses large challenges for their remediation. In this study, the impacts of zero valent iron (ZVI) and/or biochar amendments on Cd and As bioavailability were examined in pot trials with rice. Comparison with the untreated soil, both Cd and As accumulation in different rice tissues decreased significantly in the ZVI-biochar amendments and the Cd and As accumulation in rice decreased with increasing ZVI contents. In particular, the concentrations of Cd (0.15 ± 0.01 mg kg -1 ) and As (0.17 ± 0.01 mg kg -1 ) in rice grains were decreased by 93% and 61% relative to the untreated soil, respectively. A sequential extraction analysis indicated that with increasing Fe ratios in the ZVI-biochar mixtures, bioavailable Cd and As decreased, and the immobilized Cd and As increased. Furthermore, high levels of Fe, Cd, and As were detected in Fe plaque of the ZVI-biochar amendments in comparison with the single biochar or single ZVI amendments. The ZVI-biochar mixture may have a synergistic effect that simultaneously reduces Cd and As bioavailability by increasing the formation of amorphous Fe and Fe plaque for Cd and As immobilization. The single ZVI amendment significantly decreased As bioavailability, while the single biochar amendment significantly reduced the bioavailability of Cd compared with the combined amendments. Hence, using a ZVI-biochar mixture as a soil amendment could be a promising strategy for safely-utilizing Cd and As co-contaminated sites in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Phosphorus critical levels and availability in lowland soils cultivated with flooded rice

    Directory of Open Access Journals (Sweden)

    Mariano Isabela Orlando dos Santos

    2002-01-01

    Full Text Available Lowland soils present a great potential for the flooded rice crop. This work aimed to estimate critical levels of P in waterlogged soils cultivated with rice using Mehlich 1 and anion exchange resin as soil-P extractors, compare the performance of these extractors as for the evaluation of the P availability, and study the soil-P fractions involved in the P nutrition of the rice crop. Studied soils consisted of four Histosols: Low Humic Gley (GP, Aluvial (A, Humic Gley (GH and Bog Soil (O which were previously cultivated with beans. The experimental design was completely randomized, in a factorial scheme, using four soils, five P rates (75, 150, 300, 500 and 800 mg dm-3 and two liming treatments (with and without liming, with three replicates. After 60 days of flooding, soil samples were submitted to P extraction by Mehlich 1 and resin, and phosphorous fractionation. Two rice plants were cultivated in pots containing 3 dm³ of waterlogged soils. The labile P and the moderately labile P of the soils contributed for rice nutrition. The two tested extractors presented efficiency in the evaluation of P availability for the rice cultivated in lowland waterlogged soils.

  1. Mapping paddy rice distribution using multi-temporal Landsat imagery in the Sanjiang Plain, northeast China

    Science.gov (United States)

    XIAO, Xiangming; DONG, Jinwei; QIN, Yuanwei; WANG, Zongming

    2016-01-01

    Information of paddy rice distribution is essential for food production and methane emission calculation. Phenology-based algorithms have been utilized in the mapping of paddy rice fields by identifying the unique flooding and seedling transplanting phases using multi-temporal moderate resolution (500 m to 1 km) images. In this study, we developed simple algorithms to identify paddy rice at a fine resolution at the regional scale using multi-temporal Landsat imagery. Sixteen Landsat images from 2010–2012 were used to generate the 30 m paddy rice map in the Sanjiang Plain, northeast China—one of the major paddy rice cultivation regions in China. Three vegetation indices, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI), were used to identify rice fields during the flooding/transplanting and ripening phases. The user and producer accuracies of paddy rice on the resultant Landsat-based paddy rice map were 90% and 94%, respectively. The Landsat-based paddy rice map was an improvement over the paddy rice layer on the National Land Cover Dataset, which was generated through visual interpretation and digitalization on the fine-resolution images. The agricultural census data substantially underreported paddy rice area, raising serious concern about its use for studies on food security. PMID:27695637

  2. Dinitrogen fixation by blue-green algae from paddy fields

    International Nuclear Information System (INIS)

    Thomas, Joseph

    1977-01-01

    Recent work using radioactive nitrogen on the blue-green algae of paddy fields has been reviewed. These algae fix dinitrogen and photoassimilate carbon evolving oxygen, thereby augmenting nitrogen and carbon status of the soil and also providing oxygen to the water-logged rice paddies. Further studies using radioactive isotopes 13 N, 24 Na and 22 Na on their nitrogen fixation, nitrogen assimilation pathways; regulation of nitrogenase, heterocysts production and sporulation and sodium transport and metabolism have been carried out and reported. The field application of blue green algae for N 2 fixation was found to increase the status of soil nitrogen and yield of paddy. (M.G.B.)

  3. Mercury in rice (Oryza sativa L.) and rice-paddy soils under long-term fertilizer and organic amendment.

    Science.gov (United States)

    Tang, Zhenya; Fan, Fangling; Wang, Xinyue; Shi, Xiaojun; Deng, Shiping; Wang, Dingyong

    2018-04-15

    High levels of mercury (Hg), especially methylmercury (MeHg), in rice is of concern due to its potential of entering food chain and the high toxicity to human. The level and form of Hg in rice could be influenced by fertilizers and other soil amendments. Studies were conducted to evaluate the effect of 24 years application of chemical fertilizers and organic amendments on total Hg (THg) and MeHg and their translocation in soil, plants, and rice grain. All treatments led to significantly higher concentrations of MeHg in grain than those from the untreated control. Of nine treatments tested, chemical fertilizers combining with returning rice straw (NPK1+S) led to highest MeHg concentration in grain and soil; while the nitrogen and potassium (NK) treatment led to significantly higher THg in grain. Concentrations of soil MeHg were significantly correlated with THg in soil (r = 0.59 *** ) and MeHg in grain (r = 0.48 *** ). Calcium superphosphate negatively affected plant bioavailability of soil Hg. MeHg concentration in rice was heavily influenced by soil Hg levels. Phosphorus fertilizer was a main source contributing to soil THg, while returning rice straw to the field contributed significantly to MeHg in soil and rice grain. As a result, caution should be exercised in soil treatment or when utilizing Hg-contaminated soils to produce rice for human consumption. Strategic management of rice straw and phosphorus fertilizer could be effective strategies of lowering soil Hg, which would ultimately lower MeHg in rice and the risk of Hg entering food chain. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Comparative effects of application of coated and non-coated urea in clayey and sandy paddy soil microcosms examined by the 15N tracer technique. 2. Effects on soil microbial biomass N and microbial 15N immobilization

    International Nuclear Information System (INIS)

    Acquaye, Solomon; Inubushi, Kazuyuki

    2004-01-01

    Nitrogen fertilizer and soil types exert an impact on plant and soil microbial biomass (SMB). A 15 N tracer experiment was conducted to compare the effects of the application of controlled-release coated urea (CRCU) and urea on SMB in gley (clayey) and sandy paddy soils. The fertilizers were applied at the rate of 8 g N m -2 for CRCU as deep-side placement and 10 g N m -2 for urea mixed into soil or applied into floodwater. The soil type and soil layer (surface: few millimeter depth of surface soil to include benthic algae; subsurface: 1 to 20 cm depth), but not the fertilizer type, affected the amount of microbial biomass N (B N ). On an area basis, subsurface soil layers contained about 2-3 times the amount of B N in the surface layers. The seasonal average B N amount i.e. at 1 to 20 cm depth, in the gley soil was 1.67 g N m -2 , compared to 1.20 g N m -2 for the sandy soil. The proportion of B N in total soil N was significantly influenced by the soil type and soil layer, and was higher for the surface layers of both soils and subsurface layer of the sandy soil than for the subsurface layer of gley soil. Soil type, soil layer, and fertilizer type significantly influenced the amount of microbial biomass 15 N (B 15N ). Unlike B N , the amount of B 15N was significantly higher in the surface (11.9-177.3 mg N m -2 ) than in the subsurface soil layers (4.8-83.6 mg N m -2 ), especially with urea application between 60 and 120 DAT (days after transplanting). At 30 DAT, the subsurface layer of the sandy soil showed a higher B 15N (218 mg N m -2 ) amount than the surface layer (133.4 mg N m -2 ). Sandy soil (4.8-218 mg N m -2 ) and urea (6.2-218 mg N m -2 ) induced a larger increase of the amount of B 15 N than the gley soil (6.2-83.6 mg N m -2 ) and CRCU (4.8-40 mg Nm -2 ). Again, the sandy soil, surface soil layers, and urea induced a higher proportion (%) of B 15N in B N than the gley soil, subsurface soil layers, and CRCU, respectively. The soil type affected B N

  5. Peculiarities of 239,240Pu behaviour in flood-plain soils of the Techa river

    International Nuclear Information System (INIS)

    Mikhailovskaya, L.N.; Molchanova, I.V.; Karavaeva, E.N.

    2004-01-01

    The Techa river was contaminated with the liquid nuclear waste discharged from the nuclear plant 'Mayak' within 1949-1956 years. In 1999-2002 flood-plain soils of the Techa river were investigated and the levels of content, a migration and a vertical distribution of 239,240 Pu in the flood-plain soils were studied. Reference plots were located in the pre-bed and in central flood plain at different distances from the source of contamination (78-240 km). It was shown that in the soils of the pre-bed the content of Pu isotopes was decreasing from 10.5 to 2.8 kBq/m 2 with the distance from the plant 'Mayak'. Besides, a non-uniform spatial distribution of 239,240 Pu was found in those plots, which were at the same distance from the source of the contamination. As a rule, the central flood plain (25-100 m from the river-bed) was contaminated with 239,240 Pu less than the area in the pre-bed (5-20 m from the the river-bed). Thus, in the area of the middle length of the river the density of the soil contamination with 239,240 Pu of the central flood plain is 0.3 to 0.8 kBq/m 2 and that of the pre-bed is 1.0 to 4.7 kBq/m 2 at a maximum migration depth being 25 to 30 cm and 40 to 50 cm, respectively. The determined value of the 239,240 Pu/ 137 Cs ratio proves that rates of the vertical migration of the Pu isotopes in the flood plain soils of the Techa river are comparable and higher (in some cases) than those of 137 Cs. (author)

  6. Photosynthates as dominant source of CH4 and CO2 in soil water and CH4 emitted to the atmosphere from paddy fields

    Science.gov (United States)

    Minoda, Tomomi; Kimura, Mamoto; Wada, Eitaro

    1996-09-01

    Emission rates of CH4 from paddy soil with and without rice straw applications were measured with pot experiments to estimate the contribution of rice straw to the total CH4 emission during the growth period of rice plants. The CH4 derived from rice straw was calculated to be 44% of the total emission. 13CO2 uptake experiments were also carried out four times from June 30 to September 13, 1994, to estimate the contribution of photosynthesized carbon to CH4 emission. The contribution percentages of photosynthesized carbon to the total CH4 emitted to the atmosphere were 3.8% around June 30, 31% around July 25, 30% around August 19, and 14% around September 13 in the treatment with rice straw applications, and 52% around July 25, 28% around August 19, and 15% around September 13 in the treatment without rice straw applications. They were calculated to be 22% and 29% for the entire growth period in the treatments with and without rice straw applications, respectively. The contribution percentages of photosynthesized carbon to the total CH4 and inorganic carbon (Σ CO2) dissolved in soil water were 1.3%, 30%, 29%, and 34% for dissolved CH4 and 3.0%, 36%, 30% and 28% for dissolved inorganic carbon around June 30, July 25, August l9, and September 13, respectively, in the treatment with rice straw applications. They were 70%, 23%, and 32% for dissolved CH4 and 31%, 16%, and 19% for dissolved inorganic carbon around July 25, August 19, and September 13, respectively, in the treatment without rice straw applications.

  7. Mercury fluxes from air/surface interfaces in paddy field and dry land

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Jinshan [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China); Wang Dingyong, E-mail: dywang@swu.edu.cn [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China)] [Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716 (China); Liu Xiao; Zhang Yutong [Key Laboratory of Eco-Environments in Three Gorges Reservoir Region (Ministry of Education), College of Resources and Environment, Southwest University, No. 216, Tiansheng Street, Beibei, Chongqing 400715 (China)

    2011-02-15

    Research highlights: {yields} It was found that agricultural fields are important local atmospheric Hg sources in the region. {yields} The Hg emissions from dry cornfield were higher than those from the flooded rice paddy, higher mercury emissions in the warm season than the cold season, and during daytime than at night. {yields} Mercury evasion is strongly related to solar radiation which is important in the emission of Hg at both sites. - Abstract: In order to provide insight into the characteristics of Hg exchange in soil/water-air surface from cropland (including paddy field and dry land), Hg fluxes were measured in Chengjiang. Mercury fluxes were measured using the dynamic flux chamber method, coupled with a Lumex (registered) multifunctional Hg analyzer RA-915{sup +} (Lumex Ltd., Russia). The Hg fluxes from paddy field and dry land were alternatively measured every 30 min. Data were collected for 24-48 h once per month for 5 months. Mercury fluxes in both fields were synchronously measured under the same conditions to compare Hg emissions between paddy field and dry land over diurnal and seasonal periods and find out what factors affect Hg emission on each surface. These results indicated that air Hg concentrations at the monitoring site was double the value observed at the global background sites in Europe and North America. The Hg release fluxes were 46.5 {+-} 22.8 ng m{sup -2} h{sup -1} in the warm season, 15.5 {+-} 18.8 ng m{sup -2} h{sup -1} in the cold season for dry land, and 23.8 {+-} 15.6 ng m{sup -2} h{sup -1} in the warm season, 6.3 {+-} 11.9 ng m{sup -2} h{sup -1} in the cold season for paddy field. Solar radiation is important in the emission of Hg over both sites. Hg exchange at the soil/air and water/air interfaces showed temporal variations. The amount of Hg emission from dry land was higher than that from the paddy field, and the emission in daytime was higher than that at night. Moreover, Hg emissions from land covered by crops, was lower

  8. Effect of rice straw on the degradation of 14C-parathion in flooded alluvial soil

    International Nuclear Information System (INIS)

    Rajaram, K.P.; Sethunathan, N.

    1975-01-01

    Organic matter, either native or applied, influences the persistence of soil-applied pesticides. The effect of rice straw on the metabolism of parathion in an alluvial soil under flooded condition was investigated. Residues were extracted from the soil at periodic intervals after application of ethoxy 14 C-parathion to rice straw amended and unamended soil employing chloroform-diethyl ether. The radioactivity in the solvent and water fractions were estimated. The activity in the solvent phase decreased more rapidly in the rice straw amended than in unamended soil indicating enhanced degradation of parathion by rice straw amendment. The autoradiograph of thin layer chromatograms of solvent phase revealed the rapid formation of aminoparathion and an unidentified metabolite possessing P-S bond and ethoxy label in amended soil within 3 days. A polar unidentified metabolite was detected in the water phase of the unamended soil at 14 days. (author)

  9. Microbial activity promoted with organic carbon accumulation in macroaggregates of paddy soils under long-term rice cultivation

    Science.gov (United States)

    Liu, Yalong; Wang, Ping; Ding, Yuanjun; Lu, Haifei; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Filley, Timothy; Zhang, Xuhui; Zheng, Jinwei; Pan, Genxing

    2016-12-01

    While soil organic carbon (SOC) accumulation and stabilization has been increasingly the focus of ecosystem properties, how it could be linked to soil biological activity enhancement has been poorly assessed. In this study, topsoil samples were collected from a series of rice soils shifted from salt marshes for 0, 50, 100, 300 and 700 years from a coastal area of eastern China. Soil aggregates were fractioned into different sizes of coarse sand (200-2000 µm), fine sand (20-200 µm), silt (2-20 µm) and clay (Soil properties were determined to investigate niche specialization of different soil particle fractions in response to long-term rice cultivation, including recalcitrant and labile organic carbon, microbial diversity of bacterial, archaeal and fungal communities, soil respiration and enzyme activity. The results showed that the mass proportion both of coarse-sand (2000-200 µm) and clay (clay fractions (20-25 g kg-1), but was depleted in silt fractions (˜ 10 g kg-1). The recalcitrant carbon pool was higher (33-40 % of SOC) in both coarse-sand and clay fractions than in fine-sand and silt fractions (20-29 % of SOC). However, the ratio of labile organic carbon (LOC) to SOC showed a weakly decreasing trend with decreasing size of aggregate fractions. Total soil DNA (deoxyribonucleic acid) content in the size fractions followed a similar trend to that of SOC. Despite the largely similar diversity between the fractions, 16S ribosomal gene abundance of bacteria and of archaeal were concentrated in both coarse-sand and clay fractions. Being the highest generally in coarse-sand fractions, 18S rRNA gene abundance of fungi decreased sharply but the diversity gently, with decreasing size of the aggregate fractions. The soil respiration quotient (ratio of respired CO2-C to SOC) was the highest in the silt fraction, followed by the fine-sand fraction, but the lowest in coarse-sand and clay fractions in the rice soils cultivated over 100 years, whereas the microbial

  10. Anaerobic transformation of DDT related to iron(III) reduction and microbial community structure in paddy soils.

    Science.gov (United States)

    Chen, Manjia; Cao, Fang; Li, Fangbai; Liu, Chengshuai; Tong, Hui; Wu, Weijian; Hu, Min

    2013-03-06

    We studied the mechanisms of microbial transformation in functional bacteria on 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in two different field soils, Haiyan (HY) and Chenghai (CH). The results showed that microbial activities had a steady dechlorination effect on DDT and its metabolites (DDx). Adding lactate or glucose as carbon sources increased the amount of Desulfuromonas, Sedimentibacter, and Clostridium bacteria, which led to an increase in adsorbed Fe(II) and resulted in increased DDT transformation rates. The electron shuttle of anthraquinone-2,6-disulfonic disodium salt resulted in an increase in the negative potential of soil by mediating the electron transfer from the bacteria to the DDT. Moreover, the DDT-degrading bacteria in the CH soil were more abundant than those in the HY soil, which led to higher DDT transformation rates in the CH soil. The most stable compound of DDx was 1,1-dichloro-2,2-bis(p-chloro-phenyl)ethane, which also was the major dechlorination metabolite of DDT, and 1-chloro-2,2-bis-(p-chlorophenyl)ethane and 4,4'-dichlorobenzo-phenone were found to be the terminal metabolites in the anaerobic soils.

