WorldWideScience

Sample records for flooded paddy fields

  1. Flood control and loss estimation for paddy field at midstream of Chao Phraya River Basin, Thailand

    Science.gov (United States)

    Cham, T. C.; Mitani, Y.

    2015-09-01

    2011 Thailand flood has brought serious impact to downstream of Chao Phraya River Basin. The flood peak period started from August, 2011 to the end of October, 2011. This research focuses on midstream of Chao Phraya River Basin, which is Nakhon Sawan area includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. The main purpose of this research is to understand the flood generation, estimate the flood volume and loss of paddy field, also recommends applicable flood counter measurement to ease the flood condition at downstream of Chao Phraya River Basin. In order to understand the flood condition, post-analysis is conducted at Nakhon Sawan. The post-analysis consists of field survey to measure the flood marks remained and interview with residents to understand living condition during flood. The 2011 Thailand flood generation at midstream is simulated using coupling of 1D and 2D hydrodynamic model to understand the flood generation during flood peak period. It is calibrated and validated using flood marks measured and streamflow data received from Royal Irrigation Department (RID). Validation of results shows good agreement between simulated result and actual condition. Subsequently, 3 scenarios of flood control are simulated and Geographic Information System (GIS) is used to assess the spatial distribution of flood extent and reduction of loss estimation at paddy field. In addition, loss estimation for paddy field at midstream is evaluated using GIS with the calculated inundation depth. Results show the proposed flood control at midstream able to minimize 5% of the loss of paddy field in 26 provinces.

  2. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Meng-hua XIAO; Shuang-en YU; Yan-yan WANG; Rong HUANG

    2013-01-01

    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 -N+ ) concentration reached the peak value once the fertilizer was applied, and then 4 decreased to a relatively low level seven to ten days later, and that the nitrate nitrogen ( NO -N− ) 3 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 -N+ , 4 NO -N− , and total phosphorus (TP) in surface water. However, the paddy water disturbance, in the process of soil surface adsorption and nitrification, caused 3 NH -N+ to be released and increased the 4 concentrations of NH -N+ and 4 NO -N− in surface water. A multi-objective controlled drainage 3 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.

  4. The Size of Winter-Flooded Paddy Fields No Longer Limits the Foraging Habitat Use of the Endangered Crested Ibis (Nipponia nippon) in Winter.

    Science.gov (United States)

    Hu, Can-Shi; Song, Xiao; Ding, Chang-Qing; Ye, Yuan-Xing; Qing, Bao-Ping; Wang, Chao

    2016-08-01

    Paddy fields have traditionally been viewed as the key foraging habitats for the endangered crested ibis (Nipponia nippon). With the population of this species now increasing, its distribution has expanded to both lowland areas and outside the nature reserve. However, little is known about the current foraging habitat preferences of these birds, especially during winter. In this research, a total of 54 used sites and 50 unused sites were investigated during winter from December 2011 to January 2012. The results of logistic regression analysis indicate that soil softness, human disturbance, and distance to the nearest road were important factors. For the site plots of winter-flooded paddy fields, the birds prefer the paddy fields with higher coverage of vegetation, except softer foraging sites and lower human-related disturbance. In lowland areas, the size of winter-flooded paddy fields was not a limiting factor, due to the availability of other wetlands capable of providing abundant food. The micro-habitat characteristics were important indicators of foraging habitat quality rather than the size of winter-flooded paddy fields, and the food accessibility may play an important role in the process of foraging habitat use. We suggest the improvement of the foraging micro-habitat and environmental characteristics would be effective in ensuring the availability of food in the dispersed lowland areas. The local people still needed to be encouraged and compensated by their single-cropping cultivation, ploughed the paddy fields after harvesting and irrigated them with shallow water flooded in the original core areas of the nature reserve.

  5. Evidence for the cooccurrence of nitrite-dependent anaerobic ammonium and methane oxidation processes in a flooded paddy field.

    Science.gov (United States)

    Shen, Li-Dong; Liu, Shuai; Huang, Qian; Lian, Xu; He, Zhan-Fei; Geng, Sha; Jin, Ren-Cun; He, Yun-Feng; Lou, Li-Ping; Xu, Xiang-Yang; Zheng, Ping; Hu, Bao-Lan

    2014-12-01

    Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two of the most recent discoveries in the microbial nitrogen cycle. In the present study, we provide direct evidence for the cooccurrence of the anammox and n-damo processes in a flooded paddy field in southeastern China. Stable isotope experiments showed that the potential anammox rates ranged from 5.6 to 22.7 nmol N2 g(-1) (dry weight) day(-1) and the potential n-damo rates varied from 0.2 to 2.1 nmol CO2 g(-1) (dry weight) day(-1) in different layers of soil cores. Quantitative PCR showed that the abundance of anammox bacteria ranged from 1.0 × 10(5) to 2.0 × 10(6) copies g(-1) (dry weight) in different layers of soil cores and the abundance of n-damo bacteria varied from 3.8 × 10(5) to 6.1 × 10(6) copies g(-1) (dry weight). Phylogenetic analyses of the recovered 16S rRNA gene sequences showed that anammox bacteria affiliated with "Candidatus Brocadia" and "Candidatus Kuenenia" and n-damo bacteria related to "Candidatus Methylomirabilis oxyfera" were present in the soil cores. It is estimated that a total loss of 50.7 g N m(-2) per year could be linked to the anammox process, which is at intermediate levels for the nitrogen flux ranges of aerobic ammonium oxidation and denitrification reported in wetland soils. In addition, it is estimated that a total of 0.14 g CH4 m(-2) per year could be oxidized via the n-damo process, while this rate is at the lower end of the aerobic methane oxidation rates reported in wetland soils.

  6. 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

  7. Continuous field investigation assessing nitrogen and phosphorus emission from irrigated paddy field

    Science.gov (United States)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2016-04-01

    In order to maintain good river environment, it is very important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. Other than urban and industrial waste water, nutrient emission from agricultural activity is dominant pollution source into the river system. Rice is one of the staple products of Asia and paddy field occupies large areas in Asian countries. Rice is also widely cultivated in Japan. Paddy field occupies large areas in Japanese river basin areas. While paddy field can deteriorate river water quality by discharging fertilizer, it is also suggested that paddy field has water purification function. Regarding to nutrient emission from paddy field, existing monitored data are insufficient so as to discuss quantitatively seasonal change of material behavior including flooding season and dry season and to evaluate year round comprehensive impact from paddy field to the river system. These are not sufficient data for discussion of material flow and emission impact quantitatively as well as qualitatively. We have carried out field investigation in paddy fields in middle reach of the Tone River Basin. The aim of the survey is understanding of water and nutrient balance in paddy field. In order to understand emission impact from paddy field to river system, all input and output flow are measured to calculate nutrient balance in paddy field. Therefore we observed quantity of water flow into/from paddy field, water quality change of inflow and outflow during flooding season. We set focus on a monitoring paddy field IM, and monitored continuously water and nutrient behavior. By measuring water quality and flow rate of inflow, outflow, infiltrating water, ground water and depth of flooding water, we tried to quantitatively understand N and P cycle around paddy field including seasonal tendency, change accompanying with rainy events and occurred according to agricultural events like fertilization. At the beginning of flooding season, we

  8. 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

  9. In-situ measurement of free trace metal concentrations in a flooded paddy soil using the Donnan Membrane Technique

    NARCIS (Netherlands)

    Pan, Y.; Koopmans, G.F.; Bonten, L.T.C.; Song, J.; Luo, Y.; Temminghoff, E.J.M.; Comans, R.N.J.

    2015-01-01

    The field Donnan Membrane Technique (DMT) has been used successfully to measure in-situ free trace metal concentrations in surface waters. However, it has not been applied previously in submerged soil systems including flooded paddy rice fields.Wetested this technique in a columnexperimentwith a flo

  10. Long term continuous field survey to assess nutrient emission impact from irrigated paddy field into river catchment

    Science.gov (United States)

    Kogure, Kanami; Aichi, Masaatsu; Zessner, Matthias

    2017-04-01

    In order to achieve good river environment, it is very important to understand and to control nutrient behavior such as Nitrogen and Phosphorus. As we could reduce impact from urban and industrial activities by wastewater treatment, pollution from point sources are likely to be controlled. Besides them, nutrient emission from agricultural activity is dominant pollution source into the river system. In many countries in Asia and Africa, rice is widely cultivated and paddy field covers large areas. In Japan 54% of its arable land is occupied with irrigated paddy field. While paddy field can deteriorate river water quality due to fertilization, it is also suggested that paddy field can purify water. We carried out field survey in middle reach of the Tone River Basin with focus on a paddy field IM. The objectives of the research are 1) understanding of water and nutrient balance in paddy field, 2) data collection for assessing nutrient emission. Field survey was conducted from June 2015 to October 2016 covering two flooding seasons in summer. In our measurement, all input and output were measured regarding water, N and P to quantify water and nutrient balance in the paddy field. By measuring water quality and flow rate of inflow, outflow, infiltrating water, ground water and flooding water, we tried to quantitatively understand water, N and P cycle in a paddy field including seasonal trends, and changes accompanied with rainy events and agricultural activities like fertilization. Concerning water balance, infiltration rate was estimated by following equation. Infiltration=Irrigation water + Precipitation - Evapotranspiration -Outflow We estimated mean daily water balance during flooding season. Infiltration is 11.9mm/day in our estimation for summer in 2015. Daily water reduction depth (WRD) is sum of Evapotranspiration and Infiltration. WRD is 21.5mm/day in IM and agrees with average value in previous research. Regarding nutrient balance, we estimated an annual N and

  11. Effects of cracks and some key factors on emissions of nitrous oxide in paddy fields

    Institute of Scientific and Technical Information of China (English)

    HUANG Shu-hui; LU Jun; TIAN Guang-ming

    2005-01-01

    Paddy field is a primary agricultural landscape in the south of China and is often regarded as one of main sources emitting nitrous oxide to atmosphere. The nitrous oxide emissions under a variety of paddy field practices, such as fertilization, flooding/draining management were investigated to study on agricultural activities on paddy field affect the dynamic process of the emission. Under no addition of fertilizers the average emission flux of nitrous oxide was 8.55 μg/(m2· h) during the rice( Oryza Sativa L. ) growth season. The results indicated that most of nitrous oxide emissions occurred during the crack forming-and-expansion period when paddy field was being drained. The diurnal emissions peak of nitrous oxide appeared at 20:30 at night in cracked rice fields. The statistical analysis suggested that the correlation of nitrous oxide emissions flux (Y) with soil water content ( X1 ), soil temperature ( X2 ), and Eh ( X3 ), could be described in a regression equation: Y= - 1498.95 + 2895.48 X1 + 50.63 X2 -96.99X1 · X2 + 0.006X2· X3. There were the different power equations to simulate the correlations between the everyday dynamic N2O emissions and the mean surface area of cracks, mean volume and depth of cracks respectively during paddy soil drying by soil columns incubation experiments. Taken all together, the current study presented a dynamic analysis of nitrous oxide emission of paddy field under various conditions, therefore provided a basis for the management to balance between environmental effect and paddy field activities.

  12. Evaluation of the denitrification rate of terraced paddy fields

    Science.gov (United States)

    Onishi, Takeo; Nakamura, Kimihito; Horino, Haruhiko; Adachi, Toru; Mitsuno, Toru

    2012-05-01

    SummaryRice is one of the most important staple foods in the world. Lowland paddy fields are well known for functioning as denitrification areas, but few studies have been conducted of paddy fields situated on hill slopes (terraced paddy fields). These terraced paddy fields have a characteristic artificial stepped shape, and this unique shape and periodic ponding from rice production may configure unique hydrological properties that might be different from lowland paddy fields. The shape and hydrological properties may also affect transport of nutrients such as nitrogen. This study is particularly focused on the denitrification rate in terraced paddy fields. To understand the hydrological properties of terraced paddy fields, a detailed water budget including the subsurface flow components was calculated. Combining the water budget components and chemical measurements of surface and subsurface water, a nitrogen budget was calculated. The results showed that about 10% of the total nitrogen input, mainly from fertilizers, was lost, suggesting the occurrence of denitrification in the area. The average denitrification rate of the study site was estimated at about 0.53-0.67 g N m-2 year-1. Spatial variations in the measured groundwater nitrate concentration suggest that denitrification is important in both the plough layer and the sloping area. The denitrification rate in the sloping area was estimated at 0.67-0.78 g N m-2 year-1, which is slightly higher than the estimates of denitrification rate in paddy lots, i.e., 0.56-0.61 g N m-2 year-1. The result indicates the importance of sloping areas for denitrification in terraced paddy fields.

  13. Short-term Influence of Herbicide Quinclorac on Enzyme Activities in Flooded Paddy Soils

    Institute of Scientific and Technical Information of China (English)

    L(U) Zhen-Mei; MIN Hang; YE Yang-Fang

    2004-01-01

    The influence of quinclorac (3,7-dichloroquinoline-8-carboxylic acid) on enzyme activities in flooded paddy soils was assessed under laboratory conditions. The enzymes differed markedly in their response to quinclorac. Quinclorac inhibited proteinase, hydrogen peroxidase, phosphorylase, and urease activities.The higher the concentration of quinclorac applied, the more significant the inhibition to these observed activities with a longer time required to recover to the level of the control. However, soils supplemented with quinclorac were nonpersistent for proteinase, phosphorylase and urease as opposed to soils without quinclorac. Dehydrogenase activity was also sensitive to quinclorac. Three soil samples with concentrations of quinclorac higher than 1 μg g-1 soil declined to less than 20% of that in the control. However, the highest dehydrogenase activity (up to 3.28-fold) was detected in soils with 2 μg g-1 soil quinclorac on the 25th day after treatment. Quinclorac had a relatively mild effect on saccharase activity at the concentrations used in this experiment and a stimulatory one on soil respiration when added to soil at normal field concentrations.Nonetheless it was inhibited at higher concentrations in paddy soils. Quinclorac is still relatively safe to the soil ecosystem when applied at a normal concentration (0.67 μg g-1 dried soil) but may have some effects on soil enzymes at higher concentrations.

  14. Solubility of trace metals in two contaminated paddy soils exposed to alternating flooding and drainage

    NARCIS (Netherlands)

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

    2016-01-01

    Uptake of trace metals by crops is determined by the solubility of trace metals. In paddy soils, flooding and drainage influence redox chemistry and consequently trace metal solubility and thus uptake by rice plants. Current knowledge on how the dynamics in redox chemistry affect the solubility

  15. Populations of Rice Grain Bug, Paraeuscosmetus pallicomis, (Hemiptera: Lygaeidae) in Weed-free Paddy Field, Weedy Paddy Field and Paddy Dykes.

    Science.gov (United States)

    Abdullah, Tamrin; Nasruddin, Andi; Agus, Nurariaty

    2017-07-01

    Research on the populations of rice grain bug Paraeuscosmetus pallicomis Dallas (Hemiptera: Lygaeidae) in paddy field ecosystems was performed with the aim to determine the populations of rice grain bug in weed-free paddy field, weedy paddy field, and paddy dykes. Experiment was carried out in the village of Paccellekang in the district of Patallasang of Gowa Regency in South Sulawesi, Indonesia. Observations were performed during the milky grain stage (85 days after planting), the mature grain stage (105 days after planting), and one day after harvest (115 days after transplanting). Results showed that 85 days after the transplanting, the populations of rice grain bug was significantly higher in the weedy paddy field compared to weed-free field and paddy dykes with total numbers of 1.75, 3.53, and 0.31 insects per 2 hills, respectively. Similarly, 105 days after the transplanting, 2.53, 5.53, and 0.11 insects per hill, respectively. However, one day after the harvest (115 days after transplanting) the number of insects in weed-free field decreased, while in the dykes increased, and the weedy plot still had the highest number of insects per 2 hills. Our results suggested that weeds played an important role in regulating the bug population by providing alternative shelter and foods for the insect.

  16. 控制排水条件下淹水稻田田面及地下水氮浓度变化%Changes of nitrogen concentration for surface and groundwater in flooding paddy field under controlled drainage

    Institute of Scientific and Technical Information of China (English)

    肖梦华; 俞双恩; 章云龙

    2011-01-01

    为了在减少农田面源污染,提高氮肥的利用效率.该文通过蒸渗测坑进行淹水稻田不同渗漏强度控制试验,研究了稻田施肥后NH4+-N、NO3-N浓度变化及各生育阶段不同渗漏强度稻田水NH4+-N、NO3-N浓度变化.结果表明:施分蘖肥后,地表水及地下水NH4+-N浓度急剧升高而后回落,均在施肥后第5天出现峰值,分别为17.75和10.34 mg/L;地表水NO3-N浓度短暂升高后便回落,在施肥后第2天出现峰值,但地下水NO3-N浓度急剧上升而后回落,在施肥后第5天出现峰值(3.25 mg/L),6d上升了249.4%.稻田补水会扰动土壤,促进土壤表层吸附的NH4+-N的释放及硝化进程,使地表水中NH4+-N和NO3-N浓度升高,随着淹水时间的延长,NH4+-N和NO3-N浓度会随之降低.不同渗漏强度(2和4 mm/d)对稻田水氮素变化有一定影响,但各处理之间差异不显著.因此,施肥后应该避免排水,应避免雨后和灌水后立即进行地表排水.%To reduce agricultural non-point source pollution and improve nitrogen use efficiency, the research on the changes of concentrations of NH4+-N and NCV-N in surface and ground water after fertilizer application and changes of that at each growth stage was conducted based on experimental test in flooding paddy field under different leakage rates by use of lysimeter. Results showed that after fertilizer application, the concentrations of NR4+-N in both surface and ground water increased significantly and then decreased, and their peak values both appeared at the 5th day after fertilizer application, they were 17.75 and 10.34mg/L, respectively in surface water and ground water. Results also showed that the concentration of NO3"-N in surface water decreased after a brief increment, and its peak value appeared at the 2nd day after fertilizer application. While the concentration of NO3-N in ground water gradually rose and then decreased, its peak value appeared at the 5th day after fertilizer application (3.25mg

  17. Nutrients levels in paddy soils and flood waters from Tagus-Sado basin: the impact of farming system

    Science.gov (United States)

    Santos, Erika S.; Abreu, Maria Manuela; Magalhães, Maria Clara; Viegas, Wanda; Amâncio, Sara; Cordovil, Cláudia

    2017-04-01

    Application of fertilizers for crops can contribute to nutrients surplus, namely nitrogen, in both groundwater and surface waters resulting in serious environmental problems. The impacts on water quality due to fertilizers are related to land management. In paddy fields using high amounts of water, the nutrient dynamic knowledge is essential to evaluate the impact of farming system. The aims of this study were to evaluate: i)nutrients levels in soils and floodwaters from rice cultivation in Tagus-Sado basin (Portugal); ii)the effect, under controlled conditions, of different irrigation techniques on nutrient enrichment of floodwaters from rice cultivation. Composite samples (n=24) of paddy soils (0-15 cm) and floodwaters were collected, during rice flooding period. In the field, pH and electrical conductivity (EC) were determined in waters. Soil pH, concentrations of Corganic, NPK and nutrients (Ca, Cu, Fe, Mg, Mn, Zn) in soils and floodwaters (nitrites, nitrates, phosphates) were determined. A mesocosm assay was performed in lysimeters with a paddy soil (pH: 5.6; g/kg- Ntotal: 2.0, Pextractable: 0.04, Kextractable: 0.6, Corganic: 35.5) and different irrigation techniques (n=3): a)flood; b)four floods per day (great water renewal); c)flood until rice flowering and then a normal superficial irrigation. Rice cultivation was done by transplant as in the field. Irrigation water come from a well. Same chemical characterization than in field assay were determined in floodwater and irrigation water. In field conditions, paddy soils had values of pH between 5.1 and 8.1 and a great fertility range (g/kg; Ntotal: 0.4‒2.2; Pextractable: 0.01‒0.2; Kextractable: 0.04‒0.7; Corganic: 6.5‒37.9). Total soil concentrations of Cu, Fe, and Zn in soils were in same range and below maximum admissible values for agriculture. Total soil concentrations of Ca, Mg and Mn, showed higher heterogeneity (g/kg; 1.2‒19.3, 7.6‒34.2 and 0.2‒1.5 respectively). Floodwaters presented pH

  18. a Study on the SAR Data Observation Time for the Classification of Planting Condition of Paddy Fields

    Science.gov (United States)

    Kimura, A.; Kondo, A.; Mochizuki, K.

    2016-06-01

    In recent years, cultivation methods of rice have been diversified due to the low cost of rice-growing techniques. For example, there is direct sowing of seed rice in paddy field in addition to the practice of usual paddy field to flooding at the time of planting. The yield of the usual paddy field and the direct sowing is different even though the same varieties are grown in the same area. It is necessary to grasp by performing classification for the usual paddy field or direct sowing for the management of agricultural crops. The main objective of this study was to select the observation time for the classification of paddy fields' planting conditions by utilizing Synthetic Aperture Radar TerraSAR-X satellite. The planting conditions included the usual planting of rice, the direct sowing of rice and the soybean. We selected the observation time by the statistical distance of the microwave backscattering in each paddy field for maximizing the planting condition classification. In addition, the satellite data observation timing considered the processing time of the analysis and the acquisition costs. The acquisition was performed 4 periods from 2 periods in the rice growing season and the planting phase. In the current study, we were able to classify the usual planting of rice, the direct sowing of rice and the soybean by TerraSAR-X data for the later planting of rice during mid-May and initial growth of rice in early June.

  19. Protection of Paddy Field and Recommendation of Regional Planning in Cianjur Regency, West Java, Indonesia

    Science.gov (United States)

    Munibah, Khursatul; Yudarwati, Rani; Dwi Wahyunie, Enni; Wijaya, Hermanu

    2016-11-01

    Cianjur Regency is one of “lumbung” paddies in West Java Province that can contribute to rice sufficiency for West Java 13.5%. However conversion of paddy field into other land use still happen in Indonesia because of land rent of paddy field less than other land use and also the low commitment of Government to protect the paddy field to get food self-sufficiency. Objectives are analysis of paddy field protection and recommendation of regional planning. Paddy field protection was determined based on existing paddy field, land suitability, economic value and Regional Spatial Planning (RTRW). Recommendation of regional planning was determined based on priority level of paddy field protection, Regional Spatial Planning (RTRW) and rice sufficiency status. The results showed that land suitability, economic value and also allocating land for paddy field in the RTRW can support realization of paddy field protection. The paddy field that included into the first and third priority is 30.14% and 38.45%, respectively. The other priorities of paddy field protection are around 15%. This research is recommended that 87.5% of the paddy field existing can be protected to get rice sufficiency with surplus around 48.782 ton.

  20. Greenhouse gas budget from a rice paddy field in the Albufera of Valencia, Spain.

    Science.gov (United States)

    Meijide, Ana; López-Ballesteros, Ana; Calvo-Roselló, Esperanza; López-Jiménez, Ramón; Recio-Huetos, Jaime; Calatayud, Vicent; Carrara, Arnaud; Serrano-Ortiz, Penelope

    2017-04-01

    Rice paddy fields are large sources of anthropogenic methane (CH4) and therefore many studies have assessed CH4 fluxes from rice paddy fields, mainly in Asia where most of the rice cultivation takes place. However, rice is also cultivated in the Mediterranean, where climatic and management conditions greatly differ. In the Albufera of Valencia, the largest freshwater lagoon in Spain, rice paddy fields have the particularity of being flooded not only while the rice grows, but also after the harvest during the winter. These flooding conditions might result in emissions which are very specific of this ecosystem, and cannot be extrapolated from other studies. We studied CH4 fluxes in a rice paddy field in the Albufera of Valencia at different stages of rice cultivation using the eddy covariance technique and static chambers. We additionally measured carbon dioxide (CO2), water fluxes and nitrous oxide (N2O) fluxes with eddy covariance and chamber methods respectively, in order to obtain a full greenhouse gas (GHG) budget. Our study also aimed at providing a mechanistic understanding of GHG emissions at different stages of rice cultivation, and therefore we also used the Enhanced and Normalized Vegetation Indexes (EVI and NDVI, respectively), derived from remote sensing images. The general ecosystem functioning encompasses three different phases. The first one, over the autumn and the winter, a biological dormancy period causes low CO2 emissions (ca. 1-5 µmol m-2 s-1), which coincides with the EVI and NDVI. The intermittent flooding taking place during this period is expected to cause CH4 emissions. Then, during the spring months (March-May), larger CO2 respiratory emissions take place during the daytime (> 5 µmol m-2 s-1) due to an increase in air temperature, which turn to neutral at the end of spring due to the start of photosynthesis by the rice. The third phase corresponds to the vegetation growth, when the net CO2 uptake increases gradually up to maximum CO2

  1. Urbanization dramatically altered the water balances of a paddy field dominated basin in Southern China

    Directory of Open Access Journals (Sweden)

    L. Hao

    2015-02-01

    Full Text Available Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration to a large population globally. However, these benefits are declining as a result of rapid environmental and socioeconomic transformations characterized by population growth, urbanization, and climate change in many Asian countries. This case study examined the responses of streamflow and watershed water balances to the decline of rice paddy fields due to urbanization in the Qinhuai River Basin in southern China where massive industrialization has occurred in the region during the past three decades. We found that streamflow increased by 58% and evapotranspiration (ET decreased by 23% during 1986–2013 as a result of an increase in urban areas of three folds and reduction of rice paddy field by 27%. Both highflows and lowflows increased significantly by about 28% from 2002 to 2013. The increases in streamflow were consistent with the decreases in ET and leaf area index monitored by independent remote sensing MODIS data. The reduction in ET and increase in streamflow was attributed to the large cropland conversion that overwhelmed the effects of regional climate warming and climate variability. Converting traditional rice paddy fields to urban use dramatically altered land surface conditions from a water-dominated to a human-dominated landscape, and thus was considered as one of the extreme types of contemporary hydrologic disturbances. The ongoing large-scale urbanization in the rice paddy-dominated regions in the humid southern China, and East Asia, will likely elevate stormflow volume, aggravate flood risks, and intensify urban heat island effects. Understanding the linkage between land use change and changes in hydrological processes is essential for better management of urbanizing watersheds.

  2. A Water Demand Curve for Rice Paddy Field

    OpenAIRE

    佐藤, 豊信

    1989-01-01

    Demand for water use in rice paddy fields in Japan has traditionally been measured according to a unit known as "Gensuishin" However, it does not consider farmer decisions on how much water to use in rice production, while the quantity of water measured by "Gensuishin" takes into account biologocal and physical conditions. This paper reports that analysis of water demand in rice production ought to incorporate a farmer's subjective equilibrium and water demand quantity. The water demand cu...

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

    Science.gov (United States)

    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. [Effect of intermittent irrigation in paddy fields on mosquito control].

    Science.gov (United States)

    Cao, Xiao-Bin; Jiang, Jian-Ping; Gu, Guang-Ming; Zhou, Hua-Yun; Ding, Gui-Sheng; Zhong, Si-Qing; Chen, Hou-Cun

    2012-02-01

    To investigate the effects of intermittent irrigation in paddy fields on mosquito control and the impact on growth and yield of rice. The paddy fields were divided into an experimental group and a control group. In the same context of other measures, the experimental group was performed with intermittent irrigation and the control group with conventional irrigation. The densities of larvae of Anopheles sinensis and Culex tritaeniorhynchus were surveyed by the suction trapping method. The plant traits, leaf age process, tiller dynamics, yield structure and actual rice production were observed. Compared with the control group, the average densities of larvae of Anopheles sinensis and Culex tritaeniorhynchus were reduced of 10.32/m2 and 13.93/m2 respectively in the experimental group, the control rates were 79.84% and 72.14% respectively, the average yield increased of 22.5 kg/667 m2, water conservation was 187.4 m3/667 m2, and the increased revenue was 75.78 yuan/667 m2. The intermittent irrigation in paddy fields not only can control mosquito larva breeding effectively, but also save water and electricity, and increase the harvest.

  5. Periphyton: an important regulator in optimizing soil phosphorus bioavailability in paddy fields.

    Science.gov (United States)

    Wu, Yonghong; Liu, Junzhuo; Lu, Haiying; Wu, Chenxi; Kerr, Philip

    2016-11-01

    Periphyton is ubiquitous in paddy field, but its importance in influencing the bioavailability of phosphorus (P) in paddy soil has been rarely recognized. A paddy field was simulated in a greenhouse to investigate how periphyton influences P bioavailability in paddy soil. Results showed that periphyton colonizing on paddy soil greatly reduced P content in paddy floodwater but increased P bioavailability of paddy soil. Specifically, all the contents of water-soluble P (WSP), readily desorbable P (RDP), algal-available P (AAP), and NaHCO3-extractable P (Olsen-P) in paddy soil increased to an extent compared to the control (without periphyton) after fertilization. In particular, Olsen-P was the most increased P species, up to 216 mg kg(-1) after fertilization, accounting for nearly 60 % of total phosphorus (TP) in soil. The paddy periphyton captured P up to 1.4 mg g(-1) with Ca-P as the dominant P fraction and can be a potential crop fertilizer. These findings indicated that the presence of periphyton in paddy field benefited in improving P bioavailability for crops. This study provides valuable insights into the roles of periphyton in P bioavailability and migration in a paddy ecosystem and technical support for P regulation.

  6. Phosphine in paddy fields and the effects of environmental factors.

    Science.gov (United States)

    Niu, Xiaojun; Wei, Aishu; Li, Yadong; Mi, Lina; Yang, Zhiquan; Song, Xiaofei

    2013-11-01

    Ambient levels of phosphine (PH3) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368±0.6060 ng m(-3) to 24.83±6.529 ng m(-3) and averaged 14.25±4.547 ng m(-3). The highest phosphine emission flux was 22.54±3.897 ng (m(2)h)(-1), the lowest flux was 7.64±4.83 ng (m(2)h)(-1), and the average flux was 14.17±4.977 ng (m(2)h)(-1). Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg(-1)fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts>ACP>TP.

  7. Evaluation of a Dual-Purpose Chemical Applicator for Paddy Fields

    Directory of Open Access Journals (Sweden)

    Mohammed S. Abubakar

    2011-01-01

    Full Text Available Problem statement: One of the major problems of rice production is the shortage of labor resulting from migration from rural to urban areas, making it very difficult to meet peak demands for paddy production. In most developing countries of Southeast Asia, agricultural mechanization of paddy field operation is mostly carried out using conventional machines. For example in rice production powerintensive operations such as water pumping, land preparations, transplanting seedlings, harvestings and threshing are being mechanized but other operations like fertilizer and chemical (pesticides applications are not yet fully mechanized, rather they are performed manually with motorized backpack knapsack sprayers which have many disadvantages. The main objective of this study was to develop and evaluate a new concept dual-purpose chemical applicator for paddy fields farmers in order to complement the labor shortage during the peak period. Approach: A dual-purpose chemical applicator for flooded paddy field was evaluated using the S341.4 Standard in respect to the distribution patterns/droplet sizes and uniformity of spreading/spraying for the chemical application to boost agricultural mechanization in rice production and also to overcome the safety concern of hazardous spray drift during chemical application by the paddy farmers. The dual purpose applicator was mounted on a high clearance prime mover. The machine performances for both granular and liquid chemical application were reported. Results: Results for urea granular chemical indicate that at low (40 kg ha−1 and high (120 kg ha−1 rates and 550 rpm disc speed distribution pattern skewed to the left whereas the distribution pattern shape at medium (80 kg ha−1 rates was good flattop. At high rate (120 kg ha−1 and 1000 rpm disc speed, mean distribution pattern became poor (M-shape and also at low and medium application rates the distribution pattern shapes lopsided

  8. Monitoring of landscape change in paddy fields: Case study of Karawang District - West Java Province

    Science.gov (United States)

    Franjaya, E. E.; Syartinilia; Setiawan, Y.

    2017-01-01

    Paddy field is an important agricultural land in Indonesia, as one of the largest rice producing-country in the world. At least 26 from 33 provinces in Indonesia are characterized by the existence of paddy field landscape. However, due to the increasing of population and development of infrastructure building, a conversion of paddy field rapidly occurs in many sites. This study aimed to examine the dynamics change in paddy field in Karawang District-West Java during the period of 1994-2015. The method used in this study mainly by the remote sensing technique using satellite images data. The result indicated that conversion of paddy fields to built area/infrastructure in Karawang is approximately 10.326,6 ha. It took up 56% from the paddy that were changed. Based on the result, the changes are likely to occur in the middle of karawang district, near the central city. This result showed the change of paddy field in 1994 converted into some built-up areas such as settlement or roads in 2015. However, about 85.597,56 ha paddy field is not changed during these period. The study showed that paddy fields landscape is facing a changes over the last two decades.

  9. 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

  10. Heavy metals accumulation in parts of paddy Oryza sativa L. grown in paddy field adjacent to ultrabasic soil

    Science.gov (United States)

    Hadif, Waqeed Mahdi; Rahim, Sahibin Abd; Sahid, Ismail; Bhuiyan, Atiqur Rahman; Ibrahim, Izyanti

    2015-09-01

    The present study was carried out to evaluate the accumulation and translocation of heavy metals from soil around the root zone to various parts of the paddy plant, namely the roots, stems, leaves and rice grains. This study was conducted in 2014 in paddy field adjacent to ultrabasic soil (field 1 and 2) located in Ranau, Sabah and one field (Field 3) taken as control located at the UKM experimental plot in peninsular of Malaysia. The plant species used in the present investigation is Paddy Batu. The heavy metals studied were Chromium (Cr), Iron (Fe) and Nickel (Ni). Heavy metals in soil and plant were extracted by wet digestion method. Heavy metals present in paddy plants and soils extract were measured using the ICP-MS. Heavy metals concentrations in the plant parts in descending order is the root > leaves > stem > rice grain. Lower concentration of all heavy metals in soils and plant parts was shown by the control site (Field 3) in UKM Bangi. Higher concentration of heavy metals occurred in the roots compared to other above ground parts (stem, leaves, and grains) of the paddy plant in all of the paddy field. The bioaccumulation factor (BAF) of heavy metals in all locations were recorded in descending order as Ni > Cr > Fe, the BAF values for all metals in the rice grains were low, whereas the BAF values were recorded high for Ni in all locations. The results also showed that Fe was the most predominant metal ion in the roots, followed by Ni then Cr.

  11. Internal and External Factors Affecting The Size of Paddy Field Sold

    Directory of Open Access Journals (Sweden)

    Endang Rostiana

    2016-12-01

    Full Text Available This study attempted  to identify internal condition of the farmers who sold their paddy field and analyze the effects of age, education level, number of family members, field productivity, location, and production cost to the total area of paddy field sold. This study used quantitative descriptive method. This research found that age, education level, number of family members, and location of the land had positive relation to the total area of paddy field sold. On the other hand, production cost and field productivity had negative relation to the total area of paddy field sold. Partially, field production and number of family members had no significant effect to the total area of paddy field sold.

  12. Nitrogen Losses from Flooded Rice Field

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A field microplot experiment was conducted during the tillering stage of paddy rice to investigate nitrogen (N) losses from flooded rice fields following fertilizer application. After application of ammonium bicarbonate,most of nitrogen in the floodwater was present as NHq-N and its concentration varied widely with time.Concentrations of both NO3-N and NO2-N in the floodwater were low due to the weakened nitrification.Under flooded anaerobic reducing conditions, soil solution concentrations of NO3-N and NH4-N were not high, ranging from 0.6 mg L- 1 to 4.8 mg L-1, and decreased with soil depth. However, the groundwater was still contaminated with NO3-N and NH4-N. Rainfall simulation tests showed that the N losses via runoff in rice fields were closely related to the time intervals between fertilizer applications and rainfall events. When a large rain fell for a short period after fertilizer application, the N losses via runoff could be large, which could have a considerable effect on surface water quality. Both irrigation and N fertilizer application must be controlled and managed with great care to minimize N losses via runoff from agricultural land.

  13. Irrigation Difference and Productivity Variations in Paddy Cultivation: Field Evidences from Udalguri District of Assam

    OpenAIRE

    Phanindra GOYARI

    2014-01-01

    Using field survey data, the paper examines the seasonal variation of irrigation facilities for cultivation of paddy with special emphasis on summer paddy in Assam. Paddy is cultivated in three seasons: autumn, winter and summer. In terms of acreage and production, winter rice has traditionally been the most dominant. However, the acreage shares of winter and autumn rice in total rice area have been declining continuously over the years. On the contrary, the importance of summer rice has been...

  14. Nitrous oxide emissions in nonflooding period from fallow paddy fields

    Institute of Scientific and Technical Information of China (English)

    HUANG Shuhui; Hari K Pant; LU Jun

    2008-01-01

    The study was conducted to investigate the N2O emissions and dissolved N2O in the leachate during the nonflooding period in nongrowing paddy fields. Three kinds of paddy soils were repacked to soil columns and were supersaturated with water initially and dried gradually in a greenhouse to attain the N2O emissions flux during the incubation. Soils with the texture of silty clay-loam (Q and H) produced cracks during the drying of soil, but soil with the texture of silty loam (X) did not form the cracks. Cracked soils had similar amount of N2O emissions, and the mean N2O flux was 1,280.9 and 1,133.3 μg/(m2·h) from Q and H soil, respectively, during the incubation; whereas the mean N2O flux from noncracked X soil was 426.3 μg/(m2·h), i.e., significantly different from cracked soils. From cracked soils, the diurnal N2O emissions reached two peaks at 14:00 and 2:00, but such emissions peaked only at 2:00 from noncracked soil. The dissolved N2O concentrations in leachates from noncracked soil columns were greater than those from the cracked soil columns, and it indicated that the preferential flow might not affect the amounts of dissolved N2O in leachates during soil cracking. Supersaturated dissolved N2O in the leachate was potential source of N2O emissions. Fallow paddy fields have big risks of N2O emissions during nonflooding periods.

  15. Succession of methanotrophs in oxygen-methane counter-gradients of flooded rice paddies.

    Science.gov (United States)

    Krause, Sascha; Lüke, Claudia; Frenzel, Peter

    2010-12-01

    Little is known about population dynamics and contribution of specific taxa to methane oxidation in flooded rice paddies. In this article we investigate the succession of methanotrophs in oxygen-methane counter-gradients. We used a gradient microcosm system that simulates oxic-anoxic interfaces of a water-saturated paddy soils, and measured pmoA-based (gene encoding particulate methane monooxygenase) terminal restriction fragment length polymorphism (T-RFLP) profiles at both the transcription (mRNA) and the population (DNA) levels. The DNA T-RFLP profiles indicated that the methanotrophic community present clearly differed from the active methanotrophic community. We observed a succession of the methanotrophic community over time without any direct effect of pore water chemistry on the community structure. Both the total population and the active subpopulation changed with time, whereas methane oxidation rates remained nearly constant. Hence, we suggest that a diverse microbial seed bank of methanotrophs is important in maintaining the function in a dynamic ecosystem.

  16. 控制灌溉稻田的甲烷减排效果%Mitigation of methane emissions from paddy fields under controlled irrigation

    Institute of Scientific and Technical Information of China (English)

    彭世彰; 和玉璞; 杨士红; 徐俊增; 侯会静

    2013-01-01

    In order to explore the influence of soil moisture regulation on methane (CH4) emissions under water-saving irrigation and look for an irrigation mode for rice that would save water while simultaneously limiting CH4 emissions, the regularity of CH4 emissions from paddy fields under controlled irrigation was analyzed based on 5 years’of field experiment data. Two different irrigation managements were conducted as follows with the same rice variety, cultivation practices and plant protection measures:controlled irrigation (CI) and irrigated intermittently flooded single aeration irrigation (FI). Rice was cultivated in a 150 m2 (20 m×7.5 m) plot between 2006 and 2007, each plot was separated by brick concrete with a height of 30 cm and width of 30 cm. Plastic anti-seepage films were inserted into soil plough layer to a depth of 50cm to isolate water exchange between the plots. For exploring the influence of rainfall on CH4 emissions from irrigated paddy fields and controlling soil moisture accurately, experiments were conducted in lysimeter with mobile canopy between 2009 and 2011, and each plot area was 5 m2(2.5 m×2 m). Gas samples were collected using manual static chamber and were analyzed by a gas chromatograph (ShimadzuGC-14B) with a flame ionization detector (FID) for CH4 concentration. The results showed that the total CH4 emissions from CI paddy fields were 1.07±0.17g/m2, which was significantly reduced by 83.5%compared with FI paddy fields (6.49±0.17 g/m2). Total seasonal and annual CH4 emissions from CI and FI paddy fields located in Southeast China were lower than the reported values. Meanwhile, the total annual CH4 emissions from controlled irrigation paddy fields was lower than that of paddy filed in most parts of the World. When compared to irrigated intermittently flooded multiple aeration, irrigated intermittently flooded single aeration and irrigated continuously flooded paddy fields, seasonal CH4 emissions from CI paddy fields decreased 94

  17. Investigation of spatial distribution of radiocesium in a paddy field as a potential sink.

    Directory of Open Access Journals (Sweden)

    Kazuya Tanaka

    Full Text Available Surface soils, under various land uses, were contaminated by radionuclides that were released by the Fukushima Daiichi Nuclear Power Plant accident. Because paddy fields are one of the main land uses in Japan, we investigated the spatial distribution of radiocesium and the influence of irrigation water in a paddy field during cultivation. Soil core samples collected at a paddy field in Fukushima showed that plowing had disturbed the original depth distribution of radiocesium. The horizontal distribution of radiocesium did not show any evidence for significant influence of radiocesium from irrigation water, and its accumulation within the paddy field, since the original amount of radiocesium was much larger than was added into the paddy field by irrigation water. However, it is possible that rainfall significantly increases the loading of radiocesium.

  18. Plant/microbe cooperation for electricity generation in a rice paddy field.

    Science.gov (United States)

    Kaku, Nobuo; Yonezawa, Natsuki; Kodama, Yumiko; Watanabe, Kazuya

    2008-05-01

    Soils are rich in organics, particularly those that support growth of plants. These organics are possible sources of sustainable energy, and a microbial fuel cell (MFC) system can potentially be used for this purpose. Here, we report the application of an MFC system to electricity generation in a rice paddy field. In our system, graphite felt electrodes were used; an anode was set in the rice rhizosphere, and a cathode was in the flooded water above the rhizosphere. It was observed that electricity generation (as high as 6 mW/m(2), normalized to the anode projection area) was sunlight dependent and exhibited circadian oscillation. Artificial shading of rice plants in the daytime inhibited the electricity generation. In the rhizosphere, rice roots penetrated the anode graphite felt where specific bacterial populations occurred. Supplementation to the anode region with acetate (one of the major root-exhausted organic compounds) enhanced the electricity generation in the dark. These results suggest that the paddy-field electricity-generation system was an ecological solar cell in which the plant photosynthesis was coupled to the microbial conversion of organics to electricity.

  19. Estimate of Methane Emission from Rice Paddy Fields in Taihu Region,China

    Institute of Scientific and Technical Information of China (English)

    CAIZU-CONG; JINJI-SHENG; 等

    1994-01-01

    Methane fluxes from late rice and single cropping rice fields in Taihu region were measured using closed chamber method in 1992 and 1993 and CH4 emission from this region (total area of paddy soils was about 1.88 million hectares,of which 0.63 million hectares are distibuted in the south of Jiangsu province) was estimated on the basis of the meam CH4 fluxes observed.The results showed that the mean CH4 flaxes from late rice and single cropping rice field were quite similar under the prevailing cultivation practices in the region,being around 5 mg CH4/m2/h(4.31-5.31mg CH4/m2/h for various cultivars of the late rice and 3.20-6.22mg CH4/m2/h for various treatments of the single cropping rice).Total CH4 emission from paddy soils in the region was estimated to e 0.185-0.359 Tg CH4 per year.Continuously flooding the soil with a water layer till ripening caused higher mean CH4 flux;and addition of nitrification inhibitor(thiourea) stimulated CH4 emission.There was no simple repationship between CH4 flux and either soil temperature or soil Eh.

  20. Geochemical Transformation of Cadmium (Cd) from Creek to Paddy Fields in W Thailand

    Science.gov (United States)

    Kosolsaksakul, Peerapat; Graham, Margaret; Farmer, John

    2013-04-01

    Extensive Cd contamination of paddy soils in Tak Province, western Thailand, a consequence of Zn mining activities, was first established in 2005 and medical studies showed that the health of local communities was being impaired. Mae Tao, Tak Province, comprising many paddy fields and irrigation canals, has been selected for this study of the geochemical transformation of Cd from the contamination source in the mountainous region to the east of the study site through the community irrigation system to the paddy soils. The aim of this research is to (i) investigate the geochemical transformation of Cd as it is transported from the main irrigation creek through the canals and to the paddy fields, (ii) assess the availability of Cd to rice plants, which may be affected by both chemical and physical factors, and (iii) trial some practical treatments to minimise Cd concentrations in rice grains. Soils, irrigation canal sediments and water samples were collected during the dry season and at the onset of the rainy season. Rice samples were collected at harvesting time and samples of soil fertiliser were also obtained. Water samples were filtered, ultrafiltered and analysed by ICP-MS whilst sub-samples of dried, ground soils and sediments were first subjected to micro-wave assisted acid digestion (modified US EPA method 3052). XRD and SEM-EDX methods were used for mineralogical characterisation and selective chemical extractions have assisted in the characterisation of solid phase Cd associations. Soil Cd concentrations were in the range 2.5-87.6 µg g-1, with higher values being obtained for fields furthest from the main creek. Although current irrigation water Cd inputs are low (mean 1.9 μg L-1; flood period), high loads of suspended particles still contribute additional Cd (4.2-9.8 µg L-1) to the paddy fields. For bioavailability assessment by a 3-step BCR sequential extraction, 70-90% Cd was in the exchangeable; HOAc-extractable fraction. That indicated that most of

  1. Effect of air drying on speciation of heavy metals in flooded rice paddies

    Institute of Scientific and Technical Information of China (English)

    Bao Wang; Biao Huang; Yan Bing Qi; Wen You Hu; Wei Xia Sun

    2012-01-01

    Flooded soil samples were collected in the typical area of the Yangtze Delta Region; fractions of heavy metals in flooded and air dried samples were measured with BCR sequential extraction method and atomic absorption spectrometry.In flooded soils,fractions of heavy metals increased in the order of acid soluble < oxidizable < reducible < residual.The acid soluble and reducible fractions significantly decreased but residual fraction significantly increased when the samples were air dried.The data obtained from air dried soil samples could not accurately represent the speciation of heavy metals in flooded field conditions.

  2. A GIS-Based Database Management Package for Fertilizer Recommendations in Paddy Fields

    Institute of Scientific and Technical Information of China (English)

    ZHOU Lian-Qing; SHI Zhou; WANG Ren-Chao; J. BAILEY

    2004-01-01

    Over-use of fertilizer in paddy fields could lead to agro-environmental pollution. Therefore, the Paddy Fertilizer Recommendation System (PFRS) application package was designed to aid in the dissemination of fertilizer recommendations for paddy fields. PFRS utilized geographical information system (GIS) ActiveX Controls, enabling the user to select a location of interest linked to a spatial database of paddy field soil characteristics. The application package also incorporated different soil fertilizer recommendation methods, forming a relational database. The application's structure consisted primarily of building database queries using Standard Query Language (SQL) constructed during run-time, based on user provided spatial parameters of a selected location, the type of soil desired and paddy production criteria. PFRS, which was comprised of five modules including: File, View, Edit, Layer and Fertilizer/Model, provided the user with map-based fertilizer recommendations based on selected soil nutrient P and K map layers as well as N characteristics and land use maps.

  3. Nitrogen and phosphorus effluent loads from a paddy-field district adopting collective crop rotation.

    Science.gov (United States)

    Hama, T; Aoki, T; Osuga, K; Sugiyama, S; Iwasaki, D

    2012-01-01

    Japanese paddy rice systems commonly adopt the rotation of vegetables, wheat and soybeans with paddy rice. Crop rotation may, however, increase the nutrient load in effluent discharged from the district because more fertilizer is applied to the rotation crops than is applied to paddy crops. We investigated a paddy-field district subject to collective crop rotation and quantified the annual nutrient load of effluent from the district in three consecutive years. The total annual exports of nitrogen and phosphorus over the investigation period ranged from 30.3 to 40.6 kg N ha(-1) and 2.62 to 3.13 kg P ha(-1). The results suggest that rotation cropping increases the effluent nutrient load because applied fertilizer is converted to nitrate, and surface runoff is increased due to the absence of shuttering boards at the field outlets.

  4. Measurement and estimation of radiocesium discharge rate from paddy field during land preparation and mid-summer drainage.

    Science.gov (United States)

    Miyazu, Susumu; Yasutaka, Tetsuo; Yoshikawa, Natsuki; Tamaki, Shouhei; Nakajima, Kousei; Sato, Iku; Nonaka, Masanori; Harada, Naoki

    2016-05-01

    In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation.

  5. Metabolic degradation of imidacloprid in paddy field soil.

    Science.gov (United States)

    Akoijam, Romila; Singh, Balwinder

    2014-10-01

    The metabolic degradation and persistence of imidacloprid in paddy field soil were investigated following two applications of imidacloprid at 20 and 80 g a.i. ha(-1) at an interval of 10 days. The soil samples were collected at various time intervals. The limit of quantification for the analysis of imidacloprid and its metabolites was obtained at the concentration of 0.01 mg kg(-1). The initial deposits of total imidacloprid were found to be 0.44 and 1.61 mg kg(-1) following second applications. These residues could not be detected after 60 and 90 days following second applications of imidacloprid at lower and higher dosages, respectively. In soil, urea metabolite was found to be the maximum, followed by olefine, nitrosimine, 6-chloronicotinic acid, 5-hydroxy and nitroguanidine. The half-life values (t₁/₂) of imidacloprid were worked out to be 12.04 and 11.14 days, respectively, when applied at lower and higher doses, respectively.

  6. Emission Laws and Influence Factors of Greenhouse Gases in Saline-Alkali Paddy Fields

    Directory of Open Access Journals (Sweden)

    Jie Tang

    2016-02-01

    Full Text Available The study of greenhouse gas emissions has become a global focus, but few studies have considered saline-alkali paddy fields. Gas samples and saline-alkali soil samples were collected during the green, tillering, booting, heading and grain filling stages. The emission fluxes of CO2, CH4, and N2O as well as the pH, soil soluble salt, available nitrogen, and soil organic carbon contents were detected to reveal the greenhouse gas (GHG emission laws and influence factors in saline-alkali paddy fields. Overall, GHG emissions of paddy soil during the growing season increased, then decreased, and then increased again and peaked at booting stage. The emission fluxes of CO2 and CH4 were observed as having two peaks and a single peak, respectively. Both the total amount of GHG emission and its different components of CO2, CH4, and N2O increased with the increasing reclamation period of paddy fields. A positive correlation was found between the respective emission fluxes of CO2, CH4, and N2O and the available nitrogen and SOC, whereas a negative correlation was revealed between the fluxes of CO2, CH4, and N2O and soil pH and soil conductivity. The study is beneficial to assessing the impact of paddy reclamation on regional greenhouse gas emissions and is relevant to illustrating the mechanisms concerning the carbon cycle in paddy soils.

  7. Dynamic Variation Characteristics of Phosphorus in Paddy Field Runoff in Saline Land and Its Potential Environmental Effect

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [Method] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed. [Result] Surface water in paddy field was alkaline, and scattered soil had poor fertilizer conser...

  8. 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

    2016-03-16

    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.

  9. Speciation and release kinetics of cadmium in an alkaline paddy soil under various flooding periods and draining conditions.

    Science.gov (United States)

    Khaokaew, Saengdao; Chaney, Rufus L; Landrot, Gautier; Ginder-Vogel, Matthew; Sparks, Donald L

    2011-05-15

    This study determined Cd speciation and release kinetics in a Cd-Zn cocontaminated alkaline paddy soil, under various flooding periods and draining conditions, by employing synchrotron-based techniques, and a stirred-flow kinetic method. Results revealed that varying flooding periods and draining conditions affected Cd speciation and its release kinetics. Linear least-squares fitting (LLSF) of bulk X-ray absorption fine structure (XAFS) spectra of the air-dried, and the 1 day-flooded soil samples, showed that at least 50% of Cd was bound to humic acid. Cadmium carbonates were found as the major species at most flooding periods, while a small amount of cadmium sulfide was found after the soils were flooded for longer periods. Under all flooding and draining conditions, at least 14 mg/kg Cd was desorbed from the soil after a 2-hour desorption experiment. The results obtained by micro X-ray fluorescence (μ-XRF) spectroscopy showed that Cd was less associated with Zn than Ca, in most soil samples. Therefore, it is more likely that Cd and Ca will be present in the same mineral phases rather than Cd and Zn, although the source of these two latter elements may originate from the same surrounding Zn mines in the Mae Sot district.

  10. Depth distribution of radiocesium in Fukushima paddy fields three years after the accident

    Science.gov (United States)

    Lepage, Hugo; Laceby, J. Patrick; Evrard, Olivier; Onda, Yuichi; Lefèvre, Irène; Ayrault, Sophie

    2015-04-01

    Rice paddy fields located in the vicinity of the Fukushima Dai-Ichi Nuclear Power Plant (FDNPP) were contaminated by radioactive fallout from the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of radiocesium in rice paddy fields requires further examination after major typhoons occurred in this region in 2011 and 2013. Further investigations are also required because paddy fields are typically comprised of Andosols, a soil type in which radiocesium has been known to potentially migrate deeper in the depth profile. To investigate the depth migration of radiocesium we collected soil cores in 10 paddy fields located less than 20 km from the FDNPP in November 2013. The maximum depth penetration of 137Cs was attributed to field maintenance (e.g. grass cutting) (97% of 137Cs in the upper 5-cm) and farming operations (tillage/cultivation - 83% of 137Cs in the upper 5-cm). The low migration observed in undisturbed paddy fields could be attributed to the presence of phyllosilicates that were detected by X-ray diffraction in Andosols. As radiocesium is mainly located in the uppermost soil layers, we recommend the rapid removal of these upper layers (e.g. the top 5 cm) to reduce radiocesium export during erosive events such as the major typhoons known to impact the region. Further research is required to thoroughly understand the impacts of erosion on the transfer and migration of radiocesium throughout the Fukushima Prefecture.

  11. 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.

  12. [Effects of different multiple cropping systems on paddy field weed community under long term paddy-upland rotation].

    Science.gov (United States)

    Yang, Bin-Juan; Huang, Guo-Qin; Xu, Ning; Wang, Shu-Bin

    2013-09-01

    Based on a long term field experiment, this paper studied the effects of different multiple cropping systems on the weed community composition and species diversity under paddy-upland rotation. The multiple cropping rotation systems could significantly decrease weed density and inhibited weed growth. Among the rotation systems, the milk vetch-early rice-late maize --> milk vetchearly maize intercropped with early soybean-late rice (CCSR) had the lowest weed species dominance, which inhibited the dominant weeds and decreased their damage. Under different multiple cropping systems, the main weed community was all composed of Monochoia vaginalis, Echinochloa crusgalli, and Sagittaria pygmae, and the similarity of weed community was higher, with the highest similarity appeared in milk vetch-early rice-late maize intercropped with late soybean --> milk vetch-early maize-late rice (CSCR) and in CCSR. In sum, the multiple cropping rotations in paddy field could inhibit weeds to a certain extent, but attentions should be paid to the damage of some less important weeds.

  13. 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 (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 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.

  14. Identification of paddy field using Landsat image in Karawang Regency, West Java

    Science.gov (United States)

    Riadi, Bambang; Budiman Suriadi, Ahmad

    2017-01-01

    The Government of the Republic of Indonesia has a mission to achieve food self-sufficiency in 2017, therefore it is necessary efforts to the stability of food needs. Karawang Regency as a granary states have a vital role in maintaining the national rice self-sufficiency, so indispensable information paddy field area. Paddy field accurate mapping can be done with a fast and efficient method of using remote sensing technology. This study aims to identify the paddy field using remote sensing technology. The data used is Landsat TM 2002 and Landsat-8 2015. The classification method using an approach Normalized Difference Vegetation Index (NDVI) and the Tasseled Cap Transformation (TCT). This method can be implemented to identify the fields that are still green or in the growing season. TCT produces three images of the six combinations, namely Brightness (BRT), greenness (GRN), and wetness (WET). BRT provides graytone gradation of non vegetation to water. GRN is indicated the gradation of vegetation cover, begin from densely vegetated until the most rare or non-vegetated areas. While wetness (WET) indicates the area associated with the presence of water. The main results of the classification is not a wetland and paddy. Based on existing data paddy land area of research area is ± 57% of the area of Karawang Regency.

  15. The Potential for Abandoned Paddy Fields to Reduce Pollution Loads from Households in Suburban Tokyo

    Directory of Open Access Journals (Sweden)

    Makoto Yokohari

    2010-09-01

    Full Text Available Similar to other Asian nations, suburban areas in Japan are characterized by dense intermixtures of residential areas and farmlands. These hybrid rural/urban areas are evaluated negatively in modern planning frameworks. However, mixed rural/urban landscapes may prove advantageous when attempting to reconstruct sustainable wastewater treatment systems. This research examines the potential for abandoned paddy fields to reduce nitrogen (T-N and phosphorous (T-P loads, an increasingly problematic source of eutrophication in many closed water areas, from households in suburban areas. Our results indicate that abandoned paddy fields remaining in mixed urban/rural areas have significant potential to reduce both nitrogen and phosphorous loads. Accordingly, we suggest that abandoned paddy fields can play an important role in reducing pollution loads in mixed urban/rural areas.

  16. Influences of Quinclorac on Culturable Microorganisms and Soil Respiration in Flooded Paddy Soil

    Institute of Scientific and Technical Information of China (English)

    ZHEN-MEI LU; HANG MIN; YANG-FANG YE

    2003-01-01

    Objective To investigate the potential effects of herbicide quinclorac (3,7-dichloro-8-quinoline-carboxylic) on the culturable microorganisms in flooded paddy soil. Methods Total soil aerobic bacteria, actinomycetes and fungi were counted by a 10-fold serial dilution plate technique. Numbers of anaerobic fermentative bacteria (AFB), denitrifying bacteria (DNB) and hydrogen-producing acetogenic bacteria (HPAB) were numerated by three-tube anaerobic most-probable-number (MPN)methods with anaerobic liquid enrichment media. The number of methanogenic bacteria (MB) and nitrogen-fixing bacteria (NFB) was determined by the rolling tube method in triplicate. Soil respiration was monitored by a 102G-type gas chromatography with a stainless steel column filled with GDX-104 and a thermal conductivity detector. Results Quinclorac concentration was an important factor affecting the populations of various culturable microorganisms. There were some significant differences in the aerobic heterotrophic bacteria. AFB and DNB between soils were supplemented with quinclorac and non-quinclorac at the early stage of incubation, but none of them was persistent. The number of fungi and DNB was increased in soil samples treated by lower than1.33 μg·g-1 dried soil, while the CFU of fungi and HPAB was inhibited in soil samples treated by higher than 1.33 μg·g-1 dried soil. The population of actinomycete declined in negative proportion to the concentrations of quinclorac applied after 4 days. However, application of quinclorac greatly stimulated the growth of AFB and NFB. MB was more sensitive to quinclorac than the others, and the three soil samples with concentrations higher than 1 μg·g-1 dried soil declined significantly to less than 40% of that in the control, but the number of samples with lower concentrations of quinclorac was nearly equal to that in the control at the end of experiments. Conclusion Quinclorac is safe to the soil microorganisms when applied at normal

  17. Arsenic release from flooded paddy soils is influenced by speciation, Eh, pH, and iron dissolution.

    Science.gov (United States)

    Yamaguchi, N; Nakamura, T; Dong, D; Takahashi, Y; Amachi, S; Makino, T

    2011-05-01

    Arsenic (As) is highly mobilized when paddy soil is flooded, causing increased uptake of As by rice. We investigated factors controlling soil-to-solution partitioning of As under anaerobic conditions. Changes in As and iron (Fe) speciation due to flooded incubation of two paddy soils (soils A and B) were investigated by HPLC/ICP-MS and XANES. The flooded incubation resulted in a decrease in Eh, a rise in pH, and an increase in the As(III) fraction in the soil solid phase up to 80% of the total As in the soils. The solution-to-soil ratio of As(III) and As(V) (R(L/S)) increased with pH due to the flooded incubation. The R(L/S) for As(III) was higher than that for As(V), indicating that As(III) was more readily released from soil to solution than was As(V). Despite the small differences in As concentrations between the two soils, the amount of As dissolved by anaerobic incubation was lower in soil A. With the development of anaerobic conditions, Fe(II) remained in the soil solid phase as the secondary mineral siderite, and a smaller amount of Fe was dissolved from soil A than from soil B. The dissolution of Fe minerals rather than redox reaction of As(V) to As(III) explained the different dissolution amounts of As in the two paddy soils. Anaerobic incubation for 30 d after the incomplete suppression of microbial activity caused a drop in Eh. However, this decline in Eh did not induce the transformation of As(V) to As(III) in either the soil solid or solution phases, and the dissolution of As was limited. Microbial activity was necessary for the reductive reaction of As(V) to As(III) even when Eh reached the condition necessary for the dominance of As(III). Ratios of released As to Fe from the soils were decreased with incubation time during both anaerobic incubation and abiotic dissolution by sodium ascorbate, suggesting that a larger amount of As was associated with an easily soluble fraction of Fe (hydr) oxide in amorphous phase and/or smaller particles. Copyright

  18. Fertilization Management of Paddy Fields in Piedmont (NW Italy

    Directory of Open Access Journals (Sweden)

    Laura Zavattaro

    Full Text Available A well-documented analysis of fertilization management techniques in use by farmers in a given region is the first step to improving the management standards of agronomic practices. The aim of this work was to summarize the fertilization management that farmers normally utilize for the rice crop in the Piedmont Region of Northwest Italy, and to analyze its agronomic and environmental sustainability. On average, 127 kg ha-1 of N, 67 kg ha-1 of P2O5, and 161 kg ha-1 of K2O were applied to the rice crop. Inorganic fertilizers were used on most of the surface. Calcium cyanamide was the most widely used slow-release product. Commercial organic compounds were spread on about 32% of the paddy surface, while farmyard manure was distributed over 6% of the surface. Organic-mineral products were also widely used. One fourth of the paddy surface received only inorganic products. Using organic or organic-mineral fertilizers together with inorganic products was the most common strategy (55% of the paddy surface. In most cases, N and P fertilization was balanced with crop removal. The N soil surface balance was in the ± 50 kg range for 77% of the surface, P fertilization was less than removal for 53% of the surface, whereas K fertilization was excessive (surplus >100 kg ha-1 for 53% of the surface. The nutrient balance was affected by the widespread practice of burning straw after harvest (66% of the paddy surface. The farmers modulated fertilization according to the rice variety requirements and tolerance to high N supply. The largest nutrient surplus was associated with stocking farms. Inefficient use of fertilizers that should be avoided to improve the territorial nutrient balance were then outlined, and possible specific actions were proposed.

  19. Impact of fungicide and insecticide use on non-target aquatic organisms in rice paddy fields

    Directory of Open Access Journals (Sweden)

    Alana Cristina Dorneles Wandscheer

    Full Text Available ABSTRACT: The intensive use of plant protection products in rice paddy fields ( Oryza sativa L. has caused concern about the environmental impact on communities of non-target organisms that are natural inhabitants in these agroecosystems. The purpose of this review is to analyze the data currently available in the literature about some important fungicides and insecticides (such as trifloxystrobin, tebuconazole, tricyclazole, lambda-cyhalothrin, and thiamethoxam, which are currently used to control pests and diseases in rice paddy fields, as well as their effects on the community of non-target aquatic organisms.

  20. Estimation of soil moisture in paddy field using Artificial Neural Networks

    CERN Document Server

    Arif, Chusnul; Setiawan, Budi Indra; Doi, Ryoichi

    2013-01-01

    In paddy field, monitoring soil moisture is required for irrigation scheduling and water resource allocation, management and planning. The current study proposes an Artificial Neural Networks (ANN) model to estimate soil moisture in paddy field with limited meteorological data. Dynamic of ANN model was adopted to estimate soil moisture with the inputs of reference evapotranspiration (ETo) and precipitation. ETo was firstly estimated using the maximum, average and minimum values of air temperature as the inputs of model. The models were performed under different weather conditions between the two paddy cultivation periods. Training process of model was carried out using the observation data in the first period, while validation process was conducted based on the observation data in the second period. Dynamic of ANN model estimated soil moisture with R2 values of 0.80 and 0.73 for training and validation processes, respectively, indicated that tight linear correlations between observed and estimated values of s...

  1. Studies on mosquitoes (Diptera: Culicidae and anthropicenvironment: 5- Breeding of Anopheles albitarsis in flooded rice fields in South-Eastern Brazil

    Directory of Open Access Journals (Sweden)

    Forattini Oswaldo Paulo

    1994-01-01

    Full Text Available Studies on breeding Anopheles albitarsis and association with rice growth in irrigated paddy fields were carried out during the rice cultivation cycle from December 1993 to March 1994. This period corresponded to the length of time of permanent paddy flooding. Breeding occurred in the early stage up until five weeks after transplantation when rice plant height was small. That inverse correlation may give potential direction to control measures.

  2. Studies on mosquitoes (Diptera: Culicidae and anthropicenvironment: 5- Breeding of Anopheles albitarsis in flooded rice fields in South-Eastern Brazil

    Directory of Open Access Journals (Sweden)

    Oswaldo Paulo Forattini

    1994-10-01

    Full Text Available Studies on breeding Anopheles albitarsis and association with rice growth in irrigated paddy fields were carried out during the rice cultivation cycle from December 1993 to March 1994. This period corresponded to the length of time of permanent paddy flooding. Breeding occurred in the early stage up until five weeks after transplantation when rice plant height was small. That inverse correlation may give potential direction to control measures.