  11. Utilization of organic fertilizer to increase paddy growth and productivity using System of Rice Intensification (SRI method in saline soil

    Directory of Open Access Journals (Sweden)

    V . O . Subardja

    2016-01-01

    Full Text Available Soil salinity has negative effect on soil biodiversity as well as microbial activities. Hence, rice growth also effected by salinity. Application of organic fertilizer and adoption of System of Rice Intensification (SRI cultivation might improve the (biological soil properties and increase rice yield. The aim of this study was to evaluate the effect of two different rice cultivation methods namely conventional rice cultivation method and System of Rice Intensification (SRI rice cultivation method and two kinds organic fertilizer on improvement of soil biological properties and rice yield. In this study, a split plot experimental design was applied where rice cultivation method (conventional and SRI was the main plot and two kinds of organic fertilizer (market waste and rice straw was the sub plot. The treatments had four replicates. The results showed that SRI cultivation with market waste organic fertilizer could increase soil biological properties (population of microbe, fungi and soil respiration. The same treatment also increased rice growth and production. Combination of SRI and market waste organic fertilizer yielded the highest rice production (7.21 t/ha.

  12. Immediate impact of the flood (Bohemia, August 2002) on selected soil characteristics

    Czech Academy of Sciences Publication Activity Database

    Elhottová, Dana; Krištůfek, Václav; Tříska, Jan; Chrastný, V.; Uhlířová, Eva; Kalčík, Jiří; Picek, T.

    2006-01-01

    Roč. 173, č. 1-4, (2006), s. 177-193 ISSN 0049-6979 Institutional research plan: CEZ:AV0Z6066911; CEZ:AV0Z6087904; CEZ:AV0Z60870520 Keywords : flood on soil * hazardous elements * organic persistent compounds Subject RIV: EH - Ecology, Behaviour Impact factor: 1.205, year: 2006

  13. Nitrogen dynamics in flooded soil systems: An overview on concepts and performance of models

    NARCIS (Netherlands)

    Khairudin, Nurul; Gaydon, Donald S.; Jing, Qi; Zakaria, Mohamad P.; Struik, Paul C.; Keesman, Karel J.

    2018-01-01

    Extensive modelling studies on nitrogen (N) dynamics in flooded soil systems have been published. Consequently, many N dynamics models are available for users to select from. With the current research trend, inclined towards multi-disciplinary research, and with substantial progress in understanding

  14. Links between seawater flooding, soil ammonia oxidiser communities and their response to changes in salinity.

    Science.gov (United States)

    Nacke, Heiko; Schöning, Ingo; Schindler, Malte; Schrumpf, Marion; Daniel, Rolf; Nicol, Graeme W; Prosser, James I

    2017-11-01

    Coastal areas worldwide are challenged by climate change-associated increases in sea level and storm surge quantities that potentially lead to more frequent flooding of soil ecosystems. Currently, little is known of the effects of inundation events on microorganisms controlling nitrification in these ecosystems. The goal of this study was to investigate the impact of seawater flooding on the abundance, community composition and salinity tolerance of soil ammonia oxidisers. Topsoil was sampled from three islands flooded at different frequencies by the Wadden Sea. Archaeal ammonia oxidiser amoA genes were more abundant than their betaproteobacterial counterparts, and the distribution of archaeal and bacterial ammonia oxidiser amoA and 16S rRNA gene sequences significantly differed between the islands. The findings indicate selection of ammonia oxidiser phylotypes with greater tolerance to high salinity and slightly alkaline pH (e.g. Nitrosopumilus representatives) in frequently flooded soils. A cluster phylogenetically related to gammaproteobacterial ammonia oxidisers was detected in all samples analysed in this survey. Nevertheless, no gammaprotebacterial amoA genes could be amplified via PCR and only betaproteobacterial ammonia oxidisers were detected in enrichment cultures. A slurry-based experiment demonstrated the tolerance of both bacterial and archaeal ammonia oxidisers to a wide range of salinities (e.g. Wadden Sea water salinity) in soil naturally exposed to seawater at a high frequency. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. On the synergistic use of microwave and infrared satellite observations to monitor soil moisture and flooding

    Science.gov (United States)

    Extreme hydrological processes are often very dynamic and destructive.A better understanding of these processes requires an accurate mapping of key variables that control them. In this regard, soil moisture is perhaps the most important parameter that impacts the magnitude of flooding events as it c...

  16. Plant communities in relation to flooding and soil contamination in a lowland Rhine River floodplain

    International Nuclear Information System (INIS)

    Schipper, Aafke M.; Lotterman, Kim; Leuven, Rob S.E.W.; Ragas, Ad M.J.; Kroon, Hans de; Hendriks, A. Jan

    2011-01-01

    Using canonical correspondence analysis (CCA), relationships were investigated between plant species composition and flooding characteristics, heavy metal contamination and soil properties in a lowland floodplain of the Rhine River. Floodplain elevation and yearly average flooding duration turned out to be more important for explaining variation in plant species composition than soil heavy metal contamination. Nevertheless, plant species richness and diversity showed a significant decrease with the level of contamination. As single heavy metal concentrations seemed mostly too low for causing phytotoxic effects in plants, this trend is possibly explained by additive effects of multiple contaminants or by the concomitant influences of contamination and non-chemical stressors like flooding. These results suggest that impacts of soil contamination on plants in floodplains could be larger than expected from mere soil concentrations. In general, these findings emphasize the relevance of analyzing effects of toxic substances in concert with the effects of other relevant stressors. - Multiple contaminants and periodic flooding may pose cumulative stress to plants in lowland floodplains.

  17. Increased P diffusion as an explanation of increased P availability in flooded rice soils

    International Nuclear Information System (INIS)

    Turner, F.T.; Gilliam, J.W.

    1976-01-01

    Phosphorus supply factors (capacity, kinetic, intensity, and diffusivity) and plant growth were the approaches used to assess P supply of flooded rice soils. Increases in the capacity, intensity and kinetic factors, as measured by E-value, solution P concentration, and soil P release rate to a distilled water 'sink' respectively, were unpronounced and infrequent upon water-saturation of ten soils. However, increases in the diffusivity factor, as measured by 32 P diffusion coefficients, were at least ten-fold as soil moisture increased. The greatest increases in P diffusion occurred as soil moisture increased beyond one-third bar. Using a P-fertilized soil or P treated powdered cellulose as the P source and a minus P nutrient solution to nourish a split root system with water and nutrients, data were obtained which suggested that P uptake and rice shoot growth (indicators of P availability) increased with increasing moisture level. Phosphorus uptake and rice-shoot growth were greatest when the soil or P treated cellulose were water-saturated. These data indicate that increased soil P availability upon flooding can be attributed to an increase in the diffusivity factor

  18. Bioavailability and release of nonextractable (bound) residues of chiral cycloxaprid using geophagous earthworm Metaphire guillelmi in rice paddy soil

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuanqi; Xu, Xiaoyong [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Hanxue [Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Li, Chao; Shao, Xusheng [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China); Ye, Qingfu, E-mail: qfye@zju.edu.cn [Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Li, Zhong, E-mail: lizhong@ecust.edu.cn [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China)

    2015-09-01

    The widespread adoption of neonicotinoids has led to a move away from integrated pest management (IPM) and caused adverse effects on non-target invertebrate species. Due to their living in close contact with and consuming large amounts of soil, earthworms are a model organism used to study bioaccumulation. We investigated the bioaccumulation and release of bound, or non-extractable, residues (BRs) of {sup 14}C labeled racemic cycloxaprid (CYC) and its individual enantiomers by the geophagous earthworm Metaphire guillelmi. In a previous work, the fraction of BRs of {sup 14}C-CYC individual enantiomers reached up to 70–85% of the initially spiked radioactivity after 100 d of treatment. The bulk volume of the soil was then diluted by a factor of 15 with fresh soil. Here we showed that after earthworms lived in the soil-bound residues for 28 d, 11–25% of the previously bound radioactivity in soil was extractable by solvent, mineralized to CO{sub 2}, and accumulated in earthworm tissues. While earthworms were exposed to {sup 14}C-CYC a two-compartment accumulation model could explain the bio-accumulation as individual enantiomers. At the end of the experiment, the biota-sediment accumulation factors were between 0.59 and 0.82, which suggested CYC immobilization in the soil resulted in its bioavailability being reduced which enhanced its degradation. Additionally, the elimination of CYC individual enantiomers from M. guillelmi was fitted to an availability-adjusted decay model with a half-life of 9 d. Stereoselective release or bioavailability between CYC enantiomers was not observed. These results provide the important data about the release of BRs of CYC and potential transfer in the food chain to support the long-term environmental risk assessment of neonicotinoids. - Highlights: • 20% of the BRs were released and bioavailable. • Stereoselective behaviors were not observed.

  19. Bioavailability and release of nonextractable (bound) residues of chiral cycloxaprid using geophagous earthworm Metaphire guillelmi in rice paddy soil

    International Nuclear Information System (INIS)

    Liu, Xuanqi; Xu, Xiaoyong; Zhang, Hanxue; Li, Chao; Shao, Xusheng; Ye, Qingfu; Li, Zhong

    2015-01-01

    The widespread adoption of neonicotinoids has led to a move away from integrated pest management (IPM) and caused adverse effects on non-target invertebrate species. Due to their living in close contact with and consuming large amounts of soil, earthworms are a model organism used to study bioaccumulation. We investigated the bioaccumulation and release of bound, or non-extractable, residues (BRs) of 14 C labeled racemic cycloxaprid (CYC) and its individual enantiomers by the geophagous earthworm Metaphire guillelmi. In a previous work, the fraction of BRs of 14 C-CYC individual enantiomers reached up to 70–85% of the initially spiked radioactivity after 100 d of treatment. The bulk volume of the soil was then diluted by a factor of 15 with fresh soil. Here we showed that after earthworms lived in the soil-bound residues for 28 d, 11–25% of the previously bound radioactivity in soil was extractable by solvent, mineralized to CO 2 , and accumulated in earthworm tissues. While earthworms were exposed to 14 C-CYC a two-compartment accumulation model could explain the bio-accumulation as individual enantiomers. At the end of the experiment, the biota-sediment accumulation factors were between 0.59 and 0.82, which suggested CYC immobilization in the soil resulted in its bioavailability being reduced which enhanced its degradation. Additionally, the elimination of CYC individual enantiomers from M. guillelmi was fitted to an availability-adjusted decay model with a half-life of 9 d. Stereoselective release or bioavailability between CYC enantiomers was not observed. These results provide the important data about the release of BRs of CYC and potential transfer in the food chain to support the long-term environmental risk assessment of neonicotinoids. - Highlights: • 20% of the BRs were released and bioavailable. • Stereoselective behaviors were not observed

  20. A flash flood early warning system based on rainfall thresholds and daily soil moisture indexes

    Science.gov (United States)

    Brigandì, Giuseppina; Tito Aronica, Giuseppe

    2015-04-01

    Main focus of the paper is to present a flash flood early warning system, developed for Civil Protection Agency for the Sicily Region, for alerting extreme hydrometeorological events by using a methodology based on the combined use of rainfall thresholds and soil moisture indexes. As matter of fact, flash flood warning is a key element to improve the Civil Protection achievements to mitigate damages and safeguard the security of people. It is a rather complicated task, particularly in those catchments with flashy response where even brief anticipations are important and welcomed. In this context, some kind of hydrological precursors can be considered to improve the effectiveness of the emergency actions (i.e. early flood warning). Now, it is well known how soil moisture is an important factor in flood formation, because the runoff generation is strongly influenced by the antecedent soil moisture conditions of the catchment. The basic idea of the work here presented is to use soil moisture indexes derived in a continuous form to define a first alert phase in a flash flood forecasting chain and then define a unique rainfall threshold for a given day for the subsequent alarm phases activation, derived as a function of the soil moisture conditions at the beginning of the day. Daily soil moisture indexes, representative of the moisture condition of the catchment, were derived by using a parsimonious and simply to use approach based on the IHACRES model application in a modified form developed by the authors. It is a simple, spatially-lumped rainfall-streamflow model, based on the SCS-CN method and on the unit hydrograph approach that requires only rainfall, streamflow and air temperature data. It consists of two modules. In the first a non linear loss model, based on the SCS-CN method, was used to transform total rainfall into effective rainfall. In the second, a linear convolution of effective rainfall was performed using a total unit hydrograph with a configuration of

  1. Effects of elevated ozone concentration on CH4 and N2O emission from paddy soil under fully open-air field conditions.

    Science.gov (United States)

    Tang, Haoye; Liu, Gang; Zhu, Jianguo; Kobayashi, Kazuhiko

    2015-04-01

    We investigated the effects of elevated ozone concentration (E-O3) on CH4 and N2O emission from paddies with two rice cultivars: an inbred Indica cultivar Yangdao 6 (YD6) and a hybrid one II-you 084 (IIY084), under fully open-air field conditions in China. A mean 26.7% enhancement of ozone concentration above the ambient level (A-O3) significantly reduced CH4 emission at tillering and flowering stages leading to a reduction of seasonal integral CH4 emission by 29.6% on average across the two cultivars. The reduced CH4 emission is associated with O3-induced reduction in the whole-plant biomass (-13.2%), root biomass (-34.7%), and maximum tiller number (-10.3%), all of which curbed the carbon supply for belowground CH4 production and its release from submerged soil to atmosphere. Although no significant difference was detected between the cultivars in the CH4 emission response to E-O3, a larger decrease in CH4 emission with IIY084 (-33.2%) than that with YD6 (-7.0%) was observed at tillering stage, which may be due to the larger reduction in tiller number in IIY084 by E-O3. Additionally, E-O3 reduced seasonal mean NOx flux by 5.7% and 11.8% with IIY084 and YD6, respectively, but the effects were not significant statistically. We found that the relative response of CH4 emission to E-O3 was not significantly different from those reported in open-top chamber experiments. This study has thus confirmed that increasing ozone concentration would mitigate the global warming potential of CH4 and suggested consideration of the feedback mechanism between ozone and its precursor emission into the projection of future ozone effects on terrestrial ecosystem. © 2014 John Wiley & Sons Ltd.

  2. The influence of biochar type on long-term stabilization for Cd and Cu in contaminated paddy soils.

    Science.gov (United States)

    Li, Hongying; Ye, Xinxin; Geng, Zhigang; Zhou, Hongjian; Guo, Xisheng; Zhang, Yunxia; Zhao, Huijun; Wang, Guozhong

    2016-03-05

    Long-term effect of biochar on PTEs (potential toxic elements) immobilization depends upon biochar own property and its aging process in soil. To understand the role of biachar type on PTEs stabilization, two types of biochar, corn-straw-derived biochar (CB) and hardwood-derived biochar (HB), were compared for their efficacy in achieving a stable decrease in the bio-availability of Cd and Cu in soils. The 3-year pot-culture experiment showed that HB reduced the concentration of CaCl2-extractable Cd and Cu by 57.9 and 63.8% in soil, and Cd and Cu uptake by 63.6 and 56.3% in rice tissue respectively, in the first year, whereas these values increased in the next two years. On the other hand, CB decreased these values steadily year by year. At the end of the 3 years, CB at 5% level had lowered the levels of CaCl2-extractable Cd and Cu by 53.6 and 66.8%, respectively. These variations between CB and HB were due to the differences in the way the two types of biochar age in the soil. The aging process was simulated in the laboratory, and the XPS results showed that the oxidization of the biochars introduced more oxygen-containing groups (especially carboxyl) on the surface of CB than HB, leading to a correspondingly greater number of oxygenated binding sites for Cd and Cu in the case of CB. The content of lignin was the major factor resulting in the variation of oxidation degree in two biochars. These results suggest that it is important to select the right kind of biochar to stably decrease the bio-availability of potential toxic elements (Cd and Cu) in contaminated soils. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. The partitioning of mercury in the solids components of forest soils and flooded forest soils in a hydroelectric reservoir, Quebec

    International Nuclear Information System (INIS)

    Dmytriw, R.P.

    1993-11-01

    Upon inundation, the soils in a hydroelection reservoir are subjected to several years of physical, biological and chemical changes as the transition from a terrestrial to an aquatic ecosystem is achieved. Changes in Eh, pH and microbial activity are believed to alter the metal binding capacity of solid substrates (organic matter, reactive Fe and Mn oxides, and clay minerals) within the soil profile, leading to remobilization of mercury associated with these phases. Four cores were collected along a transect from an unflooded forest soil to a pre-impoundment lake bottom sediment in the La-Grande-2 reservoir and watershed. The samples were sequentially extracted to determine the distribution of mercury between three operationally defined solid compartments: organic carbon, reactive Fe and Mn oxides/hydroxides, and the solid clay residue. Results indicate that up to 80% of the mercury in the O-horizon in forest soils and flooded forest soils, and up to 85% of the mercury in the lake sediments is bound to NaOH extractable organic carbon fractions. In the B-horizon podzol where organic content is low, 40-60% of the total mercury was found to be associated with reactive Fe minerals. In contrast, the flooded soil contains very little reactive Fe at any depth and the associated mercury concentrations are low. It is proposed that, upon inundation, oxide minerals are reduced and Hg released to the pore waters where it is immediately bound to an available substrate. Analyses of the residues suggests that there is an enrichment of mercury in the residual fraction immediately above the B-horizon of a flooded soil while the sulfide mineralization appears to play a role in sequestering mercury in lake sediments. 14 refs., 22 figs., 3 tabs

  4. In Situ Evaluation of Crop Productivity and Bioaccumulation of Heavy Metals in Paddy Soils after Remediation of Metal-Contaminated Soils.

    Science.gov (United States)

    Kim, Shin Woong; Chae, Yooeun; Moon, Jongmin; Kim, Dokyung; Cui, Rongxue; An, Gyeonghyeon; Jeong, Seung-Woo; An, Youn-Joo

    2017-02-15

    Soils contaminated with heavy metals have been reused for agricultural, building, and industrial uses following remediation. This study assesses plant growth and bioaccumulation of heavy metals following remediation of industrially contaminated soil. The soil was collected from a field site near a nonferrous smelter and was subjected to laboratory- and field-scale studies. Soil from the contaminated site was remediated by washing with acid or mixed with soil taken from a distant uncontaminated site. The activities of various soil exoenzymes, the rate of plant growth, and the bioaccumulations of six heavy metals were measured to assess the efficacy of these bioremediation techniques. Growth of rice (Oryza sativa) was unaffected in acid-washed soil or the amended soil compared to untreated soil from the contaminated site. The levels of heavy metals in the rice kernels remained within safe limits in treated and untreated soils. Rice, sorghum (Sorghum bicolor), and wheat (Triticum aestivum) cultivated in the same soils in the laboratory showed similar growth rates. Soil exoenzyme activities and crop productivity were not affected by soil treatment in field experiments. In conclusion, treatment of industrially contaminated soil by acid washing or amendment did not adversely affect plant productivity or lead to increased bioaccumulation of heavy metals in rice.

  5. Methane emissions from rice paddies. Experiments and modelling

    International Nuclear Information System (INIS)

    Van Bodegom, P.M.

    2000-01-01

    This thesis describes model development and experimentation on the comprehension and prediction of methane (CH4) emissions from rice paddies. The large spatial and temporal variability in CH4 emissions and the dynamic non-linear relationships between processes underlying CH4 emissions impairs the applicability of empirical relations. Mechanistic concepts are therefore starting point of analysis throughout the thesis. The process of CH4 production was investigated by soil slurry incubation experiments at different temperatures and with additions of different electron donors and acceptors. Temperature influenced conversion rates and the competitiveness of microorganisms. The experiments were used to calibrate and validate a mechanistic model on CH4 production that describes competition for acetate and H2/CO2, inhibition effects and chemolithotrophic reactions. The redox sequence leading eventually to CH4 production was well predicted by the model, calibrating only the maximum conversion rates. Gas transport through paddy soil and rice plants was quantified by experiments in which the transport of SF6 was monitored continuously by photoacoustics. A mechanistic model on gas transport in a flooded rice system based on diffusion equations was validated by these experiments and could explain why most gases are released via plant mediated transport. Variability in root distribution led to highly variable gas transport. Experiments showed that CH4 oxidation in the rice rhizosphere was oxygen (O2) limited. Rice rhizospheric O2 consumption was dominated by chemical iron oxidation, and heterotrophic and methanotrophic respiration. The most abundant methanotrophs and heterotrophs were isolated and kinetically characterised. Based upon these experiments it was hypothesised that CH4 oxidation mainly occurred at microaerophilic, low acetate conditions not very close to the root surface. A mechanistic rhizosphere model that combined production and consumption of O2, carbon and iron

  6. Alternate wetting and drying (AWD) of paddy fields: A water-saving technology

    International Nuclear Information System (INIS)

    Salim, M.; Shehzad, F.D.

    2008-01-01

    Rice productivity in Pakistan is lower than in various rice-producing countries of the World. One of the major reasons of low productivity is the shortage of water. It is, therefore, imperative to increase water-use efficiency. Various studies in China and elsewhere have revealed that continuous flooding is not necessary for getting high yield of rice. In China, lot of effort has been made to develop water- saving rice-production technologies. The most important of these is alternate wetting and drying (AWD) of rice-fields, instead of keeping them continuously flooded or submerged. In the present article, salient advantages and disadvantages have been discussed. The advantages include less water-use for paddy-production, high paddy-productivity, and improvement in the environment, with enhanced efficiency of nutrient-use, better utilization of rainwater, less infestation/ population of insect pests. The technology may affect the grain-quality of Basmati rice in Pakistan. It is suggested that studies. on various aspects of the technology should be carried out, in various ecological zones and in different soil-types. The adoption of the technology may prove helpful to enhance rice-productivity and improve the rural economy in Pakistan. (author)

  7. Flooding

    Science.gov (United States)

    ... and soil contamination from burial. Typical methods of recycling and solid waste disposal in sanitary landfills often ... rid of standing water in rain gutters, old tires, buckets, plastic covers, toys, pools, or any other ...

  8. Early thawing after snow removal and no straw mulching accelerates organic carbon cycling in a paddy soil in Northeast China.

    Science.gov (United States)

    Zhang, Hao; Tang, Jie; Liang, Shuang; Li, Zhaoyang; Wang, Jingjing; Wang, Sining

    2018-03-01

    Variations in soil organic carbon (SOC) have implications for atmospheric CO 2 concentrations and the greenhouse effect. However, the effects of snow cover and straw mulching on the variations in SOC fractions across winter remain largely unknown. In this study, soil samples were collected during different stages of winter from an in situ experiment comprising three treatments: 1) snow removal with no straw mulching (Sn-SM-); 2) snow cover with no straw mulching (SC), and; 3) snow cover with straw mulching (SC + SM+). Results showed that labile organic carbon, semi-labile organic carbon, recalcitrant organic carbon (ROC), the light fraction of organic carbon (LFOC), and easily oxidized organic carbon (EOC) contents did not vary significantly (P > .05) during the unfrozen to hard frost stages. Compared to the unfrozen stage, microbial biomass carbon (MBC) contents decreased by 519.03 mg kg -1 , 325.21 mg kg -1 , and 244.09 mg kg -1 and dissolved organic carbon (DOC) contents increased by 473.36 mg kg -1 , 348.10 mg kg -1 , and 258.89 mg kg -1  at the hard frost stage in Sn-SM-, SC, and SC + SM + treatments, respectively. Throughout all thawing stages, > 61% and 59% of SOC and ROC accumulation, respectively in the three treatments were observed in thawing stage II, indicating that higher temperatures and microbial activities in thawing stage II accelerated the inputs of SOC and ROC. ROC accumulation accounted for >65% of the SOC accumulation and the proportions of ROC in SOC increased in the three treatments during the thawing stages. SC + SM + treatment maintained lower EOC contents during thawing stages than other treatments. The observation of lowest SOC and LFOC accumulation and contents in the SC + SM + treatment during thawing stages showed that SC + SM + experienced the least inputs of SOC in the soil. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Photosynthetic activity of young Ricinus communis L. plants under conditions of flooded soil

    Directory of Open Access Journals (Sweden)

    Davi Silva Dalberto

    2017-03-01

    Full Text Available Soil flooding is a stress condition that causes changes in hydric relationships and in the metabolism of crops, thereby affecting their productivity. To evaluate the effects of soil flooding on the chlorophyll a fluorescence transient, as well as gas exchange and Ricinus communis growth, young plants of the ‘AL Guarany 2002’ and ‘IAC Guarani’ cultivars, grown in a greenhouse, were subjected to flood conditions by maintaining a layer of water 2-3 cm above the soil. The stressed plants showed drastic reduction in net CO2 assimilation and growth variables. There was, however, an increase in performance index (PIABS e PITOTAL at different moments of stress between the two cultivars. In general, R. communis plants possess mechanisms to protect the electron transport chain during a period of stress, without causing damage and reducing functionality. However, this is not enough to maintain photosynthetic activity owing to the decrease in stomatal conductance and intrinsic carboxylation efficiency, which affects biomass accumulation in stressed plants. In summary, this study found that the ‘AL Guarany 2002’ was found to be more sensitive to stress than the ‘IAC Guarani’ was.

  10. Differences in Cellulosic Supramolecular Structure of Compositionally Similar Rice Straw Affect Biomass Metabolism by Paddy Soil Microbiota.

    Directory of Open Access Journals (Sweden)

    Tatsuki Ogura

    Full Text Available Because they are strong and stable, lignocellulosic supramolecular structures in plant cell walls are resistant to decomposition. However, they can be degraded and recycled by soil microbiota. Little is known about the biomass degradation profiles of complex microbiota based on differences in cellulosic supramolecular structures without compositional variations. Here, we characterized and evaluated the cellulosic supramolecular structures and composition of rice straw biomass processed under different milling conditions. We used a range of techniques including solid- and solution-state nuclear magnetic resonance (NMR and Fourier transform infrared spectroscopy followed by thermodynamic and microbial degradability characterization using thermogravimetric analysis, solution-state NMR, and denaturing gradient gel electrophoresis. These measured data were further analyzed using an "ECOMICS" web-based toolkit. From the results, we found that physical pretreatment of rice straw alters the lignocellulosic supramolecular structure by cleaving significant molecular lignocellulose bonds. The transformation from crystalline to amorphous cellulose shifted the thermal degradation profiles to lower temperatures. In addition, pretreated rice straw samples developed different microbiota profiles with different metabolic dynamics during the biomass degradation process. This is the first report to comprehensively characterize the structure, composition, and thermal degradation and microbiota profiles using the ECOMICS toolkit. By revealing differences between lignocellulosic supramolecular structures of biomass processed under different milling conditions, our analysis revealed how the characteristic compositions of microbiota profiles develop in addition to their metabolic profiles and dynamics during biomass degradation.

  11. Hydrology, vegetation, and soils of four north Florida River flood plains with an evaluation of state and federal wetland determinations

    Science.gov (United States)

    Light, H.M.; Darst, M.R.; MacLaughlin, M.T.; Sprecher, S.W.

    1993-01-01

    A study of hydrologic conditions, vegetation, and soils was made in wetland forests of four north Florida streams from 1987 to 1990. The study was conducted by the U.S. Geological Survey in cooperation with the Florida Department of Environmental Regulation to support State and Federal efforts to improve wetland delineation methodology in flood plains. Plant communities and soils were described and related to topographic position and long-term hydrologic conditions at 10 study plots located on 4 streams. Detailed appendixes give average duration, frequency, and depth of flooding; canopy, subcanopy, and ground-cover vegetation; and taxonomic classification, series, and profile descriptions of soils for each plot. Topographic relief, range in stage, and depth of flooding were greatest on the alluvial flood plain of the Ochlockonee River, the largest of the four streams. Soils were silty in the lower elevations of the flood plain, and tree communities were distinctly different in each topographic zone. The Aucilla River flood plain was dominated by levees and terraces with very few depressions or low backwater areas. Oaks dominated the canopy of both lower and upper terraces of the Aucilla flood plain. Telogia Creek is a blackwater stream that is a major tributary of the Ochlockonee River. Its low, wet flood plain was dominated by Wyssa ogeche (Ogeechee tupelo) trees, had soils with mucky horizons, and was inundated by frequent floods of very short duration. The St. Marks River, a spring-fed stream with high base flow, had the least topographic relief and lowest range in stage of the four streams. St. Marks soils had a higher clay content than the other streams, and limestone bedrock was relatively close to the surface. Wetland determinations of the study plots based on State and Federal regulatory criteria were evaluated. Most State and Federal wetland determinations are based primarily on vegetation and soil characteristics because hydrologic records are usually not

  12. Flood effects on efflux and net production of nitrous oxide in river floodplain soils

    Science.gov (United States)

    Riaz, Muhammad; Bruderer, Christian; Niklaus, Pascal A.; Luster, Jörg

    2016-04-01

    Floodplain soils are often rich in nutrients and exhibit high spatial heterogeneity in terms of geomorphology, soil environmental conditions and substrate availability for processes involved in carbon and nutrient cycling. In addition, fluctuating water tables lead to temporally changing redox conditions. In such systems, there are ideal conditions for the occurrence of hot spots and moments of nitrous oxide emissions, a potent greenhouse gas. The factors that govern the spatial heterogeneity and dynamics of N2O formation in floodplain soils and the surface efflux of this gas are not fully understood. A particular issue is the contribution of N2O formation in the subsoil to surface efflux. We studied this question in the floodplain of a restored section of the Thur river (NE Switzerland) which is characterized by a flashy flow regime. As a consequence, the floodplain soils are unsaturated most of the time. We showed earlier that saturation during flood pulses leads to short phases of generally anoxic conditions followed by a drying phase with anoxic conditions within aggregates and oxic conditions in larger soil pores. The latter conditions are conducive for spatially closely-coupled nitrification-denitrification and related hot moments of nitrous oxide formation. In a floodplain zone characterized by about one meter of young, sandy sediments, that are mostly covered by the tall grass Phalaris arundinacea, we measured at several time points before and after a small flood event N2O surface efflux with the closed-chamber method, and assessed N2O concentrations in the soil air at four different depths using gas-permeable tubings. In addition, we calculated the N2O diffusivity in the soil from Radon diffusivity. The latter was estimated in-situ from the recovery of Radon concentration in the gas-permeable tubings after purging with ambient air. All these data were then used to calculate net N2O production rates at different soil depths with the gradient method. In

  13. Flooding-induced N2O emission bursts controlled by pH and nitrate in agricultural soils

    DEFF Research Database (Denmark)

    Hansen, Mette; Clough, Tim J.; Elberling, Bo

    2014-01-01

    emissions is poorly studied for agricultural systems. The overall N2O dynamics during flooding of an agricultural soil and the effect of pH and NO3− concentration has been investigated based on a combination of the use of microsensors, stable isotope techniques, KCl extractions and modelling. This study...... within the soil. The magnitude of the emissions are, not surprisingly, positively correlated with the soil NO3− concentration but also negatively correlated with liming (neutral pH). The redox potential of the soil is found to influence N2O accumulation as the production and consumption of N2O occurs...... in narrow redox windows where the redox range levels are negatively correlated with the pH. This study highlights the potential importance of N2O bursts associated with flooding and infers that annual N2O emission estimates for tilled agricultural soils that are temporarily flooded will be underestimated...

  14. Effects of rice straw, biochar and mineral fertiliser on methane (CH4) and nitrous oxide (N2O) emissions from rice (Oryza sativa L.) grown in a rain-fed lowland rice soil of Cambodia

    DEFF Research Database (Denmark)

    Ly, Proyuth; Duong, Quynh Vu; Jensen, Lars Stoumann

    2015-01-01

    -control, rice straw (RS) and biochar (BC). Compound fertiliser was applied to all treatments. Rice was grown in columns packed with a paddy soil from Cambodia. Results revealed faster mineralisation of organic carbon (RS and BC) when applied in water-saturated conditions lasting for 2 weeks instead of flooding...

  15. Converting Paddy Rice Field to Urban Use Dramatically Altered the Water and Energy Balances in Southern China

    Science.gov (United States)

    Hao, L.; Sun, G.; Liu, Y.; Qin, M.; Huang, X.; Fang, D.

    2017-12-01

    Paddy rice wetlands are the main land use type across southern China, which impact the regional environments by affecting evapotranspiration (ET) and other water and energy related processes. Our study focuses on the effects of land-cover change on water and energy processes in the Qinhuai River Basin, a typical subtropical humid region that is under rapid ecological and economical transformations. This study integrates multiple methods and techniques including remote sensing, water and energy balance model (i.e., Surface Energy Balance Algorithm for Land, SEBAL), ecohydrological model (i.e., Soil and Water Assessment Tool, SWAT), and ground observation (Eddy Covariance measurement, etc.). We found that conversion of paddy rice field to urban use led to rise in vapor pressure deficit (VPD) and reduction in ET, and thus resulted in changes in local and regional water and heat balance. The effects of the land-use change on ET and VPD overwhelmed the effects of regional climate warming and climate variability. We conclude that the ongoing large-scale urbanization of the rice paddy-dominated regions in humid southern China and East Asia will likely exacerbate environmental consequences (e.g., elevated storm-flow volume, aggravated flood risks, and intensified urban heat island and urban dry island effects). The potential role of vegetated land cover in moderating water and energy balances and maintaining a stable climate should be considered in massive urban planning and global change impact assessment in southern China.

  16. Partitioning of soil CO2 efflux in un-manipulated and experimentally flooded plots of a temperate fen

    Science.gov (United States)

    Wunderlich, S.; Borken, W.

    2012-08-01

    Peatlands store large amounts of organic carbon, but the carbon stock is sensitive to changes in precipitation or water table manipulations. Restoration of drained peatlands by drain blocking and flooding is a common measure to conserve and augment the carbon stock of peatland soils. Here, we report to what extent flooding affected the contribution of heterotrophic and rhizosphere respiration to soil CO2 efflux in a grass-dominated mountain fen in Germany. Soil CO2 efflux was measured in three un-manipulated control plots and three flooded plots in two consecutive years. Flooding was achieved by permanent irrigation during the growing seasons. Radiocarbon signatures of CO2 from different sources including soil CO2 efflux, incubated peat cores and live grass roots were repeatedly analyzed for partitioning of soil CO2 efflux. Additionally, heterotrophic respiration and its radiocarbon signature were determined by eliminating rhizosphere respiration in trenched subplots (only control). In the control plots, rhizosphere respiration determined by 14C signatures contributed between 47 and 61% during the growing season, but was small (4 ± 8%) immediately before budding. Trenching revealed a smaller rhizosphere contribution of 33 ± 8% (2009) and 22 ± 9% (2010) during growing seasons. Flooding reduced annual soil CO2 efflux of the fen by 42% in 2009 and by 30% in 2010. The reduction was smaller in 2010 mainly through naturally elevated water level in the control plots. A one-week interruption of irrigation caused a strong short-lived increase in soil CO2 efflux, demonstrating the sensitivity of the fen to water table drawdown near the peat surface. The reduction in soil CO2 efflux in the flooded plots diminished the relative proportion of rhizosphere respiration from 56 to 46%, suggesting that rhizosphere respiration was slightly more sensitive to flooding than heterotrophic respiration.

  17. LEACHING AND DEGRADATION OF 2,4-DICHLOROPHENOXIACETIC ACID, IN COLOMBIA RICE FLOODED SOIL.

    Science.gov (United States)

    Huertas, J; Guerrero, J A; Martinez-Cordon, M J

    2015-01-01

    Rice is mostly cultivated on soil held under flooded conditions. Under these conditions pesticides undergo reductive transformations which are characteristic to rice fields and other anaerobic systems. The present study was undertaken to evaluate the mobility and persistence of 2,4-dichlorophenoxy acetic acid (2,4-D) under laboratory conditions for the rice crop in Espinal, Colombia. A displacement study was performed on a hand packed soil column 30 cm length. After leaching experiment, the soil from column was sliced into six successive sections (5 cm). Methanol acidified (H3PO4 0.25%) extraction was used to determine the herbicide residues in each section. 2,4-D experimental breakthrough curve was analyzed using Stanmod program (inverse problem) to obtain transport parameters. The non-equilibrium physical model fitted well the experimental breakthrough curve. The recovery percent of 2,4-D in leachates was 36.44% after 3.4 pore volumes, and retardation factor was 2.1, indicating low adsorption in that conditions. 2,4-D was rapidly degraded, with DT50 = 11.4 days. The results suggest that 2,4-D under flooded conditions have a high potential for leaching through the soil profile, although the elevated rate of degradation reduced the ground water contamination risk.

  18. Isotope technology as applied to studies of soil fertility, nutrient availability and fertilizer use on flooded rice soils

    International Nuclear Information System (INIS)

    Patnaik, S.; Mohanty, S.K.; Dash, R.N.