  3. [Distribution characteristics of soil profile nitrous oxide concentration in paddy fields with different rice-upland crop rotation systems].

    Science.gov (United States)

    Liu, Ping-li; Zhang, Xiao-lin; Xiong, Zheng-qin; Huang, Tai-qing; Ding, Min; Wang, Jin-yang

    2011-09-01

    To investigate the dynamic distribution patterns of nitrous oxide (N2O) in the soil profiles in paddy fields with different rice-upland crop rotation systems, a special soil gas collection device was adopted to monitor the dynamics of N2O at the soil depths 7, 15, 30, and 50 cm in the paddy fields under both flooding and drainage conditions. Two rotation systems were installed, i.e., wheat-single rice and oilseed rape-double rice, each with or without nitrogen (N) application. Comparing with the control, N application promoted the N2O production in the soil profiles significantly (P cropping treatments. The soil N2O concentrations in the treatments without N application peaked in the transitional period from the upland crops cropping to rice planting, while those in the treatments with N application peaked right after the second topdressing N of upland crops. Relatively high soil N2O concentrations were observed at the transitional period from the upland crops cropping to rice planting.

  4. Microbial electricity generation in rice paddy fields: recent advances and perspectives in rhizosphere microbial fuel cells.

    Science.gov (United States)

    Kouzuma, Atsushi; Kaku, Nobuo; Watanabe, Kazuya

    2014-12-01

    Microbial fuel cells (MFCs) are devices that use living microbes for the conversion of organic matter into electricity. MFC systems can be applied to the generation of electricity at water/sediment interfaces in the environment, such as bay areas, wetlands, and rice paddy fields. Using these systems, electricity generation in paddy fields as high as ∼80 mW m(-2) (based on the projected anode area) has been demonstrated, and evidence suggests that rhizosphere microbes preferentially utilize organic exudates from rice roots for generating electricity. Phylogenetic and metagenomic analyses have been conducted to identify the microbial species and catabolic pathways that are involved in the conversion of root exudates into electricity, suggesting the importance of syntrophic interactions. In parallel, pot cultures of rice and other aquatic plants have been used for rhizosphere MFC experiments under controlled laboratory conditions. The findings from these studies have demonstrated the potential of electricity generation for mitigating methane emission from the rhizosphere. Notably, however, the presence of large amounts of organics in the rhizosphere drastically reduces the effect of electricity generation on methane production. Further studies are necessary to evaluate the potential of these systems for mitigating methane emission from rice paddy fields. We suggest that paddy-field MFCs represent a promising approach for harvesting latent energy of the natural world.

  5. Behavior of Suspended Sediments with Radionuclide in the Paddy Field, Fukushima Japan

    Science.gov (United States)

    Wakahara, T.; Onda, Y.; Kato, H.

    2011-12-01

    After the nuclear reactor accident in Fukushima on March 11, 2011, huge amounts of radionuclide such as Caesium-137, which is an artificial radionuclide with a half-life of 30.17 years, has been produced. Most of the fallen Cs-137 infiltrated into soil together with rainfall and was absorbed by soil sediments. The potential concentration of radionuclides into paddy field, as investigated in this study, has consequency on health, agriculture and remediation of contaminated areas. Paddy field typically are flat, surrounded by dams (10-50 cm)delimiting small pools with a water level of approximately20cm. Therefore, they can potentially catch huge amounts of suspended sediments from incoming rivers. However, recent studies suggested the paddy field can be a source of suspended sediments in some conditions. In this study, we intended to investigate the characteristics of Cs137 associated to sediment into paddy field as well as its incoming and outgoing and flux of that in paddy field. The study site was set on the Yoshiguchi, Kawamata-cho, Fukushima prefecture(N 37 35' 26.15", E140 38' 14.97"). This place is located 30km from the damaged Fukushima nuclear reactor. Two plots were set: One was tillaged as usual (plot UE, 30x17m), while the upper 5 to 10 cm of the other plot's surface was scraped before tillage.(plot ST, 43x17m). The lower part of each plot has a Parshall flume with water gauge, turbidimeter and rain gauge. After tillage, water was put into the plot field and rice seedlings were transplanted. Every week we corrected a suspended sediment samples and measured Cs137 concentration. At the plot ST, out flow of the Cs137 density was less than 35% of that of UE plot.

  6. Effects of Fipronil Insecticide Application on Sympetrum sp. Larvae and Adults in Experimental Rice Paddy Field

    Science.gov (United States)

    Jinguji, Hiroshi; Ueda, Tetsuyuki; Tsunoda, Manami; Aihara, Shoko; Saito, Mitsuo

    The effect of on sowing and before transplanting application of the phenyl pyrazole insecticide, fipronil, on the survivorship Sympetrum spp. was investigated in plots of an experimental rice paddy field. In addition, the effect of two pesticide applications on rice weevils was investigated. A total of nine paddy plots were used in this study: three were treated with fipronil at the before transplanting application , three at the on sowing application, and the three remaining plots were left untreated for use as controls. Fipronil concentrations in paddy water at the time of application in before transplanting and on sowing treatments reached 1.45 and 1.20 μg/L, respectively. A comparison of experimental and control plots revealed a marked absence of Sympetrum frequens larvae, exuviae and adults from fipronil-treated fields. Adult density of Sympetrum sp. and members of Lestidae in paddy fields before transplanting application were considerably lower than in control plots. Our results show that before transplanting application is more effective than on sowing application for treating rice weevils, but that on sowing application may still be harm against dragonflies.

  7. Dermatoses among paddy field workers - A descriptive, cross-sectional pilot study

    Directory of Open Access Journals (Sweden)

    Shenoi Shrutakirthi

    2005-01-01

    Full Text Available BACKGROUND: Paddy farming is one of the main occupations in coastal South India. Dermatological problems in paddy field workers have not received much attention. AIM : The purpose of this study was to study the dermatoses of the exposed parts of the body, viz. face, hands, and feet, in paddy field workers. METHODS: Three hundred and forty-one workers were questioned and clinical findings noted. Scrapings for bacterial and fungal examination were taken by random selection. RESULTS: Seventy-three per cent had work-related itching. Melasma was the commonest facial lesion (41.1%. The main problems on the hands were hyperkeratosis (26.4%, nail dystrophy (15.2% and paronychia (8.8%. Common feet dermatoses included nail dystrophy (57.1%, pitted keratolysis (42.5% and fissuring (23.5%. Common aerobic and anaerobic bacteria isolated from pitted keratolysis and intertrigo were Klebsiella and Clostridium species. Aspergillus species were the commonest fungus grown from intertrigo. CONCLUSIONS: Occupational dermatoses are common in paddy field workers.

  8. Changes in Soil Properties of Paddy Fields Across A Cultivation Chronosequence in Subtropical China

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-Pei; ZHANG Tao-Lin; LI De-Cheng; B.VELDE; HAN Feng-Xiang

    2005-01-01

    Rice production plays a crucial role ia the food supply of China and a better understanding of the changes in paddy soil fertility and the management effects is of practical importance for increasing rice productivity. In this study, field sampling in a typical red soil region of subtropical China, Jiangxi Province, was used to observe changes in the soil physical, chemical,and biological properties in a cultivation chronosequence of paddy fields. After cultivation, clay (< 0.002 mm) content in the soil, which was 39% in the original uncultivated wasteland, decreased to 17% in the 80-year paddy field, while silt(0.02-0.002 mm) content increased. Additionally, macroporosity increased and pore shapes became more homogeneous.Soil pH generally increased. Soil organic C and total N contents of the 0-10 cm layer increased from 4.58 and 0.39 g kg-1to 19.6 and 1.62 g kg-1, respectively, in the paddy fields after 30-year cultivation and then remained stable. Soil total P content increased from 0.5 to 1.3 g kg-1 after 3 years of rice cultivation, indicating that application of phosphate fertilizer could accelerate phosphorous accumulation in the soil. Total K content in the 0-10 cm soil layer for the 80-year paddy field decreased by 28% compared to that of the uncultivated wasteland land. Total Fe and free Fe contents declined with years of cultivation. The bacterial population increased and urease activity noticeably intensified after years of cultivation.In this chronosequence it appeared that it took 30 years to increase soil fertility to a relatively constant value that was seen after 80 years of cultivation.

  9. Dynamics, Residue and Risk Assessment of Nitenpyram in Rice and Paddy Field

    Directory of Open Access Journals (Sweden)

    YUAN Xue-xia

    2016-09-01

    Full Text Available Residues dynamics, final residual levels and dietary intake risk of nitenpyram in rice and paddy field were investigated in three dif-ferent regions of China(Shandong, Henan and Anhui. A method was illustrated to detect nitenpyram residues in paddy, plant, brown rice, paddy water and soil. The residues in paddy and rice were extracted with methanol+phosphate buffer(0.2 mol·L-1, pH=7.0(60+40, adjust pH to 2.5, then cleaned up with solid phase extraction column and 0.22 μm filter membrane, and then analyzed by HPLC with an ul-traviolet detector at 260 nm. When spiked 0.05, 0.5, 1.0 mg·kg-1, the recoveries of nitenpyram in paddy plant and brown rice were 78.4%~94.7% and 84.0%~94.2%, respectively. The residues in paddy water and soil were extracted with phosphate buffer (0.2 mol·L-1, pH=7.0, when spiked 0.01, 0.5, 1.0 mg·kg-1, the recoveries of nitenpyram in paddy water and soil were 84.6%~98.0% and 93.7%~97.1%, respective-ly, which indicated this method match the requirement of the detection. Two years results showed that nitenpyram belongs to easily degraded pesticides, because all half-lives were below 1.4 d in rice plant, as well as below 4.2 d in paddy water. Final residual levels of nitenpyram in rice were all below 0.05 mg·kg-1,which was far below the Japanese maximum residue limit(0.5 mg·kg-1. The risk quotients (RQs were low for different populations in China, which indicated its low risk in rice. Therefore, the rice with nitenpyram applied, according to the recom-mend method, 45 g·hm-2 application once, with 21 days collection interval, was safe.

  10. Sustainability of terraced paddy fields in traditional satoyama landscapes of Japan.

    Science.gov (United States)

    Fukamachi, Katsue

    2016-12-03

    Terraced paddy fields are essential components of the traditional cultural landscape of Japan, the satoyama landscape. They have been sustainably cultivated in a variety of ecological and social environments through time, and are highly valued as local resources with multiple functions. This paper reviews the recent nationwide movement for conservation of satoyama landscapes and shows that over the last decades, the government has increasingly created policies based on national regulation or international frameworks that concern the culture and environment in rural areas. Recent measures for the sustainability of terraced paddy fields do not only focus on rice terraces, but are directed at each satoyama landscape as a whole under careful consideration of how landscape elements are connected while taking into account the unique features of each area. Nevertheless, it has become difficult to ensure the continued use and maintenance of terraced rice paddies both in depopulated and suburban satoyama landscapes. The motivation for conserving satoyama landscapes, including those with terraced rice paddies, can be found in the awareness and appreciation of the unique characteristics of each locality that offer opportunities that can only be experienced in that particular area. A satoyama landscape that offers such opportunities allows continuity of traditional practices while integrating necessary changes.

  11. The Effects of Controlled Drainage on N Concentration and Loss in Paddy Field

    Directory of Open Access Journals (Sweden)

    Bin Lu

    2016-01-01

    Full Text Available To relieve the situation of the agricultural nonpoint pollution (NPS in south and east China, paddy field controlled drainage (PFCD is applied as an important and efficient approach to agricultural water management. A series of PFCD tests at four major growth stages of rice were conducted by use of 18 lysimeters. Concentration of ammonia nitrogen (NH4+-N and nitrate nitrogen (NO3--N in surface and subsurface paddy water was observed. The results indicated that the concentration of NH4+-N and NO3--N in paddy water declined with the persistence of a waterlogged condition. Compared to traditional drainage, PFCD reduced N loss in surface water by 95.6%, 78.7%, 59.6%, and 87.4% at the stage of tillering, jointing-booting, heading-flowering, and milking, respectively. It should be noted that loads of N losses in surface water increased on the fourth day after waterlogging at the jointing-booting and milking stage, and surface water exhibited higher N concentration on the first day after waterlogging at each stage. Therefore, paddy field surface water drainage should be avoided in these periods.

  12. Mapping paddy rice distribution using multi-temporal Landsat imagery in the Sanjiang Plain, northeast China

    Institute of Scientific and Technical Information of China (English)

    Cui JIN; Xiangming XIAO; Jinwei DONG; Yuanwei QIN; Zongming WANG

    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 (500m 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.

  13. Ecological interaction between insect pests, climatic factors and plant traits on abundance of beneficial insects in paddy field

    Directory of Open Access Journals (Sweden)

    Norazliza, R.

    2016-04-01

    Full Text Available The presences of beneficial insects in the paddy field are very important for the ecological systems of paddy field as those insects could help managing the population of the pests. Hence, it will reduce the dependence on pesticides usage to combat the population of insect pests. This study was aimed to study on ecological interaction between environmental factors such as insect pests, plant height, rainfall, temperature and humidity with abundance of beneficial insects in paddy field of Sungai Burong, Tanjung Karang, Selangor for two seasons of paddy planting. Low number of insects composition were recorded in paddy field at Sungai Burong during the vegetative phase and highest during the reproductive and maturity phases for two seasons of paddy planting. The trend of mean composition of insects were gradually increasing from vegetative to maturity phases while, the ecological interaction between insect pests, climatic factors and plant traits were acceptable as good predictor for all beneficial insects collected in this study namely Zygoptera, Gerridae, Coccinellidae and Staphylinidae except for Anisoptera. Therefore, consideration on several stated factors by maintaining or conserving ecology and controlling practices in good manner in paddy field has high potential and more reliable to control insect pests effectively using beneficial insects.

  14. Screening of inorganic and organic contaminants in floodwater in paddy fields of Hue and Thanh Hoa in Vietnam

    DEFF Research Database (Denmark)

    Trinh Thu, Ha; Marcussen, Helle; Hansen, Hans Chr. Bruun

    2017-01-01

    was investigated in Thanh Hoa and Hue. Water samples were taken at 16 locations in canals, paddy fields and rivers before and during the flood. In total, 940 organic micro-pollutants in the water samples were determined simultaneously by GC-MS method with automatic identification and quantification system (AIQS......In the rainy season, rice growing areas in Vietnam often become flooded by up to 1.5 m water. The floodwater brings contaminants from cultivated areas, farms and villages to the rice fields resulting in widespread contamination. In 2012 and 2013, the inorganic and organic contaminants in floodwater......), while ICP-MS was used for determination of ten trace elements in the samples. The concentrations of 277 organic micro-pollutants and ten elements (As, Cu, Cd, Cr, Co, Pb, Zn, Fe, Mn, Al) ranged from 0.01 to 7.6 μg L−1 and 0.1 to 3170 μg L−1, respectively, in the floodwater. Contaminants originated from...

  15. 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.

  16. First flush characteristics of rainfall runoff from a paddy field in the Taihu Lake watershed, China.

    Science.gov (United States)

    Li, Songmin; Wang, Xiaoling; Qiao, Bin; Li, Jiansheng; Tu, Jiamin

    2017-02-06

    Nonpoint storm runoff remains a major threat to surface water quality in China. As a paddy matures, numerous fertilizers are needed, especially in the rainy seasons; the concentration of nitrogen and phosphorus in rainfall runoff from farmland is much higher than at other times, and this poses a great threat to water bodies and is the main reason for water eutrophication, especially in high concentration drainages. To date, most studies regarding the characteristics of pollutants in rainfall runoff have mainly been concentrated on urban runoff and watershed runoff; therefore, it is particularly important to investigate the characteristics of nitrogen and phosphorus loss in rainfall runoff from paddy fields. To study the characteristics of nitrogen and phosphorus loss and whether the first flush effect exists, continuous monitoring of the rainfall runoff process of six rainfall events was conducted in 2013, of which four rainfall events during storm, high, middle, and low intensity rainfalls were analyzed, and runoff and quality parameters, such as suspended solids (SS), total nitrogen (TN), ammonium nitrogen (NH4(+)-N), nitrate nitrogen (NO3(-)-N), total phosphorus (TP), and phosphate (PO4(3-)-P), were analyzed to determine the relationship between runoff and water quality. The paddy field is located north of Wuxi Lake Basin along the Hejia River upstream in Zhoutie town, Yixing city. An analysis of the load distribution during rainfall runoff was conducted. Event mean concentration (EMC) was used to evaluate the pollution situation of the paddy field's rainfall runoff. A curve of the dimensionless normalized cumulative load (L) vs. normalized cumulative flow (F) (L-F curve), the probability of the mass first flush (MFFn), and the pollutants carried by the initial 25% of runoff (FF25) were used to analyze the first flush effect of the paddy field runoff, and different contaminants show different results: the concentration of nitrogen and phosphorus fluctuate and

  17. 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

  18. [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.

  19. Purification of contaminated paddy fields by clean water irrigation over two decades.

    Science.gov (United States)

    Tai, Yiping; Lu, Huanping; Li, Zhian; Zhuang, Ping; Zou, Bi; Xia, Hanping; Wang, Faming; Wang, Gang; Duan, Jun; Zhang, Jianxia

    2013-10-01

    Paddy fields near a mining site in north part of Guangdong Province, PR China, were severely contaminated by heavy metals as a result of wastewater irrigation from the tailing pond. The following clean water irrigation for 2 decades produced marked rinsing effect, especially on Pb and Zn. Paddy fields continuously irrigated with wastewater ever since mining started (50 years) had 1,050.0 mg kg−1 of Pb and 810.3 mg kg−1 of Zn for upper 20 cm soil, in comparison with 215.9 mg kg−1 of Pb and 525.4 mg kg−1 of Zn, respectively, with clean water irrigation for 20 years. Rinsing effect mainly occurred to a depth of upper 40 cm, of which the soil contained highest metals. Copper and Cd in the farmlands were also reduced due to clean water irrigation. Higher availability of Pb might partly account for more Pb transferred from the tailing pond to the farmland and also more Pb removal from the farmland as a result of clean water irrigation. Neither rice in the paddy field nor dense weeds in the uncultivated field largely took up the metals. However, they might contribute to activate metals differently, leading to a different purification extent. Rotation of rice and weed reduced metal retention in the farmland soil, in comparison with sole rice growth. Harvesting of rice grain (and partially rice stalk) only contributed small fraction of total amount of removed metal. In summary, heavy metal in paddy field resulting from irrigation of mining wastewater could be largely removed by clean water irrigation for sufficient time.

  20. Investigation of possible horizontal gene transfer from transgenic rice to soil microorganisms in paddy rice field.

    Science.gov (United States)

    Kim, Sung Eun; Moon, Jae Sun; Kim, Jung Kyu; Choi, Won Sik; Lee, Sang Han; Kim, Sung Uk

    2010-01-01

    In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in paddy rice field, the gene flow from bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected every month from the paddy rice field during June, 2004 to March, 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomics DNAs was not detected by PCR. Soil genomic DNAs were not shown its homologies on the Southern blotting data, indicating that gene-transfer did not occur during the last two years in paddy rice field. In addition, the AFLP band patterns produced by both soil genomic DNAs extracted from transgenic and non-transgenic rice field appeared similar to each other when analyzed by NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms although long-term observation may be needed.

  1. Distribution and identification of proteolytic Bacillus spp. in paddy field soil under rice cultivation.

    Science.gov (United States)

    Watanabe, K; Hayano, K

    1993-07-01

    Proteolytic bacteria in paddy field soils under rice cultivation were characterized and enumerated using azocoll agar plates. Bacillus spp. were the proteolytic bacteria that were most frequently present, comprising 59% of the isolates. They were always the numerically dominant proteolytic bacteria isolated from three kinds of fertilizer treatments (yearly application of rice-straw compost and chemical fertilizer, yearly application of chemical fertilizer, and no fertilizer application) and at three different stages of rice development (vegetative growth stage, maximal tillering stage, and harvest stage). Of the 411 proteolytic bacteria isolated, 124 isolates had stronger proteolytic activity than others on the basis of gelatin liquefaction tests and most of them were Bacillus spp. (100% in 1989 and 92.4% in 1991). Bacillus subtilis and Bacillus cereus were the main bacteria of this group and Bacillus mycoides, Bacillus licheniformis, and Bacillus megaterium were also present. We conclude that these Bacillus spp. are the primary source of soil protease in these paddy fields.

  2. Modeling the fate of paddy field pesticide in surface water and environmental risk assessment

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The risk of drinking water is greatly concerned because of the large amount of pesticide applied to paddy field and the contamination of drinking water sources due to the runoff. A mathematical model is developed, based on the mass balance, to predict the fate of paddy field pesticides from application, runoff and mixing in a river, taking account of the physical-chemical properties and processes of volatilization, degradation, adsorption and desorption. The model is applied to a river basin in Japan to estimate the contaminant level of several popularly used pesticides at the water intakes. The health risk in drinking water induced by each pesticide concerned is estimated and evaluated by comparing with the acceptable daily intake values (ADI) and with that induced by trihalomethanes. An index to evaluate the total risk of all pesticides appearing in water is proposed. The methods for risk management are also discussed.

  3. The Increase of Arthropods Biodiversity in Paddy Field Ecosystem Managed by Using Integrated Pest Management at South Borneo

    Directory of Open Access Journals (Sweden)

    Samharinto

    2012-12-01

    Full Text Available We have studied the arthropods biodiversity in two paddy field ecosystems, namely, paddy field ecosystem using Integrated Pest Management (IPM system and non-IPM paddy field ecosystem. This study was conducted from April 2011 – November 2011 in three locations, that is, Pasar Kamis village and Sungai Rangas village in Banjar regency, and Guntung Payung village in Banjarbaru city, South Borneo Province. In this study, we used insect nets, yellow sticky traps, light trap and pitfall trap to get the sample or catch the arthropods in one period of planting season. The arthropods caught were then classified into some classes: pest (herbivore, natural enemy (parasitoid and predator, and other arthropods. After that, the Species Diversity Index was determined using its Shannon-Wiener Index (H’, Evenness (e, Species Richness (R, and Species Similarity Index (IS. The sum of arthropods which have the characteristic of pest and parasitoid were higher in the IPM paddy fields than in the non-IPM paddy fields, and the sum of other arthropods were the same. The highest H’ and e values were in the IPM paddy field in Pasar Kamis village. The IS value for each three locations were 77.5% in Pasar Kamis village, 93.42% in Guntung Payung village, and 78.76% in Sungai Rangas village.

  4. The Potential for Abandoned Paddy Fields to Reduce Pollution Loads from Households in Suburban Tokyo

    OpenAIRE

    Makoto Yokohari; Mariko Miyamoto; Jay Bolthouse; Jiro Kogi

    2010-01-01

    Similar to other Asian nations, suburban areas in Japan are characterized by dense intermixtures of residential areas and farmlands. These hybrid rural/urban areas are evaluated negatively in modern planning frameworks. However, mixed rural/urban landscapes may prove advantageous when attempting to reconstruct sustainable wastewater treatment systems. This research examines the potential for abandoned paddy fields to reduce nitrogen (T-N) and phosphorous (T-P) loads, an increasingly problemat...

  5. Evaluating health of paddy rice field ecosystem with remote sensing and GIS in Lower Yangtze River Plain, China

    Science.gov (United States)

    Li, Jingjing; Qin, Zhihao; Li, Wenjuan; Lin, Lu

    2008-10-01

    A paddy rice ecosystem is a farming system composed of paddy, animals, microbes and other environmental factors in specific time and space, with particular temporal and spatial dynamics. Since paddy rice is a main grain crop to feed above half of population in China, the performance of paddy rice ecosystem is highly concerned to yield level of paddy and food supply safety in China. Therefore, monitoring the performance of paddy rice ecosystem is very important to obtain the required information for evaluation of ecosystem health. In the study we intend to develop an approach to monitor the ecosystem performance spatially and dynamically in a regional scale using MODIS remote sensing data and GIS spatial mapping. On the basis of key factors governing the paddy rice ecosystem, we accordingly develop the following three indicators for the evaluation: Crop growing index (CGI), environmental Index (EI), and pests-diseases index (PDI). Then, we integrated the three indicators into a model with different weight coefficients to calculate Comprehensive ecosystem health index (CEHI) to evaluate the performance and functioning of paddy rice ecosystem in a regional scale. CGI indicates the health status of paddy rice calculated from the normalizing enhanced vegetation Index (EVI) retrieved from MODIS data. EI is estimated from temperature Index (TI) and precipitation Index (PI) indicating heat and water stress on the rice field. PDI reflects the damage brought by pests and diseases, which can be estimated using the information obtained from governmental websites. Applying the approach to Lower Yangtze River Plain, we monitor and evaluate the performance of paddy rice ecosystem in various stages of rice growing period in 2006. The results indicated that the performance of the ecosystem was generally very encouraging. During booting stage and heading and blooming stage, the health level was the highest in Anhui province, which is the main paddy rice producer in the region

  6. Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields

    Science.gov (United States)

    Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

    2014-01-01

    To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

  7. [Effects of different rice farming systems on paddy field weed community].

    Science.gov (United States)

    Zhang, Dan; Min, Qing-Wen; Cheng, Sheng-Kui; Yang, Hai-Long; He, Lu; Jiao, Wen-Jun; Liu, Shan

    2010-06-01

    Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on Monochoia vaginalis and Rotala indica being 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community.

  8. Depth distribution of radiocesium in Fukushima paddy fields and implications for ongoing decontamination works

    Science.gov (United States)

    Lepage, H.; Evrard, O.; Onda, Y.; Lefèvre, I.; Laceby, J. P.; Ayrault, S.

    2014-09-01

    Large quantities of radiocesium were deposited across a 3000 km2 area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of radiocesium in soil in the months following the accident, the potential migration of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields or transfer of radioactive contaminants from soils to rice. Radionuclide activity concentrations and organic content were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of radiocesium with the majority concentrated in the uppermost layers of soils (maintenance (grass cutting - 97% of 137Cs in the upper 5 cm) and farming operations (tilling - 83% of 137Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Remediation efforts should be concentrated on soils characterised by radiocesium activities > 10 000 Bq kg-1 to prevent the contamination of rice. Further analysis is required to clarify the redistribution of radiocesium eroded on river channels.

  9. [Effects of controlled release fertilizers on N2O emission from paddy field].

    Science.gov (United States)

    Li, Fangmin; Fan, Xiaolin; Liu, Fang; Wang, Qiang

    2004-11-01

    With close chamber method, this paper studied the effects of controlled release fertilizer (CRF), non-coated compound fertilizer (Com) and conventional urea (CK) on N2O emission from paddy field. The results showed that within 10 days after transplanting, the ammonium and nitrate concentrations in the surface water of the plot treated with CRF were significantly different from those treated with Com. The partial coefficient between N2O emission rates and corresponding nitrate concentrations in the water was significantly high (r = 0.6834). Compared with Com, CRF was able to reduce N2O emission from the paddy field. Within 100 days after basal application, the N2O emission rate of treatment CRF was only 13.45%-21.26% of Corn and 71.17%-112.47% of CK. The N2O emission of Com was mainly concentrated in 1-25 d after basal fertilization and mid-aeration period, but that of CRF was remarkably lower during same period, while the peak of N2O emission of CK was postponed and reduced. It was concluded that both one-time fertilization of CRF and several-time fertilizations of conventional urea were able to reduce N2O emission from the paddy field.

  10. On dealing with the pollution costs in agriculture: A case study of paddy fields.

    Science.gov (United States)

    Yaqubi, Morteza; Shahraki, Javad; Sabouhi Sabouni, Mahmood

    2016-06-15

    The main purpose of this study is to evaluate marginal abatement cost of the main agricultural pollutants. In this sense, we construct three indices including Net Global Warming Potential (NGWP) and Nitrogen Surplus (NS), simulated by a biogeochemistry model, and also an Environmental Impact Quotient (EQI) for paddy fields. Then, using a Data Envelopment Analysis (DEA) model, we evaluate environmental inefficiencies and shadow values of these indices. The results show that there is still room for improvement at no extra cost just through a better input management. Besides, enormous potential for pollution reduction in the region is feasible. Moreover, in paddy cultivation, marginal abatement cost of pesticides and herbicides are much bigger than nitrogen surplus and greenhouse gasses. In addition, in the status quo, the mitigation costs are irrelevant to production decisions. Finally, to deal with the private pollution costs, market-based instruments are proved to be better than command-and-control regulation.

  11. 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

    2016-10-14

    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.

  12. On dealing with the pollution costs in agriculture: A case study of paddy fields

    Energy Technology Data Exchange (ETDEWEB)

    Yaqubi, Morteza, E-mail: yaqubi@pgs.usb.ac.ir [Faculty of Management and Economics, Department of Agricultural Economics, University of Sistan and Baluchestan Zahedan (Iran, Islamic Republic of); Shahraki, Javad, E-mail: j.shahraki@eco.usb.ac.ir [Faculty of Management and Economics, Department of Agricultural Economics, University of Sistan and Baluchestan Zahedan (Iran, Islamic Republic of); Sabouhi Sabouni, Mahmood, E-mail: sabouhi@ferdowsi.um.ac.ir [Department of Agricultural Economics, Ferdowsi University of Mashhad, Azadi Square, Mashhad (Iran, Islamic Republic of)

    2016-06-15

    The main purpose of this study is to evaluate marginal abatement cost of the main agricultural pollutants. In this sense, we construct three indices including Net Global Warming Potential (NGWP) and Nitrogen Surplus (NS), simulated by a biogeochemistry model, and also an Environmental Impact Quotient (EQI) for paddy fields. Then, using a Data Envelopment Analysis (DEA) model, we evaluate environmental inefficiencies and shadow values of these indices. The results show that there is still room for improvement at no extra cost just through a better input management. Besides, enormous potential for pollution reduction in the region is feasible. Moreover, in paddy cultivation, marginal abatement cost of pesticides and herbicides are much bigger than nitrogen surplus and greenhouse gasses. In addition, in the status quo, the mitigation costs are irrelevant to production decisions. Finally, to deal with the private pollution costs, market-based instruments are proved to be better than command-and-control regulation. - Highlights: • To evaluate agricultural pollution costs, a combination of two DNDC and DEA models was introduced. • The shadow values of three main agricultural pollutants in paddy fields were evaluated. • In the study area, a high potential for pollution reduction is feasible. • The pollution cost of pesticides are much bigger than nitrogen surplus and greenhouse gases. • From the farmers' viewpoint, a positive shadow value of undesirable outputs also is feasible. • To deal with the pollution costs, market-based instruments are preferred to command-and-control regulation.

  13. 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.

  14. Estimation of soil moisture in paddy field using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Chusnul Arif

    2012-04-01

    Full Text Available In paddy field, monitoring soil moisture is required for irrigation scheduling and water resource allocation, management and planning. The current study proposes an Artificial Neural Networks (ANN model to estimate soil moisture in paddy field with limited meteorological data. Dynamic of ANN model was adopted to estimate soil moisture with the inputs of reference evapotranspiration (ETo and precipitation. ETo was firstly estimated using the maximum, average and minimum values of air temperature as the inputs of model. The models were performed under different weather conditions between the two paddy cultivation periods. Training process of model was carried out using the observation data in the first period, while validation process was conducted based on the observation data in the second period. Dynamic of ANN model estimated soil moisture with R2 values of 0.80 and 0.73 for training and validation processes, respectively, indicated that tight linear correlations between observed and estimated values of soil moisture were observed. Thus, the ANN model reliably estimates soil moisture with limited meteorological data.

  15. Microbial fuel cell as mitigation strategy for methane emissions from paddy field

    Science.gov (United States)

    Rizzo, Anacleto; Boano, Fulvio; Revelli, Roberto; Ridolfi, Luca

    2013-04-01

    Microbial fuel cells (MFCs) are bioelectrochemical systems able to generate electricity from wetland soils, including paddies, exploiting the microbial decomposition of organic matter. A MFC is composed of an anode buried in the anaerobic submerged soil linked to a cathode placed on the top of the soil in the aerobic ponding water. A biofilm develops on the anode, where bacteria release electrons, oxidizing dissolved organic carbon (DOC) and using oxygen available at the cathode as electron acceptor. MFC technology is now in an early development stage and the efficiency in electricity production is still low. However, MFC can also be applied for secondary aims, among which one of great interest is the reduction of methane (CH4) emissions from paddy fields. Indeed, DOC oxidation at the anode can be seen as an additional DOC sink in paddy soil environment, limiting the DOC availability for methanogens. In this work, a process-based mathematical model is proposed for a preliminary investigation of the efficiency of MFCs in limiting CH4 emissions. The model relies on a system of partial differential mass balance equations to describe the vertical dynamics of the chemical compounds leading to CH4 production. Many physico-chemical processes and features characteristic of paddy soil are included: paddy soil stratigraphy; spatio-temporal variations of plant-root compartment; water and heat transport; SOC decomposition; heterotrophic reactions in both aerobic and anaerobic conditions; root radial oxygen loss; root solute uptake; DOC root exudation; plant-mediated, ebullition, and diffusion gas exchange pathways. MFC is modeled as a DOC sink term, following a zero-order kinetic where the current density is assumed constant for the whole growing season. Different values of current density are tested, in accordance with values reported in literature about efficiency reached in paddy soils. Our results show a reduction of CH4 emissions up to -28.1%, -24.1%, and -26.5% of daily

  16. Some topological properties of arthropod food webs in paddy fields of South China

    Directory of Open Access Journals (Sweden)

    LiQin Jiang

    2015-09-01

    Full Text Available To explore the topological properties of paddy arthropod food webs is of significance for understanding natural equilibrium of rice pests. In present study, we used Pajek software to analyze the topological properties of four full arthropod food webs in South China. The results showed that predators were significantly abundant than preys, and the proportion of predators to preys (3.07 was significantly higher than previously reported by Cohen in 1977 (1.33. In the food webs, the number of top species was the largest, accounted for about 50% of the total. The number of intermediate-intermediate links was far greater than the other three links. The average degree of paddy arthropod food webs is 6.0, 6.04, 5.74 and 7.75, respectively. Average degree and link density did not change significantly with the change of the number of species, but the connectance reduced significantly. In the paddy ecosystems, the increase of species diversity does not lead to an increase proportionally to the links among species. The link density and connectance of food webs of early season rice field were less than that from late season rice field. Cycles of all food webs cycles were 0. The maximum chain length of the basal species was 3, and the largest chain length of the top species was typically 2 or 3. Neutral insects were found to play a very important role in the paddy ecosystem. Nilaparvata lugens and Sogatella furcifera were found to be the dominant species of rice pests. Pardosa pseudoannulata, Tetragnatha maxillosa, Pirata subparaticus, Arctosa stigmosa and Clubiona corrugate were identified as the important predatory species that may effectively control the pest population. The keystone species calculated from keystone index and network analysis are analogous, indicating either keystone index or network analysis can be used in the analysis of keystone species.

  17. Simulation of future global warming scenarios in rice paddies with an open-field warming facility

    Directory of Open Access Journals (Sweden)

    Rehmani Muhammad

    2011-12-01

    Full Text Available Abstract To simulate expected future global warming, hexagonal arrays of infrared heaters have previously been used to warm open-field canopies of upland crops such as wheat. Through the use of concrete-anchored posts, improved software, overhead wires, extensive grounding, and monitoring with a thermal camera, the technology was safely and reliably extended to paddy rice fields. The system maintained canopy temperature increases within 0.5°C of daytime and nighttime set-point differences of 1.3 and 2.7°C 67% of the time.

  18. Measurement of Ammonia Emission Following Surface Application of Urea Fertilizer from Irrigated Paddy Rice Fields

    Institute of Scientific and Technical Information of China (English)

    Md.Toufiq Iqbal; TIAN Guang-ming; LIANG Xin-qiang; Fatima Rukshana

    2005-01-01

    Ammonia emission is one of the most important pathways of nitrogen loss from agricultural cultivated field. In this paper, we report the measurement of ammonia emission from paddy rice field obtained by surface application of urea fertilizer with water management. The main objective of the present study were to assess the amount of NH3 emission and the loss of nitrogen from paddy field as affected by various N doses, i.e., 0 (control), 90 (N1), 180 (N2), 270 (N3) and 360 (N4) kg ha-1, following field surface application of urea fertilizer with water management. Ammonia emissions were measured by continuous airflow enclosure method from plots fertilized with the application of surface urea. Increase in urea-N dosage increased NH3 emission thatwas measured from paddy rice field. Ammonia emission started immediately and was almost complete within 12 days after top dressing of urea application to the soils. Ammonia emissions were nearly constant in all treatments from 12 days after fertilizer application. Highest ammonia emission rate was 28 g/day and total amount of ammonia emission was 56.21 kg ha-1 for 360 kg N ha-1 dose. No remarkable observation was found about temperature for ammonia emission. Due to proper water management practices less emission was observed throughout the experiment period. The results also show that N loss through NH3 emission accounted for 11 to 16% during the ricegrowing season. These magnitudes of loss of N appear to be most important for environmental point of view.

  19. Impact of Some Agronomic Practices on Paddy Field Soil Health Under Varied Ecological Conditions:I.Influence of Soil Moisture

    Institute of Scientific and Technical Information of China (English)

    A.SUBHANI; LIAOMIN; 等

    2001-01-01

    The effects of individual and combined additions of urea(100μg N g-1soil) and insecticide (triazophos at field rate,FR) under different moisture levles of air-dried soil(AD),50% of water-holding capacity(WHC),100%,WHC and flooded soil(FS) on some selected soil properties in a paddy field soil were examined in a laboratory incubation study.The results indicated that after 21-day incubation at 25℃ ,the different moisture levels led to significant changes in the parameters studied,Flooding of soil with distilled waer significantly increased the electron transport system(ETS)/dehydrogenase activity and phenol content of the soil compared to the other moisture levels,while protein and phospholipis behaved differently at varied moisture levels with or without the addition of urea and /or triazophos.Increased ETS activity was observed with N addition at higher moisture levels thile insecticide incorporation decreased it at all moisture levels as compared to the control(moisture only).The phenol contents slightly decreasd and increased with N and insecticide applications ,respectively,The soil protein contents were found to be unaffected among all the soil treatents at all moisture levels.The soil protein contents were found to be unaffected among all the soil treatments at all moisture levels.However,among different moisture levels,reduced quantities of proteins were estimated at 50% WHC ,suggesting more N-mineralization.Lower quantities of soil biomass phospholipids,among all treatments,were recored at higher moisture levels(100% WHC and FS) than at the loer levels,An overall slight enhancement in phospholipid contents with N and small reduction with insecticide addition,respectively,was noticed against the untreated soil.The toxictiy of fertilizer and insecticide decreased as the soil moisture contents increased,suggesting rapid degradation of agrochemicals.

  20. Water management reduces greenhouse gas emissions in a Mediterranean rice paddy field

    Science.gov (United States)

    Gruening, Carsten; Meijide, Ana; Manca, Giovanni; Goded, Ignacio; Seufert, Guenther; Cescatti, Alessandro

    2016-04-01

    Rice paddy fields are one of the biggest anthropogenic sources of methane (CH4), the second most important greenhouse gas (GHG) after carbon dioxide (CO2). Therefore most studies on greenhouse gases (GHG) in these agricultural systems focus on the evaluation of CH4 production. However, there are other GHGs such as CO2 and nitrous oxide (N2O) also exchanged within the atmosphere. Since each of the GHGs has its own radiative forcing effect, the total GHG budget of rice cultivation and its global warming potential (GWP) must be assessed. For this purpose a field experiment was carried out in a Mediterranean rice paddy field in the Po Valley (Italy), the largest rice producing region in Europe. Ecosystem CO2 and CH4 fluxes were assessed using the eddy covariance technique, while soil respiration and soil CH4 and N2O fluxes were measured with closed chambers for two complete years. Combining all GHGs measured, the rice paddy field acted as a sink of -368 and -828 g CO2 eq m-2 year-1 in the first and second years respectively. Both years, it was a CO2 sink and a CH4 source, while the N2O contribution to the GWP was relatively small. Differences in the GHG budget between the two years of measurements were mainly caused by the greater CH4 emissions in the first year (37.4 g CH4 m-2 compared to 21.03 g CH4 m-2 in the second year), probably as a consequence of the drainage of the water table in the middle of the growing season during the second year, which resulted in lower CH4 emissions without significant increases of N2O and CO2 fluxes. However, midseason drainage also resulted in small decreases of yield, indicating that GHG budget studies from agricultural systems should consider carbon exports through the harvest. The balance between net GWP and carbon yield indicated a loss of carbon equivalents from the system, which was more than 30-fold higher in the first year. Our results therefore suggest that an adequate management of the water table has the potential to be an

  1. Comparative Metagenomics of Anode-Associated Microbiomes Developed in Rice Paddy-Field Microbial Fuel Cells

    Science.gov (United States)

    Kouzuma, Atsushi; Kasai, Takuya; Nakagawa, Gen; Yamamuro, Ayaka; Abe, Takashi; Watanabe, Kazuya

    2013-01-01

    In sediment-type microbial fuel cells (sMFCs) operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors. PMID:24223712

  2. Comparative metagenomics of anode-associated microbiomes developed in rice paddy-field microbial fuel cells.

    Science.gov (United States)

    Kouzuma, Atsushi; Kasai, Takuya; Nakagawa, Gen; Yamamuro, Ayaka; Abe, Takashi; Watanabe, Kazuya

    2013-01-01

    In sediment-type microbial fuel cells (sMFCs) operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors.

  3. Comparative metagenomics of anode-associated microbiomes developed in rice paddy-field microbial fuel cells.

    Directory of Open Access Journals (Sweden)

    Atsushi Kouzuma

    Full Text Available In sediment-type microbial fuel cells (sMFCs operating in rice paddy fields, rice-root exudates are converted to electricity by anode-associated rhizosphere microbes. Previous studies have shown that members of the family Geobacteraceae are enriched on the anodes of rhizosphere sMFCs. To deepen our understanding of rhizosphere microbes involved in electricity generation in sMFCs, here, we conducted comparative analyses of anode-associated microbiomes in three MFC systems: a rice paddy-field sMFC, and acetate- and glucose-fed MFCs in which pieces of graphite felt that had functioned as anodes in rice paddy-field sMFC were used as rhizosphere microbe-bearing anodes. After electric outputs became stable, microbiomes associated with the anodes of these MFC systems were analyzed by pyrotag sequencing of 16S rRNA gene amplicons and Illumina shotgun metagenomics. Pyrotag sequencing showed that Geobacteraceae bacteria were associated with the anodes of all three systems, but the dominant Geobacter species in each MFC were different. Specifically, species closely related to G. metallireducens comprised 90% of the anode Geobacteraceae in the acetate-fed MFC, but were only relatively minor components of the rhizosphere sMFC and glucose-fed MFC, whereas species closely related to G. psychrophilus were abundantly detected. This trend was confirmed by the phylogenetic assignments of predicted genes in shotgun metagenome sequences of the anode microbiomes. Our findings suggest that G. psychrophilus and its related species preferentially grow on the anodes of rhizosphere sMFCs and generate electricity through syntrophic interactions with organisms that excrete electron donors.

  4. Depth distribution of cesium-137 in paddy fields across the Fukushima pollution plume in 2013.

    Science.gov (United States)

    Lepage, Hugo; Evrard, Olivier; Onda, Yuichi; Lefèvre, Irène; Laceby, J Patrick; Ayrault, Sophie

    2015-09-01

    Large quantities of radiocesium were deposited across a 3000 km(2) area northwest of the Fukushima Dai-ichi nuclear power plant after the March 2011 accident. Although many studies have investigated the fate of (137)Cs in soil in the months following the accident, the depth distribution of this radioactive contaminant in rice paddy fields requires further examination after the typhoons that occurred in this region. Such investigations will help minimize potential human exposure in rice paddy fields. Radionuclide activity concentrations, organic content and particle size were analysed in 10 soil cores sampled from paddy fields in November 2013, 20 km north of the Fukushima power plant. Our results demonstrate limited depth migration of (137)Cs with the majority concentrated in the uppermost layers of soils (accident, between 46.8 and 98.7% of the total (137)Cs inventories was found within the top 5 cm of the soil surface, despite cumulative rainfall totalling 3300 mm. Furthermore, there were no significant correlations between (137)Cs depth distribution and the other parameters. We attributed the maximum depth penetration of (137)Cs to grass cutting (73.6-98.5% of (137)Cs in the upper 5 cm) and farming operations (tillage - 46.8-51.6% of (137)Cs in the upper 5 cm). As this area is exposed to erosive events, ongoing decontamination works may increase soil erodibility. We therefore recommend the rapid removal of the uppermost - contaminated - layer of the soil after removing the vegetation to avoid erosion of contaminated material during the subsequent rainfall events. Further analysis is required to thoroughly understand the impacts of erosion on the redistribution of radiocesium throughout the Fukushima Prefecture.

  5. Basic Oxygen Furnace Slag as a Liming Agent for Paddy and Upland Field Soils

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Choong Il [Pohang Research Institute of Industrial Science and Technology, Pohang(Korea)

    1998-03-31

    Basic oxygen furnace (BOF) slag, a by-product of the iron and steelmaking industry produced in large quantities in Korea, poses a substantial disposal challenge. The BOF slag used in this study was 1/3 CaCO{sub 3} in total neutralizing power and application of 7-8 Mgha{sup -1} was needed to bring soil pH to 6.5 from pH 5.0-5.5 in silty clay or clay loam soil contained about 10% organic matter. A field assay was conducted to study whether BOF slag could be used as a dolomitic liming agent for agricultural soils. Four slag rates (0, 4, 8, 12 Mgha{sup -1})were investigated for their effect on soil properties, mineral concentrations in leaf tissues of rice and soybean, and yield of the crops. Slag application at 8 Mgha{sup -1} rate in paddy field increased pH, Ca, Mg, P, Si and Fe content in soil and rice yield by 4.3-14.2% depending on the soil type. In upland field the 8 Mgha{sup -1} rate increased pH, Ca and Fe content in soil and soybean yield by 36.6%. Thus, BOF slag appears to be a useful liming material for correcting soil acidity on both paddy and upland field soils and for increasing Ca, Mg, P, Si, and Fe concentration in plants. (author). 27 refs., 7 tabs.

  6. Requirements for Vertically Installed Runoff Control Boards for the “Paddy Field Dam” and Appropriate Orifice Shapes

    Science.gov (United States)

    Natsuki, Yoshikawa; Hideyuki, Koide; Shin-Ichi, Misawa

    While the “Paddy Field Dam” project has been recognized as an effective flood control measure, there are some cases in which the runoff control boards are vertically installed on the opening of the drainage boxes without careful consideration of the orifice shape and size. The important criteria for the runoff control boards to be satisfied are: 1. to maintain a sufficient peak runoff control function, 2. to avoid excessive ponding causing overflow, 3. to minimize the influence to the ordinary water management, and 4. to reserve sufficient orifice area to avoid blockage of the orifice with floating litters. The purpose of this study is to examine proper shapes and sizes of the orifice to satisfy the criteria for the vertically installed runoff control boards through experiments and simulations. Given the condition that the orifice has sufficient area to avoid overflow with 10 and 20 year return period rainfall event (criteria 2), the simulation results show that the orifice with horizontally wider shapes has advantages over the square or circular shapes in terms of the criteria 1 and 3. The disadvantage of the horizontally wider shapes is the blockage of the orifice with floating litters (criteria 4). In conclusion, we proposed to secure sufficient vertical distance to avoid this problem by setting a lower limit on the vertical distance and then determine the widest horizontal distance to optimize all the criteria. In addition, we have constructed the “Orifice Design Assist Tool” on the basis of the examinations in this study.

  7. Impact of Some Agronomic Practices on Paddy Field Soil Health Under Varied Ecological Conditions:II.Influence of Soil Temperature

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A 21-d incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10,25,and 40 ℃) on some microbiological and biochemical properties in flooded paddy soil amended or unamended with urea at 100 μg N g-1 soil and/or insecticide (triazophos) at field rate (FR).Enhancements in temperature led to increase the electron transport system (ETS)/dehydrogenase activity and phospholipid contents of the soil,while soil organic matter phenol and protein contents decreased with increasing temperature with or without the addition of inputs.An increase of temperature from 10 ℃ to 25 or 40 ℃ enhanced the ETS activity 2 folds (on average for all soils),while the inclusion of N and insecticide increased and decreased it,respectively,compared to the control.The soil phenol and protein contents were highly correlated with temperatures (for all soils,r = -0.936 and -0.971,respectively) and the additions of N and insecticide produced slight reductions and enhancements in them,respectively.At a particular temperature,the soil protein contents remained unaffected among all the soil treatments.An overall slight increase in phospholipid contents with N and a small decline with insecticide addition were noticed against the untreated soil.The toxicity of fertilizer and insecticide decreased as the incubation temperature increased,suggesting faster degradation of agrochemicals with raising temperature.

  8. Can arbuscular mycorrhiza and fertilizer management reduce phosphorus runoff from paddy fields?

    Science.gov (United States)

    Zhang, Shujuan; Wang, Li; Ma, Fang; Zhang, Xue; Li, Zhe; Li, Shiyang; Jiang, Xiaofeng

    2015-07-01

    Our study sought to assess how much phosphorus (P) runoff from paddy fields could be cut down by fertilizer management and inoculation with arbuscular mycorrhizal fungi. A field experiment was conducted in Lalin River basin, in the northeast China: six nitrogen-phosphorus-potassium fertilizer levels were provided (0, 20%, 40%, 60%, 80%, and 100% of the recommended fertilizer supply), with or without inoculation with Glomus mosseae. The volume and concentrations of particle P (PP) and dissolved P (DP) were measured for each runoff during the rice growing season. It was found that the seasonal P runoff, including DP and PP, under the local fertilization was 3.7 kg/ha, with PP, rather than DP, being the main form of P in runoff water. Additionally, the seasonal P runoff dropped only by 8.9% when fertilization decreased by 20%; rice yields decreased with declining fertilization. We also found that inoculation increased rice yields and decreased P runoff at each fertilizer level and these effects were lower under higher fertilization. Conclusively, while rice yields were guaranteed arbuscular mycorrhizal inoculation and fertilizer management would play a key role in reducing P runoff from paddy fields. Copyright © 2015. Published by Elsevier B.V.

  9. Soil type-depending effect of paddy management: Organic carbon distribution and stocks

    Science.gov (United States)

    Kölbl, Angelika; Drechsler, Susanne; Wissing, Livia; Schad, Peter; Rahayu Utami, Sri; Cao, Zhihong; Kögel-Knabner, Ingrid

    2013-04-01

    Paddy soils may originate from many different types of soil but are highly modified by human activities. These soils are mostly managed under submerged conditions, a management which is assumed to favour carbon sequestration. Therefore, the present study aims to investigate the impact of paddy management on soil organic carbon distributions and stocks in major soil types that are typically used for rice cultivation in Asia. Fluvisol and Acrisol sites (sub-tropical monsoon climate, PR China) as well as Andosol, Vertisol and Ferralsol sites (tropical climate of Java, Indonesia) were compared, as they represent a large range of soil properties to be expected in Asian paddy fields. Paddy rice at all of these sites is cultivated under flooded conditions followed by an upland crop. To evaluate the impact of paddy management, paddy soils as well as adjacent agricultural soils which are not used for paddy rice production (non-paddy soils) were chosen. At each site, three soil profiles of paddy and non-paddy soils were sampled horizontally. All samples were analysed for bulk density and organic carbon (OC) concentrations, and the corresponding OC stocks were calculated. Paddy soils derived from Fluvisols and Acrisols(PR China) showed clearly higher OC concentrations in the topsoils, leading to higher cumulative OC stocks in paddy soils compared to the respective non-paddy soils. However, other soil types did not show the expected higher OC sequestration under paddy management. For example, paddy soils derived from Ferralsols and Vertisols of Java are characterised by very similar OC concentrations and OC stocks as compared to their respective non-paddy soils. Also paddy and non-paddy soils derived from Andosols (Java) showed similar OC concentrations and depth distributions; only the slightly higher bulk density values under paddy management lead to slightly higher OC stocks in these soils. As clearly shown by our results, we cannot necessarily assume that rice production

  10. Object-Based Analysis and Change Detection of Paddy Field at Hokkaido, Japan

    Science.gov (United States)

    PARK, J.; Kim, Y.; Kwak, Y.

    2015-12-01

    Remote sensing technology has been used in land use and land cover classification. Especially paddy fields is an important cultivated area in Asia. To accurately extract the area is the important indicator to estimate the food production. In this research paddy fields classification in Hokkaido was performed using Topographical features (DEM), Climatic features (accumulated temperature), Spectrometer features (MODIS). Fig. 1. shows the overview of the analysis methods of this research. The process of this research is carried out in 3 steps.1. Determine the accumulated temperature by retrieving the temperature data from the AMeDAS data. 2. Extract the river from the DEM. Set the elevation of the river to 0 to seek the land elevation around it relatively. 3. Calculate the WI (Water Index) using MODIS band 4(Green)and Band 2(NIR). Time series NDVI has been corrected by the FFT method (use a low-pass filter). Phenology information was extracted such as vegetation Onset time, Max value and Duration. Result of the classification was compared with the current vegetation map of the Ministry of the Environment. As a result we can confirm that existence of vegetation map around Sapporo and Asahikawa is almost same. but around Obihiro it was clear that overestimate by water index.

  11. Effects of Cropping System Change for Paddy Field with Double Harvest Rice on the Crops Growth and Soil Nutrient

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of the cropping system change for paddy field with double harvest rice on crops growth and soil nutrient in red soil were studied. The results indicated that the economic benefit and the ratio of the output to input were all increased in terms of the market price for the crops under various treatments. The greatest economic benefit was obtained in the treatment of paddy-upland rotation, and the corresponding economic benefit was increased by 34.7, 21.4, and 2.2% in comparison with that of control (rice-rice-astragali), pasture, and upland cropping treatments. The economic benefits in pasture and upland cultivation treatments were increased by 11.0 and 31.8%, respectively, when compared with that of the control treatment (CK). The ratio of output to input in pasture, paddy-upland rotation, and upland cropping treatments was enhanced by 0.9, 0.6, and 0.3, respectively, in comparison with that of control. To grow pasture is beneficial for improving soil fertility since the contents of soil organic matter, total nitrogen, total phosphorus, and available phosphorus are all enhanced significantly. However, the concentrations of the soil available nitrogen, the total potassium, the available potassium were somewhat reduced in all the treatments, suggesting that increasing the input of nitrogen,particularly potassium, was necessary under the present fertilization level. Based on the conditions of fertility, climate,cultivation, and management of paddy field with double harvest rice in red soil regions, it is feasible to alter the cultivation system of paddy field with bad irrigation condition. In particular, cultivation systems such as pasture and paddy-upland rotation can be selected to extend because better economic benefit and improvement of soil fertility in the purpose region were obtained.

  12. Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

    Directory of Open Access Journals (Sweden)

    A. Meijide

    2011-09-01

    Full Text Available Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4, the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem.

    For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd. was installed in an eddy-covariance field set-up in a rice paddy field in the Po Valley (Northern Italy. Methane fluxes were measured during the rice growing season, both with EC and with manually operated closed chambers. Methane fluxes were strongly influenced by the presence of the water table, with emissions peaking when it was above 10–12 cm. Further studies are required to evaluate if water table management could decrease CH4 emissions. The development of rice plants and soil temperature were also responsible of the seasonal variation on the fluxes. The EC measured showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between both measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.8 g CH4 m−2

  13. [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 (benefits, and soil physical and chemical properties were improved.

  14. Effects of organic matter application on methane emission from paddy fields adopting organic farming system

    Directory of Open Access Journals (Sweden)

    P Nungkat

    2015-01-01

    Full Text Available A study that was aimed to determine the effect of the use of organic manure and azolla on methane emission on paddy field of organic systems was conducted on paddy fields in the Gempol Village, Sambirejo District of Sragen Regency, Indonesia. The experimental design performed for this study was a completely randomized block design consisting of three factors; the factor I was rice cultivars (Mira-1; Mentik Wangi; Merah Putih; factor II was dose of organic manure (0 t/ha and 10 t/ha and factor III was Azolla inoculums dose (0 t/ha and 2 t/ha. Gas sampling was conducted 3 times in one growing season when the rice plants reached ages of 38, 66 and 90 days after planting. The results showed that there was no correlation between the uses of organic fertilizers for rice production on methane emission. The increase of methane emission was very much influenced by the redox potential. Methane emission from Mira-1 field was higher than that from Mentik Wangi and Merah Putih fields. Emission of methane gas from Mira-1 field ranged from -509.82 to 791.34 kg CH4/ha; that from Wangi ranged from -756.77 to d 547.50 kg CH4/ha and that from Merah Putih ranged from -399.63 to 459.94 kg CH4/ha. Application of 10 t organic manure /ha and 2 t azolla/ha in Mentik Wangi reduced methane emissions with a high rice production compared to Merah Putih and Mira-1.

  15. Seasonal trends and environmental controls of methane emissions in a rice paddy field in Northern Italy

    Directory of Open Access Journals (Sweden)

    A. Meijide

    2011-12-01

    Full Text Available Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4, the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem.

    For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd. was installed in a rice paddy field in the Po Valley (Northern Italy. Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10–12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30 % higher seasonal estimations with the chambers than with the EC (41.1 and 31.7 g CH4 m−2 measured with chambers and EC respectively and even greater differences are found if shorter periods with high chamber sampling

  16. Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan

    Science.gov (United States)

    Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M.; Lai, Bo-Chi; Kam, Yeong-Choy

    2011-01-01

    Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC50 for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC50 for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

  17. Improvements in the Weeding of Levee Slope of Terraced Paddy Fields with Statutory Regulation of Places of Scenic Beauty

    Science.gov (United States)

    Uchikawa, Yoshiyuki; Kimura, Kazuhiro; Hirata, Ayumi

    A growing number of terraced paddy fields in Japan are being conserved as cultural assets like places of scenic beauty. This has meant that the task of weeding levee slope of these terraced paddy fields has become increasingly important, not only for general maintenance of the terraced paddy fields, but also because of the impact landscape, vegetation and the surrounding environment. However, the steep gradient of the levee slope and lack of footholds mean that the workability and safety associated with this weeding work is problematic. In addition, in the event that an area has been designated as a cultural asset, there are restrictions regarding how it can be modified and local farmers are reluctant to change their traditional farming methods in such cases. This study therefore sought to clarify the actual condition of the levee slope weeding work undertaken in the places of scenic beauty Obasute Tanada district. Empirical validations of potential measures for reforming the work environment were evaluated based on the findings of this investigation. We demonstrated that it is possible to modify current work practices while still maintaining and preserving the terraced paddy fields, even in designated scenic locations. To improve the working environment for levee slope weeding, we propose creating berms to serve as footholds at the toes of slopes.

  18. Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan.

    Science.gov (United States)

    Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M; Lai, Bo-Chi; Kam, Yeong-Choy

    2011-03-01

    Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC(50) for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC(50) for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

  19. Characterization of soil heavy metal pools in paddy fields in Taiwan: chemical extraction and solid-solution partitioning

    NARCIS (Netherlands)

    Römkens, P.F.A.M.; Guo, H.Y.; Chu, C.L.; Liu, T.S.; Chiang, C.F.; Koopmans, G.F.

    2009-01-01

    Ongoing industrialization has resulted in an accumulation of metals like Cd, Cu, Cr, Ni, Zn, and Pb in paddy fields across Southeast Asia. Risks of metals in soils depend on soil properties and the availability of metals in soil. At present, however, limited information is available on how to measur

  20. Heavy Metals Uptake by Asian Swamp Eel, Monopterus albus from Paddy Fields of Kelantan, Peninsular Malaysia: Preliminary Study.

    Science.gov (United States)

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

    2012-12-01

    Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 μg/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution.

  1. Purification Performance and Production of a Re-circulating Pond Aquaculture System Based on Paddy Field

    Directory of Open Access Journals (Sweden)

    Gu Li

    2012-10-01

    Full Text Available Developing improved aquaculture systems with a more efficient use of water and less environmental impact is becoming a crying need. A re-circulating aquaculture system consisting of paddy field and fish pond is a new culture mode due to aquaculture combing with agriculture. The present study focused on the purification capacity of the paddy field on nitrogen, phosphorus and organic matter, the fluctuation trend of water quality conditions during the whole rearing process and the culture efficacy of the main culture species of grass carp (Ctenopharyngodon idella. The results were as follows: under a flow rate of 1.4-5.5 m3/h for the recirculation treatment, the average removal rate of ammonia nitrogen, nitrate nitrogen, total nitrogen, total phosphorus and biochemical oxygen demand for the aquaculture effluent amounted to 40.5, 43.5, 31.9, 23.9, 20.7 and 52.4%, respectively, But the dissolved oxygen content in the rice fields increased obviously. During the whole process of fish rearing, the main physicochemical parameters of water quality for the experimental ponds were all maintained at a suitable level for the growth of the grass carp. In addition, there were significant differences (p<0.05 in DO, TSS, NH4+ -N, NO--N, BOD5 and Chl-&alpha between the experimental and control ponds. As far as the yield per unit and survival rate was concerned, the level of the experimental ponds was obviously higher than that of the control, while the feed conversion ratio displayed the opposite trend. Overall, the new aquaculture system realized the double aims of water reuse and the reduction of waste water discharge.

  2. Effects of industrial and agricultural waste amendment on soil greenhouse gas production in a paddy field in Southeastern China

    Science.gov (United States)

    Wang, Weiqi; Neogi, Suvadip; Lai, Derrick Y. F.; Zeng, Congsheng; Wang, Chun; Zeng, Dongping

    2017-09-01

    Controlling the production and subsequent emissions of greenhouse gases (GHGs) from paddy fields is crucial to minimize the climatic impacts arising from crop production. The application of chemical or biological amendments is one possible way to limit the production of GHGs in paddy soils. Yet, few existing studies have examined the impacts of applying fertilizers originated from industrial and agricultural wastes on soil GHG production and its governing factors in subtropical paddy fields. In this study, we examined the effects of various agricultural and industrial amendments, including biochar, steel slag, shell slag, gypsum slag, and slag-derived silicate and calcium fertilizers, on the production potential of GHGs in an early paddy field in southeast China. The mean CO2 production rates from soils amended with steel slag as well as silicate and calcium fertilizers were significantly higher than those of the controls by 13.4% and 18.6%, respectively (P 0.05). Overall, the soil production rate of CO2 was positively correlated with that of CH4 (P greenhouse gas production and mitigate climate change impacts of rice cultivation, largely attributable to the reduction in methanogenesis.

  3. 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.

  4. Sediment trap efficiency of paddy fields at the watershed scale in a mountainous catchment in northwest Vietnam

    Science.gov (United States)

    Slaets, Johanna I. F.; Schmitter, Petra; Hilger, Thomas; Vien, Tran Duc; Cadisch, Georg

    2016-06-01

    Composite agricultural systems with permanent maize cultivation in the uplands and irrigated rice in the valleys are very common in mountainous southeast Asia. The soil loss and fertility decline of the upland fields is well documented, but little is known about reallocation of these sediments within the landscape. In this study, a turbidity-based linear mixed model was used to quantify sediment inputs, from surface reservoir irrigation water and from direct overland flow, into a paddy area of 13 ha. Simultaneously, the sediment load exported from the rice fields was determined. Mid-infrared spectroscopy was applied to analyze sediment particle size. Our results showed that per year, 64 Mg ha-1 of sediments were imported into paddy fields, of which around 75 % were delivered by irrigation water and the remainder by direct overland flow during rainfall events. Overland flow contributed one-third of the received sandy fraction, while irrigated sediments were predominantly silty. Overall, rice fields were a net sink for sediments, trapping 28 Mg ha-1 a-1 or almost half of total sediment inputs. As paddy outflow consisted almost exclusively of silt- and clay-sized material, 24 Mg ha-1 a-1 of the trapped amount of sediment was estimated to be sandy. Under continued intensive upland maize cultivation, such a sustained input of coarse material could jeopardize paddy soil fertility, puddling capacity and ultimately food security of the inhabitants of these mountainous areas. Preventing direct overland flow from entering the paddy fields, however, could reduce sand inputs by up to 34 %.

  5. Object-Based Flood Mapping and Affected Rice Field Estimation with Landsat 8 OLI and MODIS Data

    Directory of Open Access Journals (Sweden)

    Phuong D. Dao

    2015-04-01

    Full Text Available Cambodia is one of the most flood-prone countries in Southeast Asia. It is geographically situated in the downstream region of the Mekong River with a lowland floodplain in the middle, surrounded by plateaus and high mountains. It usually experiences devastating floods induced by an overwhelming concentration of rainfall water over the Tonle Sap Lake’s and Mekong River’s banks during monsoon seasons. Flood damage assessment in the rice ecosystem plays an important role in this region as local residents rely heavily on agricultural production. This study introduced an object-based approach to flood mapping and affected rice field estimation in central Cambodia. In this approach, image segmentation processing was conducted with optimal scale parameter estimation based on the variation of objects’ local variances. The inundated area was identified by using Landsat 8 images with an overall accuracy of higher than 95% compared to those derived from finer spatial resolution images. Moderate Resolution Imaging Spectroradiometer (MODIS vegetation index products were utilized to identify the paddy rice field based on seasonal inter-variation between vegetation and water index during the transplanting stage. The rice classification result was well correlated with the statistical data at a commune level (R2 = 0.675. The flood mapping and affected rice estimation results are useful to provide local governments with valuable information for flooding mitigation and post-flooding compensation and restoration.