    1979-01-01

    Research is reviewed on soil fertility and nutrient availability in relation to fertilizer efficiency, especially o stimulated the mineralization of soil N. Losses of added N from oxidation, leaching, denitrification and volatilization could be minimized through placement of N fertilizer in the reduced zone or by the addition of rice straw for rapid immobilization of added N. Fe-P and, to some extent, Al-P provided P to the rice plants, particularly in P-deficient soils. Added phosphates were converted to these forms which, under waterlogged soil conditions, released more P into the soil solution through reductive solubilization of Fe-P and hydrolytic dissolution of Al-P. The rice plants generally absorbed fertilizer N during the vegetative growth period and N mineralized from soil organic matter during the reproductive growth period. 15 N studies indicated higher grain yield and utilization of applied N through fractional application of 70-80% during the vegetative growth period, and the remaining 20-30% top-dressed at the panicle initiation stage. Ammonia-containing and -forming (urea) fertilizers were superior to the nitrate form of N. In field tests, however, the crop recovery of applied N was relatively low. Phosphatic fertilizers were best applied at puddling. In general, water-soluble phosphates were superior to citrate-soluble or insoluble phosphates. The latter could be made as efficient as the water-soluble phosphate, at comparable low rates, by applying to the moist aerobic acid soil 2-3 weeks before flooding and transplanting rice. Tracer studies have been used to evaluate the nutrient-supplying capacity of the soil from the 'A' value concept. 'A' values varied with varying conditions of soil, rate, time and form of fertilizer application. Zn nutrition of the rice plant and fertilizer use with 65 Zn have been studied relatively little. Some lines of future work are suggested

  19. Soil CH4 and N2O Emissions from Rice Paddy Fields in Southern Brazil as Affected by Crop Management Levels: a Three-Year Field Study

    Directory of Open Access Journals (Sweden)

    Tiago Zschornack

    2018-05-01

    Full Text Available ABSTRACT Rice yield increases in response to improvements in crop management, but the impact on greenhouse gas (GHG emissions in the subtropical region of Southern Brazil remains unknown. A three-year field study was developed aiming to evaluate the impact that an increase in crop management levels (high and very high has on soil methane (CH4 and nitrous oxide (N2O emissions, as compared to the level (medium currently adopted by farmers in Southern Brazil. Differences in crop management included seed and fertilizer rates, irrigation, and pesticide use. The effect of crop management levels on the annual partial global warming potential (pGWP = CH4 × 25 + N2O × 298 ranged from 7,547 to 17,711 kg CO2eq ha−1 and this effect was larger than on the rice grain yield (9,280 to 12,260 kg ha−1, resulting in approximately 60 % higher yield-scaled GHG with the high crop management level compared to the current level. Soil CH4 emissions accounted for 98 % of pGWP in the flooded rice season, whereas N2O prevailed during the drained non-rice season (≈65 %. Although it was impossible to relate emissions to any individual input or practice, soil CH4 emissions in the rice season were linearly related to the biomass produced by the rice crop (p<0.01 and by ryegrass in the previous non-rice season (p<0.1, both of which were possibly related to the supply of labile C for methanogenesis. A future increase in rice yield as a result of the adoption of improved crop management may require additional agricultural practices (e.g., intermittent irrigation to offset the increased GHG emissions.

  20. Cycling of 137Cs in soil and vegetation of a flood plain 30 years after initial contamination

    International Nuclear Information System (INIS)

    Dahlman, R.C.; Van Voris, P.

    1976-01-01

    Distribution of radiocesium was determined in soil and vegetation components of a flood plain contaminated by Manhattan Project operations in 1944. Thirty years after contaminated waste effluents were deposited in a temporary holding basin, practically all the soil 137 Cs was still within 60 cm of the soil surface. Maximum 137 Cs concentrations occurred in the 12- to 22-cm horizon. Concentrations throughout the flood plain were variable; maximum levels of 137 Cs exceeded 20,000 pCi/g; intermediate levels of 5,000 to 20,000 pCi/g were encountered along the watercourse, and concentrations less than 5,000 pCi/g were found along the flood plain margins. Relative concentrations in soil, roots and aboveground vegetation (expressed as ratios on a gram per gram basis) were 0.6 for root/soil, 0.03 for aboveground vegetation/soil, and 0.04 for aboveground vegetation/roots. Vegetation-soil ratios ranged from 0.001 to 0.53 for all species, and average ratios for the 30-yr postcontamination study showed that the relative 137 Cs distribution between plants and soil has not changed from distributions reported 15 yr ago. The results also indicated that ratios were higher at low soil- 137 Cs concentration. Thus, when soil and environmental conditions remain unchanged over a 30-yr period, the relative concentration of 137 Cs between plants and soil does not appear to change as a function of time

  1. Vegetation and soil at the terraces of the Dřevnice and the Morava rivers after flood

    Czech Academy of Sciences Publication Activity Database

    Šerá, Božena; Cudlín, Pavel; Dušek, L.; Hofman, J.

    2008-01-01

    Roč. 27, č. 4 (2008), s. 430-445 ISSN 1335-342X R&D Projects: GA ČR(CZ) GA103/99/1470 Institutional research plan: CEZ:AV0Z60870520 Keywords : flood * vegetation change * invasive plant * life strategy * soil parameter * soil contamination Subject RIV: EH - Ecology, Behaviour

  2. Temporal changes of radiocesium in irrigated paddy fields and its accumulation in rice plants in Fukushima.

    Science.gov (United States)

    Yang, Baolu; Onda, Yuichi; Wakiyama, Yoshifumi; Yoshimura, Kazuya; Sekimoto, Hitoshi; Ha, Yiming

    2016-01-01

    About half of the total paddy field area, which is the dominant agricultural land in Fukushima Prefecture, was contaminated by radiocesium released by the Fukushima Daiichi Nuclear Power Plant accident. In this study, we investigated the temporal changes of radiocesium in soil, irrigation water, and rice plant in two adjacent rice paddies, with and without surface-soil-removal, in Fukushima Prefecture for over three years (2012-2014) after the nuclear accident. Our results showed that radiocesium migrated into 24-28 cm soil layers and that the activity concentration of radiocesium in paddy soils showed a significant reduction in 2014. The newly added radiocesium to paddies through irrigation water contributed only a maximum value of 0.15% and 0.75% of the total amount present in control and decontaminated paddies, respectively, throughout the study period. The radiocesium activity concentration in suspended sediment in irrigation water exponentially decreased, and the effective half-lives (Teff) for (137)Cs and (134)Cs were 1.3 and 0.9 years, respectively. Additionally, the average suspended sediment concentration in irrigation water increased between 2012 and 2014, suggesting that enhanced soil erosion had occurred in the surrounding environment. Radiocesium accumulation in rice plant also decreased with time in both paddies. However, the concentration ratio of radiocesium for rice plant in the decontaminated paddy increased compared with control paddy, despite approximately 96% of fallout radiocesium removed in paddy soil. Further analysis is required to clarify the reasons of high concentration ratio of radiocesium for rice plant in the decontaminated paddy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Nitrogen cycling in a flooded-soil ecosystem planted to rice (Oryza sativa L.)

    International Nuclear Information System (INIS)

    Reddy, K.R.

    1982-01-01

    15 N studies of various aspects of the nitrogen cycle in a flooded rice ecosystem on Crowley silt loam soil in Louisiana were reviewed to construct a mass balance model of the nitrogen cycle for this system. Nitrogen transformations modeled included 1) net ammonification (0.22 mg NH 4+ -N kg dry soil - 1 day - 1 ). 2) net nitrification (207 mg NO 3- -N kg dry soil - 1 day - 1 ). 3) denitrification (0.37 mg N kg dry soil - 1 day - 1 ), and 4) biological N 2 fixation (0.16 mg N kg dry soil - 1 day - 1 ). Nitrogen inputs included 1) application of fertilizers, 2) incorporation of crop residues, 3) biological N 2 fixation, and 4) deposition. Nitrogen outputs included 1) crop removal, 2) gaseous losses from NH 3 volatilization and simultaneous occurrence of nitrification-denitrification, and 3) leaching and runoff. Mass balance calculations indicated that 33% of the available inorganic nitrogen was recovered by rice, and the remaining nitrogen was lost from the system. Losses of N due to ammonia volatilization were minimal because fertilizer-N was incorporated into the soil. A significant portion of inorganic-N was lost by ammonium diffusion from the anaerobic layer to the aerobic layer in response to a concentration gradient and subsequent nitrification in the aerobic layer followed by nitrate diffusion into the anaerobic layer and denitrification into gaseous end products. Leaching and surface runoff losses were minimal. (orig.)

  4. Effect of urea placement on leaching losses of nitrogen from flooded rice soils

    International Nuclear Information System (INIS)

    Vlek, P.L.G.; Byrnes, B.H.; Craswell, E.T.

    1980-01-01

    In an effort to provide an explanation for the reported variability in fertilizer N efficiency from deep-placed urea on flooded rice, a set of controlled experiments was conducted to evaluate the effect of water percolation on fertilizer loss and plant uptake from 15 N labeled urea supergranules. Three soils of different texture (silt loam-clay) were subjected to various percolation rates (0-20 mm/day) while planted to rice which was harvested after approximately 40 days. The results indicate that moderate to high percolation through silt loam soil will lead to significant fertilizer N losses and drastically decrease the fertilizer uptake by plants. The permeability of the clay soil was too low for any leaching to take place. It is therefore concluded that deep placement of urea supergranules not be recommended in soils where percolation rates may exceed 5 mm/day, particularly if the cation exchange capacity of the soil is low. This experiment points to the need of evaluating and reporting the percolation rates in soils where experiments with supergranular urea are conducted. (orig.)

  5. The significance of denitrification of applied nitrogen in fallow and cropped rice soils under different flooding regimes. Pt. 1

    International Nuclear Information System (INIS)

    Fillery, I.R.P.; Vlek, P.L.G.

    1982-01-01

    The role of nitrification-denitrification in the loss of nitrogen from urea applied to puddled soils planted to rice and subjected to continuous and intermittent flooding was evaluated in three greenhouse pot studies. The loss of N via denitrification was estimated indirectly using the 15 N balance, after either first accounting for NH 3 volatilization or by analyzing the 15 N balance immediately before and after the soil was dried and reflooded. When urea was broadcast and incorporated the loss of 15 N from the soil-plant systems depended on the soil, being about 20% - 25% for the silt loams and only 10% - 12% for the clay. Ammonia volatilization accounted for an average 20% of the N applied in the silt loam. Denitrification losses could not account for more than 10% of the applied N in any of the continuously flooded soil-plant systems under study and were most likely less than 5%. Intermittent flooding of soil planted to rice did not increase the loss of N. Denitrification appeared to be an important loss mechanism in continuously flooded fallow soils, accounting for the loss of approximately 40% of the applied 15 N. Loss of 15 N was not appreciably enhanced in fallow soils undergoing intermittent flooding. Apparently, nitrate formed in oxidized zones in the soil was readily denitrified in the absence of plant roots. Extensive loss (66%) of 15 N-labeled nitrate was obtained when 100 mg/pot of nitrate-N was applied to the surface of nonflooded soil prior to reflooding. This result suggests that rice plants may not compete effectively with denitrifiers if large quantities of nitrate were to accumulate during intermittent dry periods. (orig.)

  6. Developing Automatic Water Table Control System for Reducing Greenhouse Gas Emissions from Paddy Fields

    Science.gov (United States)

    Arif, C.; Fauzan, M. I.; Satyanto, K. S.; Budi, I. S.; Masaru, M.

    2018-05-01

    Water table in rice fields play important role to mitigate greenhouse gas (GHG) emissions from paddy fields. Continuous flooding by maintenance water table 2-5 cm above soil surface is not effective and release more GHG emissions. System of Rice Intensification (SRI) as alternative rice farming apply intermittent irrigation by maintaining lower water table is proven can reduce GHG emissions reducing productivity significantly. The objectives of this study were to develop automatic water table control system for SRI application and then evaluate the performances. The control system was developed based on fuzzy logic algorithms using the mini PC of Raspberry Pi. Based on laboratory and field tests, the developed system was working well as indicated by lower MAPE (mean absolute percentage error) values. MAPE values for simulation and field tests were 16.88% and 15.80%, respectively. This system can save irrigation water up to 42.54% without reducing productivity significantly when compared to manual irrigation systems.

  7. Photosynthesis, Growth and Development of Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae in Flooded Soil

    Directory of Open Access Journals (Sweden)

    Viviane M. Davanso

    2002-09-01

    Full Text Available Morphological, anatomical and ecophysiological modifications caused by flooding in the growth and development of Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae were studied and correlated with tolerance to the excess of water in the soil. Three-month-old plants, grown in a greenhouse, underwent a period of 56 days of flooding and a post-flooding period. Photosynthesis rate and growth decreased in T. avellanedae when flooding duration increased. Though not much tolerant, plant adapted itself to short flooding periods. This relative tolerance was probably due to the capacity of T. avellanedae in developing structures which lessened flooding effects and promoted internal diffusion of oxygen from the aerial part to the roots, such as stem fissures, superficial roots and hypertrophied lenticels in the roots. As there was no great variation in the internal anatomy of T. avellanedae leaves and roots, metabolic alterations might have helped in the survival of the species during flooding.Foram estudadas as modificações morfo-anatômicas e ecofisiológicas que o alagamento provoca em Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae, correlacionando-as com sua capacidade de tolerar o excesso de água no solo. Plantas com três meses de idade, crescendo em casa de vegetação, foram submetidas a 56 dias de alagamento e a um período de pós-alagamento. A taxa fotossintética e o crescimento de T. avellanedae decresceram conforme aumentou o tempo de alagamento, mas mesmo não sendo altamente tolerante, a espécie foi capaz de se adaptar a curtos períodos de alagamento. Esta relativa tolerância provavelmente se deve à capacidade apresentada por T. avellanedae de desenvolver estruturas que amenizam os efeitos do alagamento, promovendo a difusão interna de oxigênio da parte aérea para as raízes, tais como rachaduras caulinares, raízes superficiais e lenticelas hipertrofiadas nas raízes. Como não houve acentuada variação na anatomia interna

  8. Geochemical associations and availability of cadmium (Cd) in a paddy field system, northwestern Thailand.

    Science.gov (United States)

    Kosolsaksakul, Peerapat; Farmer, John G; Oliver, Ian W; Graham, Margaret C

    2014-04-01

    The Mae Tao watershed, northwest Thailand, has become contaminated with cadmium (Cd) as a result of zinc ore extraction (Padaeng deposit) in the nearby Thanon-Thongchai mountains. Consumption of contaminated rice has led to documented human health impacts. The aim of this study was to elucidate transfer pathways from creek and canal waters to the paddy field soils near Baan Mae Tao Mai village and to determine the relationship between Cd speciation in the soil and uptake by rice plants. Transfer mainly occurred in association with particulate matter during flooding and channel dredging and, in contrast with many other studies, most of the soil Cd was associated with exchangeable and carbonate-bound fractions. Moreover, there was a linear relationship between soil total Cd and rice grain Cd (R(2) = 0.715), but a stronger relationship between both the Tessier-exchangeable soil Cd and the BCR-exchangeable soil Cd and rice grain Cd (R(2) = 0.898 and 0.862, respectively). Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. PCDD/Fs and dioxin-like PCBs in soils after the flooding of River Elbe and Mulde in 2002

    Energy Technology Data Exchange (ETDEWEB)

    Umlauf, G.; Christoph, E.H.; Bidoglio, G. [European Commission, Ispra (IT). Institute for Environment and Sustainability (IES), Joint Research Center (JRC)

    2004-09-15

    On account of the Elbe and Mulde flooding in 2002 the UFZ Centre for Environmental Research Leipzig/Halle co-ordinated an ad hoc project entitled 'Pollutant studies following the flooding in August 2002 - determining the potential hazards in the Elbe and the Mulde' (BMBF ad-hoc- Verbundprojekt Elbe Hochwasser 2002). In the frame of this project, the Institute of Environment and Sustainability of the Joint Research Centre of the European Commission addressed the issue of the contamination of PCDD/Fs and dioxin-like PCBs in flooded soils. The objective of this survey was to assess the contamination of urban and agricultural soils in relation to current land use, to estimate the specific impact of the flooding in 2002 and to link the contamination data to possible sources.

  10. Transformations of N from the fertilizer applied to dark plastic soil under flooding conditions

    International Nuclear Information System (INIS)

    Lachataignerais B, E.; Aguilera, R.M.; Romero, R.M.; Sosa, J.L.

    1993-01-01

    The influence of flooding in dark plastic soil on the dynamics of amonification, nitrification of the contents of organic nitrogen, of the volatilization of the ammonia and other losses of nitrogen applied as enriched urea at 10 at of 15N , by means of laboratory experiments, using isotopic techniques have been studied. It has been observed that the interchangeable nitrogen from the fertilizer reached approximately a 75% of the one applied a week later, thus diminishing quickly up to values below the 20% seven weeks later

  11. The influence of flooding on soil proportion and plant growth. 1. The influence on root development and growth of barley

    International Nuclear Information System (INIS)

    Sisworo, E.L.

    1975-01-01

    An experiment has been carried out to study the extent of root and shoot of barley exposed to flooding at various time of flooding. Several parameters were used in the experiment, namely the percentage of 86 Rb in the root system, dry weight of root as well as shoot, increase of leaf size, number of leaves and tillers and nitrogen content in leaf tissue. Radioactive 86 Rb-Cl was used in the experiment and injected into the plant 24 hours before harvest. The plants were harvested 2, 6, and 20 days after flooding. From the result obtained, it turned out that flooding conditions apparently reduced root development in the lower part of soil layer, while in the top layer a proper development of root was concentrated. Injury symptoms were mainly observed in the shoot; where leaf yellowing occured and started with the first leaf five days after flooding and subsequently reduced the number of leaves and tillers. (author)

  12. Phosphate Release Upon Long- and Short -Term Flooding of Fen Meadows Depends on Land Use History and Soil pH

    NARCIS (Netherlands)

    Beltman, B.; Van Der Ven, P. J. M.; Verhoeven, J. T. A.; Sarneel, J. M.

    2014-01-01

    Flooding of acidified and desiccated fen meadows is a management approach for mitigating loss of plant species as well as a short-term measure to prevent flooding in urban areas. Studies have shown that flooding events can cause extreme P release from soils. We questioned whether the occurrence of

  13. Mercury transformation and release differs with depth and time in a contaminated riparian soil during simulated flooding

    Science.gov (United States)

    Poulin, Brett; Aiken, George R.; Nagy, Kathryn L.; Manceau, Alain; Krabbenhoft, David P.; Ryan, Joseph N.