  6. Emission and distribution of phosphine in paddy fields and its relationship with greenhouse gases.

    Science.gov (United States)

    Chen, Weiyi; Niu, Xiaojun; An, Shaorong; Sheng, Hong; Tang, Zhenghua; Yang, Zhiquan; Gu, Xiaohong

    2017-12-01

    Phosphine (PH3), as a gaseous phosphide, plays an important role in the phosphorus cycle in ecosystems. In this study, the emission and distribution of phosphine, carbon dioxide (CO2) and methane (CH4) in paddy fields were investigated to speculate the future potential impacts of enhanced greenhouse effect on phosphorus cycle involved in phosphine by the method of Pearson correlation analysis and multiple linear regression analysis. During the whole period of rice growth, there was a significant positive correlation between CO2 emission flux and PH3 emission flux (r=0.592, p=0.026, n=14). Similarly, a significant positive correlation of emission flux was also observed between CH4 and PH3 (r=0.563, p=0.036, n=14). The linear regression relationship was determined as [PH3]flux=0.007[CO2]flux+0.063[CH4]flux-4.638. No significant differences were observed for all values of matrix-bound phosphine (MBP), soil carbon dioxide (SCO2), and soil methane (SCH4) in paddy soils. However, there was a significant positive correlation between MBP and SCO2 at heading, flowering and ripening stage. The correlation coefficients were 0.909, 0.890 and 0.827, respectively. In vertical distribution, MBP had the analogical variation trend with SCO2 and SCH4. Through Pearson correlation analysis and multiple stepwise linear regression analysis, pH, redox potential (Eh), total phosphorus (TP) and acid phosphatase (ACP) were identified as the principal factors affecting MBP levels, with correlative rankings of Eh>pH>TP>ACP. The multiple stepwise regression model ([MBP]=0.456∗[ACP]+0.235∗[TP]-1.458∗[Eh]-36.547∗[pH]+352.298) was obtained. The findings in this study hold great reference values to the global biogeochemical cycling of phosphorus in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Spatial and temporal changes of cyanophage communities in paddy field soils as revealed by the capsid assembly protein gene g20.

    Science.gov (United States)

    Wang, Guanghua; Asakawa, Susumu; Kimura, Makoto

    2011-05-01

    Bacteriophages are ubiquitous in various environments. Our previous study revealed the diversity of the cyanophage community in paddy floodwater. In this study, the phylogeny and genetic diversity of cyanophage communities in paddy field soils were reported. The viral capsid assembly protein gene (g20) of cyanophage was amplified with the primers CPS1 and CPS8 from soil DNA extracted during two different sampling times at three sampling sites in Japan. The sequencing results indicated that about 93% of the clones were g20 genes. In total, 70 clones of g20 genes were obtained in this study, of which 69 clones were of cyanophage origin. As evaluated by g20 sequence assemblages in paddy field soils, the unifrac analyses results indicated that cyanophage communities changed among the sampling sites and times and differed from those communities detected in paddy floodwater. The phylogenetic analysis showed that the g20 sequences in paddy field soils were very diverse and distributed into Clusters α, β and ɛ, as well as four newly formed clusters. Within Clusters β and ɛ, four unique subclusters were formed from the g20 clones that were only observed in this study. These findings suggested that the cyanophage communities in paddy field soils are different from those found in freshwater, marine water and paddy floodwater.

  8. [Comparisons of Microbial Numbers, Biomasses and Soil Enzyme Activities Between Paddy Field and Drvland Origins in Karst Cave Wetland].

    Science.gov (United States)

    Jin, Zhen-jiang; Zeng, Hong-hu; Li, Qiang; Cheng, Ya-ping; Tang, Hua-feng; Li, Min; Huang, Bing-fu

    2016-01-15

    The purpose of this study is to compare microbial number, microbial biomass as well as soil enzyme activity between paddy field and dryland originated karst wetland ecosystems. The soil samples (0-20 cm) of uncultivated wetland, paddy field and dryland were collected in Huixian karst cave wetland, Guilin, China. Microbial numbers and biomass were detected using dilute plate incubation counting and chloroform fumigation-extraction, respectively. Microbial DNA was extracted according to the manufacturer's instructions of the kit. Microbial activity was examined using soil enzyme assays as well. The result showed that the bacteria number in paddy filed was (4.36 +/- 2.25) x 10(7) CFU x g(-1), which was significantly higher than those in wetland and dryland. Fungi numbers were (6.41 +/- 2.16) x 10(4) CFU x g(-1) in rice paddy and (6.52 +/- 1.55) x 10(4) CFU x g(-1) in wetland, which were higher than that in dryland. Actinomycetes number was (2.65 +/- 0.72) x 10(6) CFU x g(-1) in dryland, which was higher than that in wetland. Microbial DNA concentration in rice paddy was (11.92 +/- 3.69) microg x g(-1), which was higher than that in dryland. Invertase activity was (66.87 +/- 18.61) mg x (g x 24 h)(-1) in rice paddy and alkaline phosphatase activity was (2.07 +/- 0.99) mg x (g x 2 h)(-1) in wetland, both of which were higher than those in dryland. Statistical analysis showed there was a significant positive correlation of microbial DNA content, alkaline phosphatase activity and microbial carbon with soil pH, soil organic carbon (SOC), total nitrogen, alkali-hydrolyzable nitrogen, soil moisture, exchangeable Ca2+ and exchangeable Mg2+, as well as a significant positive correlation of intervase activity with the former three microbial factors. The above results indicated that microbial biomass and function responded much more sensitively to land-use change than microbial number in karst cave wetland system. Soil moisture, SOC and some factors induced by land-use change

  9. Impact of Some Agronomic Practices on Paddy Field Soil HealthUnder Varied Ecological Conditions: I. Influence 1mmof SoilMoisture

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of individual and combined additions of urea (100 Ng{-1 soil) and insecticide (triazophos at field rate, FR) underdifferent moisture levels of air-dried soil (AD), 50% of water-holdingcapacity (WHC), 100% WHC and flooded soil (FS) on some selected soilproperties in a paddy field soil were examined in a laboratoryincubation study. The results indicated that after 21-day incubation at25 C, the different moisture levels led to significant changesin the parameters studied. Flooding of soil with distilled watersignificantly increased the electron transport system(ETS)/dehydrogenase activity and phenol contents of the soil comparedto the other moisture levels, while protein and phospholipids behaveddifferently at varied moisture levels with or without the addition ofurea and/or triazophos. Increased ETS activity was observed with Naddition at higher moisture levels while insecticide incorporationdecreased it at all moisture levels as compared to the control(moisture only). The phenol contents slightly decreased and increasedwith N and insecticide applications, respectively. The soil proteincontents were found to be unaffected among all the soil treatments atall moisture levels. However, among different moisture levels, reducedquantities of proteins were estimated at 50% WHC, suggesting moreN-mineralization. Lower quantities of soil biomass phospholipids, amongall treatments, were recorded at higher moisture levels (100% WHC andFS) than at the lower levels. An overall slight enhancement inphospholipid contents with N and small reduction with insecticideaddition, respectively, was noticed against the untreated soil. Thetoxicity of fertilizer and insecticide decreased as the soil moisturecontents increased, suggesting rapid degradation of agrochemicals.

  10. Radiocesium discharge from paddy fields with different initial scrapings for decontamination after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Wakahara, Taeko; Onda, Yuich; Kato, Hiroaki; Sakaguchi, Aya; Yoshimura, Kazuya

    2014-11-01

    To explore the behavior of radionuclides released after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011, and the distribution of radiocesium in paddy fields, we monitored radiocesium (Cs) and suspended sediment (SS) discharge from paddy fields. We proposed a rating scale for measuring the effectiveness of surface soil removal. Our experimental plots in paddy fields were located ∼40 km from the FDNPP. Two plots were established: one in a paddy field where surface soil was not removed (the "normally cultivated paddy field") and the second in a paddy field where the top 5-10 cm of soil was removed before cultivation (the "surface-removed paddy field"). The amounts of Cs and SS discharge from the paddy fields were continuously measured from June to August 2011. The Cs soil inventory measured 3 months after the FDNPP accident was approximately 200 kBq m(-2). However, after removing the surface soil, the concentration of Cs-137 decreased to 5 kBq m(-2). SS discharged from the normally cultivated and surface-removed paddy fields after puddling (mixing of soil and water before planting rice) was 11.0 kg and 3.1 kg, respectively, and Cs-137 discharge was 630,000 Bq (1240 Bq m(-2)) and 24,800 Bq (47.8 Bq m(-2)), respectively. The total amount of SS discharge after irrigation (natural rainfall-runoff) was 5.5 kg for the normally cultivated field and 70 kg for the surface-removed field, and the total amounts of Cs-137 discharge were 51,900 Bq (102 Bq m(-2)) and 165,000 Bq (317 Bq m(-2)), respectively. During the irrigation period, discharge from the surface-removed plot showed a twofold greater inflow than that from the normally cultivated plot. Thus, Cs inflow may originate from the upper canal. The topsoil removal process eliminated at least approximately 95% of the Cs-137, but upstream water contaminated with Cs-137 flowed into the paddy field. Therefore, to accurately determine the Cs discharge, it is important to examine Cs inflow from the

  11. [Effects of winter cover crop on methane and nitrous oxide emission from paddy field].

    Science.gov (United States)

    Tang, Hai-ming; Tang, Wen-guang; Shuai, Xi-qiang; Yang, Guang-li; Tang, Hai-tao; Xiao, Xiao-Ping

    2010-12-01

    Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T1), no-tillage and directly sowing Chinese milk vetch (T2), tillage and transplanting rape (T3), no-tillage and directly sowing rape (T4), and fallowing (CK), on the CH4 and N2O emission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH4 and N2O emission in treatments T1-T4 was significantly higher than that in CK (P winter cover crops returned to field, the CH4 emission from early and late rice fields in treatments T1, T2, T3, and T4 was larger than that in CK. In early rice field, treatments T1 and T2 had the largest CH4 emission (21.70 and 20.75 g x m(-2)); while in late rice field, treatments T3 and T4 had the largest one (58.90 and 54.51 g x m(-2) respectively). Treatments T1-T4 also had larger N2O emission from early and late rice fields than the CK did. The N2O emission from early rice field in treatments T1, T2, T3, and T4 was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK.

  12. Effects of Bt-transgenic rice cultivation on planktonic communities in paddy fields and adjacent ditches

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongbo, E-mail: liuyb@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Liu, Fang [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Chao [Pearl River Fisheries Research Institute, Chinese Academy of Fishery Science, Guangzhou 510380 (China); Quan, Zhanjun [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Li, Junsheng, E-mail: lijsh@creas.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    2016-09-15

    The non-target effects of transgenic plants are issues of concern; however, their impacts in cultivated agricultural fields and adjacent natural aquatic ecosystems are poorly understood. We conducted field experiments during two growing seasons to determine the effects of cultivating Bacillus thuringiensis (Bt)-transgenic rice on the phytoplankton and zooplankton communities in a paddy field and an adjacent ditch. Bt toxin was detected in soil but not in water. Water quality was not significantly different between non-Bt and Bt rice fields, but varied among up-, mid- and downstream locations in the ditch. Cultivation of Bt-transgenic rice had no effects on zooplankton communities. Phytoplankton abundance and biodiversity were not significantly different between transgenic and non-transgenic rice fields in 2013; however, phytoplankton were more abundant in the transgenic rice field than in the non-transgenic rice field in 2014. Water quality and rice type explained 65.9% and 12.8% of this difference in 2014, respectively. Phytoplankton and zooplankton were more abundant in mid- and downstream, than upstream, locations in the ditch, an effect that we attribute to water quality differences. Thus, the release of Bt toxins into field water during the cultivation of transgenic crops had no direct negative effects on plankton community composition, but indirect effects that alter environmental conditions should be taken into account during the processes of management planning and policymaking. - Highlights: • We detect fusion Cry1Ab/1Ac proteins from Bt rice entering into aquatic ecosystems. • Bt-transgenic rice cultivation have no significant effect on zooplankton community. • Bt-transgenic rice cultivation have indirect effect on phytoplankton community. • Water quality explains the difference of plankton communities in adjacent ditches.

  13. Subsurface N cycling under variable paddy flood management: what role does it play in N2O emissions?

    Science.gov (United States)

    Verhoeven, Elizabeth; Pierreux, Sofie; Decock, Charlotte; Romani, Marco; Sleutel, Steven; Six, Johan

    2016-04-01

    There is increasing pressure to grow rice with less water in order to save water and mitigate methane (CH4) emissions. However, there is frequently a trade-off with yield declines and increased nitrous oxide (N2O) emissions, potentially increasing the global warming potential of the system. A field trial in Northern Italy was established with two water regimes: continuously flooded (flooded) and alternate wetting and drying (AWD), to investigate the impact of such water management on N2O emissions and N cycling along a depth profile. Surface gas fluxes were complimented by depth profile measurements of soil gas, inorganic N, DOC, dissolved gas concentrations, redox potential and moisture. Sampling was concentrated around two periods during the 2015 growing season which were hypothesized to show significant variation in N dynamics; a fertilization event and final season drainage. For N cycling and N2O emissions, stable isotope measurements were taken to obtain process-level information in situ. During the first field campaign, maximum mean daily N2O emissions did not peak at fertilization but rather a week earlier, demonstrating a greater response to soil conditions (i.e. higher redox and lower moisture) than inorganic N concentrations. This was especially the case in the AWD treatment where emissions peaked at 82.3 ± 126.0 g N2O-N ha-1 d-1 relative to a peak of 2.83 ± 1.1 g N2O-N ha-1 d-1 in the flooded treatment. Considering the upper depths (0-15 cm), peak emissions corresponded well to higher redox potentials in the AWD treatment (72-406 mV versus -100 to -12 mV for AWD and flooded treatments, respectively). These emissions also correlated well to pore space N2O concentrations at 5 and 12.5 cm, suggesting important production of N2O at these depths and subsequent diffusion to the soil surface. Pore space and dissolved N2O concentrations were much lower in the flooded treatment and no such spikes were observed. No significant N2O emissions were observed in

  14. Nannophya pygmaea (Odonata: Libellulidae), an endangered dragonfly in Korea, prefers abandoned paddy fields in the early seral stage.

    Science.gov (United States)

    Yoon, Jihyun; Nam, Jong Min; Kim, Heungtae; Bae, Yeon Jae; Kim, Jae Geun

    2010-04-01

    To characterize habitats of Nannophya pygmaea Rambur (the northern pygmyfly; Odonata: Lilbellulidae), which is endangered in Korea, we analyzed characteristics of surface water and soil, landscape properties, and vegetation types in 22 habitats in eight areas of Korea where nymphs of N. pygmaea have been found since 2005. We divided the habitats into two groups: DS (dwelling site) habitats, where N. pygmaea was observed at the time of the study, and PDS (past dwelling site) habitats, where N. pygmaea recently lived but is no longer found. The habitats were mostly located in former paddy fields on mountain slopes that have been abandoned for 3-7 yr. The main water sources for these habitats were ground water and surface runoff, and the water level was stable at 3-7 cm in depth. The habitats ranged from 300 to 1000 m(2) and were dominated by Juncus effusus, which formed tussock mounds. According to the hydrosere model of succession, N. pygmaea appeared mostly in the early stages of plant succession (the period approximately 3-7 yr after the initiation of succession in former paddy fields) and N. pygmaea preferred habitats displaying the water and soil characteristics that are typical of the early stages of succession in abandoned paddy fields. These results indicate that the primary habitats of N. pygmaea in Korea are recently abandoned paddy fields that are in an oligotrophic state. As succession proceeds in these habitats, N. pygmaea disappears. A habitat management program should be launched to conserve the habitats and populations of N. pygmaea.

  15. Localization and Classification of Paddy Field Pests using a Saliency Map and Deep Convolutional Neural Network.

    Science.gov (United States)

    Liu, Ziyi; Gao, Junfeng; Yang, Guoguo; Zhang, Huan; He, Yong

    2016-01-01

    We present a pipeline for the visual localization and classification of agricultural pest insects by computing a saliency map and applying deep convolutional neural network (DCNN) learning. First, we used a global contrast region-based approach to compute a saliency map for localizing pest insect objects. Bounding squares containing targets were then extracted, resized to a fixed size, and used to construct a large standard database called Pest ID. This database was then utilized for self-learning of local image features which were, in turn, used for classification by DCNN. DCNN learning optimized the critical parameters, including size, number and convolutional stride of local receptive fields, dropout ratio and the final loss function. To demonstrate the practical utility of using DCNN, we explored different architectures by shrinking depth and width, and found effective sizes that can act as alternatives for practical applications. On the test set of paddy field images, our architectures achieved a mean Accuracy Precision (mAP) of 0.951, a significant improvement over previous methods.

  16. Balance of Water Supply-demand in Paddy Fields in Hilly Regions in Sichuan Province

    Institute of Scientific and Technical Information of China (English)

    Hong ZHANG; Xinlu JIANG; Hongzhu FAN; Jiaguo ZHENG

    2012-01-01

    Abstract [Objective] The aim was to study the effects of water supply and con- sumption on water saving and drought resistance. [Method] Controlling field experi- ment was conducted to explore water balance between supply and demand in paddy fields in hilly regions in Sichuan Province. [Result] Rainfall in hilly areas was 3 611.10 m3/hm2; water for irrigation was 6 299.25 m3/hm~, evapotranspiration of rice was 6 424.95 m3/hm2; deep leakage was 2 459.55 m3/hm2; overflowing amount was 1 026.00 m3/hm2. In addition, water consumption totaled 8 884.50 m3/hm2 during rice production; water use was 0.99 kg/m3 and use efficiency of irrigated water was 1.40 kg/m3, [Conclu- sion] Water supply and consumption should be further organized to save water and fight against drought in hilly areas in Sichuan Province.

  17. Photolytic and photocatalytic degradation of quinclorac in ultrapure and paddy field water: identification of transformation products and pathways.

    Science.gov (United States)

    Pareja, Lucía; Pérez-Parada, Andrés; Agüera, Ana; Cesio, Verónica; Heinzen, Horacio; Fernández-Alba, Amadeo R

    2012-05-01

    Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO(2) photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700 W m(-2), respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40 min of TiO(2) photocatalysis in ultrapure water, whereas 130 min were necessary to degrade 98% of the initial concentration in paddy field water. Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. [Effects of different fertilization modes on paddy field topsoil organic carbon content and carbon sequestration duration in South China].

    Science.gov (United States)

    Zhu, Li-Qun; Yang, Min-Fang; Xu, Min-Lun; Zhang, Wu-Yi; Bian, Xin-Min

    2012-01-01

    Based on the organic carbon data of 222 topsoil samples taken from 38 paddy field experiment sites in South China, calculations were made on the relative annual change of topsoil organic carbon content (RAC) and carbon sequestration duration in the paddy fields in South China under five fertilization modes (inorganic nitrogen fertilization, N; inorganic nitrogen and phosphorus fertilization, NP; inorganic nitrogen, phosphorus, and potassium fertilization, NPK; organic fertilization, O; and inorganic plus organic fertilization, OF). The RAC under the fertilizations was 0-0.4 g x kg(-1) x a(-1), with an increment of 0.20 and 0.26 g x kg(-1) x a(-1) in double and triple cropping systems, respectively. The RAC was higher in treatments O and OF than in treatments N, NP, and NPK, being the highest (0.32 g x kg(-1) x a(-1)) in treatment OF. The topsoil organic carbon accumulation rate decreased with increasing time, and the carbon sequestration duration in treatments N, NP, NPK, O, and OF was about 22, 28, 38, 57, and 54 years, respectively. Inorganic plus organic fertilization was the most effective practice for soil carbon sequestration in the paddy fields in South China.

  19. Field note from Pakistan floods: Preventing future flood disasters

    Directory of Open Access Journals (Sweden)

    Marcus Oxley

    2011-04-01

    Full Text Available Unusually heavy monsoon rains in Northern Pakistan have caused disproportionate levels of extreme flooding and unprecedented flood losses across the entire Indus River basin. Extensive land use changes and environmental degradation in the uplands and lowlands of the river basin together with the construction of a “built environment” out of balance with the functioning, capacities, scale and limits of the local ecosystems have exposed millions of people to an increased risk of extreme #ooding. The catastrophic nature of the August #ooding provides a unique opportunity to fundamentally change Pakistan’s current socio-economic development path by incorporating disaster risk reduction and climate change measures into the post-disaster recovery process to rebuild a safer, more resilient nation. In January 2005 one hundred and sixty-eight nations adopted the Hyogo Framework for Action (HFA2005-2015 to bring about a “substantial reduction in disaster losses” by 2015. Despite this global initiative a series of major disasters, including the recent flooding in Pakistan, all indicate that we are not on track to achieve the substantial reduction of disaster losses. The following fieldnote considers what can be done to accelerate progress towards implementation of the Hyogo Framework, drawing on insights and lessons learnt from the August flooding to understand how Pakistan and neighbouring countries can prevent a repeat of such catastrophic disasters in future years.

  20. Changes of Phosphate Solubilizing Bacteria Population on Paddy Field with Intensive Farming became Sustainable Organic Farming System

    Directory of Open Access Journals (Sweden)

    Dermiyati

    2009-05-01

    Full Text Available The research aimed to study the change of population of phosphate solubilizing microorganisms according to the application time of bokashi which were applied continously on organic paddy rice fields since years of 2000 up to 2006. The research was conducted in a Randomized Completely Block Design in four replicates. The treatments were without bokashi (control; with intensively application of NPK fertilizers, bokashi application for 3 planting seasons (12 t ha-1, bokashi application for 4 planting seasons (16 t ha-1, bokashi application for 7 planting seasons (28 t ha-1, and bokashi application for 9 planting seasons (36 t ha-1. The results showed that the population of phosphate solubilizing microorganisms were not affected by continously applied of bokashi and did not have correlations to organic carbon, total nitrogen, ratio C/N, soil pH, and soil water content. However, the phosphate solubilizing microorganisms had played a role in the availability of the soil available-P which were shown by increasing of paddy yields year by year, although the contribution of soil phosphorus from bokashi is a relatively low. Yet, the bokashi application on the organic paddy fields did not increase the soil availble-P because most of the P which was absorbed by the plants coming from residual P fertilizers either from bokashi or SP-36 which were intensevely given before.

  1. Seasonality of ecosystem respiration in a double-cropping paddy field in Bangladesh

    Directory of Open Access Journals (Sweden)

    M. S. Hossen

    2011-08-01

    Full Text Available Ecosystem respiration (RE from cultivated ecosystems is important for understanding the role of these ecosystems in the global carbon balance. To evaluate carbon dynamics in a double-rice cropping paddy field, we conducted long-term measurements at Mymensingh, Bangladesh in 2007 using a tower-based eddy covariance technique. The study objectives were to investigate the diurnal and seasonal variations in RE and to develop and evaluate empirical models for predicting variations in RE using environmental parameters. We found that the diurnal pattern of RE was driven by soil temperature (Ts whereas the seasonal variation in RE was controlled primarily by Ts and soil water content (SWC. Under high biomass conditions, Ts plays a dominant role in the magnitude of CO2 release. Both the amount and magnitude of RE variation were larger in the "Boro" dry-season rice growing period from late winter to mid-summer than in the "Aman" wet-season rice growing period from late summer to early winter. Annually, the ratio of RE to gross primary production (GPP was 0.67, indicating a net sink of carbon; the two growing seasons had RE/GPP ratios of 0.58 and 0.52. A model using Ts, SWC, and aboveground biomass predicted daily RE with R2 values of 0.87 and 0.62 for the Boro and Aman seasons, respectively.

  2. [Further reduction of nitrogen fertilizer application in paddy field under green manuring of Taihu Area, China].

    Science.gov (United States)

    Zhao, Dong; Yan, Ting-mei; Qiao, Jun; Yang, Lin-zhang; Tang, Fang; Song, Yun-fei

    2015-06-01

    This study focused on the nitrogen loss via runoff, change of nitrogen in different forms in surface water in paddy field, and grain yield, through further reduction of nitrogen fertilizer application rate under green manuring without basal dressing. Results showed that with 150 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil, no basal dressing could not only sharply reduce N concentration in surface water and decrease 17.2% of N loss, but also increase 2.8% of grain yield in comparison with basal dressing. It was a worthwhile farming method that inorganic nitrogen fertilizer was not used for basal dressing but for topdressing after return of green ma- nure to soil in Taihu Area. However, the grain yield would decrease if the rate of topdressing nitro- gen was excessively reduced or increased. After all, it was feasible to realize harmonization of grain yield and environmental benefits in Taihu Area, with 133 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil as well as no application of basal dressing, which could greatly reduce N fertilizer input and N loss as well as ensure rice yield.

  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. Investigation the Rototiller Blade Operational Factors on the Soil Tillage of Orchard and Paddy Fields

    Directory of Open Access Journals (Sweden)

    R Tabatabae Koloor

    2011-03-01

    Full Text Available In recent years using rototillers in orchards and small fields especially in northern areas of Iran has been increased. In this study, a multi-function rototiller was developed and its performance was analyzed and evaluated in the field conditions. The specifications of this machine were determined according to the standard and operational situation. The calculations were performed for determining the rotor speed at different gears and then power transmission system was designed. Theoretical analysis was conducted to investigate the machine forward speed and blade rotational speed on the quality of rototilling operation. Results indicated that the forward speed and blade rotational speed affected the thickness of soil cut layer and soil crushing rate. Field tests were performed to determine the thickness of soil cut layer and soil crushing rate for orchard and paddy field conditions. In addition, some physical properties of soil such as composition, moisture content, weeding height, and DENSITY at 15 cm depth were measured. Data analysis was performed by Completely Randomized Design (CRD with factorial test 3×3 at three replications. Duncan test presented the best combinations of forward speed and blade rotational speed for thickness of soil cut layer were 0.4 ms-1 and 50 rpm, respectively. Also, the best combinations of these two factors for soil crushing rate lower than 40 mm were 0.2 ms-1 and 110 rpm, between 40-80 mm; 0.3 ms-1 and 50 rpm and higher than 80 mm; 0.4 ms-1 and 50 rpm, respectively.

  5. Solubility and leaching risks of organic carbon in paddy soils as affected by irrigation managements.

    Science.gov (United States)

    Xu, Junzeng; Yang, Shihong; Peng, Shizhang; Wei, Qi; Gao, Xiaoli

    2013-01-01

    Influence of nonflooding controlled irrigation (NFI) on solubility and leaching risk of soil organic carbon (SOC) were investigated. Compared with flooding irrigation (FI) paddies, soil water extractable organic carbon (WEOC) and dissolved organic carbon (DOC) in NFI paddies increased in surface soil but decreased in deep soil. The DOC leaching loss in NFI field was 63.3 kg C ha⁻¹, reduced by 46.4% than in the FI fields. It indicated that multi-wet-dry cycles in NFI paddies enhanced the decomposition of SOC in surface soils, and less carbon moved downward to deep soils due to less percolation. That also led to lower SOC in surface soils in NFI paddies than in FI paddies, which implied that more carbon was released into the atmosphere from the surface soil in NFI paddies. Change of solubility of SOC in NFI paddies might lead to potential change in soil fertility and sustainability, greenhouse gas emission, and bioavailability of trace metals or organic pollutants.

  6. Changes in Soil Physicochemical Properties Following Land Use Change from Paddy Fields to Greenhouse and Upland Fields in the Southeastern Basin of Dianchi Lake, Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    N.MORITSUKA; T.NISHIKAWA; S.YAMAMOTO; N.MATSUI; H.INOUE; LI Kun-Zhi; T.INAMURA

    2013-01-01

    Paddy fields in the southeastern basin of Dianchi Lake have rapidly changed to greenhouses since 1999.A total of 61 surface soil samples,including 43 greenhouse soils,12 upland soils,and 6 paddy soils,were collected from a flat lowland area mainly used for agricultural production fields in the southeastern basin of Dianchi Lake.Analyses of the soil samples indicated that the greenhouse soils were characterized by a lower organic matter content,lower pH,and higher soluble nutrients than the paddy soils in the area.The lower organic matter content of the greenhouse soils was ascribed to environmental or management factors rather than the clay content of the soil.Accumulation of soluble nutrients,especially inorganic N,was due to over-application of fertilizers,which also caused soil acidification.The average amount of readily available N,P,and K accumulated in the greenhouse soils was estimated to be equal to or higher than the annual input of these nutrients as a fertilizer,indicating that a reduction in fertilizer application was possible and recommended.In contrast,a very low available Si content was observed in the paddy soils,suggesting the need for Si application for rice production.

  7. Regional Differences and Characteristics of Soil Organic Carbon Density Between Dry Land and Paddy Field in China

    Institute of Scientific and Technical Information of China (English)

    XU Quan; RUI Wen-yi; BIAN Xin-min; ZHANG Wei-jian

    2007-01-01

    Study on the regional characteristics of soil organic carbon (SOC) density in farmland will not only contribute greatly to the technique of soil productivity enhancement, but also give evidences of technique selection and policy making for carbon sequestration in soils. Based on the second national soil survey of China, the situation of SOC density in the plow layer of farmland was analyzed under different land use patterns. Results showed that SOC density in the plow layer was about 3.15 kg m-2 in average ranging from 0.81 to 12.68 kg m-2. The highest density was found in the southeastern region with an average of 3.63 kg m-2, while the lowest occurring in the northwestern region with an average of 3.00 kg m-2. The variation coefficient of SOC density in the plow layer of farmland was 57%, which was 35% lower than that of non-farmland soils. Compared to SOC density in the dry land, SOC density in paddy soils was 13% higher with a lower variation coefficient between different regions. In addition, the relationships between the climatic factors (annual average temperature and precipitation) and SOC density were lower in farmland than those in non-farmland soils, as well as lower in paddy soils than those in dry land of farmland. These results suggest that anthropogenic disturbances have great impacts on SOC density in farmland soils, especially in paddy soils, indicating that Chinese rice cropping may contribute greatly to the SOC stability and sequestration in paddy field.

  8. METHANE EMISSION FROM PADDY FIELDS AS INFLUENCED BY DIFFERENT WATER REGIMES IN CENTRAL JAVA

    Directory of Open Access Journals (Sweden)

    Prihasto Setyanto

    2013-07-01

    Full Text Available The concentration of methane (CH4 in the atmosphere is increasing at 1% per annum and rice fields are one of the sources that contribute to about 10-15% of the atmospheric CH4. One of the options to reduce greenhouse gas emission from rice fields is probably through water management. A field study was conducted to investigate the effects of water management practices on CH4 emission from rice field plots on a silty sand Aeric Tropaquept soil at Research Station for Agricultural Environment Preservation, Jakenan, Central Java, Indonesia, during the dry season of March to June 2002. Four water regimes tested were: (1 5 cm continuous flooding (CF, (2 0-1 cm continuous flooding (ST, (3 intermittent irrigation (IR where plots received continuously 5 cm of flooding with two times of draining at 15-20 and 25-30 days after transplanting (DAT, and (4 pulse irrigation (PI where plots were watered until 5 cm level and left to dry by itself until the water table reached 30 cm beneath soil surface then watered again. The total CH4 emissions of the four water treatments were 254, 185, 136 and 96 kg CH4 ha-1 for CF, ST, IR and PI, respectively. Methane emission increased during the early growing season, which coincided with the low redox potential of -100 to -150 mV in all treatments. Dry matter weight of straw and filled grain among the water treatments did not show significant differences. Likewise, total grain yield at 14% moisture content was not significantly different among treatments. However, this result should be carefully interpreted because the rice plants in all water treatments were infested by stem borer, which reduced the total grain yield of IR64 between 11% and 16%. This study suggests that intermittent and pulse irrigation practices will be important not only for water use efficiency, but also for CH4 emission reduction.

  9. A DYNAMIC MIXED MODEL WITH NITROGEN LEACHING LOSSES FROM THE PONDED PADDY RICE FIELD UNDER SITUATION OF BURIED PIPE DRAINAGE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In order to study the law of nitrogen leaching losses from the paddy field under the condition of drainage, based on the theories of potential energy and solute transport, a water-nitrogen dynamic mixed model by combining the flow net with dynamic method was established. In the computation of buried pipe drainage, the superposition principle was used to simplify the complex solving of the two-dimensional problem about water-nitrogen transportation in Soil-Plant-Air-Continuous (SPAC) system into several one-dimensional problems. The presented method is simple and practical. Some field experiments were carried out to demonstrate the validity of the model.

  10. Effect of Organic Acids and Protons on Release of Non-Exchangeable NH4+ in Flooded Paddy Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong-Song; SHAO Xing-Hua; LIN Xian-Yong; H. W. SCHERER

    2005-01-01

    In a model experiment, which imitated the rhizosphere of rice, the effect of organic acids (oxalic acid, citric acid) and protons on the release of non-exchangeable NH4+ and the resin adsorption of N was studied in a paddy soil, typical for Zhejiang Province, China. Oxalic and citric acids under low pH conditions, in combination with proton secretion, favored the mobilization of NH4+ ions and increased resin adsorption of N. The release of non-exchangeable NH4+ was associated with less formation of iron oxides. These could coat clay minerals and thus hinder the diffusion of NH4+ ions out of the interlayer. Protons enhanced the release of NH4+, and then they could enter the wedge zones of the clay minerals and displace non-exchangeable NH4+ ions.