    2016-01-01

    Riparian soils are an important environment in the transport of mercury in rivers and wetlands, but the biogeochemical factors controlling mercury dynamics under transient redox conditions in these soils are not well understood. Mercury release and transformations in the Oa and underlying A horizons of a contaminated riparian soil were characterized in microcosms and an intact soil core under saturation conditions. Pore water dynamics of total mercury (HgT), methylmercury (MeHg), and dissolved gaseous mercury (Hg0(aq)) along with selected anions, major elements, and trace metals were characterized across redox transitions during 36 d of flooding in microcosms. Next, HgT dynamics were characterized over successive flooding (17 d), drying (28 d), and flooding (36 d) periods in the intact core. The observed mercury dynamics exhibit depth and temporal variability. At the onset of flooding in microcosms (1–3 d), mercury in the Oa horizon soil, present as a combination of ionic mercury (Hg(II)) bound to thiol groups in the soil organic matter (SOM) and nanoparticulate metacinnabar (b-HgS), was mobilized with organic matter of high molecular weight. Subsequently, under anoxic conditions, pore water HgT declined coincident with sulfate (3–11 d) and the proportion of nanoparticulate b-HgS in the Oa horizon soil increased slightly. Redox oscillations in the intact Oa horizon soil exhausted the mobile mercury pool associated with organic matter. In contrast, mercury in the A horizon soil, present predominantly as nanoparticulate b-HgS, was mobilized primarily as Hg0(aq) under strongly reducing conditions (5–18 d). The concentration of Hg0(aq) under dark reducing conditions correlated positively with byproducts of dissimilatory metal reduction (P(Fe,Mn)). Mercury dynamics in intact A horizon soil were consistent over two periods of flooding, indicating that nanoparticulate b-HgS was an accessible pool of mobile mercury over recurrent reducing conditions. The

  14. Causal mechanisms of soil organic matter decomposition: Deconstructing salinity and flooding impacts in coastal wetlands

    Science.gov (United States)

    Stagg, Camille L.; Schoolmaster, Donald; Krauss, Ken W.; Cormier, Nicole; Conner, William H.

    2017-01-01

    Coastal wetlands significantly contribute to global carbon storage potential. Sea-level rise and other climate change-induced disturbances threaten coastal wetland sustainability and carbon storage capacity. It is critical that we understand the mechanisms controlling wetland carbon loss so that we can predict and manage these resources in anticipation of climate change. However, our current understanding of the mechanisms that control soil organic matter decomposition, in particular the impacts of elevated salinity, are limited, and literature reports are contradictory. In an attempt to improve our understanding of these complex processes, we measured root and rhizome decomposition and developed a causal model to identify and quantify the mechanisms that influence soil organic matter decomposition in coastal wetlands that are impacted by sea-level rise. We identified three causal pathways: 1) a direct pathway representing the effects of flooding on soil moisture, 2) a direct pathway representing the effects of salinity on decomposer microbial communities and soil biogeochemistry, and 3) an indirect pathway representing the effects of salinity on litter quality through changes in plant community composition over time. We used this model to test the effects of alternate scenarios on the response of tidal freshwater forested wetlands and oligohaline marshes to short- and long-term climate-induced disturbances of flooding and salinity. In tidal freshwater forested wetlands, the model predicted less decomposition in response to drought, hurricane salinity pulsing, and long-term sea-level rise. In contrast, in the oligohaline marsh, the model predicted no change in response to sea-level rise, and increased decomposition following a drought or a hurricane salinity pulse. Our results show that it is critical to consider the temporal scale of disturbance and the magnitude of exposure when assessing the effects of salinity intrusion on carbon mineralization in coastal

  15. Analysis of gene expression and proteomic profiles of clonal genotypes from Theobroma cacao subjected to soil flooding.

    Science.gov (United States)

    Bertolde, Fabiana Z; Almeida, Alex-Alan F; Pirovani, Carlos P

    2014-01-01

    Soil flooding causes changes in gene transcription, synthesis and degradation of proteins and cell metabolism. The main objective of this study was to understand the biological events of Theobroma cacao during soil flooding-induced stress, using the analyses of gene expression and activity of key enzymes involved in fermentation, as well as the identification of differentially expressed proteins by mass spectrometry in two contrasting genotypes for flooding tolerance (tolerant - TSA-792 and susceptible - TSH-774). Soil anoxia caused by flooding has led to changes in the expression pattern of genes associated with the biosynthesis of alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC) and lactate dehydrogenase (LDH) in leaves and roots of the two evaluated genotypes. Significant differences were observed between the enzyme activities of the two genotypes. Leaves and roots of the TSA-792 genotype showed higher ADH activity as compared to the TSH-774 genotype, whereas the activities of PDC and LDH have varied over the 96 h of soil flooding, being higher for TSA-792 genotype, at the initial stage, and TSH-774 genotype, at the final stage. Some of the identified proteins are those typical of the anaerobic metabolism-involved in glycolysis and alcoholic fermentation-and different proteins associated with photosynthesis, protein metabolism and oxidative stress. The ability to maintain glycolysis and induce fermentation was observed to play an important role in anoxia tolerance in cacao and may also serve to distinguish tolerant and susceptible genotypes in relation to this stressor.

  16. Sap flow characteristics of neotropical mangroves in flooded and drained soils

    Science.gov (United States)

    Krauss, Ken W.; Young, P. Joy; Chambers, Jim L.; Doyle, Thomas W.; Twilley, Robert R.

    2007-01-01

    Effects of flooding on water transport in mangroves have previously been investigated in a few studies, most of which were conducted on seedlings in controlled settings. In this study, we used heat-dissipation sap probes to determine if sap flow (Js) attenuates with radial depth into the xylem of mature trees of three south Florida mangrove species growing in Rookery Bay. This was accomplished by inserting sap probes at multiple depths and monitoring diurnal flow. For most species and diameter size class combinations tested, Js decreased dramatically beyond a radial depth of 2 or 4 cm, with little sap flow beyond a depth of 6 cm. Mean Js was reduced on average by 20% in Avicennia germinans (L.) Stearn, Laguncularia racemosa (L.) Gaertn. f. and Rhizophora mangle L. trees when soils were flooded. Species differences were highly significant, with L. racemosahaving the greatest midday Js of about 26g H2O H2O m−2s−1 at a radial depth of 2 cm compared with a mean for the other two species of about 15 g H2O m−2s−1. Sap flow at a depth of 2 cm in mangroves was commensurate with rates reported for other forested wetland tree species. We conclude that: (1) early spring flooding of basin mangrove forests causes reductions in sap flow in mature mangrove trees; (2) the sharp attenuations in Js along the radial profile have implications for understanding whole-tree water use strategies by mangrove forests; and (3) regardless of flood state, individual mangrove tree water use follows leaf-level mechanisms in being conservative.

  17. Modeling of the solid-solution partitioning of heavy metals and arsenic in embanked flood plain soils of the rivers Rhine and Meuse

    NARCIS (Netherlands)

    Schröder, T.J.; Hiemstra, T.; Vink, J.P.M.

    2005-01-01

    The aim of this study is to predict the solid-solution partitioning of heavy metals in river flood plain soils. We compared mechanistic geochemical modeling with a statistical approach. To characterize the heavy metal contamination of embanked river flood plain soils in The Netherlands, we collected

  18. Influence of flooding and metal immobilising soil amendments on availability of metals for willows and earthworms in calcareous dredged sediment-derived soils

    Energy Technology Data Exchange (ETDEWEB)

    Vandecasteele, Bart, E-mail: bart.vandecasteele@ilvo.vlaanderen.b [Institute for Agricultural and Fisheries Research (ILVO), Scientific Institute of the Flemish Government, Burg. Van Gansberghelaan 109, B-9820 Merelbeke (Belgium); Du Laing, Gijs [Ghent University, Department of Applied Analytical and Physical Chemistry, Coupure 653, B-9000 Ghent (Belgium); Lettens, Suzanna [Research Institute for Nature and Forest (INBO), Scientific Institute of the Flemish Government, Gaverstraat 4, B-9500 Geraardsbergen (Belgium); Jordaens, Kurt [Department of Biology, Evolutionary Biology Group, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Tack, Filip M.G. [Ghent University, Department of Applied Analytical and Physical Chemistry, Coupure 653, B-9000 Ghent (Belgium)

    2010-06-15

    Soil amendments previously shown to be effective in reducing metal bioavailability and/or mobility in calcareous metal-polluted soils were tested on a calcareous dredged sediment-derived soil with 26 mg Cd/kg dry soil, 2200 mg Cr/kg dry soil, 220 mg Pb/kg dry soil, and 3000 mg Zn/kg dry soil. The amendments were 5% modified aluminosilicate (AS), 10% w/w lignin, 1% w/w diammonium phosphate (DAP, (NH{sub 4}){sub 2}HPO{sub 4}), 1% w/w MnO, and 5% w/w CaSO{sub 4}. In an additional treatment, the contaminated soil was submerged. Endpoints were metal uptake in Salix cinerea and Lumbricus terrestris, and effect on oxidation-reduction potential (ORP) in submerged soils. Results illustrated that the selected soil amendments were not effective in reducing ecological risk to vegetation or soil inhabiting invertebrates, as metal uptake in willows and earthworms did not significantly decrease following their application. Flooding the polluted soil resulted in metal uptake in S. cinerea comparable with concentrations for an uncontaminated soil. - Some soil amendments resulted in higher metal uptake by earthworms and willows than when the polluted soil was not amended but submersion of the polluted soil resulted in reduced Cd and Zn uptake in Salix cinerea.

  19. Effects of different fertilizers on methane emission from paddy field of ...

    African Journals Online (AJOL)

    deltafuture

    Methane (CH4) emissions from Chinese paddy soil (Zhejiang province) were ... 52, 20 and 19 times, respectively of that given by control, and among chemical fertilizers it was ... The rapid increase of the world population over the past.

  20. Assessment of the environmental fate of cycloxaprid in flooded and anaerobic soils by radioisotopic tracing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xuanqi; Xu, Xiaoyong; Li, Chao [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China, University of Science and Technology, Shanghai 200237 (China); Zhang, Hanxue; Fu, Qiuguo [Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Shao, Xusheng [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China, University of Science and Technology, Shanghai 200237 (China); Ye, Qingfu, E-mail: qfye@zju.edu.cn [Institute of Nuclear Agricultural Sciences, Zhejiang University, Hangzhou 310029 (China); Li, Zhong, E-mail: lizhong@ecust.edu.cn [Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China, University of Science and Technology, Shanghai 200237 (China)

    2016-02-01

    Cycloxaprid (CYC) is a novel broad-spectrum neonicotinoid insecticide that has been developed for agricultural pest control. The fate of the {sup 14}C-labeled racemic and enantio-pure CYC isomers in flooded and anaerobic soil was investigated using radioisotope tracing techniques. After 100 d of incubation, only a minor portion (< 1%) of the applied CYC isomers is mineralized by each of the four tested soil types. The fraction of initially applied radioactive CYC dissipated into the bound or non-extractable residues (BR) increases with increase in the length of the incubation period, reaching up to 53.0–81.6%. The dissipation of the CYC through mineralization or formation of BR is strongly influenced by soil properties, such as humic content, pH value, and retained microbial activity. Amongst the soils studied, the fluvio-marine yellow loamy soil displayed the highest tendency to mineralize CYC while the coastal saline soil exhibited the strongest tendency to form BR. The observation that the water phase retained the large portion(> 60%) of the radioactivity attributed to the total extractable residue suggested that under the experimental condition, the initially applied {sup 14}C-labeled CYC residues were readily available for leaching or offsite transport. Additionally, no enantiomer-specific behaviors are observed. The results from this study provide a framework for assessing the environmental impact resulting from the use of this pesticide. - Highlights: • Only a minor portion (<1%) of the applied CYC was mineralized. • The bound residue increased over time, reaching up to 53.0-81.6%. • CYC residues were readily available for leaching. • No enantiomer-specific behaviors were observed.

  1. Paddy field – A natural sequential anaerobic–aerobic bioreactor for polychlorinated biphenyls transformation

    International Nuclear Information System (INIS)

    Chen, Chen; Yu, Chunna; Shen, Chaofeng; Tang, Xianjin; Qin, Zhihui; Yang, Kai; Hashmi, Muhammad Zaffar; Huang, Ronglang; Shi, Huixiang

    2014-01-01

    The environmental pollution and health risks caused by the improper disposal of electric and electronic waste (e-waste) have become urgent issues for the developing countries. One of the typical pollutants, polychlorinated biphenyls (PCBs), is commonly found in farmland in Taizhou, a major hotspot of e-waste recycling in China. This study investigated the amount of PCB residue in local farmlands. Biotransformation of PCBs was further studied under different water management conditions in paddy field with or without rice cultivation, with a special focus on the alternating flooded and drying processes. It was found that paddy field improved the attenuation of PCBs, especially for highly chlorinated congeners. In the microcosm experiment, 40% or more of the initial total PCBs was removed after sequential flood–drying treatments, compared to less than 10% in the sterilized control and 20% in the constant-drying system. Variation in the quantity of PCBs degrading and dechlorinating bacterial groups were closely related to the alteration of anaerobic–aerobic conditions. These results suggested that alternating anoxic–oxic environment in paddy field led to the sequential aerobic–anaerobic transformation of PCBs, which provided a favorable environment for natural PCB attenuation. - Highlights: • Paddy fields hold significantly lower level of PCBs than drylands, especially highly-chlorinated PCBs. • Microbial dechlorination of PCBs is favored under flooded conditions in paddy field. • Aerobic biodegradation of PCBs is benefited under dry conditions in paddy field. • PCBs dechlorination rate is accelerated in rice planted paddy field compared to the unplanted one. • Alternating anoxic–oxic environment in paddy field led to the sequential aerobic–anaerobic transformation of PCBs. - Alternating anoxic–oxic environment led to the sequential aerobic–anaerobic transformation of PCBs in paddy field, which could act as a natural sequential anaerobic

  2. Cycling of 137Cs in soil and vegetation of a flood plain 30 years after initial contamination

    International Nuclear Information System (INIS)

    Dahlman, R.C.; Van Voris, P.

    1975-01-01

    Distribution of radiocesium was determined in soil and vegetation components of a flood plain contaminated by Manhattan Project operations in 1944. Thirty years after contaminated waste effluents were deposited in a temporary holding basin, practically all the soil 137 Cs was still within 60 cm of the soil surface. Maximum 137 Cs concentrations occurred in the 12- to 22-cm horizon. Concentrations throughout the flood plain were variable; maximum levels of 137 Cs exceeded 20,000 pCi/g; intermediate levels of 5,000 to 20,000 pCi/g were encountered along the watercourse, and concentrations less than 5,000 pCi/g were found along the flood plain margins. Relative concentrations in soil, roots, and above-ground vegetation (expressed as ratios on a gram per gram basis) were 0.6 for root/soil, 0.05 for above-ground vegetation/soil, and 0.03 for above-ground vegetation/roots. Ratios ranged from 0.001 to 0.53 for all species, and average ratios for the 30-year post-contamination study showed that the relative 137 Cs distribution between plants and soil has not changed significantly from distributions reported 15 years ago (plant/soil ratio 0.05 vs 0.03 by Auerbach et al., 1959). The results also indicated that ratios were higher at low soil- 137 Cs concentration. Thus, when soil and environmental conditions remain unchanged over a 30-year period, the relative concentration of 137 Cs between plants and soil does not appear to change significantly as a function of time. (U.S.)

  3. Solubilização dos fosfatos naturais Patos de Minas e Arad em dois solos alagados Solubilization of Patos de Minas and Arad rock phosphate in two flooded soils

    Directory of Open Access Journals (Sweden)

    Gustavo Krüger Gonçalves

    2008-10-01

    Full Text Available Na cultura do arroz irrigado, não foram observadas diferenças significativas no rendimento de grãos em experimentos de campo que confrontaram fontes solúveis e fosfatos naturais como fontes de P. No entanto, as alterações químicas que ocorrem durante o alagamento, principalmente aumento do pH e dos teores de P e Ca na solução do solo, provavelmente dificultam a dissolução de fosfatos naturais. O objetivo deste trabalho foi avaliar a solubilização dos fosfatos naturais de Patos de Minas e de Arad em dois solos alagados. Foram realizados dois experimentos, delineados em blocos ao acaso, com quatro repetições, em tipos de solos diferentes (Planossolo e Cambissolo. Foram testadas fontes de P: (a testemunha, sem P; (b superfosfato triplo; (c fosfato de Patos de Minas; e (d fosfato de Arad. Na solução do solo, foram avaliados os valores de pH e os teores de Fe, Mn, Ca, e P durante 88 dias de alagamento. O pH e os teores de Fe e Mn na solução do Planossolo e do Cambissolo não foram influenciados pela adição de superfosfato triplo e pelos fosfatos naturais de Arad e de Patos. Os teores de P na solução dos solos foram maiores com superfosfato triplo do que com os fosfatos naturais, indicando maior solubilização do primeiro durante o alagamento. Entre os fosfatos naturais, o de Arad apresentou maior solubilização do que o de Patos apenas no Planossolo.Differences in grain yield were not observed in experiments with paddy rice when comparing soluble phosphates and rock phosphate as phosphorus sources. However, chemical changes in flooded soils such as increases in pH and phosphorus and calcium levels in the soil solution probably decrease the dissolution of rock phosphates in flooded soils. The current work was therefore carried out with the objective of studying the solubilization of phosphate rocks in flooded soils. Two experiments, conducted in a random block design with four replications, were set up in two soil types

  4. Legumelogic in paddy

    OpenAIRE

    Basavanagowda, B.N. Nandish

    2014-01-01

    Brown plant hopper showed me the way into organic farming. In 2001, I started my practice with logic of legumes just to cut down the 45 percent expenses of my paddy on fertilizers, pesticides and herbicides. Later as I realized each and every plant carries it’s own nutrients, medicinal values and characters. Plants like millets, oil seeds, spices, di-cots, monocots and weeds all being used as a green manure. For all my agriculture problems and crop demands, I look for the answers only thro...

  5. Sensor-Based Assessment of Soil Salinity during the First Years of Transition from Flood to Sprinkler Irrigation

    Directory of Open Access Journals (Sweden)

    Mª Auxiliadora Casterad

    2018-02-01

    Full Text Available A key issue for agriculture in irrigated arid lands is the control of soil salinity, and this is one of the goals for irrigated districts when changing from flood to sprinkling irrigation. We combined soil sampling, proximal electromagnetic induction, and satellite data to appraise how soil salinity and its distribution along a previously flood-irrigated field evolved after its transformation to sprinkling. We also show that the relationship between NDVI (normalized difference vegetation index and ECe (electrical conductivity of the soil saturation extracts mimics the production function between yield and soil salinity. Under sprinkling, the field had a double crop of barley and then sunflower in 2009 and 2011. In both years, about 50% of the soil of the entire studied field—45 ha—had ECe < 8 dS m−1, i.e., allowing barley cultivation, while the percent of surface having ECe ≥ 16 dS m−1 increased from 8.4% in 2009 to 13.7% in 2011. Our methodology may help monitor the soil salinity oscillations associated with irrigation management. After quantifying and mapping the soil salinity in 2009 and 2011, we show that barley was stunted in places of the field where salinity was higher. Additionally, the areas of salinity persisted after the subsequent alfalfa cropping in 2013. Application of differential doses of water to the saline patches is a viable method to optimize irrigation water distribution and lessen soil salinity in sprinkler-irrigated agriculture.