  11. STUDY ON BEHAVIOUR OF CR FORMULATION OF THIOBENCARB IN A MODEL PADDY FIELD

    Institute of Scientific and Technical Information of China (English)

    孙锦荷; 李兴明; 等

    1994-01-01

    The fate of CR formulation of 14C-thiobencarb (thio.)was studied at the high rate of application in a model paddy field.Thio.could be released from the alginate formulation (TAL-17189) into water.The concentration of thio.in water increased with time,then declined.Thio.in water could be converted to more than 1214C-degradation products which changed with time.An unknown degradation product(Mo) was always prevailing after application.Thio.in water could be adsorbed by soil particles.Most of the adsorbed thio.retained in upper layer.Thio.in soil could be also degraded to more than 6 products.Thio.and its degradation products could conjugate with the compositions of soil to bound residues(BR),Thio.was 45.6% of the total 14C-extractable residues(ER) in upper layer soil at harvest,14C-thio.in water and soil could be uptaken by rice plants.Thio.In plants existed in ER and BR.Most of 14C-residues in straw,roots,brown rice and husk were in bound form,more than 92% of the total 14C in them at harvest respectively,Thio.in plants could be metabolzed to more than 9 metabolites which changed with time.14C-thio.in straw brown rice and husk accounted for 55.88,6.06 and 11.18% of the total 14C-ER of them at harvest respectively.An unknown 14C-metabolite in brown rice was prevailing accounted for 63.03% of the total 14C-ER.

  12. {sup 137}Cs in irrigation water and its effect on paddy fields in Japan after the Fukushima nuclear accident

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Natsuki [Institute of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Obara, Hitomi [Oriental Consultants, Sumitomo Fudosan Nishi Shinjuku Bldg. No. 6, 3-12-1 Honmachi, Shibuya-ku, Tokyo 151-0071 (Japan); Ogasa, Marie; Miyazu, Susumu [Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Harada, Naoki [Institute of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan); Nonaka, Masanori [Graduate School for Management of Technology, Niigata University, 8050 Ikarashi 2-nocho, Nishi-ku, Niigata 950-2181 (Japan)

    2014-05-01

    There is concern that radiocesium deposited in the environment after the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 will migrate to paddy fields through hydrological pathways and cause serious and long-lasting damage to the agricultural activities. This study was conducted in the Towa region of Nihonmatsu in the northern part of Fukushima Prefecture, Japan, (1) to quantify {sup 137}Cs in stream water used to irrigate paddy fields by separating the dissolved and particulate components in water samples and then fractionating the particulate components bonded in different ways using a sequential extraction procedure, and (2) to determine the amounts of radiocesium newly added to paddy fields in irrigation water relative to the amounts of radiocesium already present in the fields from the deposition of atmospheric fallout immediately after the FDNPP accident. Three catchments were studied, and the {sup 137}Cs activity concentrations in stream water samples were 79–198 mBq L{sup −1} under stable runoff conditions and 702–13,400 Bq L{sup −1} under storm runoff conditions. The residual fraction (F4, considered to be non-bioavailable) was dominant, accounting for 59.5–82.6% of the total {sup 137}Cs activity under stable runoff conditions and 69.4–95.1% under storm runoff conditions. The {sup 137}Cs newly added to paddy fields in irrigation water only contributed 0.03–0.05% of the amount already present in the soil (201–348 kBq m{sup −2}). This indicates that the {sup 137}Cs inflow load in irrigation water is negligible compared with that already in the soil. However, the contribution from the potentially bioavailable fractions (F1 + F2 + F3) was one order of magnitude larger, accounting for 0.20–0.59%. The increase in the dissolved and soluble radiocesium fraction (F1) was especially large (3.0% to infinity), suggesting that radiocesium migration in irrigation water is increasing the accumulation of radiocesium in rice

  13. Comparison of greenhouse gas emissions from rice paddy fields under different nitrogen fertilization loads in Chongming Island, Eastern China.

    Science.gov (United States)

    Zhang, Xianxian; Yin, Shan; Li, Yinsheng; Zhuang, Honglei; Li, Changsheng; Liu, Chunjiang

    2014-02-15

    Rice is one of the major crops of southern China and Southeast Asia. Rice paddies are one of the largest agricultural greenhouse gas (GHG) sources in this region because of the application of large quantities of nitrogen (N) fertilizers to the plants. In particular, the production of methane (CH4) is a concern. Investigating a reasonable amount of fertilizers to apply to plants is essential to maintaining high yields while reducing GHG emissions. In this study, three levels of fertilizer application [high (300 kg N/ha), moderate (210 kg N/ha), and low (150 kg N/ha)] were designed to examine the effects of variation in N fertilizer application rate on carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from the paddy fields in Chongming Island, Shanghai, China. The high level (300 kg N/ha) represented the typical practice adopted by the local farmers in the area. Maximum amounts of CH4 and N2O fluxes were observed upon high-level fertilizer application in the plots. Cumulative N2O emissions of 23.09, 40.10, and 71.08 mg N2O/m(2) were observed over the growing season in 2011 under the low-, moderate-, and high-level applications plots, respectively. The field data also indicated that soil temperatures at 5 and 10 cm soil depths significantly affected soil respiration; the relationship between Rs and soil temperature in this study could be described by an exponential model. Our study showed that reducing the high rate of fertilizer application is a feasible way of attenuating the global-warming potential while maintaining the optimum yield for the studied paddy fields.

  14. Using natural Chinese zeolite to remove ammonium from rainfall runoff following urea fertilization of a paddy rice field.

    Science.gov (United States)

    Wang, Xiao-Ling; Qiao, Bin; Li, Song-Min; Li, Jian-Sheng

    2016-03-01

    The potential of natural Chinese zeolite to remove ammonium from rainfall runoff following urea applications to a paddy rice field is assessed in this study. Laboratory batch kinetic and isotherm experiments were carried out first to investigate the ammonium adsorption capacity of the natural zeolite. Field experiments using zeolite adsorption barriers installed at drain outlets in a paddy rice field were also carried out during natural rainfall events to evaluate the barrier's dynamic removal capacity of ammonium. The results demonstrate that the adsorption kinetics are accurately described by the Elovich model, with a coefficient of determination (R (2)) ranging from 0.9705 to 0.9709, whereas the adsorption isotherm results indicate that the Langmuir-Freundlich model provides the best fit (R (2) = 0.992) for the equilibrium data. The field experiments show that both the flow rate and the barrier volume are important controls on ammonium removal from rainfall runoff. A low flow rate leads to a higher ammonium removal efficiency at the beginning of the tests, while a high flow rate leads to a higher quantity of ammonium adsorbed over the entire runoff process.

  15. Detection of pesticides residues in water samples from organic and conventional paddy fields of Ledang, Johor, Malaysia

    Science.gov (United States)

    Abdullah, Md Pauzi; Othman, Mohamed Rozali; Ishak, Anizan; Nabhan, Khitam Jaber

    2016-11-01

    Pesticides have been used extensively by the farmers in Malaysia during the last few decades. Sixteen water samples, collected from paddy fields both organic and conventional, from Ledang, Johor, were analyzed to determine the occurrence and distribution of organochlorine (OCPs) and organophosphorus (OPPs) pesticide residues. GC-ECD instrument was used to identify and determine the concentrations of these pesticide residues. Pesticide residues were detected in conventional fields in the range about 0.036-0.508 µg/L higher than detected in organic fields about 0.015-0.428 µg/L. However the level of concentration of pesticide residues in water sample from both paddy fields are in the exceed limit for human consumption, according to European Economic Commission (EEC) (Directive 98/83/EC) at 0.1 µg/L for any pesticide or 0.5 µg/L for total pesticides. The results that the organic plot is still contaminated with pesticides although pesticides were not use at all in plot possibly from historical used as well as from airborne contamination.

  16. POISON SPIDER FIELD CHEMICAL FLOOD PROJECT, WYOMING

    Energy Technology Data Exchange (ETDEWEB)

    Douglas Arnell; Malcolm Pitts; Jie Qi

    2004-11-01

    -rock compatibility, polymer injectivity, dynamic chemical retention by rock, and recommended injected polymer concentration. Average initial oil saturation was 0.796 Vp. Produced water injection recovered 53% OOIP leaving an average residual oil saturation of 0.375 Vp. Poison Spider rock was strongly water-wet with a mobility ratio for produced water displacing the 280 cp crude oil of 8.6. Core was not sensitive to either alkali or surfactant injection. Injectivity increased 60 to 80% with alkali plus surfactant injection. Low and medium molecular weight polyacrylamide polymers (Flopaam 3330S and Flopaam 3430S) dissolved in either an alkaline-surfactant solution or softened produced water injected and flowed through Poison Spider rock. Recommended injected polyacrylamide concentration is 2,100 mg/L for both polymers for a unit mobility ratio. Radial corefloods were performed to evaluate oil recovery efficiency of different chemical solutions. Waterflood oil recovery averaged 46.4 OOIP and alkaline-surfactant-polymer flood oil recovery averaged an additional 18.1% OIP for a total of 64.6% OOIP. Oil cut change due to injection of a 1.5 wt% Na{sub 2}CO{sub 3} plus 0.05 wt% Petrostep B-100 plus 0.05 wt% Stepantan AS1216 plus 2100 mg/L Flopaam 3430S was from 2% to a peak of 23.5%. Additional study might determine the impact on oil recovery of a lower polymer concentration. An alkaline-surfactant-polymer flood field implementation outline report was written.

  17. Comparison of greenhouse gas emissions from rice paddy fields under different nitrogen fertilization loads in Chongming Island, Eastern China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xianxian [School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Research Centre for Low Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Key Laboratory for Urban Agriculture (South), Ministry of Agriculture, PR China, Dongchuan Rd. 800, Shanghai 200240 (China); Yin, Shan, E-mail: yinshan@sjtu.edu.cn [School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Research Centre for Low Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Key Laboratory for Urban Agriculture (South), Ministry of Agriculture, PR China, Dongchuan Rd. 800, Shanghai 200240 (China); Li, Yinsheng [School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Research Centre for Low Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Zhuang, Honglei [School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Research Centre for Low Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Key Laboratory for Urban Agriculture (South), Ministry of Agriculture, PR China, Dongchuan Rd. 800, Shanghai 200240 (China); Li, Changsheng [School of Agriculture and Biology, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Research Centre for Low Carbon Agriculture, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai 200240 (China); Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, College Road, NH 03824-3525 (United States); and others

    2014-02-01

    Rice is one of the major crops of southern China and Southeast Asia. Rice paddies are one of the largest agricultural greenhouse gas (GHG) sources in this region because of the application of large quantities of nitrogen (N) fertilizers to the plants. In particular, the production of methane (CH{sub 4}) is a concern. Investigating a reasonable amount of fertilizers to apply to plants is essential to maintaining high yields while reducing GHG emissions. In this study, three levels of fertilizer application [high (300 kg N/ha), moderate (210 kg N/ha), and low (150 kg N/ha)] were designed to examine the effects of variation in N fertilizer application rate on carbon dioxide (CO{sub 2}), methane (CH{sub 4}), and nitrous oxide (N{sub 2}O) emissions from the paddy fields in Chongming Island, Shanghai, China. The high level (300 kg N/ha) represented the typical practice adopted by the local farmers in the area. Maximum amounts of CH{sub 4} and N{sub 2}O fluxes were observed upon high-level fertilizer application in the plots. Cumulative N{sub 2}O emissions of 23.09, 40.10, and 71.08 mg N{sub 2}O/m{sup 2} were observed over the growing season in 2011 under the low-, moderate-, and high-level applications plots, respectively. The field data also indicated that soil temperatures at 5 and 10 cm soil depths significantly affected soil respiration; the relationship between Rs and soil temperature in this study could be described by an exponential model. Our study showed that reducing the high rate of fertilizer application is a feasible way of attenuating the global-warming potential while maintaining the optimum yield for the studied paddy fields. - Highlights: • In Chongming Island, Shanghai, GHG emissions were measured under different nitrogen fertilizer rates from the paddy. • Low nitrogen fertilizer application reduced CH{sub 4} and N{sub 2}O emissions. • The study showed that 210 kg N/ha was the suitable fertilizer application rate.

  18. Mosquitoes and other aquatic insects in fallow field biotopes and rice paddy fields.

    Science.gov (United States)

    Ohba, S Y; Matsuo, T; Takagi, M

    2013-03-01

    Fallow field biotopes that develop from abandoned rice fields are man-made wetlands that provide new habitats for various aquatic animals. Although consideration of such biotopes generally focuses on their positive aspects, this study evaluated the negative aspects of establishing fallow field biotopes with regard to mosquito breeding sites. To determine whether fallow field biotopes become breeding habitats for vector mosquitoes, we evaluated mosquito fauna in fallow field biotopes and adjacent rice fields. We found larvae of Anopheles lesteri, Anopheles sinensis and Culex tritaeniorhynchus (all: Diptera: Culicidae) in the biotopes. Although abundances of mosquito larvae in the biotopes and rice fields were statistically similar, mosquito abundances in rice fields increased dramatically in August when the water level reduced after the rainy season. The abundance and variety of the mosquitoes' natural predators were greater in biotopes than in rice fields because the former are a permanent and stable aquatic environment. A generalized linear mixed model showed a negative effect of predator diversity on mosquito larvae abundance in both habitats. Although fallow field biotopes become breeding habitats for vector mosquitoes, establishing biotopes from fallow fields in order to protect various aquatic animals, including mosquito insect predators, may help to control mosquito breeding. © 2012 The Royal Entomological Society.

  19. 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)

  20. Combination system of full-scale constructed wetlands and wetland paddy fields to remove nitrogen and phosphorus from rural unregulated non-point sources.

    Science.gov (United States)

    Sun, Haijun; Zhang, Hailin; Yu, Zhimin; Wu, Jiasen; Jiang, Peikun; Yuan, Xiaoyan; Shi, Weiming

    2013-12-01

    Constructed wetlands (CWs) have been used effectively to remove nitrogen (N) and phosphorus (P) from non-point sources. Effluents of some CWs were, however, still with high N and P concentrations and remained to be pollution sources. Widely distributed paddy fields can be exploited to alleviate this concern. We were the first to investigate a combination system of three-level CWs with wetland paddy fields in a full scale to remove N and P from rural unregulated non-point sources. The removal efficiencies (REs) of CWs reached 57.3 % (37.4-75.1 %) for N and 76.3 % (62.0-98.4 %) for P. The CWs retained about 1,278 kg N ha(-1) year(-1) and 121 kg P ha(-1) year(-1). There was a notable seasonal change in REs of N and P, and the REs were different in different processing components of CWs. The removal rates of wetland paddy fields adopt "zero-drainage" water management according to local rainfall forecast and physiological water demand of crop growth reached 93.2 kg N ha(-1) year(-1) and 5.4 kg P ha(-1) year(-1). The rice season had higher potential in removing N and P than that in the wheat season. The whole combined system (0.56 ha CWs and 5.5 ha wetland paddy fields) removed 1,790 kg N year(-1) and 151 kg P year(-1), which were higher than those from CWs functioned alone. However, another 4.7-ha paddy fields were needed to fully remove the N and P in the effluents of CWs. The combination of CWs and paddy fields proved to be a more efficient nutrient removal system.

  1. Automated Counting of Rice Planthoppers in Paddy Fields Based on Image Processing

    Institute of Scientific and Technical Information of China (English)

    YAO Qing; XIAN Ding-xiang; LIU Qing-jie; YANG Bao-jun; DIAO Guang-qiang; TANG Jian

    2014-01-01

    A quantitative survey of rice planthoppers in paddy ifelds is important to assess the population density and make forecasting decisions. Manual rice planthopper survey methods in paddy ifelds are time-consuming, fatiguing and tedious. This paper describes a handheld device for easily capturing planthopper images on rice stems and an automatic method for counting rice planthoppers based on image processing. The handheld device consists of a digital camera with WiFi, a smartphone and an extrendable pole. The surveyor can use the smartphone to control the camera, which is ifxed on the front of the pole by WiFi, and to photograph planthoppers on rice stems. For the counting of planthoppers on rice stems, we adopt three layers of detection that involve the following:(a) the ifrst layer of detection is an AdaBoost classiifer based on Haar features;(b) the second layer of detection is a support vector machine (SVM) classiifer based on histogram of oriented gradient (HOG) features;(c) the third layer of detection is the threshold judgment of the three features. We use this method to detect and count whiteback planthoppers (Sogatella furcifera) on rice plant images and achieve an 85.2%detection rate and a 9.6%false detection rate. The method is easy, rapid and accurate for the assessment of the population density of rice planthoppers in paddy ifelds.

  2. Optimizing rice plant photosynthate allocation reduces N2O emissions from paddy fields

    Science.gov (United States)

    Jiang, Yu; Huang, Xiaomin; Zhang, Xin; Zhang, Xingyue; Zhang, Yi; Zheng, Chengyan; Deng, Aixing; Zhang, Jun; Wu, Lianhai; Hu, Shuijin; Zhang, Weijian

    2016-07-01

    Rice paddies are a major source of anthropogenic nitrous oxide (N2O) emissions, especially under alternate wetting-drying irrigation and high N input. Increasing photosynthate allocation to the grain in rice (Oryza sativa L.) has been identified as an effective strategy of genetic and agronomic innovation for yield enhancement; however, its impacts on N2O emissions are still unknown. We conducted three independent but complementary experiments (variety, mutant study, and spikelet clipping) to examine the impacts of rice plant photosynthate allocation on paddy N2O emissions. The three experiments showed that N2O fluxes were significantly and negatively correlated with the ratio of grain yield to total aboveground biomass, known as the harvest index (HI) in agronomy (P < 0.01). Biomass accumulation and N uptake after anthesis were significantly and positively correlated with HI (P < 0.05). Reducing photosynthate allocation to the grain by spikelet clipping significantly increased white root biomass and soil dissolved organic C and reduced plant N uptake, resulting in high soil denitrification potential (P < 0.05). Our findings demonstrate that optimizing photosynthate allocation to the grain can reduce paddy N2O emissions through decreasing belowground C input and increasing plant N uptake, suggesting the potential for genetic and agronomic efforts to produce more rice with less N2O emissions.

  3. 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.

  4. Phylogenetic and functional diversity of denitrifying bacteria isolated from various rice paddy and rice-soybean rotation fields.

    Science.gov (United States)

    Tago, Kanako; Ishii, Satoshi; Nishizawa, Tomoyasu; Otsuka, Shigeto; Senoo, Keishi

    2011-01-01

    Denitrifiers can produce and consume nitrous oxide (N(2)O). While little N(2)O is emitted from rice paddy soil, the same soil produces N(2)O when the land is drained and used for upland crop cultivation. In this study, we collected soils from two types of fields each at three locations in Japan; one type of field had been used for continuous cultivation of rice and the other for rotational cultivation of rice and soybean. Active denitrifiers were isolated from these soils using a functional single-cell isolation method, and their taxonomy and denitrifying properties were examined. A total of 110 denitrifiers were obtained, including those previously detected by a culture-independent analysis. Strains belonging to the genus Pseudogulbenkiania were dominant at all locations, suggesting that Pseudogulbenkiania denitrifiers are ubiquitous in various rice paddy soils. Potential denitrifying activity was similar among the strains, regardless of the differences in taxonomic position and soil of origin. However, relative amounts of N(2) in denitrification end products varied among strains isolated from different locations. Our results also showed that crop rotation had minimal impact on the functional diversity of the denitrifying strains. These results indicate that soil and other environmental factors, excluding cropping systems, could select for N(2)-producing denitrifiers.

  5. Study of Environmental Impacts Before and After Using the Organic-Chemical Fertilizer in Rice Paddy Fields

    Directory of Open Access Journals (Sweden)

    Wipawee KHAMWICHIT

    2006-01-01

    Full Text Available The environmental impact of an organic-chemical fertilizer developed by the Institute of National Science and Technology has been studied at Bansrangsabaeng Posai Ubonratchathani. The study revealed that the values of pH, EC, OC, total N, available P, and exchangeable K in soils from two varieties of rice tested Kor-Khor 10 and         Kor-Khor 15 paddy fields are almost the same. The concentrations of VOC, NH3, and CH4 in the air from the rice paddy fields mentioned above are lower than 0.001 mg/m3 indicating no air pollution problems. Analysis of the water supply (ground water and surface water within the studied area before and after using organic-chemical fertilizer, found that most of the water supply parameters including pH, Total Hardness, TDS, SS, Fe, Mn, and   NO3-N were not significantly changed and all of them met water supply standards. In terms of surface water quality, slightly different values of pH, TDS, SS, NO3-N, TKN, PO4-P, BOD, COD, and DO were observed compared with a standard fertilizer. In conclusion, the organic-chemical fertilizer is a viable alternative to standard chemical fertilizer and may help to reduce the environmental impact of such chemicals upon the land.

  6. Effect of chemical amendments on remediation of potentially toxic trace elements (PTEs) and soil quality improvement in paddy fields.

    Science.gov (United States)

    Kim, Sung Chul; Hong, Young Kyu; Oh, Se Jin; Oh, Seung Min; Lee, Sang Phil; Kim, Do Hyung; Yang, Jae E

    2017-04-01

    Remediation of potentially toxic trace elements (PTEs) in paddy fields is fundamental for crop safety. In situ application of chemical amendments has been widely adapted because of its cost-effectiveness and environmental safety. The main purpose of this research was to (1) evaluate the reduction in dissolved concentrations of cadmium (Cd) and arsenic (As) with the application of chemical amendments and (2) monitor microbial activity in the soil to determine the remediation efficiency. Three different chemical amendments, lime stone, steel slag, and acid mine drainage sludge, were applied to paddy fields, and rice (Oryza sativa L. Milyang 23) was cultivated. The application of chemical amendments immobilized both Cd and As in soil. Between the two PTEs, As reduction was significant (p chemical amendments, whereas no significant reduction was observed for Cd than that for the control. Among six soil-related variables, PTE concentration showed a negative correlation with soil pH (r = -0.70 for As and r = -0.54 for Cd) and soil respiration (SR) (r = -0.88 for As and r = -0.45 for Cd). This result indicated that immobilization of PTEs in soil is dependent on soil pH and reduces PTE toxicity. Overall, the application of chemical amendments could be utilized for decreasing PTE (As and Cd) bioavailability and increasing microbial activity in the soil.

  7. Relationships between the potential production of the greenhouse gases CO2, CH4 and N2O and soil concentrations of C, N and P across 26 paddy fields in southeastern China

    Science.gov (United States)

    Wang, Weiqi; Sardans, Jordi; Wang, Chun; Zeng, Congsheng; Tong, Chuan; Asensio, Dolores; Peñuelas, Josep

    2017-09-01

    Paddy fields are a major global anthropogenic source of greenhouse gases. China has the second largest area under rice cultivation, so determining the relationships between the emission of greenhouse gases and soil carbon content, nutrient availabilities and concentrations and physical properties is crucial for minimizing the climatic impacts of rice agriculture. We examined soil nutrients and other properties, greenhouse-gas production and their relationships in 26 paddy fields throughout the province of Fujian in China, one of the most important provinces for rice production. High P and K concentrations, contents and availabilities were correlated with low rates of CO2 production, whereas high C and N contents were correlated with high rates of CH4 production. Mean annual precipitation (MAP) and rates of gas production were not clearly correlated, at least partly due to the management of flooding that can mask the effect of precipitation. Higher mean annual temperatures and soil Fe contents favored the production of N2O. C, N, P and K concentrations and their ratios, especially the C:K and N:K ratios, and P availability were correlated with CO2 and CH4 production across the province, with higher C:K and N:K ratios correlated positively with increased CO2 production and available P correlated negatively with CH4 production. A management strategy to avoid excessive C accumulation in the soil and to increase P availability and decrease available Fe contents would likely decrease the production of greenhouse gases.

  8. Actual Condition of Paddy Field Levee Maintenance by Various Farm Households including Large-scale Farming in the Developed Land Renting Area

    Science.gov (United States)

    Sakata, Yasuyo

    The survey of interview, resource acquisition, photographic operation, and questionnaire were carried out in the “n” Community in the “y” District in Hakusan City in Ishikawa Prefecture to investigate the actual condition of paddy field levee maintenance in the area where land-renting market was proceeding, large-scale farming was dominant, and the problems of geographically scattered farm-land existed. In the study zone, 1) an agricultural production legal person rent-cultivated some of the paddy fields and maintained the levees, 2) another agricultural production legal person rent-cultivated some of the soy bean fields for crop changeover and land owners maintained the levees. The results indicated that sufficient maintenance was executed on the levees of the paddy fields cultivated by the agricultural production legal person, the soy bean fields for crop changeover, and the paddy fields cultivated by the land owners. Each reason is considered to be the managerial strategy, the economic incentive, the mutual monitoring and cross-regulatory mechanism, etc.

  9. Can't See the Forest for the Rice: Factors Influencing Spatial Variations in the Density of Trees in Paddy Fields in Northeast Thailand

    Science.gov (United States)

    Watanabe, Moriaki; Vityakon, Patma; Rambo, A. Terry

    2014-02-01

    The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand's agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast "invisible forest" represented by trees in paddy fields may truly disappear, with negative consequences for the villagers' livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem.

  10. Mapping paddy rice planting area in cold temperate climate region through analysis of time series Landsat 8 (OLI), Landsat 7 (ETM+) and MODIS imagery

    Science.gov (United States)

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

    2015-07-01

    Accurate and timely rice paddy field maps with a fine spatial resolution would greatly improve our understanding of the effects of paddy rice agriculture on greenhouse gases emissions, food and water security, and human health. Rice paddy field maps were developed using optical images with high temporal resolution and coarse spatial resolution (e.g., Moderate Resolution Imaging Spectroradiometer (MODIS)) or low temporal resolution and high spatial resolution (e.g., Landsat TM/ETM+). In the past, the accuracy and efficiency for rice paddy field mapping at fine spatial resolutions were limited by the poor data availability and image-based algorithms. In this paper, time series MODIS and Landsat ETM+/OLI images, and the pixel- and phenology-based algorithm are used to map paddy rice planting area. The unique physical features of rice paddy fields during the flooding/open-canopy period are captured with the dynamics of vegetation indices, which are then used to identify rice paddy fields. The algorithm is tested in the Sanjiang Plain (path/row 114/27) in China in 2013. The overall accuracy of the resulted map of paddy rice planting area generated by both Landsat ETM+ and OLI is 97.3%, when evaluated with areas of interest (AOIs) derived from geo-referenced field photos. The paddy rice planting area map also agrees reasonably well with the official statistics at the level of state farms (R2 = 0.94). These results demonstrate that the combination of fine spatial resolution images and the phenology-based algorithm can provide a simple, robust, and automated approach to map the distribution of paddy rice agriculture in a year.

  11. Mapping paddy rice planting area in cold temperate climate region through analysis of time series Landsat 8 (OLI), Landsat 7 (ETM+) and MODIS imagery.

    Science.gov (United States)

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

    2015-07-01

    Accurate and timely rice paddy field maps with a fine spatial resolution would greatly improve our understanding of the effects of paddy rice agriculture on greenhouse gases emissions, food and water security, and human health. Rice paddy field maps were developed using optical images with high temporal resolution and coarse spatial resolution (e.g., Moderate Resolution Imaging Spectroradiometer (MODIS)) or low temporal resolution and high spatial resolution (e.g., Landsat TM/ETM+). In the past, the accuracy and efficiency for rice paddy field mapping at fine spatial resolutions were limited by the poor data availability and image-based algorithms. In this paper, time series MODIS and Landsat ETM+/OLI images, and the pixel- and phenology-based algorithm are used to map paddy rice planting area. The unique physical features of rice paddy fields during the flooding/open-canopy period are captured with the dynamics of vegetation indices, which are then used to identify rice paddy fields. The algorithm is tested in the Sanjiang Plain (path/row 114/27) in China in 2013. The overall accuracy of the resulted map of paddy rice planting area generated by both Landsat ETM+ and OLI is 97.3%, when evaluated with areas of interest (AOIs) derived from geo-referenced field photos. The paddy rice planting area map also agrees reasonably well with the official statistics at the level of state farms (R(2) = 0.94). These results demonstrate that the combination of fine spatial resolution images and the phenology-based algorithm can provide a simple, robust, and automated approach to map the distribution of paddy rice agriculture in a year.

  12. High resolution depth distribution of Bacteria, Archaea, methanotrophs, and methanogens in the bulk and rhizosphere soils of a flooded rice paddy

    Directory of Open Access Journals (Sweden)

    Hyo Jung eLee

    2015-06-01

    Full Text Available The communities and abundances of methanotrophs and methanogens, along with the oxygen, methane, and total organic carbon (TOC concentrations, were investigated along a depth gradient in a flooded rice paddy. Broad patterns in vertical profiles of oxygen, methane, TOC, and microbial abundances were similar in the bulk and rhizosphere soils, though methane and TOC concentrations and 16S rRNA gene copies were clearly higher in the rhizosphere soil than in the bulk soil. Oxygen concentrations decreased sharply to below detection limits at the 8 mm depth. Pyrosequencing of 16S rRNA genes showed that bacterial and archaeal communities varied according to the oxic, oxic-anoxic, and anoxic zones, indicating that oxygen is a determining factor for the distribution of bacterial and archaeal communities. Aerobic methanotrophs were maximally observed near the oxic-anoxic interface, while methane, TOC, and methanogens were highest in the rhizosphere soil at 30–200 mm depth, suggesting that methane is produced mainly from organic carbon derived from rice plants and is metabolized aerobically. The relative abundances of type I methanotrophs such as Methylococcus, Methylomonas, and Methylocaldum decreased more drastically than those of type II methanotrophs (such as Methylocystis and Methylosinus with increasing depth. Methanosaeta and Methanoregula were predominant methanogens at all depths, and the relative abundances of Methanosaeta, Methanoregula, and Methanosphaerula, and GOM_Arc_I increased with increasing depth. Based on contrasts between absolute abundances of methanogens and methanotrophs at depths sampled across rhizosphere and bulk soils (especially millimeter-scale slices at the surface, we have identified populations of methanogens (Methanosaeta, Methanoregula, Methanocella, Methanobacterium, and Methanosphaerula and methanotrophs (Methylosarcina, Methylococcus, Methylosinus, and unclassified Methylocystaceae that are likely physiologically

  13. Land-use induced changes in topsoil organic carbon stock of paddy fields using MODIS and TM/ETM analysis: a case study of Wujiang County, China

    Institute of Scientific and Technical Information of China (English)

    GAO Jianfeng; PAN Genxing; JIANG Xiaosan; PAN Jianjun; ZHUANG Dafang

    2008-01-01

    Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO2) buildup is greatly affected by human activities. To evaluate the influence of land-use changes on SOC stocks in paddy soils, a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County. Thereafter, the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estimate land use-induced carbon (C) pool changes in paddy topsoil of Wujiang County based upon the nationwide arable soil monitoring data and county level SOC reconnaissance data in 2003. The results showed that irrigation-based rice cultivation in Wujiang County has resulted in SOC content at an annual increasing rate of 0.01 g/kg over the period of 1984-2003, while the density of SOC in uplands and woodlands has decreased. Annual decreasing rate of SOC content was estimated to be 0.03 g/kg in uplands and 0.06 g/kg in woodlands. The total topsoil SOC stocks in paddy fields of Wujiang County have increased from 2.67× 106 t C in 1984 to 2.69 × 106 t C in 2005. During 1984-2005, the total SOC sequestrations in rice paddies were greater than the SOC losses in woodlands and uplands. The temporal C loss might have exceeded the SOC sequestration in rice paddies due to their conversion to nursery lands and uplands since 2001. The results of this study suggest that changes of land use have a great influence on soil C sequestration, particularly on C stocks and C sequestration potential in paddy fields in developed areas of China.

  14. Land-use induced changes in topsoil organic carbon stock of paddy fields using MODIS and TM/ETM analysis: a case study of Wujiang County, China.

    Science.gov (United States)

    Gao, Jianfeng; Pan, Genxing; Jiang, Xiaosan; Pan, Jianjun; Zhuang, Dafang

    2008-01-01

    Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO2) buildup is greatly affected by human activities. To evaluate the influence of land-use changes on SOC stocks in paddy soils, a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County. Thereafter, the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estimate land use-induced carbon (C) pool changes in paddy topsoil of Wujiang County based upon the nationwide arable soil monitoring data and county level SOC reconnaissance data in 2003. The results showed that irrigation-based rice cultivation in Wujiang County has resulted in SOC content at an annual increasing rate of 0.01 g/kg over the period of 1984-2003, while the density of SOC in uplands and woodlands has decreased. Annual decreasing rate of SOC content was estimated to be 0.03 g/kg in uplands and 0.06 g/kg in woodlands. The total topsoil SOC stocks in paddy fields of Wujiang County have increased from 2.67 x 10(6) t C in 1984 to 2.69 x 10(6) t C in 2005. During 1984-2005, the total SOC sequestrations in rice paddies were greater than the SOC losses in woodlands and uplands. The temporal C loss might have exceeded the SOC sequestration in rice paddies due to their conversion to nursery lands and uplands since 2001. The results of this study suggest that changes of land use have a great influence on soil C sequestration, particularly on C stocks and C sequestration potential in paddy fields in developed areas of China.

  15. Effects of nitrogen fertilizer sources and tillage practices on greenhouse gas emissions in paddy fields of central China

    Science.gov (United States)

    Zhang, Z. S.; Chen, J.; Liu, T. Q.; Cao, C. G.; Li, C. F.

    2016-11-01

    The effects of nitrogen (N) fertilizer sources and tillage practices on greenhouse gas (GHG) emission have been well elucidated separately. However, it is still remained unclear regarding the combined effects of N fertilization and tillage practices on the global warming potential (GWP) and net ecosystem economic budget (NEEB) in paddy fields. In this paper, a 2-year field experiment was performed to investigate the effects of N fertilizer sources (N0, no N; IF, 100% N from chemical fertilizer; SRIF, 50% N from slow-release fertilizer and 50% N from chemical fertilizer; OF, 100% N from organic fertilizer; OFIF, 50% N from organic fertilizer and 50% N from chemical fertilizer) and tillage practices (CT, conventional intensive tillage; NT, no-tillage) on the emissions of methane (CH4) and nitrous oxide (N2O), GWP, greenhouse gas intensity (GHGI), and NEEB in paddy fields of central China. Compared with N0 treatment, IF, SRIF, OF and OFIF treatments greatly enhanced the cumulative seasonal CH4 emissions (by 54.7%, 41.7%, 51.1% and 66.0%, respectively) and N2O emissions (by 164.5%, 93.4%, 130.2% and 251.3%, respectively). NT treatment significantly decreased the GWP and GHGI compared with CT treatment. On the other hand, NT treatment significantly decreased CH4 emissions by 8.5-13.7%, but did not affect N2O emissions relative to CT treatment. Application of N fertilizers significantly increased GWP and GHGI. It was worth noting that the combined treatment of OFIF and NT resulted in the second-highest GWP and GHGI and the largest NEEB among all treatments. Therefore, our results suggest that OFIF combined with NT is an eco-friendly strategy to optimize the economic and environmental benefits of paddy fields in central China. Although the treatment of SRIF plus NT showed the lowest GWP and GHGI and the highest grain yield among all treatments, it led to the lowest NEEB due to its highest fertilizer cost. These results indicate that the government should provide

  16. Exploring a suitable nitrogen fertilizer rate to reduce greenhouse gas emissions and ensure rice yields in paddy fields

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yiming; Wang, Xiaopeng; Yang, Jingping, E-mail: jpyang@zju.edu.cn; Zhao, Xing; Ye, Xinyi

    2016-09-15

    The application rate of nitrogen fertilizer was believed to dramatically influence greenhouse gas (GHG) emissions from paddy fields. Thus, providing a suitable nitrogen fertilization rate to ensure rice yields, reducing GHG emissions and exploring emission behavior are important issues for field management. In this paper, a two year experiment with six rates (0, 75, 150, 225, 300, 375 kg N/ha) of nitrogen fertilizer application was designed to examine GHG emissions by measuring carbon dioxide (CO{sub 2}), methane (CH{sub 4}), nitrous oxide (N{sub 2}O) flux and their cumulative global warming potential (GWP) from paddy fields in Hangzhou, Zhejiang in 2013 and 2014. The results indicated that the GWP and rice yields increased with an increasing application rate of nitrogen fertilizer. Emission peaks of CH{sub 4} mainly appeared at the vegetative phase, and emission peaks of CO{sub 2}, and N{sub 2}O mainly appeared at reproductive phase of rice growth. The CO{sub 2} flux was significantly correlated with soil temperature, while the CH{sub 4} flux was influenced by logging water remaining period and N{sub 2}O flux was significantly associated with nitrogen application rates. This study showed that 225 kg N/ha was a suitable nitrogen fertilizer rate to minimize GHG emissions with low yield-scaled emissions of 3.69 (in 2013) and 2.23 (in 2014) kg CO{sub 2}-eq/kg rice yield as well as to ensure rice yields remained at a relatively high level of 8.89 t/ha in paddy fields. - Highlights: • Exploiting co-benefits of rice yield and reduction of greenhouse gas emission. • Global warming potential and rice yield increased with nitrogen fertilizer rate up. • Emission peaks of CH{sub 4,} CO{sub 2} and N{sub 2}O appeared at vegetative and reproductive phase. • 225 kg N/ha rate benefits both rice yields and GWP reduction.

  17. Arsenic and heavy metal contamination and their seasonal variation in the paddy field around the Daduk Au-Pb-Zn mine in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Churl-Gyu [Korea Petroleum Association, Seoul(Korea); Chon, Hyo-Taek [Seoul National University, Seoul(Korea); Jung, Myung Chae [Semyung University, Jecheon(Korea)

    2000-02-28

    Arsenic and heavy metal contamination, seasonal variation of the metal contents in soils and plants and their migration characteristics from soils into plants in the vicinity of the abandoned Daduk Au-Pb-Zn mine were studied. Soils collected downstream from the mine show high contents of As and heavy metals due to surface erosion and wind blowing in the tailings. However, their contamination was limited around the old dressing plant and paddy field nearby the polluted stream. Enriched concentrations of Cd and Zn were found in various agricultural crops grown in the paddy fields nearby the mine site, and Zn was accumulated specially in soybean leaves. Elevated level of As was also found in rice stalks and leaves. Biological absorption coefficients of the crop plants for heavy metals decreased in the order of soybean leaves, red peppers, rice stalks and leaves, and rice grain, and were higher for Cd and Cu than Pb and Zn. Seasonal variation of As and heavy metals in paddy fields showed that relatively higher concentrations and biological absorption coefficients were found in rice stalks and leaves grown under oxidizing conditions in September rather than under reducing conditions in August, especially for As, Cd, Pb and Zn. It is suggested that the amount of As and heavy metals absorbed by rice crops might be changed under the different condition of paddy fields throughout the period of growing. (author). 26 refs., 6 tabs., 8 figs.

  18. Water footprint assessment for crop production based on field measurements: A case study of irrigated paddy rice in East China.

    Science.gov (United States)

    Xinchun, Cao; Mengyang, Wu; Rui, Shu; La, Zhuo; Dan, Chen; Guangcheng, Shao; Xiangping, Guo; Weiguang, Wang; Shuhai, Tang

    2018-01-01

    Water footprint (WF) is a comprehensive measure of water consumption by human activities and can be used to assess the impact on both water volume and quality. This study aims to explore the feasibility of evaluating green, blue and grey WFs of crop production based on field measurements. The irrigated paddy rice grown in three different experimental sites in different typical irrigation districts in Huai'an, East China over 2011 to 2014 was taken as study case. With fixed irrigation and fertilization, on the basis of measuring field water and fertilizer balance at daily step, we calculated WF of crop production under different test treatments. Results show that crop water requirement of rice was measured as 667.1mm and 6.2% of the total nitrogen (T-N) was washed away from farmland accompany with drainage and percolation. Average annual WF of paddy rice during 2011-2014 in Huai'an was 1.760m(3)/kg (33.3% green, 25.8% blue and 40.9% grey). The level of WF and blue water proportion in different locations (irrigation districts) and different years changed slightly, while the proportion of green and grey WF changed with the variance of precipitation. Green water proportion was 25.1%, 34.2 and 44.2%, while 48.0%, 40.2% and 31.0% for grey water proportion under precipitation levels of 400, 600 and 800mm, respectively. The reduced grey WF was due to increased drainage. This study not only proved the feasibility of assessing WF of crop production with field experiments, but also provided a new method for WF calculation based on field water and fertilizer migration processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Characteristics of Feeding Preference and Nutrients Utilization of Golden Apple Snail (Pomacea canaliculata on Macrophytes in Paddy Fields

    Directory of Open Access Journals (Sweden)

    Benliang Zhao

    2012-10-01

    Full Text Available Golden apple snail was a harmful invasive gastropod in Asian wetlands. In order to clarify the effect of Pomacea canaliculata on macrophytes in paddy fields, feeding preference and nutrients utilization of snail were studied. Feeding preference of snail was Alternanthera philoxenoides>Monochoria vaginalis>Oryza sativa L. Snail showed a higher approximate digestion coefficient on Oryza sativa L. than that on Monochoria vaginalis. Nitrogen utilization coefficient of snail on Alternanthera philoxenoides was significantly higher than that on Oryza sativa L. Snail exhibited a higher calcium utilization coefficient on Alternanthera philoxenoides and Monochoria vaginalis than that on Oryza sativa L. Oryza sativa L. was not preferred among three plants under the same available and exposure condition.

  20. Changes in Soil C and N Contents and Mineralization Across a Cultivation Chronosequence of Paddy Fields in Subtropical China

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-Pei; ZHANG Tao-Lin; HAN Feng-Xiang; P. FELIX-HENNINGSEN

    2005-01-01

    Dynamics of soil organic matter in a cultivation chronosequence of paddy fields were studied in subtropical China.Mineralization of soil organic matter was determined by measuring CO2 evolution from soil during 20 days of laboratory incubation. In the first 30 years of cultivation, soil organic C and N contents increased rapidly. After 30 years, 0-10 cm soil contained 19.6 g kg-1 organic C and 1.62 g kg-1 total N, with the corresponding values of 18.1 g kg-1 and 1.50 g kg-1 for 10-20 cm, and then remained stable even after 80 years of rice cultivation. During 20 days incubation the mineralization rates of organic C and N in surface soil (0-10 cm) ranged from 2.2% to 3.3% and from 2.8% to 6.7%,respectively, of organic C and total N contents. Biologically active C size generally increased with increasing soil organic C and N contents. Soil dissolved organic C decreased after cultivation of wasteland to 10 years paddy field and then increased. Soil microbial biomass C increased with number of years under cultivation, while soil microbial biomass N increased during the first 30 years of cultivation and then stabilized. After 30 years of cultivation surface soil (0-10 cm)contained 332.8 mg kg-1 of microbial biomass C and 23.85 mg kg-1 of microbial biomass N, which were 111% and 47% higher than those in soil cultivated for 3 years. It was suggested that surface soil with 30 years of rice cultivation in subtropical China would have attained a steady state of organic C content, being about 19 g kg-1.

  1. 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.

  2. NUMERICAL SIMULATION OF METHANE EMISSIONS FROM RICE PADDY FIELDS IN THE YANGTZE DELTA OF CHINA

    Institute of Scientific and Technical Information of China (English)

    刘建栋; 周秀骥; 张宇

    2001-01-01

    A numerical simulation model is presented in this paper, which comprises the processes of crop growth, soil organic carbon decomposition, and methane emissions in agroecosystems.Simulation results show that the model can simulate the main process of methane emissions well,and the correlation coefficient between the simulated values and observed data is 0. 79 with 239 samples, which passed a significance test of 0. 01. The average error of methane emission simulation in whole growth period is about 15%. Numerical analysis of the model indicates that the average temperature during rice growth period has much impacts on methane emissions, and the basic trend of interannual methane emissions is similar to that of average temperature. The amount of methane emissions reduces about 34. 93%, when the fertilizer is used instead of manure in single rice paddy.

  3. Land use planning of paddy field using geographic information system and land evaluation in West Lombok, Indonesia

    Directory of Open Access Journals (Sweden)

    Widiatmaka .

    2014-06-01

    Full Text Available Planning analysis to increase rice production either through intensiḀcation of existing paddy Ḁeld area or ex-tensiḀcation in potential land area was conducted in West Lombok Regency, West Nusa Tenggara Province, Indonesia. Existing paddy Ḁeld was delineated using high-resolution data from IKONOS imagery of 2012. Land use and land cover outside existing paddy Ḁeld were interpreted using SPOT-5 imagery of 2012. ἀe Automated Land Evaluation System (ALES was used for land suitability analysis for paddy. ἀe results are interpreted in terms of the potential of paddy Ḁeld intensiḀcation in existing paddy Ḁeld area and the potential of extensiḀcation in land potentially used for paddy Ḁeld. ἀe result of analysis showed that in West Lombok Regency, there are still possible to do intensiḀcation and extensiḀca-tion of paddy Ḁeld to increase rice production in order to improve regional food security.

  4. 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.

  5. Microbial lipids in Paddy Soils of the Yangtze Area

    Science.gov (United States)

    Mueller-Niggemann, Cornelia; Bannert, Andrea; Schloter, Michael; Cao, Zhihong; Schwark, Lorenz

    2010-05-01

    Geobiochemical studies of rice paddy soils and their effect on the global carbon cycle are of paramount importance. Paddy soils comprise manmade wetlands because soil flooding is a prerequisite for lowland rice cultivation. Except for sulphate-rich substrates, rice growth is not very sensitive to soil conditions prevailing prior to conversion of marine tidal flat sediments to paddy cultivation. Thus, soil management practices, such as artificial submergence or drainage, ploughing and puddling (i.e. ploughing a submerged soil), manuring, liming, and fertilization, are the major driving factors of paddy soil development. Soil organic matter (SOM) decomposition and humification proceeds in hydromorphic soils at a slower rate than in well-drained, aerated soils. Rice paddy soils thus also represent a suitable model system to study fundamental aspects of redox sensitive soil processes. These processes are of special interest because in flooded rice fields the anaerobic fermentation of SOM leads to the release of methane and to denitrification losses of inorganic nitrogen. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. We here describe the biomarker geochemistry of six paddy soils that developed on marine tidal sediments and where cultivation started 50, 100, 300, 700, 1000 or 2000 years before present. As reference substrates recent marine and lacustrine sediments were selected. The differentiation of the lipid biomass was achieved by investigating glycerol dialkyl glycerol tetraethers (GDGT). These specific organic geochemical biomarkers allow for determining the abundance of fossil microbial consortia (archaea and bacteria input) into paddy soils, justified by the diversity of the archaeal and bacterial cell membrane constituents. The dominant proportion of

  6. Influence of water management and fertilizer application on (137)Cs and (133)Cs uptake in paddy rice fields.

    Science.gov (United States)

    Wakabayashi, Shokichi; Itoh, Sumio; Kihou, Nobuharu; Matsunami, Hisaya; Hachinohe, Mayumi; Hamamatsu, Shioka; Takahashi, Shigeru

    2016-06-01

    Cesium-137 derived from the Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident contaminated large areas of agricultural land in Eastern Japan. Previous studies before the accident have indicated that flooding enhances radiocesium uptake in rice fields. We investigated the influence of water management in combination with fertilizers on (137)Cs concentrations in rice plants at two fields in southern Ibaraki Prefecture. Stable Cs ((133)Cs) in the plants was also determined as an analogue for predicting (137)Cs behavior after long-term aging of soil (137)Cs. The experimental periods comprised 3 y starting from 2012 in one field, and 2 y from 2013 in another field. These fields were divided into three water management sections: a long-flooding section without midsummer drainage, and medial-flooding, and short-flooding sections with one- or two-week midsummer drainage and earlier end of flooding than the long-flooding section. Six or four types of fertilizer subsections (most differing only in potassium application) were nested in each water management section. Generally, the long-flooding treatment led to higher (137)Cs and (133)Cs concentrations in both straw and brown rice than medial- and short-flooding treatments, although there were some notable exceptions in the first experimental year at each site. Effects of differing potassium fertilizer treatments were cumulative; the effects on (137)Cs and (133)Cs concentrations in rice plants were not obvious in 2012 and 2013, but in 2014, these concentrations were highest where potassium fertilizer had been absent and lowest where basal dressings of K had been tripled. The relationship between (137)Cs and (133)Cs in rice plants was not correlative in the first experimental year at each site, but correlation became evident in the subsequent year(s). This study demonstrates a novel finding that omitting midsummer drainage and/or delaying drainage during the grain-filling period enhances

  7. A GIS-based Upscaling Estimation of Nutrient Runoff Losses from Rice Paddy Fields to a Regional Level.

    Science.gov (United States)

    Sun, Xiaoxiao; Liang, Xinqiang; Zhang, Feng; Fu, Chaodong

    2016-11-01

    Nutrient runoff losses from cropping fields can lead to nonpoint source pollution; however, the level of nutrient export is difficult to evaluate, particularly at the regional scale. This study aimed to establish a novel yet simple approach for estimating total nitrogen (TN) and total phosphorus (TP) runoff losses from regional paddy fields. In this approach, temporal changes of nutrient concentrations in floodwater were coupled with runoff-processing functions in rice ( L.) fields to calculate nutrient runoff losses for three site-specific field experiments. Validation experiments verified the accuracy of this method. The geographic information system technique was used to upscale and visualize the TN and TP runoff losses from field to regional scales. The results indicated that nutrient runoff losses had significant spatio-temporal variation characteristics during rice seasons, which were positively related to fertilizer rate and precipitation. The average runoff losses over five study seasons were 20.21 kg N ha for TN and 0.76 kg P ha for TP. Scenario analysis showed that TN and TP losses dropped by 7.64 and 3.0%, respectively, for each 10% reduction of fertilizer input. For alternate wetting and drying water management, the corresponding reduction ratio was 24.7 and 14.0% respectively. Our results suggest that, although both water and fertilizer management can mitigate nutrient runoff losses, the former is significantly more effective. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  8. Temporal trends and sources of PCDD/Fs, pentachlorophenol and chlornitrofen in paddy field soils along the Yoneshiro River basin, Japan.

    Science.gov (United States)

    Kobayashi, Jun; Sakai, Mizuki; Kajihara, Hideo; Takahashi, Yukio

    2008-12-01

    In order to understand the long-term behaviors of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), pentachlorophenol (PCP), and 2,4,6-trichlorophenyl-4'-nitrophenyl ether (chlornitrofen, CNP) in paddy soil, we measured their concentrations in paddy soil samples collected in 1982 and 1984 (1980s) and in 2000 and 2002 (2000s) from the Yoneshiro River basin, Japan. The concentrations of PCP and CNP decreased from the 1980s to the 2000s, whereas the concentrations of PCDD/Fs and their toxic equivalency (WHO2006-TEQ) remained. The major sources of PCDD/Fs in the paddy soil samples were attributed to impurities in PCP and CNP as a result of comparisons of homologue and congener profiles and principal component analysis. Based on the results of comparison of total input and remaining amount, it is estimated that more than 99% of PCP and CNP applied to the paddy fields had disappeared, whereas most of the applied PCDD/Fs and TEQ remained.

  9. Characterization of contamination, source and degradation of petroleum between upland and paddy fields based on geochemical characteristics and phospholipid fatty acids

    Institute of Scientific and Technical Information of China (English)

    Juan Zhang; Renqing Wang; Xiaoming Du; Fasheng Li; Jiulan Dai

    2012-01-01

    To evaluate contamination caused by petroleum,surface soil samples were collected from both upland and paddy fields along the irrigation canals in the Hunpu wastewater irrigation region in northeast China.N-alkanes,terpanes,steranes,and phospholipid fatty acids (PLFA) in the surface soil samples were analyzed.The aliphatic hydrocarbon concentration was highest in the samples obtained from the upland field near an operational oil well; it was lowest at I-3P where wastewater irrigation promoted the downward movement of hydrocarbons.The Hunpu region was found contaminated by heavy petroleum from oxic lacustrine fresh water or marine deltaic source rocks.Geochemical parameters also indicated significantly heavier contamination and degradation in the upland fields compared with the paddy fields.Principal component analysis based on PLFA showed various microbial communities between petroleum contaminated upland and paddy fields.Gram-negative bacteria indicated by 15:0,3OH 12:0,and 16:1(9) were significantly higher in the paddy fields,whereas Gram-positive bacteria indicated by i16:0 and 18:1(9)c were significantly higher in the upland fields (p < 0.05).These PLFAs were related to petroleum contamination.Poly-unsaturated PLFA (18:2ω6,9; indicative of hydrocarbondegrading bacteria and fungi) was also significantly elevated in the upland fields.This paper recommends more sensitive indicators of contamination and degradation of petroleum in soil.The results also provide guidelines on soil pollution control and remediation in the Hunpu region and other similar regions.

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

    Directory of Open Access Journals (Sweden)

    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

  11. Suppression of Rice Stem Borer, Chilo suppressalis by Mass Trapping Using Synthetic Sex Pheromone in Paddy Field

    Institute of Scientific and Technical Information of China (English)

    SU Jian-wei; XUAN Wei-jian; SHENG Cheng-fa; GE Feng

    2003-01-01

    Suppressing effects of mass trapping using synthetic sex pheromone with main active ingredients of Z-11-hexadecenal, Z-13-octadecenal and Z-9-hexadecenal on the rice stem borer, Chilo suppressalis were investigated during the flight periods of the overwintering and 1st generation in the paddy area of 60 ha in 1999. Population density of C. suppressalis in the pheromone-treated fields was lower than that in control. The egg masses decreased by 74.39% and population size of adult males of the 1st generation decreased by 61.64% in the treated fields as compared to control. Meanwhile, the damage by C.suppressalis larvae was significantly lower in the treated fields than control (t-test, P=0.05). Percentages of brownish leaf sheath, dead heart, and white head in the treated fields were decreased by 70.90%, 57.01% and 44.30%, respectively in contrast to control. The present study demonstrated that mass trapping to C. suppressalis using synthetic sex pheromone shows great potential as an alternative measure in an environment-friendly pest management and at the same challenging the insecticide use that has some environment impacts.

  12. Ammonia Volatilization from the Biogas Slurry Irrigation Paddy Field%大量沼液施灌稻田的氨挥发特征

    Institute of Scientific and Technical Information of China (English)

    邓欧平; 姜丽娜; 陈丁江; 孙嗣旸; 吕军

    2011-01-01

    基千沼液灌溉田间试验,采用通气法研究化肥和沼液施灌稻田的氨挥发特征及其差异性.结果表明,尿素施用处理的氨挥发速率峰值出现在每次施氦后当天或第2天,而各沼液施灌处理则在施氮后当天.氨挥发速率和累计量均随着施氮量的增加而提高.沼液灌溉田间氨挥发速率随时间的动态变化主要取决于田面水中铵氮浓度的变化.每次沼液施灌后的前7天是稻田氨挥发的关键时期.水稻分蘖初期氨挥发明显高于其他时期的.等氮量沼液施灌处理的平均氨挥发速率为(1.48±2.08)kg/(hm2·d),累计量为(51.00±4.46)kg/hm2,全生育期氮素损失率(14.90±1.65)%,分别是尿素施用处理的5.1,3.0,6.4倍.因此,若以等氮量的沼液代替尿素不仅存在稻田供氮不足的风险,而且增加了氨挥发对生态环境产生不良影响的可能,这需要在沼液广泛应用于水稻生产的过程中特别关注.%In situ field experiment combined with venting method was conducted to study the ammonia volatilization from the biogas slurry (BS) and chemical fertilizer applied paddy field and their difference. The field experiment designed four treatments with three replications according to applied nitrogen (N) quantities, I. E. , 270 N kg/hm2(I-F) from urea, and 270 (I-B), 540 and 1 080 N kg/hm2 from BS. The amount of BS or fertilizer for each treatment was finished for application in three times with ten days intervals. The results showed that the peak ammonia volatilization rate at CF and each BS applied treatment plot appeared on the first or second day and the first after N application, respectively. The temporal dynamic of ammonia volatilization rate was mainly dominated by the ammonia concentration in the flood water. The period within seven days after N application and the early stage of tillering (I. E. , the second time for nitrogen application) was the critical time to control ammonia volatilization in paddy field for

  13. Influence of Soil Factors on the Stereoselective Fate of a Novel Chiral Insecticide, Paichongding, in Flooded Paddy Soils.

    Science.gov (United States)

    Li, Juying; Huang, Tuo; Li, Lizong; Ding, Tengda; Zhu, Hong; Yang, Bo; Ye, Qingfu; Gan, Jay

    2016-11-02

    In this study, the fate of paichongding was investigated in three soils with contrasting soil properties. In general, low soil pH has the potential to retard the mineralization and promote the dissipation of paichongding and the formation of its primary transformation product and to accelerate the formation of bound residue. The dissipation of paichongding stereoisomers was very fast and diastereoselective. This selectivity was found only between diastereomers and not between enantiomers and was observed to be soil dependent. In the acidic soil, the enantiomers (5R,7R)- and (5S,7S)-paichongding were degraded more quickly than (5R,7S)- and (5S,7R)-paichongding, whereas a contrary trend was observed in the neutral soil, and such selectivity did not occur in the alkaline soil. The OM and clay contents also played important roles in the fate of paichongding. This effect of soil properties should be considered in risk assessment of chiral pesticides and their application in the field.

  14. Method for NIR Reflectance Estimation with Visible Camera Data based on Regression for NDVI Estimation and its Application for Insect Damage Detection of Rice Paddy Fields

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2016-10-01

    Full Text Available Method for Near Infrared: NIR reflectance estimation with visible camera data based on regression for Normalized Vegetation Index: NDVI estimation is proposed together with its application for insect damage detection of rice paddy fields. Through experiments at rice paddy fields which is situated at Saga Prefectural Agriculture Research Institute SPARI in Saga city, Kyushu, Japan, it is found that there is high correlation between NIR reflectance and Green color reflectance. Therefore, it is possible to estimate NIR reflectance with visible camera data which results in possibility of estimation of NDVI with drone mounted visible camera data. As is well known that the protein content in rice crops is highly correlated with NIR intensity, or reflectance of rice leaves, it is possible to estimate rice crop quality with drone based visible camera data.

  15. Spatial Distribution and Minimum Sample Size for Overwintering Larvae of the Rice Stem Borer Chilo suppressalis (Walker) in Paddy Fields.

    Science.gov (United States)

    Arbab, A

    2014-10-01

    The rice stem borer, Chilo suppressalis (Walker), feeds almost exclusively in paddy fields in most regions of the world. The study of its spatial distribution is fundamental for designing correct control strategies, improving sampling procedures, and adopting precise agricultural techniques. Field experiments were conducted during 2011 and 2012 to estimate the spatial distribution pattern of the overwintering larvae. Data were analyzed using five distribution indices and two regression models (Taylor and Iwao). All of the indices and Taylor's model indicated random spatial distribution pattern of the rice stem borer overwintering larvae. Iwao's patchiness regression was inappropriate for our data as shown by the non-homogeneity of variance, whereas Taylor's power law fitted the data well. The coefficients of Taylor's power law for a combined 2 years of data were a = -0.1118, b = 0.9202 ± 0.02, and r (2) = 96.81. Taylor's power law parameters were used to compute minimum sample size needed to estimate populations at three fixed precision levels, 5, 10, and 25% at 0.05 probabilities. Results based on this equation parameters suggesting that minimum sample sizes needed for a precision level of 0.25 were 74 and 20 rice stubble for rice stem borer larvae when the average larvae is near 0.10 and 0.20 larvae per rice stubble, respectively.

  16. [Effects of no-tillage and stubble-remaining on soil enzyme activities in broadcasting rice seedlings paddy field].

    Science.gov (United States)

    Ren, Wan-Jun; Huang, Yun; Wu, Jin-Xiu; Liu, Dai-Yin; Yang, Wen-Yu

    2011-11-01

    A field experiment was conducted to study the effects of four cultivation modes (conventional tillage, no-tillage, conventional tillage + stubble-remaining, and no-tillage + stubble-remaining) on the activities of urease, acid phosphatase, protease, and cellulose in different soil layers in a broadcasting rice seedlings paddy field. Under the four cultivation modes, the activities of test enzymes were higher in upper than in deeper soil layers, and had a greater difference between the soil layers under no-tillage + stubble-remaining. In upper soil layers, the activities of test enzymes were higher in the treatments of no-tillage than in the treatments of conventional tillage, being the highest under no-tillage + stubble-remaining and the lowest under conventional tillage. In deeper soil layers, the test enzyme activities were the highest under conventional tillage + stubble-remaining, followed by no-tillage + stubble-remaining, no-tillage, and conventional tillage. During the growth period of rice, soil urease and cellulose activities were lower at tillering stage, increased to the maximum at booting stage, and decreased then, soil acid phosphatase activity was higher at tillering stage but lower at elongating stage, whereas soil protease activity peaked at tillering and heading stages.

  17. [Effect of controlled release fertilizer on nitrous oxide emission from paddy field under plastic film mulching cultivation].

    Science.gov (United States)

    Zhang, Yi; Lü, Shi-Hua; Ma, Jing; Xu, Hua; Yuan, Jiang; Dong, Yu-Jiao

    2014-03-01

    A field experiment was conducted to assess the effect of controlled release fertilizer on N2O emission in paddy field under plastic film mulching cultivation (PM) with water-saving irrigation. Results showed that in the rice growing season, cumulative N2O emissions from the plots applied with urea (PM+U) and with controlled release fertilizer (PM+CRF) were (38.2 +/- 4.4) and (21.5 +/- 5.2) mg N x m(-2), respectively. The N2O emission factors were 0.25% and 0.14% in the treatments PM+U and PM+CRF, respectively. The controlled release fertilizer decreased the total N2O emission by 43.6% compared with urea, of which 49.6% was reduced before the drying period. It also reduced the peak of N2O emission by 52.6%. However, it did not affect soil microbial biomass N and soil NH(4+)-N content at any rice growing stage, and grain yield either. No significant correlation was observed between N2O flux and soil Eh or soil temperature at the depth of 5 cm.

  18. A three-year experiment confirms continuous immobilization of cadmium and lead in contaminated paddy field with biochar amendment

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Rongjun [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Joseph, Stephen [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Discipline of Chemistry, University of Newcastle, Callaghan, NSW 2308 (Australia); Cui, Liqiang [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Pan, Genxing, E-mail: pangenxing@aliyun.com [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Li, Lianqing [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Liu, Xiaoyu; Zhang, Afeng [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Rutlidge, Helen [Solid State and Elemental Analysis Unit, Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Wong, Singwei [Electron Microscope Unit, University of Newcastle, Callaghan, NSW 2308 (Australia); Chia, Chee [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Marjo, Chris; Gong, Bin [Solid State and Elemental Analysis Unit, Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Munroe, Paul [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Donne, Scott [Discipline of Chemistry, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2014-05-01

    Highlights: • Biochar significantly increased soil pH, organic matter and immobilized soil Cd and Pb. • Biochar treatment consistently reduced rice Cd and Pb content in three years. • Contaminated biochar from the study field contained much higher heavy metals than fresh biochar. • Biochar caused metal immobilization primarily due to the precipitation and surface adsorption. - Abstract: Heavy metal contamination in croplands has been a serious concern because of its high health risk through soil-food chain transfer. A field experiment was conducted in 2010–2012 in a contaminated rice paddy in southern China to determine if bioavailability of soil Cd and Pb could be reduced while grain yield was sustained over 3 years after a single soil amendment of wheat straw biochar. Contaminated biochar particles were separated from the biochar amended soil and microscopically analyzed to help determine where, and how, metals were immobilized with biochar. Biochar soil amendment (BSA) consistently and significantly increased soil pH, total organic carbon and decreased soil extractable Cd and Pb over the 3 year period. While rice plant tissues’ Cd content was significantly reduced, depending on biochar application rate, reduction in plant Pb concentration was found only in root tissue. Analysis of the fresh and contaminated biochar particles indicated that Cd and Pb had probably been bonded with the mineral phases of Al, Fe and P on and around and inside the contaminated biochar particle. Immobilization of the Pb and Cd also occurred to cation exchange on the porous carbon structure.

  19. Avian diversity and feeding guilds in a secondary forest, an oil palm plantation and a paddy field in riparian areas of the kerian river basin, perak, malaysia.

    Science.gov (United States)

    Azman, Nur Munira; Latip, Nurul Salmi Abdul; Sah, Shahrul Anuar Mohd; Akil, Mohd Abdul Muin Md; Shafie, Nur Juliani; Khairuddin, Nurul Liyana

    2011-12-01

    The diversity and the feeding guilds of birds in three different habitats (secondary forest, oil palm plantation and paddy field) were investigated in riparian areas of the Kerian River Basin (KRB), Perak, Malaysia. Point-count observation and mist-netting methods were used to determine bird diversity and abundance. A total of 132 species of birds from 46 families were recorded in the 3 habitats. Species diversity, measured by Shannon's diversity index, was 3.561, 3.183 and 1.042 in the secondary forest, the paddy field and the oil palm plantation, respectively. The vegetation diversity and the habitat structure were important determinants of the number of bird species occurring in an area. The relative abundance of the insectivore, insectivore-frugivore and frugivore guilds was greater in the forest than in the monoculture plantation. In contrast, the relative abundance of the carnivore, granivore and omnivore guilds was higher in the plantation. The results of the study show that the conversion of forest to either oil palm plantation or paddy fields produced a decline in bird diversity and changes in the distribution of bird feeding guilds.

  20. NUMERICAL SIMULATION AND FIELD IMPLEMENTATION OF SURFACTANT FLOODING

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the features of surfactant flooding, a mathematical model for surfactant flooding is established. The adsorption-retention, convection diffusion of surfactant and influence of concentration change upon relative permeability curve are included in the model. The novel description of adsorption quantity of surfactant and relative permeability curve are presented, which enhance the coincidence between mathematical model and field practice, the relative errors of main development indexes are within 6%. The model is applied to the numerical research of the surfactant flooding in the untabulated beds of Xing1-3 surfactant flooding pilot site of No.4 Oil Production Company of Daqing Oilfield, the influences of surfactant concentration, injection quantity, slug combination mode upon the development effect and economic benefit are quantitatively analyzed, the injection scheme is optimized as follows: surfactant concentration is 0.5%, slug volume is 0.02 PV, slug combination mode is 2 slugs. After the implementation of scheme in oilfield, the cumulative increase of oil is 2186.0 t, up to nearly 30%.