  6. Development of a method for estimating total CH{sub 4} emission from rice paddies in Japan using the DNDC-Rice model

    Energy Technology Data Exchange (ETDEWEB)

    Katayanagi, Nobuko [National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan); Fumoto, Tamon, E-mail: tamon@affrc.go.jp [National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan); Hayano, Michiko [National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan); Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Anno 1742-1, Nishinoomote, Kagoshima 891-3102 (Japan); Takata, Yusuke; Kuwagata, Tsuneo; Shirato, Yasuhito [National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan); Sawano, Shinji [Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki 305-8687 (Japan); Kajiura, Masako; Sudo, Shigeto; Ishigooka, Yasushi; Yagi, Kazuyuki [National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)

    2016-03-15

    Methane (CH{sub 4}) is a greenhouse gas, and paddy fields are one of its main anthropogenic emission sources. To mitigate this emission based on effective management measures, CH{sub 4} emission from paddy fields must be quantified at a national scale. In Japan, country-specific emission factors have been applied since 2003 to estimate national CH{sub 4} emission from paddy fields. However, this method cannot account for the effects of weather conditions and temporal variability of nitrogen fertilizer and organic matter application rates; thus, the estimated emission is highly uncertain. To improve the accuracy of national-scale estimates, we calculated country-specific emission factors using the DeNitrification–DeComposition-Rice (DNDC-Rice) model. First, we calculated CH{sub 4} emission from 1981 to 2010 using 986 datasets that included soil properties, meteorological data, and field management data. Using the simulated site-specific emission, we calculated annual mean emission for each of Japan's seven administrative regions, two water management regimes (continuous flooding and conventional mid-season drainage), and three soil drainage rates (slow, moderate, and fast). The mean emission was positively correlated with organic carbon input to the field, and we developed linear regressions for the relationships among the regions, water management regimes, and drainage rates. The regression results were within the range of published observation values for site-specific relationships between CH{sub 4} emission and organic carbon input rates. This suggests that the regressions provide a simplified method for estimating CH{sub 4} emission from Japanese paddy fields, though some modifications can further improve the estimation accuracy. - Highlights: • DNDC-Rice is a process-based model to simulate rice CH{sub 4} emission from rice paddies. • We simulated annual CH{sub 4} emissions from 986 paddy fields in Japan by DNDC-Rice. • Regional means of CH{sub 4

  7. Effects of light and soil flooding on the growth and photosynthesis of ramin (Gonystylus bancanus) seedlings in Malaysia

    NARCIS (Netherlands)

    Jans, W.W.P.; Dibor, L.; Verwer, C.C.; Kruijt, B.; Tan, S.; Meer, van der P.J.

    2012-01-01

    We studied the ecophysiology of ramin (Gonystylus bancanus) seedlings in an experimental set up at the Forest Research Centre in Kuching, Sarawak, Malaysia. Ramin seedlings were grown on flooded and drained peat soil under 100, 76, 46 and 23% sunlight, thus simulating effects of different light

  8. Fate of fertilizer nitrogen in flooded rice soil - I. Leaching losses of nitrogen

    International Nuclear Information System (INIS)

    Daftardar, S.Y.; Deb, D.L.; Datta, N.P.

    1979-01-01

    A greenhouse experiment on rice (Oryza sativa L. cv IR 22) was conducted under flooded conditions using CO( 15 NH 2 ) 2 , 15 NH 4 NO 3 and NH 4 ( 15 NO 3 ) to study the leaching loss of added fertilizer nitrogen in two typical rice soils. The loss of nitrogen was in the order: NO 3 -N (4 to 25.6 percent) > amide-N (1.2 to 16.2 percent) > NH 4 -N (0.07 to 0.3 percent). The basal applied urea was lost by percolation in the first month while the basal applied NO 3 -N was lost in the first 8 days. Leaching loss did not occur after split application of fertilizer nitrogen at primordial initiation stage. The loss of nitrogen in kaolinitic Dapoli clay loam soil was about 2.5 to 4.5 times more than that in montmorillonitic Karjat sandy loam soil. Cropping reduced the percolation loss of N by 40 to 60 percent. (auth.)

  9. Dissipation and residues of emamectin benzoate study in paddy under field conditions.

    Science.gov (United States)

    Li, Minghui; Chen, Weitao; Li, Mengyi; Han, Lijun

    2011-12-01

    The objective of this experiment was not only to provide a simple residue analytical method to evaluate the safe application rate of Emamectin Benzoate for paddy crops but also to give a suitable recommended dosage in paddy crops. Paddy samples were detected using HPLC-MS/MS. The half-lives of emamectin benzoate in paddy plants, water and soil were 2.04-8.66 days, 2.89-4.95 days and 3.65-5.78 days with a dissipation rate of 90% over 7 days after application, respectively. Low residues and short half-life suggested that Emamectin Benzoate could be safely used in paddy crops with the suitable dosage and application.

  10. A Preliminary Study of the Application of Electromagnetic Conductivity Meter on Soil Properties of Paddy Cultivation Areas at Wue Village, Jantho, Aceh Besar District, Indonesia

    OpenAIRE

    Marwan,

    2015-01-01

    Conventional soil sampling is time consuming and requires meticulous laboratory analysis. Hence, mapping of soil apparent in respect to electrical conductivity (ECa) has been developed to identify areas of contrasting soil properties. Such ECa values are represent measures of soil properties. The sensor system, GF Instrument model CMD-4 were used to analyze soil physical properties. This system consists of three important parts, ECa sensor, data logger and Global Positioning System (DGPS) rec...

  11. Redox-controlled release dynamics of thallium in periodically flooded arable soil.

    Science.gov (United States)

    Antić-Mladenović, Svetlana; Frohne, Tina; Kresović, Mirjana; Stärk, Hans-Joachim; Savić, Dubravka; Ličina, Vlado; Rinklebe, Jörg

    2017-07-01

    To our knowledge, this is the first work to mechanistically study the impact of the redox potential (E H ) and principal factors, such as pH, iron (Fe), manganese (Mn), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), chlorides (Cl - ) and sulfates (SO 4 2- ), on the release dynamics of thallium (Tl) in periodically flooded soil. We simulated flooding using an automated biogeochemical microcosm system that allows for systematical control of pre-defined redox windows. The E H value was increased mechanistically at intervals of approximately 100 mV from reducing (-211 mV) to oxidizing (475 mV) conditions. Soluble Tl levels (0.02-0.28 μg L -1 ) increased significantly with increases in E H (r = 0.80, p Thallium mobilization was found to be related to several simultaneous processes involving the gradual oxidation of Tl-bearing sulfides, reductive dissolution of Fe-Mn oxides and desorption from mineral sorbents. Manganese oxides did not appear to have a considerable effect on Tl retention under oxidizing conditions. Before conducting the microcosm experiment, Tl geochemical fractionation was assessed using the modified BCR sequential extraction procedure. The BCR revealed a majority of Tl in the residual fraction (77.7%), followed by reducible (13.3%) and oxidizable fractions (5.9%). By generating high levels of Tl toxicity at low doses, Tl released under oxidizing conditions may pose an environmental threat. In the future, similar studies should be conducted on various soils along with a determination of the Tl species and monitoring of the Tl content in plants to achieve more detailed insight into soluble Tl behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Microbial-driven arsenic cycling in rice paddies amended with monosodium methanearsonate

    Science.gov (United States)

    Maguffin, S. C.; McClung, A.; Rohila, J. S.; Derry, L. A.; Huang, R.; Reid, M. C.

    2017-12-01

    Rice consumption is the second largest contributor to human arsenic exposure worldwide and is linked to many serious diseases. Because rice is uniquely adapted for agricultural production under flooded soils, arsenic species solubilized in such environments can be effectively transported into plant tissue via root transporters. Through this process, both inorganic and organic (methylated) arsenic species can accumulate to problematic concentrations and may affect grain yield as well as crop value. The distribution of these species in plant tissue is determined by arsenic sources, as well as enzymatic redox and methylation-demethylation reactions in soils and pore water. Historic use of organoarsenic-based pesticides in US agriculture may provide an enduring source of arsenic in rice paddies. However, it is unclear how persistent these organic species are in the adsorbed phase or how available they remain to rice cultivars throughout the growing season. We conducted a field experiment in a 2x2 factorial design examining the effects of irrigation methods (continuous flooding and alternate wetting and drying) and monosodium methanearsonate (MSMA) application on the abundance and speciation of arsenic in pore water, soil, and rice plant tissues. We monitored arsenic speciation and partitioning between these reservoirs at semi-weekly to semi-monthly frequencies. Pore water arsenic speciation was determined using LC-ICP-MS, and X-ray absorption near-edge structure (XANES) analysis was employed to speciate the arsenic within solid-phase soil and plant tissue throughout the growing season. These data help clarify the role of two irrigation methods and MSMA amendments for arsenic bioavailability and speciation in rice. Furthermore, the study illuminates the significance of microbial metabolism in the reapportionment of arsenic within the soil-plant-water system and its impact on arsenic levels in rice grains.

  13. Effects of flooding on the spatial distribution of soil seed and spore banks of native grasslands of the Pantanal wetland

    Directory of Open Access Journals (Sweden)

    Patricia Carla de Oliveira

    2015-09-01

    Full Text Available ABSTRACTTo better understand the role that flooding plays in shaping plant communities of native floodable grasslands of the Pantanal and to characterize the spatial distribution of plants, we present the results of a survey of soil seed and spore banks using the seedling emergence method. We hypothesized that terrain subjected to the deepest and longest flooding should have higher propagule abundance and richness. The species composition and distribution of seeds and spores in the soil were assessed at five sites using three sampling positions at each according to inundation intensity. In each sample position 2cm-thick soil samples were collected in quadrats to a depth of 10cm. Litter was also collected as an independent layer. Sample monitoring in the greenhouse resulted in the emergence of 5489 seedlings, or 6353 propagules.m-2. Both the litter layer and the deepest soil layer had low abundances. A total of forty-four morphospecies (16 families were recorded. Both seedling abundance and species richness were concentrated in the more floodable center sections. Isoetes pedersenii, Eleocharis minima, Sagittaria guayanensis, Rotala mexicana, Eleocharis plicarhachis, and Panicum laxum were the most abundant species. The species composition and spatial distribution of the propagule bank suggests that flooding plays a crucial role in seasonal vegetation dynamics in Pantanal wetlands, mediated by the ability of the soil to host seeds and spores during dry season.

  14. Improving Flood Prediction By the Assimilation of Satellite Soil Moisture in Poorly Monitored Catchments.

    Science.gov (United States)

    Alvarez-Garreton, C. D.; Ryu, D.; Western, A. W.; Crow, W. T.; Su, C. H.; Robertson, D. E.

    2014-12-01

    Flood prediction in poorly monitored catchments is among the greatest challenges faced by hydrologists. To address this challenge, an increasing number of studies in the last decade have explored methods to integrate various existing observations from ground and satellites. One approach in particular, is the assimilation of satellite soil moisture (SM-DA) into rainfall-runoff models. The rationale is that satellite soil moisture (SSM) can be used to correct model soil water states, enabling more accurate prediction of catchment response to precipitation and thus better streamflow. However, there is still no consensus on the most effective SM-DA scheme and how this might depend on catchment scale, climate characteristics, runoff mechanisms, model and SSM products used, etc. In this work, an operational SM-DA scheme was set up in the poorly monitored, large (>40,000 km2), semi-arid Warrego catchment situated in eastern Australia. We assimilated passive and active SSM products into the probability distributed model (PDM) using an ensemble Kalman filter. We explored factors influencing the SM-DA framework, including relatively new techniques to remove model-observation bias, estimate observation errors and represent model errors. Furthermore, we explored the advantages of accounting for the spatial distribution of forcing and channel routing processes within the catchment by implementing and comparing lumped and semi-distributed model setups. Flood prediction is improved by SM-DA (Figure), with a 30% reduction of the average root-mean-squared difference of the ensemble prediction, a 20% reduction of the false alarm ratio and a 40% increase of the ensemble mean Nash-Sutcliffe efficiency. SM-DA skill does not significantly change with different observation error assumptions, but the skill strongly depends on the observational bias correction technique used, and more importantly, on the performance of the open-loop model before assimilation. Our findings imply that proper

  15. The influence of pH and organic matter content in paddy soil on heavy metal availability and their uptake by rice plants

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Fanrong; Ali Shafaqat; Zhang Haitao [Department of Agronomy, College of Agriculture and Biotechnology, Huajiachi Campus, Zhejiang University, Hangzhou 310029 (China); Ouyang Younan [China National Rice Research Institute, Fuyang 310041 (China); Qiu Boyin; Wu Feibo [Department of Agronomy, College of Agriculture and Biotechnology, Huajiachi Campus, Zhejiang University, Hangzhou 310029 (China); Zhang Guoping, E-mail: zhanggp@zju.edu.c [China National Rice Research Institute, Fuyang 310041 (China)

    2011-01-15

    The experiments were done to investigate the effect of soil pH and organic matter content on EDTA-extractable heavy metal contents in soils and heavy metal concentrations in rice straw and grains. EDTA-extractable Cr contents in soils and concentrations in rice tissues were negatively correlated with soil pH, but positively correlated with organic matter content. The combination of soil pH and organic matter content would produce the more precise regression models for estimation of EDTA-Cu, Pb and Zn contents in soils, demonstrating the distinct effect of the two factors on the availability of these heavy metals in soils. Soil pH greatly affected heavy metal concentrations in rice plants. Furthermore, inclusion of other soil properties in the stepwise regression analysis improved the regression models for predicting straw Fe and grain Zn concentrations, indicating that other soil properties should be taken into consideration for precise predicting of heavy metal concentrations in rice plants. - Soil pH and organic matter content significantly affect heavy metal availability and accumulation in rice plants.

  16. Clay stabilization by using gypsum and paddy husk ash with reference to UCT and CBR value

    Science.gov (United States)

    Roesyanto; Iskandar, R.; Hastuty, I. P.; Dianty, W. O.

    2018-02-01

    Clays that have low shear strength need to be stabilized in order to meet the technical requirements to serve as a subgrade material. One of the usual soil stabilization methods is by adding chemicals such as Portland cement, lime, and bitumen. The clay stabilization research was done by adding gypsum and paddy husk ash. The research goals were to find out the value of engineering properties of clay due to the addition of 2% gypsum and 2% - 15% paddy husk ash. The soil was classified as Clay - Low Plasticity (CL) based on USCS and was classified as A-7-6 (10) based on AASHTO classification system. The UCT value of original soil was 1.41 kg/cm2. While the CBR soaked and unsoaked values of original soil were 4.41% and 6.23% respectively. The research results showed the addition of paddy husk ash decreased the value of unconfined compressive strength as well as CBR. The stabilized soil by 2% gypsum and 0% paddy husk ash gave maximum UCT value of 1.67 kg/cm2, while the maximum value of CBR were found 6.71% for CBR soaked and 8.00% for CBR unsoaked. The addition of paddy husk ash did not alter the soil classification according to AASHTO or USCS, even degrade the engineering properties of original soil.

  17. Mapping paddy rice planting areas through time series analysis of MODIS land surface temperature and vegetation index data.

    Science.gov (United States)

    Zhang, Geli; Xiao, Xiangming; Dong, Jinwei; Kou, Weili; Jin, Cui; Qin, Yuanwei; Zhou, Yuting; Wang, Jie; Menarguez, Michael Angelo; Biradar, Chandrashekhar

    2015-08-01

    Knowledge of the area and spatial distribution of paddy rice is important for assessment of food security, management of water resources, and estimation of greenhouse gas (methane) emissions. Paddy rice agriculture has expanded rapidly in northeastern China in the last decade, but there are no updated maps of paddy rice fields in the region. Existing algorithms for identifying paddy rice fields are based on the unique physical features of paddy rice during the flooding and transplanting phases and use vegetation indices that are sensitive to the dynamics of the canopy and surface water content. However, the flooding phenomena in high latitude area could also be from spring snowmelt flooding. We used land surface temperature (LST) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor to determine the temporal window of flooding and rice transplantation over a year to improve the existing phenology-based approach. Other land cover types (e.g., evergreen vegetation, permanent water bodies, and sparse vegetation) with potential influences on paddy rice identification were removed (masked out) due to their different temporal profiles. The accuracy assessment using high-resolution images showed that the resultant MODIS-derived paddy rice map of northeastern China in 2010 had a high accuracy (producer and user accuracies of 92% and 96%, respectively). The MODIS-based map also had a comparable accuracy to the 2010 Landsat-based National Land Cover Dataset (NLCD) of China in terms of both area and spatial pattern. This study demonstrated that our improved algorithm by using both thermal and optical MODIS data, provides a robust, simple and automated approach to identify and map paddy rice fields in temperate and cold temperate zones, the northern frontier of rice planting.

  18. The effects of soil flooding on the establishment of cogongrass (Imperata cylindrica), a nonindigenous invader of the southeastern United States

    Science.gov (United States)

    King, S.E.; Grace, J.B.

    2000-01-01

    Cogongrass (Imperata cylindrica), an invasive perennial introduced from Southeast Asia, is currently spreading throughout the southeastern United States from Florida to Louisiana. In the U.S., cogongrass is generally not considered a wetland species, although it's range is expanding in regions with high wetland abundance. The objective of this study was to determine if excessive soil moisture might prevent cogongrass from establishing in areas with seasonally flooded soils. In one greenhouse experiment, we examined cogongrass germination and seedling growth in soils that were freely drained, saturated, and inundated. We performed a second greenhouse experiment to evaluate growth and survival of cogongrass seedlings of four different size classes in five soil moisture treatments ranging from dry to inundated. Cogongrass germination was lowest when seeds were overtopped with water. There were no differences in germination between saturated and freely drained treatments; however, seedlings grew largest in freely drained soil and were smallest when immersed. In our second experiment, most cogongrass plants survived except when given no water, but growth differed by watering treatment depending on seedling size. Increasing moisture was more detrimental to the growth of small seedlings compared to the growth of larger cogongrass plants. Overall, cogongrass was most sensitive to soil inundation in the earliest stages of establishment; thus, excessive moisture conditions in the spring, during early seedling development, could restrict invasion of cogongrass by seed. Once cogongrass is established, however, its tolerance of flooding appears to increase.

  19. Towards Global Simulation of Irrigation in a Land Surface Model: Multiple Cropping and Rice Paddy in Southeast Asia

    Science.gov (United States)

    Beaudoing, Hiroko Kato; Rodell, Matthew; Ozdogan, Mutlu

    2010-01-01

    Agricultural land use significantly influences the surface water and energy balances. Effects of irrigation on land surface states and fluxes include repartitioning of latent and sensible heat fluxes, an increase in net radiation, and an increase in soil moisture and runoff. We are working on representing irrigation practices in continental- to global-scale land surface simulation in NASA's Global Land Data Assimilation System (GLDAS). Because agricultural practices across the nations are diverse, and complex, we are attempting to capture the first-order reality of the regional practices before achieving a global implementation. This study focuses on two issues in Southeast Asia: multiple cropping and rice paddy irrigation systems. We first characterize agricultural practices in the region (i.e., crop types, growing seasons, and irrigation) using the Global data set of monthly irrigated and rainfed crop areas around the year 2000 (MIRCA2000) dataset. Rice paddy extent is identified using remote sensing products. Whether irrigated or rainfed, flooded fields need to be represented and treated explicitly. By incorporating these properties and processes into a physically based land surface model, we are able to quantify the impacts on the simulated states and fluxes.

  20. Promotion of biochar on adsorption of cadmium and retardation on water transport in paddy soil%生物碳促进水稻土镉吸附并阻滞水分运移

    Institute of Scientific and Technical Information of China (English)

    逄雅萍; 黄爽; 杨金忠; 彭紫赟; 王亚卿; 赵迪

    2013-01-01

      该文以研究生物碳施加对中国南方酸性水稻土中镉的吸附能力和水分运移能力的影响为研究目的。以中国南方稻田耕层(0~20 cm)和下层(>60~80 cm)的土壤为研究对象,采用批量平衡法研究不同的生物碳添加量及其粒径对土壤中重金属镉吸附的影响;采用柱法研究生物碳对土壤水分运移能力的影响。结果表明,生物碳添加可提高土壤pH值,对于耕层土壤,细碳(粒径为60-80 cm) from a paddy field in Changzhou Rice Research Institute, Jiangsu Province were tested. Biochar treatments were fine biochar (particle size range:0.048-0.56 mm) and coarse biochar (particle size range: 0.3-0.7 mm). The soil pH was measured at a 1:1 soil/water ratio. The pH of the soil increased with an increasing amount of the applied biochar. The pH of topsoil and subsoil increased by 1.5 and 0.84, respectively, for the 9%fine biochar treatments. But the increment of soil pH decreased with an increasing amount of applied biochar, and fine biochar was more effective to increase the soil pH. The Cd adsorption isotherms of soil with different biochar treatments were tested at a 1:10 soil/solution ratio. Cadmium solutions (1, 2, 5, 10, 20 and 50 mg/L) were prepared by dissolving Cd(NO3)2·4H2O, in the background electrolyte of 0.005 M CaCl2. All solutions were adjusted to pH 6.0 with dilute HNO3. Biochar treatments of topsoil were 0, 3, 6, 9%for fine biochar, and 0, 3%for coarse biochar;biochar treatments of subsoil were 0, 3%of both for fine and coarse biochar. The suspensions were shaken for 48 hours, centrifuged. Then the Cd2+ concentration of the supernatant was determined, which were used to calculate the sorption distribution coefficient (K). Models of Freundlich, Henry, Langmuir and Temkin were used to fit the adsorption isotherms. The Freundlich and Langmuir models provided good fitting results to the isothermal adsorption process of Cd2+for topsoil and subsoil

  1. Novel groups and unique distribution of phage phoH genes in paddy waters in northeast China

    Science.gov (United States)

    Wang, Xinzhen; Liu, Junjie; Yu, Zhenhua; Jin, Jian; Liu, Xiaobing; Wang, Guanghua

    2016-01-01

    Although bacteriophages are ubiquitous in various environments, their genetic diversity is primarily investigated in pelagic marine environments. Corresponding studies in terrestrial environments are few. In this study, we conducted the first survey of phage diversity in the paddy ecosystem by targeting a new viral biomarker gene, phoH. A total of 424 phoH sequences were obtained from four paddy waters generated from a pot experiment with different soils collected from open paddy fields in northeast China. The majority of phoH sequences in paddy waters were novel, with the highest identity of ≤70% with known phoH sequences. Four unique groups (Group α, Group β, Group γ and Group δ) and seven new subgroups (Group 2b, Group 3d, Group 3e, Group 6a, Group 6b, Group 6c and Group 6d) were formed exclusively with the clones from the paddy waters, suggesting novel phage phoH groups exist in the paddy ecosystem. Additionally, the distribution proportions of phoH clones in different groups varied among paddy water samples, suggesting the phage community in paddy fields is biogeographically distributed. Furthermore, non-metric multidimensional scaling analysis indicated that phage phoH assemblages in paddy waters were distinct from those in marine waters. PMID:27910929

  2. Impact of tree planting configuration on canopy interception and soil hydrological properties: Implications for flood mitigation in silvopastoral systems

    Science.gov (United States)

    Lunka, Peter; Patil, Sopan

    2015-04-01

    Compaction of upper soil layers by intensive sheep grazing has been connected with increased local flood risk in silvopastoral systems. A 12 week field study was conducted at the Henfaes Research Station near Bangor, Wales to compare two silvopastoral configurations, trees planted in fenced off clumps and trees planted evenly spaced, in terms of canopy throughfall, soil water infiltration and soil bulk density. The study's aim was to characterize the potential of these tree planting configurations to reduce local flood risk. The study site (Henfaes) was established in 1992 on 14 ha of agricultural land and is part of the Silvopastoral National Network Experiment sites that have been set up across the UK to examine the potential of silvopasture and agroforestry on UK farms. Automated throughfall gauges were installed in each silvopastoral treatment along with a similarly designed control gauge located in the grazed control pasture. Soil water infiltration and bulk density were measured 20 times in a stratified random design for each treatment and the control. Soil infiltration capacity in the clumped configuration was significantly higher than in the even spaced configuration and control pasture. The clumped configuration had mean infiltration capacity 504% greater than the control pasture and 454% greater than the even spaced configuration. Canopy interception was higher in the clumped trees than in the evenly spaced trees. Average canopy interception was 34% in the clumped treatment and 28% in the evenly spaced treatment. Soil bulk density was lower in the clumped configuration than in the control pasture and evenly spaced configuration. Results suggest that in silvopastoral systems the clumped tree configuration is more likely to reduce local flood risk than the evenly spaced tree configuration due to enhanced infiltration and increased canopy interception.

  3. Sistemas de manejo e a matéria orgânica de solo de várzea com cultivo de arroz Soil management effect on organic matter in a flooded soil under rice in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Paulo César do Nascimento

    2009-12-01

    experiment at IRGA (Instituto Rio Grandense do Arroz experimental station in Cachoeirinha, Rio Grande do Sul, southern Brazil. The main objectives of this study were to evaluate the effect of no-tillage (NT on organic C stocks, on OM lability and on the physical protection of OM in soil aggregates of a Gleysol (200 g kg-1 clay cultivated with paddy rice (Oryza sativa L in comparison to conventional tillage (CT. Organic C (0-20 cm was not affected by soil management systems (38.39 Mg ha-1 in CT soil and 37.36 Mg ha-1 in NT soil indicating that decomposition rates of OM in this anaerobic environment were not influenced by soil disturbance. The lability of OM in this flooded soil, calculated by the ratio of particulate organic C (POC/mineral-associated organic C was higher than the values usually verified for well-drained soils of subtropical regions and, in the 0-20 cm soil layer, C was not affected by soil management systems (0.24 in CT and 0.28 in NT. The increase of the occluded light OM fraction (intra-aggregate light fraction was only a small proportion (9% in relation to the total organic carbon increase in NT, compared to CT, in the surface layer (0-5 cm. These data suggest that the physical protection of OM in soil aggregates was not an important mechanism of OM stabilization in this environment of restrained drainage. The reason is probably the weak soil aggregation and/or the easy access of microorganisms and their enzymes to the decomposition of the intra-aggregate OM pool due to the soil saturation by water.

  4. The role of the antecedent soil moisture condition on the distributed hydrologic modelling of the Toce alpine basin floods.

    Science.gov (United States)

    Ravazzani, G.; Montaldo, N.; Mancini, M.; Rosso, R.

    2003-04-01

    Event-based hydrologic models need the antecedent soil moisture condition, as critical boundary initial condition for flood simulation. Land-surface models (LSMs) have been developed to simulate mass and energy transfers, and to update the soil moisture condition through time from the solution of water and energy balance equations. They are recently used in distributed hydrologic modeling for flood prediction systems. Recent developments have made LSMs more complex by inclusion of more processes and controlling variables, increasing parameter number and uncertainty of their estimates. This also led to increasing of computational burden and parameterization of the distributed hydrologic models. In this study we investigate: 1) the role of soil moisture initial conditions in the modeling of Alpine basin floods; 2) the adequate complexity level of LSMs for the distributed hydrologic modeling of Alpine basin floods. The Toce basin is the case study; it is located in the North Piedmont (Italian Alps), and it has a total drainage area of 1534 km2 at Candoglia section. Three distributed hydrologic models of different level of complexity are developed and compared: two (TDLSM and SDLSM) are continuous models, one (FEST02) is an event model based on the simplified SCS-CN method for rainfall abstractions. In the TDLSM model a two-layer LSM computes both saturation and infiltration excess runoff, and simulates the evolution of the water table spatial distribution using the topographic index; in the SDLSM model a simplified one-layer distributed LSM only computes hortonian runoff, and doesn’t simulate the water table dynamic. All the three hydrologic models simulate the surface runoff propagation through the Muskingum-Cunge method. TDLSM and SDLSM models have been applied for the two-year (1996 and 1997) simulation period, during which two major floods occurred in the November 1996 and in the June 1997. The models have been calibrated and tested comparing simulated and

  5. Soil biochemical properties and microbial resilience in agroforestry systems: effects on wheat growth under controlled drought and flooding conditions.

    Science.gov (United States)

    Rivest, David; Lorente, Miren; Olivier, Alain; Messier, Christian

    2013-10-01

    Agroforestry is increasingly viewed as an effective means of maintaining or even increasing crop and tree productivity under climate change while promoting other ecosystem functions and services. This study focused on soil biochemical properties and resilience following disturbance within agroforestry and conventional agricultural systems and aimed to determine whether soil differences in terms of these biochemical properties and resilience would subsequently affect crop productivity under extreme soil water conditions. Two research sites that had been established on agricultural land were selected for this study. The first site included an 18-year-old windbreak, while the second site consisted in an 8-year-old tree-based intercropping system. In each site, soil samples were used for the determination of soil nutrient availability, microbial dynamics and microbial resilience to different wetting-drying perturbations and for a greenhouse pot experiment with wheat. Drying and flooding were selected as water stress treatments and compared to a control. These treatments were initiated at the beginning of the wheat anthesis period and maintained over 10 days. Trees contributed to increase soil nutrient pools, as evidenced by the higher extractable-P (both sites), and the higher total N and mineralizable N (tree-based intercropping site) found in the agroforestry compared to the conventional agricultural system. Metabolic quotient (qCO2) was lower in the agroforestry than in the conventional agricultural system, suggesting higher microbial substrate use efficiency in agroforestry systems. Microbial resilience was higher in the agroforestry soils compared to soils from the conventional agricultural system (windbreak site only). At the windbreak site, wheat growing in soils from agroforestry system exhibited higher aboveground biomass and number of grains per spike than in conventional agricultural system soils in the three water stress treatments. At the tree

  6. Modeling the hydrophysical soil properties as a part of self-regulated flood dams projection in gis-environment for sustainable urban development

    Science.gov (United States)

    Nikonorov, Aleksandr; Terleev, Vitaly; Badenko, Vladimir; Mirschel, Wilfried; Abakumov, Evgeny; Ginevsky, Roman; Lazarev, Viktor; Togo, Issa; Volkova, Yulia; Melnichuk, Aleksandr; Dunaieva, Ielizaveta; Akimov, Luka

    2017-10-01

    The problem of flood protection measures are considered in the paper. The regulation of river flow by the system of Self-Regulated Flood Dams (SRFD) is analyzed. The method of SRFD modeling in GIS environment is proposed. The question of the ecological aspect of the SRFD management is considered based on the hydrophysical properties of the soil. The improved Mualem-Van Genuchted method is proposed for the evaluation of the possible SRFD location influence on the soil of flooded territory - the temporary reservoirs. The importance and utility of the proposed complex method is stated.

  7. Variations in eco-enzymatic stoichiometric and microbial characteristics in paddy soil as affected by long-term integrated organic-inorganic fertilization

    Science.gov (United States)

    Lin, Sen; Wang, Shaoxian; Si, Yuanli; Yang, Wenhao; Zhu, Shaowei

    2017-01-01

    To investigate the effects of different nutrient management regimes on the soil chemical, eco-enzymatic stoichiometric and microbial characteristics, soil samples were collected from a 30-year, long-term field experiment with six plots growing rice. The results showed that as integrated fertilization increased, so did the concentrations of soil total or available nutrients and microbial biomass carbon (MBC). Our results also found enhanced soil basal respiration and cumulative carbon mineralization compared to chemical fertilization alone at the same nutrient doses. The activities of soil protease (Pro), β-glucosidase (βG), N-acetyl-glucosaminidase (NAG) and acid phosphatase (AP) from the integrated fertilization treatments were significantly higher than those of the treatments without organic manure, so did the activities of soil leucyl aminopeptidase (LAP) and urease (Ure) from the treatment with organic manure in addition to farmer practise fertilization (NPKM2). The stoichiometric ratios, expressed as lnβG/ln(NAG+LAP)/lnPro/lnUre/lnAP, ranged from 1:0.94:1.04:0.67:1.01 to 1:0.98:1.10:0.78:1.25, indicating that the acquisition of C, N and P changed consistently and synchronously under different nutrient management strategies. Integrated fertilization was more beneficial to the acquisition and utilization of soil organic carbon compared to low-molecular-weight organic nitrogen. We concluded that protease and urease should be considered in eco-enzymatic stoichiometric assessments for the hydrolysis of proteins, amino acids, carbohydrates and phosphomonoesters in soil, and integrated fertilization with chemical fertilizers and organic manure should be recommended as a preferable nutrient management system for intensive rice cultivation. PMID:29253000

  8. Estimation of methane and nitrous oxide emissions from paddy fields in Taiwan

    International Nuclear Information System (INIS)

    Yang, Shang-Shyng; Lai, Chao-Ming; Chang, Hsiu-Lan; Chang, Ed-Huan; Wei, Chia-Bei

    2009-01-01

    To investigate the greenhouse gases emissions from paddy fields, methane and nitrous oxide emissions were estimated with the local measurement and the IPCC method during 1990-2006 in Taiwan. Annual methane emission ranged from 9001 to 14,980 ton in the first crop season for 135,314-242,298 ha of paddy fields, and it was between 16,412 and 35,208 ton for 101,710-211,968 ha in the second crop season with the local measurement for intermittent irrigation. The value ranged from 31,122 to 55,729 ton of methane emission in the first crop season, and it was between 29,493 and 61,471 ton in the second crop season with the IPCC guideline for continuous flooding. Annual nitrous oxide emission from paddy fields was between 371 and 728 ton in the first crop season, and the value ranged from 163 to 365 ton in the second crop season with the local measurement. Methane emission from paddy fields in Taiwan for intermittent irrigation was only 26.72-28.92%, 55.65-57.32% and 41.19-43.10% with the IPCC guidelines for continuous flooding and mean temperature of transplanting stage in the first crop, the second crop and total paddy fields, respectively. The values were 53.44-57.84%, 111.29-114.55% and 82.38-86.20% with the IPCC guidelines for single aeration and mean temperature of transplanting stage, respectively; and the values were 133.60-144.61%, 282.56-286.62% and 205.96-215.49% with the IPCC guidelines for multiple aeration and mean temperature of transplanting stage, respectively. Intermittent irrigation in paddy fields reduces methane emission significantly; appropriate application of nitrogen fertilizer and irrigation in paddy fields also decreases nitrous oxide emission. (author)

  9. Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils.

    Science.gov (United States)

    Guimarães, J R; Meili, M; Hylander, L D; de Castro e Silva, E; Roulet, M; Mauro, J B; de Lemos, R

    2000-10-16

    In aquatic systems, bottom sediments have often been considered as the main methylmercury (MeHg) production site. In tropical floodplain areas, however, floating meadows and flooded forests extend over large areas and can be important Hg methylating sites. We present here a cross-system comparison of the Hg net methylation capacity in surface sediments, flooded soils and roots of floating aquatic macrophytes, assayed by in situ incubation with 203Hg and extraction of formed Me203 Hg by acid leaching and toluene. The presence of mono-MeHg was confirmed by thin layer chromatography and other techniques. Study areas included floodplain lakes in the Amazon basin (Tapajós, Negro and Amazon rivers), the Pantanal floodplain (Paraguay river basin), freshwater coastal lagoons in Rio de Janeiro and oxbow lakes in the Mogi-Guaçú river, São Paulo state. Different Hg levels were added in assays performed in 1994-1998, but great care was taken to standardise all other test parameters, to allow data comparisons. Net MeHg production was one order of magnitude higher (mean 13.8%, range 0.28-35) in the living or decomposing roots of floating or rooted macrophyte mats (Eichhornia azurea, E. crassipes, Paspalum sp., Eleocharis sellowiana, Salvinia sp., S. rotundifolia and Scirpus cubensis) than in the surface layer of underlying lake sediments (mean 0.6%, range 0.022-2.5). Methylation in flooded soils presented a wide range and was in some cases similar to the one found in macrophyte roots but usually much lower. In a Tapajós floodplain lake, natural concentrations of MeHg in soil and sediment cores taken along a lake-forest transect agreed well with data on net methylation potentials in the same samples. E. azurea, E. crassipes and Salvinia presented the highest methylation potentials, up to 113 times higher than in sediments. Methylation in E. azurea from six lakes of the Paraguay and Cuiabá rivers, high Pantanal, was determined in the 1998 dry and wet seasons and ranged from

  10. In situ stabilization of heavy metals in multiple-metal contaminated paddy soil using different steel slag-based silicon fertilizer.

    Science.gov (United States)

    Ning, Dongfeng; Liang, Yongchao; Song, Alin; Duan, Aiwang; Liu, Zhandong

    2016-12-01

    Steel slag has been widely used as amendment and silicon fertilizer to alleviate the mobility and bioavailability of heavy metals in soil. The objective of this study was to evaluate the influence of particle size, composition, and application rate of slag on metal immobilization in acidic soil, metals uptake by rice and rice growth. The results indicated that application of slag increased soil pH, plant-available silicon concentrations in soil, and decreased the bioavailability of metals compared with control treatment, whereas pulverous slag (S1) was more effective than granular slag (S2 and S3). The acid-extractable fraction of Cd in the spiked soil was significantly decreased with application of S1 at rates of 1 and 3 %, acid-extractable fractions of Cu and Zn were decreased when treated at 3 %. Use of S1 at both rates resulted in significantly lower Cd, Cu, and Zn concentrations in rice tissues than in controls by 82.6-92.9, 88.4-95.6, and 67.4-81.4 %, respectively. However, use of pulverous slag at 1 % significantly promotes rice growth, restricted rice growth when treated at 3 %. Thus, the results explained that reduced particle size and suitable application rate of slag could be beneficial to rice growth and metals stabilization.

  11. Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice

    International Nuclear Information System (INIS)

    Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

    2015-01-01

    A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ( 137 Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the 137 Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. - Highlights: • Nonexchangeable K of added trioctahedral mica decreased 137 Cs uptake by paddy rice. • TPB-extractable K would be a more reliable indicator than exchangeable K. • Phlogopite would be a good amendment for radiocesium-contaminated paddy fields

  12. Spatial landuse planning using land evaluation and dynamic system to define sustainable area of paddy field: Case study in Karawang Regency, West Java, Indonesia

    Science.gov (United States)

    Widiatmaka, Widiatmaka; Ambarwulan, Wiwin; Firmansyah, Irman; Munibah, Khursatul; Santoso, Paulus B. K.

    2015-04-01

    Indonesia is the country with the 4th largest population in the worlds; the population reached more than 237 million people. With rice as the staple food for more than 95 percent of the population, there is an important role of paddy field in Indonesian food security. Actually, paddy field in Java has produced 52,6% of the total rice production in Indonesia, showing the very high dependence of Indonesia on food production from paddy fields in Java island. Karawang Regency is one of the regions in West Java Province that contribute to the national food supply, due to its high soil fertility and its high extent of paddy field. Dynamics of land use change in this region are high because of its proximity to urban area; this dynamics has led to paddy field conversion to industry and residential landuse, which in turn change the regional rice production capacity. Decreasing paddy field landuse in this region could be serve as an example case of the general phenomena which occurred in Javanese rice production region. The objective of this study were: (i) to identify the suitable area for paddy field, (ii) to modelize the decreasing of paddy field in socio-economic context of the region, and (iii) to plan the spatial priority area of paddy field protection according to model prediction. A land evaluation for paddy was completed after a soil survey, while IKONOS imagery was analyzed to delineate paddy fields. Dynamic system model of paddy field land use is built, and then based on the model built, the land area of paddy field untill 2040 in some scenarios was developped. The research results showed that the land suitability class for paddy fields in Karawang Regency ranged from very suitable (S1) to marginally suitable (S3), with various land characteristics as limiting factors. The model predicts that if the situation of paddy field land use change continues in its business as usual path, paddy field area that would exist in the region in 2040 will stay half of the recent

  13. Fipronil application on rice paddy fields reduces densities of common skimmer and scarlet skimmer

    Science.gov (United States)

    Kasai, Atsushi; Hayashi, Takehiko I.; Ohnishi, Hitoshi; Suzuki, Kazutaka; Hayasaka, Daisuke; Goka, Koichi

    2016-01-01

    Several reports suggested that rice seedling nursery-box application of some systemic insecticides (neonicotinoids and fipronil) is the cause of the decline in dragonfly species noted since the 1990s in Japan. We conducted paddy mesocosm experiments to investigate the effect of the systemic insecticides clothianidin, fipronil and chlorantraniliprole on rice paddy field biological communities. Concentrations of all insecticides in the paddy water were reduced to the limit of detection within 3 months after application. However, residuals of these insecticides in the paddy soil were detected throughout the experimental period. Plankton species were affected by clothianidin and chlorantraniliprole right after the applications, but they recovered after the concentrations decreased. On the other hand, the effects of fipronil treatment, especially on Odonata, were larger than those of any other treatment. The number of adult dragonflies completing eclosion was severely decreased in the fipronil treatment. These results suggest that the accumulation of these insecticides in paddy soil reduces biodiversity by eliminating dragonfly nymphs, which occupy a high trophic level in paddy fields. PMID:26979488

  14. Mercury bioaccumulation in fishes of a paddy field in Southern of Brazil

    Directory of Open Access Journals (Sweden)

    Vinicius Tavares Kütter

    2015-06-01

    Full Text Available Aim: The aim of present study was to evaluate the Hg concentration in two species of fish (Astyanax sp and Corydoras paleatus and its potential use as a biomonitor, in order to know if the use of pesticides and fertilizers in paddy can enhance the Hg contamination to adjacent aquatic environment.MethodsSoil, suspended particulate matter and fish samples were sampled in a paddy field in South Brazil. A cold vapor system, coupled with a GBC 932 atomic absorption spectrophotometer was used for total Hg determinations in samples.ResultsThe paddy soil shows Hg concentration 2-fold higher (mean 31 ng g-1 in comparison to background areas (not cultivated. Suspended particle matter Hg concentration in paddy channels (mean 232.5 ± 44.2 ng g–1 are 1.5 times higher than the regional background. The analyzed fish specimens Astyanax sp in paddy showed Hg concentration 4-fold higher and significant different to background area. The mean Hg concentration in fish was: 51.7 ± 19.5 ng g–1 in Astyanax sp and 156.8 ± 44.0 ng g–1 in Corydoras paleatus.ConclusionsConsidering the linear regression and Man whitney test hypothesis to Hg concentration in fish tissue from paddy suggests that Astyanax sp. can be a good biomonitor of Hg contamination, whereas Corydoras paleatus is a potential biomonitor. However, more studies with Corydoras are necessary in order to aggregate consistency to this hypothesis.

  15. Absorption of gamma-emitting fission products and activation products by rice under flooded and unflooded conditions from two tropical soils

    International Nuclear Information System (INIS)

    D'Souza, T.J.; Mistry, K.B.

    1980-01-01

    The absorption of gamma-emitting fission products 106 Ru, 125 Sb, 137 Cs and 144 Ce and activation products 59 Fe, 58 Co, 54 Mn and 65 Zn by rice plants grown on two contrasting tropical soils, namely, a blak soil (pellustert) and a laterite (oxisol), and the effects of flooding were studied under controlled conditions. Results indicated greater uptake of 106 Ru and 125 Sb from the black soil than from the laterite. In contrast, the uptake of 144 Ce and 137 Cs was greater in the laterite than in the black soil. Flooding treatment enhanced the uptake of all these fission products by rice plants in the laterite soil whereas this effect was observed only for 125 Sb and 137 Cs in the black soil. The plant uptake of activation products from the two soil types showed maximum accumulation of 65 Zn followed by 54 Mn, 59 Fe and 58 Co in both soil types. Besides, uptake of these nuclides was greater from the laterite soil than from the black soil. Flooding treatment for rice while showing a reduction of 59 Fe uptake showed an increase in plant uptake of 58 Co, 54 Mn and 65 Zn in both soil types. (orig.)

  16. Absorption of gamma-emitting fission products and activation products by rice under flooded and unflooded conditions from two tropical soils

    Energy Technology Data Exchange (ETDEWEB)

    D' Souza, T J; Mistry, K B [Bhabha Atomic Research Centre, Bombay (India). Biology and Agriculture Div.

    1980-01-01

    The absorption of gamma-emitting fission products /sup 106/Ru, /sup 125/Sb, /sup 137/Cs and /sup 144/Ce and activation products /sup 59/Fe, /sup 58/Co, /sup 54/Mn and /sup 65/Zn by rice plants grown on two contrasting tropical soils, namely, a blak soil (pellustert) and a laterite (oxisol), and the effects of flooding were studied under controlled conditions. Results indicated greater uptake of /sup 106/Ru and /sup 125/Sb from the black soil than from the laterite. In contrast, the uptake of /sup 144/Ce and /sup 137/Cs was greater in the laterite than in the black soil. Flooding treatment enhanced the uptake of all these fission products by rice plants in the laterite soil whereas this effect was observed only for /sup 125/Sb and /sup 137/Cs in the black soil. The plant uptake of activation products from the two soil types showed maximum accumulation of /sup 65/Zn followed by /sup 54/Mn, /sup 59/Fe and /sup 58/Co in both soil types. Besides, uptake of these nuclides was greater from the laterite soil than from the black soil. Flooding treatment for rice while showing a reduction of /sup 59/Fe uptake showed an increase in plant uptake of /sup 58/Co, /sup 54/Mn and /sup 65/Zn in both soil types.

  17. Representativeness of soil samples collected to assess mining-related contamination of flood plains in southeast Kansas

    Science.gov (United States)

    Juracek, Kyle E.

    2015-01-01

    Historical lead and zinc mining in the Tri-State Mining District (TSMD), located in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma, has resulted in a substantial ongoing input of lead and zinc to the environment (Juracek, 2006; Juracek and Becker, 2009). In response to concern about the mining-related contamination, southeast Cherokee County, Kansas, was listed on the U.S. Environmental Protection Agency’s (USEPA) National Priority List as a Superfund hazardous waste site (fig. 1). To provide some of the information needed to support remediation efforts in the Cherokee County Superfund site, a study was begun in 2009 by the U.S. Geological Survey (USGS) that was requested and funded by USEPA. As part of the study, surficial-soil sampling was used to investigate the extent and magnitude of mining-related lead and zinc contamination in the flood plains of the Spring River and several tributaries within the Superfund site. In mining-affected areas, flood-plain soils had lead and zinc concentrations that far exceeded background levels as well as probable-effects guidelines for toxic aquatic biological effects (Juracek, 2013). Lead- and zinc-contaminated flood plains are a concern, in part, because they represent a long-term source of contamination to the fluvial environment.

  18. Combined effects of soil moisture and carbaryl to earthworms and plants: Simulation of flood and drought scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Maria P.R.; Soares, Amadeu M.V.M. [Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro (Portugal); Loureiro, Susana, E-mail: sloureiro@ua.pt [Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro (Portugal)

    2011-07-15

    Studying tolerance limits in organisms exposed to climatic variations is key to understanding effects on behaviour and physiology. The presence of pollutants may influence these tolerance limits, by altering the toxicity or bioavailability of the chemical. In this work, the plant species Brassica rapa and Triticum aestivum and the earthworm Eisenia andrei were exposed to different levels of soil moisture and carbaryl, as natural and chemical stressors, respectively. Both stress factors were tested individually, as well as in combination. Acute and chronic tests were performed and results were discussed in order to evaluate the responses of organisms to the combination of stressors. When possible, data was fitted to widely employed models for describing chemical mixture responses. Synergistic interactions were observed in earthworms exposed to carbaryl and drought conditions, while antagonistic interactions were more representative for plants, especially in relation to biomass loss under flood-simulation conditions. - Highlights: > Climate variations may cause changes on chemicals' toxicity or bioavailability. > Earthworms and plants are exposed simultaneously to carbaryl and flood and drought conditions. > The IA model and possible deviations were used to evaluate combination exposures. > Synergism was observed for earthworms exposed to carbaryl and drought conditions. > Antagonistic interactions were observed for plants, in flood conditions and carbaryl. - Soil moisture can play an important role in carbaryl toxicity towards plants and earthworms.

  19. Combined effects of soil moisture and carbaryl to earthworms and plants: Simulation of flood and drought scenarios

    International Nuclear Information System (INIS)

    Lima, Maria P.R.; Soares, Amadeu M.V.M.; Loureiro, Susana

    2011-01-01

    Studying tolerance limits in organisms exposed to climatic variations is key to understanding effects on behaviour and physiology. The presence of pollutants may influence these tolerance limits, by altering the toxicity or bioavailability of the chemical. In this work, the plant species Brassica rapa and Triticum aestivum and the earthworm Eisenia andrei were exposed to different levels of soil moisture and carbaryl, as natural and chemical stressors, respectively. Both stress factors were tested individually, as well as in combination. Acute and chronic tests were performed and results were discussed in order to evaluate the responses of organisms to the combination of stressors. When possible, data was fitted to widely employed models for describing chemical mixture responses. Synergistic interactions were observed in earthworms exposed to carbaryl and drought conditions, while antagonistic interactions were more representative for plants, especially in relation to biomass loss under flood-simulation conditions. - Highlights: → Climate variations may cause changes on chemicals' toxicity or bioavailability. → Earthworms and plants are exposed simultaneously to carbaryl and flood and drought conditions. → The IA model and possible deviations were used to evaluate combination exposures. → Synergism was observed for earthworms exposed to carbaryl and drought conditions. → Antagonistic interactions were observed for plants, in flood conditions and carbaryl. - Soil moisture can play an important role in carbaryl toxicity towards plants and earthworms.

  20. N2O-reducing activity of soil amended with organic and inorganic enrichments under flooded conditions

    Directory of Open Access Journals (Sweden)

    Alicja Księżopolska

    Full Text Available ABSTRACT Changes, apparent after investigation, in the physical and chemical properties in soil, as a result of organic and inorganic enrichments under flooded conditions, influence the growth of denitrifiers. The aim of this study was to determine the effect of the addition of manure (8 kg m−2 (M, clay (50 kg m−2 (CL and lime (1.12 kg m−2 (Ca on the N2O-reducing activity (N2O-RA of sandy loam soil (clay content - 24 % in 0-20 cm, during NO3 reduction under flooding. The soil samples were taken from field plots after 3 years of enrichment with grass cultivation. The enrichments had a distinct effect on the N2O-RA and N2O-released, due to the change in pH, the porosity, and the sorptive properties of the soil. The pH had the greatest impact on the N2O-RA of the soil and ranged from 4.9 to 7.6. For actual denitrification to N2O-realized (aD-N2O, the maximum N2O-releasing (mcN2O-releasing followed the order: 1.36 for the M-treatment, 6.39 for the M+CL+Ca-treatment, 7.79 for the c-soil and 8.69 N2O-N mg kg−1 for the M+CL-treatment. For actual denitrification (aD, the mcN2O-releasing was followed the order: 10.37 for the M-treatment, 10.49 for the control soil, 14.60 for the M+CL+Ca-treatment and 20.00 N2O-N mg kg−1 for the M+CL-treatment. The N2O-RA of the soil samples increased as pH increased. The average N2O/N2+N2O ratio and the N2O-RA of the soil samples increased in the following order: M+CL, control soil, M+CL+Ca, M-enrichments. The addition of enrichments did not pose a threat to the environment due to increased N2O emissions, but as regards conserving NO3− in the soil, the addition of clay distinctly increased the complete denitrification process.

  1. Carbon degradation in agricultural soils flooded with seawater after managed coastal realignment

    DEFF Research Database (Denmark)

    Sjøgaard, Kamilla Schneekloth; Treusch, Alexander H.; Valdemarsen, Thomas Bruun

    2017-01-01

    Strand) that was planned to be flooded in a coastal realignment project. We found rapid carbon degradation almost immediately after flooding and microbial sulfate reduction rapidly established as the dominant mineralization pathway. Nevertheless, no free sulfide was observed as it precipitated as Fe...

  2. Transformations of sup(15)N labelled urea applied to a soil with maize strain incorporation under continuous flood

    International Nuclear Information System (INIS)

    Colaco, W.

    1991-01-01

    A greenhouse experiment with deep placed sup(15)N-labelled urea was conducted in an Aluvial soil in which maize straw was incorporated. The transformations of total-N, NH sub(4) sup(+) -N, and NO sub(3) sup(-) -N, - were investigated under continuous flooded conditions in soil planted or not to rice. Total -N and inorganic-N levels decreased in both conditions. The rapid inorganic decrease in planted soil would be mainly due to assimilation by the rice plants. However losses occurred in all cases. Such losses increased in the absence of rice plants and seemed to be mainly to nitrification - denitrification mechanisms although NH sub(3) volatilization could also be involved. Dry matter yield and N-uptake by rice increased with increasing rate of N-application. Maize straw was an important source of N for rice. N losses are modified by the incorporation of maize straw. (author)

  3. Influence of the nonexchangeable potassium of mica on radiocesium uptake by paddy rice.

    Science.gov (United States)

    Eguchi, Tetsuya; Ohta, Takeshi; Ishikawa, Tetsuya; Matsunami, Hisaya; Takahashi, Yoshihiko; Kubo, Katashi; Yamaguchi, Noriko; Kihou, Nobuharu; Shinano, Takuro

    2015-09-01

    A pot cultivation experiment was conducted to elucidate the influence of the nonexchangeable potassium (K) of mica on radiocesium ((137)Cs) uptake by paddy rice (Oryza sativa L. cv. Koshihikari), and to evaluate the potential of mica application as a countermeasure to reduce radiocesium transfer from soil to paddy rice. The increase in the exchangeable K concentrations of soils, measured before planting, due to mica (muscovite, biotite, and phlogopite) application was negligible. However, in trioctahedral mica (biotite and phlogopite)-treated soil, the release of nonexchangeable K from the mica interlayer maintained the soil-solution K at a higher level during the growing season in comparison to the control, and consequently decreased the (137)Cs transfer factor for brown rice (TF). The sodium tetraphenylboron (TPB)-extractable K concentration of the soils, measured before planting, was strongly negatively correlated with the TF, whereas the exchangeable K concentration of the soils, also measured before planting, was not correlated with the TF. Therefore, we conclude that TPB-extractable K is more reliable than exchangeable K as a basis of fertilizer recommendations for radiocesium-contaminated paddy fields. Phlogopite-treated soils exhibited higher TPB-extractable K concentrations and lower TF values than biotite-treated soils. We thus conclude that phlogopite application is an effective countermeasure to reduce radiocesium uptake in paddy rice. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Alluvial and riparian soils as major sources of lead exposure in young children in the Philippines: the role of floods.

    Science.gov (United States)

    Ostrea, Enrique M; Ostrea, Angelo M; Villanueva-Uy, Ma Esterlita; Chiodo, Lisa; Janisse, James

    2015-04-01

    The objective of this paper was to determine the prevalence and sources of high lead (Pb) exposure among children in Bulacan, Philippines. A total of 150 children (6-7 years old) and their caregivers were studied. Lead was analyzed in children hair and deciduous teeth. Sources of lead exposure were determined by caregiver interview and Pb analysis of house soil, drinking faucet water, air, and water from seven Bulacan rivers. Lead was positive in 91.3% of children's hair (MC or median concentration = 8.9 μg/g; range = 0-38.29), in 46.2%