  1. Effects of organic amendments on soil carbon sequestration in paddy fields of subtropical China

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenju; Xu, Minggang [Chinese Academy of Agricultural Sciences, Beijing (China). Ministry of Agriculture Key Lab. of Crop Nutrition and Fertilization; Wang, Xiujun [Chinese Academy of Sciences, Urumqi (China). Xinjiang Inst. of Ecology and Geography; Maryland Univ., College Park, MD (United States). Earth System Science Interdisciplinary Centre; Huang, Qinhai [National Engineering and Technology Research Center for Red Soil Improvement, Jinxian (China). Jiangxi Inst. of Red Soils; Nie, Jun [Soil and Fertilizer Institute of Hunan Province, Changsha (China); Li, Zuzhang [Jiangxi Academy of Agricultural Sciences, Nanchang (China). Inst. of Soils and Fertilizers and Agricultural Resources; Li, Shuanglai [Hubei Academy of Agricultural Sciences, Wuhan (China). Inst. of Plant Protection and Soil Science; Hwang, Seon Woong; Lee, Kyeong Bo [National Institute of Crop Sciences, Iksan (Korea, Republic of). Dept. of Rice and Winter Cereal Crop

    2012-04-15

    carbon input for all sites. Conclusions: We concluded that organic amendments applied as substitution and extra nutrients had significant effect on soil carbon sequestration and served as a carbon sink for the duration of the experiments. Paddy soil high in clay content had the potential to sequester more carbon. Soil carbon sequestration efficiency-declined with carbon input at some sites with loam soil texture, suggesting applying a large amount of organic amendments is not recommended as a sustainable agricultural management practice because of the high risk of non-point environment pollution. (orig.)

  2. 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 ...

  3. Water-requirement Characteristics and Water-saving Irrigation Indices of Dry-raised Rice Seedlings in Paddy Field

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-chang; WANG Wei; WANG Zhi-qin; LIU Li-jun; DING Zhi-jia; ZHU Qing-sen

    2001-01-01

    The dry-raised seedlings (D-RS)of rice had obvious superiority in tillering and growth after transplanting. Especially under the condition of water-saving irrigation or low soil moisture, D-RS had more productive tillers, higher dry matter accumulation, larger grain-filling rate, slower senescence of leaves and stronger root activity during ripening, and higher grain yield, compared with the moist-raised seedlings (MRS). D-RS had smaller yield reduction than M-RS when subject to heavy water stress. The results suggested that D-RS had the ability to adapt to lower soil moisture in paddy field. Basedon the response of D-RS to soil moisture at each growth stage, the water-saving and high-yielding irrigation indices through controlling lowlimit soil water potential were proposed, i.e. soil water potential was - 15 - - 20 kPa from the recovery to the criticalleaf-age of productive tillering, - 20 - - 40 kPa from the critical leaf-age of productive tillering to secondary branch-differentiating stage, - 15 - - 25 kPa from secondary branch-differentiating stage to 20 days after heading and - 25 - - 35 kPa from 21 to 45 days after heading.

  4. Replacement of mineral fertilizers with anaerobically digested pig slurry in paddy fields: assessment of plant growth and grain quality.

    Science.gov (United States)

    Zhang, Jin; Wang, Minyan; Cao, Yucheng; Liang, Peng; Wu, Shengchun; Leung, Anna Oi Wah; Christie, Peter

    2017-04-01

    Rice cultivation requires large quantities of irrigation water and mineral fertilizers. This provides an opportunity for the recycling of the plant nutrients in anaerobically digested pig slurry, large amounts of which are generated in Chinese pig farms. Hence, to promote the sustainable development of livestock and poultry breeding and rice production, a micro-plot field experiment was carried out to assess whether or not slurry can replace mineral fertilizers in rice paddy production in terms of plant tillering, grain quality, and yields. The results indicate that the total N content of the slurry can serve as an alternative source of N when compared to the control (450 kg ha(-1) commercial compound fertilizer (N/P2O5/K2O = 15:15:15) as basal fertilizer, 300 kg ha(-1) urea (N% = 46), and 150 kg ha(-1) commercial compound fertilizer as top-dressed fertilizer). No negative effects on plant growth or grain yield were observed, although there may be a potential risk due to an increase in grain Cu concentration. The amylose content and gel consistency of the rice grains were enhanced significantly by the use of slurry as a basal fertilizer, but the grain protein and total amino acid contents decreased. The results suggest that anaerobically digested pig slurry can replace mineral fertilizers in rice production when applied as a basal dressing together with urea and commercial compound fertilizer as top-dressed fertilizers.

  5. Characterization of Nivalenol-Producing Fusarium culmorum Isolates Obtained from the Air at a Rice Paddy Field in Korea

    Directory of Open Access Journals (Sweden)

    Da-Woon Kim

    2016-06-01

    Full Text Available Together with the Fusarium graminearum species complex, F. culmorum is a major member of the causal agents of Fusarium head blight on cereals such as wheat, barley and corn. It causes significant yield and quality losses and results in the contamination of grain with mycotoxins that are harmful to humans and animals. In Korea, F. culmorum is listed as a quarantine fungal species since it has yet to be found in the country. In this paper, we report that two isolates (J1 and J2 of F. culmorum were collected from the air at a rice paddy field in Korea. Species identification was confirmed by phylogenetic analysis using multi-locus sequence data derived from five genes encoding translation elongation factor, histone H3, phosphate permease, a reductase, and an ammonia ligase and by morphological comparison with reference strains. Both diagnostic PCR and chemical analysis confirmed that these F. culmorum isolates had the capacity to produce nivalenol, the trichothecene mycotoxin, in rice substrate. In addition, both isolates were pathogenic on wheat heads and corn stalks. This is the first report on the occurrence of F. culmorum in Korea.

  6. Factors Affecting Methane Emission from Rice Paddies

    Institute of Scientific and Technical Information of China (English)

    于心科; 王卫东; 等

    1995-01-01

    A comparative study of rice paddies and the uncovered water field in Taoyuan(Hunan) showed that methane emission from rice-vegetated paddy fields in 1993 was different from that in 1992(I,e,lower in rates and irregular in pattern).Climate has obvious influence on methane emission .And ebullition made a considerable contribution to the total flux of methane emission from rice paddies (45%).This implies that the intensification of paddy cultivation of rice might not be,as was proposed,the main con-tributor to the observed gradual increasing of atmospheric methane.24-hour automatic measurements of atmospheric temperature,air temperature and methane concentration in the static sampling boxes revealed that temperature,in addition to fertilization and irrigation style,is one of the most important factors that control the emission of methane from rice paddies.

  7. Spatial Distribution and Coexisting Patterns of Adults and Nymphs of Tibraca limbativentris (Hemiptera: Pentatomidae) in Paddy Rice Fields.

    Science.gov (United States)

    Alves, Tavvs M; Maia, Aline H N; Barrigossi, José A F

    2016-12-01

    The rice stem stink bug, Tibraca limbativentris Stål (Hemiptera: Pentatomidae), is a primary insect pest of paddy rice in South America. Knowledge of its spatial distribution can support sampling plans needed for timely decisions about pest control. This study aimed to investigate the spatial distribution of adults and nymphs of T. limbativentris and determine the spatial coexistence of these stages of development. Fifteen paddy rice fields were scouted once each season to estimate insect densities. Scouting was performed on regular grids with sampling points separated by ∼50 m. Moran's I and semivariograms were used to determine spatial distribution patterns. Spatial coexistence of nymphs and adults was explored via spatial point process. Here, adults and nymphs had typically contrasting spatial distribution patterns within the same field; however, the frequency of aggregation was not different between these developmental stages. Adults and nymphs were aggregated in seven fields and randomly distributed in the other eight fields. Uniform distribution of adults or nymphs was not observed. The study-wide semivariogram ranges were ∼40 m for adults and ∼55 m for nymphs. Nymphs and adults spatially coexisted on 67% of the fields. Coexisting patterns were classified using one of the following processes: stage-independent, bidirectional attractive, unidirectional attractive, bidirectional inhibiting, or unidirectional inhibiting. The information presented herein can be important for developing sampling plans for decision-making, implementing tactics for site-specific management, and monitoring areas free of T. limbativentrisResumoO percevejo-do-colmo Tibraca limbativentris Stål (Hemiptera: Pentatomidae) é uma praga primária na cultura do arroz irrigado na América do Sul. O conhecimento de sua distribuição espacial é essencial para desenvolver planos de amostragem e para o controle desta praga. Nosso objetivo foi investigar a distribuição espacial de

  8. Effects of raising frogs and putting pest-killing lamps in paddy fields on the prevention of rice pests and diseases

    Science.gov (United States)

    Teng, Qing; Hu, Xue-Feng; Luo, Fan; Cao, Ming-Yang

    2014-05-01

    Frogs in paddy fields become less and less due to applying large amounts of pesticides and human hunting for a long time, which causes the aggravation of rice pests and diseases. A field experiment was carried out in the suburb of Shanghai to study the effects of artificially raising frogs and putting frequency oscillation pest-killing lamps in paddy fields on the prevention of rice pests and diseases. The field experiment includes three treatments. Treatment I: 150 frogs, each 20 g in weight, per 100 m2 were put in the fields; Treatment II: a frequency oscillation pest-killing lamp was put in the fields; Treatment III: no frogs and pest-killing lamps were put in the fields. All the experimental fields were operated based on the organic faming system. The amount of organic manure, 7500 kg/hm2, was applied to the fields as base fertilizer before sowing in early June, 2013. No any chemical fertilizers and pesticides were used during the entire period of rice growth. Each treatment is in triplicate and each plot is 67 m2 in area. The results are as follows: (1) During the entire growth period, the incidences of rice pests and diseases with Treatment I and II are significantly lower than those with CK (Treatment III). The incidence of chilo suppressalis with Treatment I, II and III is 0, 0.46% and 1.69%, respectively; that of cnaphalocrocis medinalis is 7.67%, 6.62% and 10.10%, respectively; that of rice sheath blight is 0, 11.11% and 5.43%, respectively; that of rice planthopper is 4.25 per hill, 5.75 per hill and 11 per hill, respectively. (2) The grain yield of the three treatments is significantly different. That of Treatment I, II and III is 5157.73 kg/hm2, 4761.60 kg/hm2 and 3645.14kg/hm2 on average, respectively. (3) Affected by frog activities, the contents of NH4-N, available P and available K in the soil with Treatment I are significantly raised. All the above suggest that artificially raising frogs in paddy fields could effectively prevent rice pests and

  9. 氮肥对稻田土壤反硝化细菌群落结构和丰度的影响%Response of denitrifying bacteria community structure and abundance to nitrogen in paddy fields

    Institute of Scientific and Technical Information of China (English)

    宋亚娜; 林智敏; 林艳

    2012-01-01

    Denitrification is critical for nitrogen cycle in the ecosystem,where fixed nitrogen is released into the atmosphere as N2.Nitrite reductase,the product of nirS or nirK nitrite reductase genes,is the key enzyme of bacteria dissimilatory denitrification process.Denitrifying bacteria community composition varies with environmental factors such as temperature,moisture,pH,O2 and nutrient availability.There is obvious denitrification process in flooded paddy fields.Hence denitrifying bacteria community structure and abundance in paddy fields are used to investigate the response of denitrifying bacteria to nitrogen fertilizer application in paddy fields.The experiment was conducted in a second-year nitrogen fertilization field with the aid of denaturing gradient gel electropho-resis and real-time PCR assay copies of nirS gene.DGGE images of nirS gene in root-zone soil and surface soil showed rich abun-dance of denitrifying bacteria in paddy soils.DGGE band number in surface soil image was higher than that in root-zone soil.Principle components analysis (PCA) of nirS gene DGGE profile showed that denitrifying bacteria community structure in root-zone or surface soil of paddy fields with nitrogen fertilizer [N: 150 kg(N)-hm-2] was similar to that of paddy fields without fertilizer (CK) during rice growth stages of tillering,heading and maturity.Also no difference was noted in denitrifying bacteria community structure in root-zone soil or surface soil among different growth stages of rice.Denitrifying bacteria nirS gene copy abundance in root-zone or in surface soil with nitrogen fertilizer treatment was significantly (P < 0.05) higher than that of CK treatment during rice growth.In both nitrogen fertilizer and CK treatments,denitrifying bacteria nirS gene copies in root-zone soil markedly (P < 0.05) dropped at maturity stage of rice growth.There were,however,no differences in nirS gene copies in surface soil among the different rice growth stages.At maturity stage

  10. Phylogeny of Indonesian Nostoc (Cyanobac teria Isolated from Paddy Fields as Inferred from Partial Se quence of 16S rRNA Gene

    Directory of Open Access Journals (Sweden)

    Dian Hendrayanti

    2012-12-01

    Full Text Available In order to collect Indonesian Nostoc, isolation of soil microflora from several paddy fields in West Java, Bali, andSouth Celebes was carried out. Fast-growing isolates of Nostoc were selected to describe and perform molecular identification using partial sequences of 16S rRNA. The results showed that partial sequences of 16S rRNA could not resolve the phylogeny of the isolates. However, it supported the morphological studies that recognize isolates as different species of Nostoc. Potential use of Nostoc as a nitrogen source for paddy growth was carried out using six strains as single inoculums. A total biomass of 2 g (fresh weight for each strain was inoculated, respectively, into the pot planted with three paddy plants. This experiment was conducted in the green house for 115 days. Statistical analyses (ANOVA; α = 0.05 showed that of six strains tested in this study, only strain GIA13a had influence on the augmentation of root length and the total number of filled grains.

  11. Surfactant-enhanced alkaline flooding field project. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    French, T.R.; Josephson, C.B.

    1993-12-01

    The Tucker sand from Hepler field, Crawford County, Kansas, was characterized using routine and advanced analytical methods. The characterization is part of a chemical flooding pilot test to be conducted in the field, which is classified as a DOE Class I (fluvial-dominated delta) reservoir. Routine and advanced methods of characterization were compared. Traditional wireline logs indicate that the reservoir is vertically compartmentalized on the foot scale. Routine core analysis, X-ray computed tomography (CT), minipermeameter measurement, and petrographic analysis indicate that compartmentalization and lamination extend to the microscale. An idealized model of how the reservoir is probably structured (complex layering with small compartments) is presented. There was good agreement among the several methods used for characterization, and advanced characterization methods adequately explained the coreflood and tracer tests conducted with short core plugs. Tracer and chemical flooding tests were conducted in short core plugs while monitoring with CT to establish flow patterns and to monitor oil saturations in different zones of the core plugs. Channeling of injected fluids occurred in laboratory experiments because, on core plug scale, permeability streaks extended the full length of the core plugs. A graphic example of how channeling in field core plugs can affect oil recovery during chemical injection is presented. The small scale of compartmentalization indicated by plugs of the Tucker sand may actually help improve sweep between wells. The success of field-scale waterflooding and the fluid flow patterns observed in highly heterogeneous outcrop samples are reasons to expect that reservoir flow patterns are different from those observed with short core plugs, and better sweep efficiency may be obtained in the field than has been observed in laboratory floods conducted with short core plugs.

  12. 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.

  13. [Effects of controlled release nitrogen fertilizer on surface water N dynamics and its runoff loss in double cropping paddy fields in Dongtinghu Lake area].

    Science.gov (United States)

    Ji, Xiong-Hui; Zheng, Sheng-Xian; Lu, Yan-Hong; Liao, Yu-Lin

    2007-07-01

    By using leakage pond to simulate the double cropping paddy fields in Dongtinghu Lake area, this paper studied the effects of urea (CF) and controlled release nitrogen fertilizer (CRNF) on the dynamics of surface water pH, electrical conductivity (EC), total nitrogen (TN), ammonia nitrogen (NH4(+)-N) and nitrate nitrogen (NO3(-)-N) and the runoff loss of TN in alluvial sandy loamy paddy soil and purple calcareous clayed paddy soil, the two main paddy soils in this area. The results showed that after applying urea, the surface water TN and NH4(+)-N concentrations reached the peak at the 1st and 3rd day, respectively, and decreased rapidly then. Surface water NO3(-)-N concentration was very low, though it showed a little raise at the 3rd to 7th day after applying urea in purple calcareous clayed paddy soil. In early rice field, surface water pH rose gradually within 15 days after applying urea, while in late rice field, it did within 3 days. EC kept consistent with the dynamics of NH4(+)-N. CRNF, especially 70% N CRNF, gave rise to distinctly lower surface water pH, EC, and TN and NH4(+)-N concentrations within 15 days after application, but NO3- concentration rose slightly at late growth stages, compared with urea application. The monitoring of TN runoff loss indicated that during double cropping rice growth season, the loss amount of TN under urea application was 7.70 kg x hm(-2), accounting for 2.57% of applied urea-N. The two runoff events occurred within 20 days after urea application contributed significantly to the TN runoff loss. CRNF application resulted in a significantly lower TN concentration in runoff water from the 1st runoff event occurred within 10 days of its application, and thereafter, the total TN runoff loss for CRNF and 70% N CRNF application was decreased by 24.5% and 27.2%, respectively, compared with urea application.

  14. Irrigation ponds:Possibility and potentials for the treatment of drainage water from paddy fields in Zhanghe Irrigation System

    Institute of Scientific and Technical Information of China (English)

    BROWN; Larry

    2009-01-01

    Excessive application of fertilizers and pesticides as well as discharge of undecontaminated and unrecycled waste of livestock and poultry into farmland has caused serious non-point source pollution (NSP) of farmland in China. With the traditional mode of irrigation and drainage in rice-based irrigation systems, the pollution of farmland drainage water has become more and more serious. Traditional irrigation and drainage systems only focus on issues concerning water quantity, i.e. the capacity of irrigation in drought and drainage in waterlogging period, yet have no requirement on water quality improvement. how to clean the water quality of farmland drainage through remodeling the existing irrigation and drainage systems has a very important realistic meaning. Pond is an important irrigation facility in rice-based irrigation systems in southern China, which has the functions of not only a storage of water from canals but also collections of surface runoffs and farmland drainage for recycling use. Such water storage features of pond provide the possibility and potential capacity for drainage water treatment by managing such features as treatment basins as the growth of aquatic plants as well as living of fishes, batrachia and microorganisms in pond forms a soil-plant-microorganism ecological system. To explore the potential capacity of pond for drainage water nutrient reduction, the Zhanghe Irrigation System of Hubei, a typical "melon-on-the-vine" system in southern China is selected as the research site. The results of pond survey and field experiments demonstrate that plenty of ponds are suitable for collecting and cleaning paddy field drainage, and the ponds are favorable in reducing N, P nutrients in the drainage water. Other issues, e.g. how to maximize such capacity and what strategies should be sought to make existing treatment basins hydraulically more efficient, are also discussed.

  15. Irrigation ponds: Possibility and potentials for the treatment of drainage water from paddy fields in Zhanghe Irrigation System

    Institute of Scientific and Technical Information of China (English)

    DONG Bin; MAO Zhi; BROWN Larry; CHEN XiuHong; PENG LiYuan; WANG JianZhang

    2009-01-01

    Excessive application of fertilizers and pesticides as well as discharge of undecontaminated and un-recycled waste of livestock and poultry into farmland has caused serious non-point source pollution (NSP) of farmland in China.With the traditional mode of irrigation and drainage in rice-based irrigation systems, the pollution of farmland drainage water has become more and more serious.Traditional ir-rigation and drainage systems only focus on issues concerning water quantity, i.e.the capacity of irri-gation in drought and drainage in waterlogging period, yet have no requirement on water quality im-provement, how to clean the water quality of farmland drainage through remodeling the existing irriga-tion and drainage systems has a very important realistic meaning.Pond is an important irrigation facil-ity in rice-based irrigation systems in southern China, which has the functions of not only a storage of water from canals but also collections of surface runoffs and farmland drainage for recycling use.Such water storage features of pond provide the possibility and potential capacity for drainage water treat-ment by managing such features as treatment basins as the growth of aquatic plants as well as living of fishes, batrachia and microorganisms in pond forms a soil-plant-microorganism ecological system.To explore the potential capacity of pond for drainage water nutrient reduction, the Zhanghe Irrigation System of Hubei, a typical "melon-on-the-vine" system in southern China is selected as the research site.The results of pond survey and field experiments demonstrate that plenty of ponds are suitable for collecting and cleaning paddy field drainage, and the ponds are favorable in reducing N, P nutrients in the drainage water.Other issues, e.g.how to maximize such capacity and what strategies should be sought to make existing treatment basins hydraulically more efficient, are also discussed.

  16. [Effects of returning straw to soil and different tillage methods on paddy field soil fertility and microbial population].

    Science.gov (United States)

    Ren, Wan-Jun; Liu, Dai-Yin; Wu, Jin-Xiu; Wu, Ju-Xian; De, Chen-Chun; Yang, Wen-Yu

    2009-04-01

    A field experiment was conducted on a paddy field to study the effects of returning straw to soil and different tillage methods (no-tillage + returning straw, no-tillage, tillage + returning straw, and tillage) on the fertility level and microbial quantities of different soil layers. The results showed that in upper soil layer, the organic matter content in treatment 'no-tillage + returning straw' was 5.33, 2.79, and 5.37 g x kg(-1) higher than that in treatments 'no-tillage', 'tillage + returning straw', and 'tillage', respectively, and the contents of total and available N, P and K in treatment 'no-tillage + returning straw' were also the highest, followed by in treatments 'no-tillage' and 'tillage + returning straw', and in treatment 'tillage'. In deeper soil layer, all the fertility indices were higher in treatment 'tillage + returning straw'. Treatments of 'returning straw to soil' had the highest quantities of soil microbes. The quantities of bacteria, fungi, and actinomycetes in upper soil layer were the highest in treatment 'no-tillage + returning straw', and thus, the cellulose decomposition intensity in this treatment at maturity period was 26.44%, 79.01%, and 98. 15% higher than that in treatments 'tillage + returning straw', 'no-tillage', and 'tillage', respectively. In deeper soil layer, the quantities of bacteria, fungi, and actinomycetes were the highest in treatment 'tillage + returning straw'. Treatment 'no-tillage + returning straw' had the features of high fertility and abundant microbes in surface soil layer. The quantities of soil bacteria and actinomycetes and the decomposition intensity of soil cellulose were significantly positively correlated with soil fertility level.

  17. Effect of timing of joint application of hydroquinone and dicyandiamide on nitrous oxide emission from irrigated lowland rice paddy field.

    Science.gov (United States)

    Li, Xianglan; Zhang, Guangbin; Xu, Hua; Cai, Zucong; Yagi, Kazuyuki

    2009-06-01

    A field experiment was conducted to study the effect of timing of joint application of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) on N(2)O emission from irrigated lowland rice paddy field. Four treatments including Treatment CK (the control with urea alone), HQ/DCD-1 (application of HQ and DCD together with fertilizer before transplanting), HQ/DCD-2 (HQ and DCD with fertilizer at tillering stage) and HQ/DCD-3 (HQ and DCD with fertilizer at panicle initiation stage) were designed and implemented separately during rice growth period. Seasonal peaks of N(2)O flux occurred during midseason drainage and significant negative correlation between N(2)O flux and water layer depth was observed (r=-0.69 to -0.75, P<0.01). Mean N(2)O flux was the highest in the control with urea alone, while joint addition of HQ and DCD with urea lowered mean N(2)O flux considerably (P<0.05). Total N(2)O emission during rice growth season in Treatment CK, HQ/DCD-1, HQ/DCD-2 and HQ/DCD-3 was 3.90, 2.98, 1.73 and 3.23kgN(2)O-N ha(-1), respectively. Application of HQ and DCD together with basal fertilizer, tillering fertilizer and panicle initiation fertilizer decreased the total N(2)O emission by 24%, 56% and 17%, respectively, while increased grain yield by 10%, 18% and 6%, respectively. Effect of application of inhibitors on N(2)O emission during the continuous period from incorporation of HQ and DCD to rice harvest was also studied, where results indicating that the highest inhibiting efficiency of inhibitors on N(2)O emission was recorded when HQ and DCD applied with fertilizer at tillering stage.

  18. [Emission of volatile sulfur gases from Chinese paddy soils].

    Science.gov (United States)

    Qiao, W; Yang, Z; Cao, J; Li, Z

    2001-09-01

    In the paper, emission of volatile sulfur gases from paddy soil was discussed in a growth period of paddy rice by constructing a field sampling system. The result showed that COS, CS2, DMS and DMDS were mainly emitted from paddy soil. The order of emission fluxes was 81.11, 6.33 and 10.71 mg.(m2.a)-1. Sulphur emission fluxes of Chinese paddy soil was 0.013662 Tg/a, and those of world paddy soil was 0.07992 Tg/a.

  19. Analysis of Spatial Variability in a Korean Paddy Field Using Median Polish Detrending

    Science.gov (United States)

    There is developing interest in precision agriculture in Korea, despite the fact that typical fields are less than 1 ha in size. Describing within-field variability in typical Korean production settings is a fundamental first step toward determining the size of management zones and the inter-relatio...

  20. [Influences of water-saved and nitrogen-reduced practice on soil microbial and microfauna assemblage in paddy field].

    Science.gov (United States)

    Gui, Juan; Chen, Xiao-yun; Liu, Man-qiang; Zhuang, Xi-ping; Sun, Zhen; Hu, Feng

    2016-01-01

    The resource and environmental problems caused by excessive consumption of water and fertilizer in rice production have recently aroused widespread concern. This study investigated the effects of irrigation modes (conventional irrigation and 25% water-saved irrigation) and different N application rates (conventional high-nitrogen fertilization and 40% nitrogen-reduced fertilization) on microbial and microfauna assemblages at tillering and ripening stages in paddy field. The results showed that compared with conventional irrigation (CF), water-saved irrigation (WS) decreased the soil pH at tillering stage. Soil dissolved organic matter (dissolved organic C and N) and microbial biomass C and N were significantly affected by irrigation, nitrogen fertilizer and their interactions. WS or N-reduced fertilization (LN) decreased the contents of dissolved organic matter; WS increased microbial biomass C but decreased microbial biomass N. Nitrate was significantly higher in WS than CF, while ammonium showed reverse pattern. At tillering stage, the soil microbial biomass from bacteria, fungi, actinomy and protozoa was higher in WS than in CF, but the trend was opposite at ripening stage. There was a significant interation between irrigation and fertilization on soil rotifer numbers and microbial-feeding nematodes. At tillering stage, WS increased the numbers of rotifer and nematode, and also the proportion of bacterial-feeding nematode; LN increased the abundance of rotifer but decreased the abundance of nematode. In summary, soil microbial and microfauna assemblages showed different response to water-saved and nitrogen-reduced agricultural managements, which depended on different crop growth stages, but also the complex interactions of water and nitrogen and between biological groups in food webs.

  1. Environmental conditions of some paddy cum prawn culture fields of Cochin backwaters, southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, K.K.C.; Sankaranarayanan, V.N.; Gopalakrishnan, T.C.; Balasubramanian, T.; Devi, C.B.L.; Aravindakshan, P.N.; Kutty, M.K.

    Temperature, salinity, pH, dissolved oxygen, inorganic phosphate, ammonia, nitrate and nitrite of seasonal and perennial prawn culture fields from 3 areas of Cochin backwaters are studied. Area 1 is a region least affected ecologically...

  2. Impact analysis of the decline of agricultural land-use on flood risk and material flux in hilly and mountainous watersheds

    Science.gov (United States)

    Shimizu, Y.; Onodera, S.; Takahashi, H.; Matsumori, K.

    2015-06-01

    Agricultural land-use has been reduced by mainly urbanization and devastation in Japan. The objective of this study is to evaluate the impact of the decline of agricultural land-use on flood risk and material flux in hilly and mountainous watersheds using Soil Water Assessment Tool. The results indicated that increase of flood risk due to abandonment of agricultural land-use. Furthermore, the abandonment of rice paddy field on steep slope areas may have larger impacts on sediment discharges than cultivated field. Therefore, it is suggested that prevention of expansion of abandonment of rice paddy field is an important factor in the decrease of yields of sediment and nutrients.

  3. [Distribution characteristics of soil humus fractions stable carbon isotope natural abundance (delta 13C) in paddy field under long-term ridge culture].

    Science.gov (United States)

    Tang, Xiao-hong; Luo, You-jin; Ren, Zhen-jiang; Lü, Jia-ke; Wei, Chao-fu

    2011-04-01

    A 16-year field experiment was conducted in a ridge culture paddy field in the hilly region of Sichuan Basin, aimed to investigate the distribution characteristics of stable carbon isotope natural abundance (delta 13C) in soil humus fractions. The soil organic carbon (SOC) content in the paddy field under different cultivation modes ranked in the order of wide ridge culture > ridge culture > paddy and upland rotation. In soil humus substances (HS), humin (HU) was the main composition, occupying 21% - 30% of the total SOC. In the extracted soil carbon, humic acid (HA) dominated, occupying 17% - 21% of SOC and 38% - 65% of HS. The delta 13C value of SOC ranged from -27.9 per thousand to -25.6 per thousand, and the difference of the delta 13C value between 0-5 cm and 20-40 cm soil layers was about 1.9 per thousand. The delta 13C value of HA under different cultivation modes was 1 per thousand - 2 per thousand lower than that of SOC, and more approached to the delta 13C value of rapeseed and rice residues. As for fulvic acid (FA), its delta 13C value was about 2 per thousand and 4 per thousand higher than that of SOC and HA, respectively. The delta 13C value of HU in plough layer (0-20 cm) and plow layer (20-40 cm) ranged from -23.7 per thousand - -24.9 per thousand and -22.6 per thousand - -24.2 per thousand, respectively, reflecting the admixture of young and old HS. The delta 13C value in various organic carbon fractions was HU>FA>SOC>rapeseed and rice residues>HA. Long-term rice planting benefited the increase of SOC content, and cultivation mode played an important role in affecting the distribution patterns of soil humus delta 13C in plough layer and plow layer.

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

    Science.gov (United States)

    Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

    2013-02-01

    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.

  5. Crop Species Recognition and Discrimination Paddy-Rice from Reaped-Fields by the Radar Vegetation Index (rvi) of ALOS-2/PALSAR2

    Science.gov (United States)

    Yamada, Y.

    2016-06-01

    The Japanese ALOS-2 satellite was launched on May 24th, 2014. It has the L-band SAR, PALSAR-2. Kim,Y. and van Zyl, J.J. proposed a kind of Radar Vegetation Index (RVI) as RVI = 8 * σ0hv / (σ0hh + σ0vv + 2* σ0hv) by L-band full-polarimetric radar data. Kim, Y. and Jackson, T.J., et al. applied the equation into rice and soybean by multi-frequency polarimetric scatterometer above 4.16 meters from the ground. Their report showed the L-band was the most promising wave length for estimating LAI and NDVI from RVI. The author tried to apply the analysis to the actual paddy field areas, both Inashiki region and Miyagi region in the eastern main island, "Honshu", areas of Japan by ALOS-2/PALSAR-2 full-polarimetry data in the summer season, the main crop growing time, of 2015. Judging from conventional methods, it will be possible to discriminate paddy rice growing fields from reaped fields or the other crops growing fields by the PALSAR-2 data. But the RVI value is vaguely related to such land use or biomass at the present preliminary experiment. The continuous research by the additional PALSAR-2 full-polarimetry data should be desired.

  6. Variations and constancy of mercury and methylmercury accumulation in rice grown at contaminated paddy field sites in three Provinces of China.

    Science.gov (United States)

    Li, B; Shi, J B; Wang, X; Meng, M; Huang, L; Qi, X L; He, B; Ye, Z H

    2013-10-01

    Many paddy fields have been contaminated by mercury (Hg) in mining areas of China. In this study, twenty-six rice cultivars and three Hg contaminated paddy fields in different geographic regions were selected for field trials and aimed to investigate the variations and similarities in total Hg (THg) and methylmercury (MeHg) accumulations in brown rice (seeds) across sites. Our results revealed widescale cultivar variation in THg (13-52 ng g(-1) at Wanshan) and MeHg (3.5-23 ng g(-1)) accumulation and %MeHg (17.7-89%) in seeds. The ability to translocate is an important factor in the levels of THg and MeHg in seed. Cultivar tended to stability in THg accumulation across sites. Some cultivars accumulated lower concentrations of both THg and MeHg in seeds at fields seriously contaminated by Hg. Present results suggest that appropriate cultivar selection is a possible way to reduce THg and MeHg accumulation in seeds of rice grown in Hg-contaminated regions.

  7. Mechanism Analysis and Detection on Paddy Field Water Leakage Caused by Mining Subsidence in Southwest of China%我国西南地区采煤塌陷水田漏水探测及机理分析

    Institute of Scientific and Technical Information of China (English)

    李晓静; 胡振琪; 赵艳玲; 李晶; 信凯

    2012-01-01

    为解决我国西南地区采煤塌陷地造成水田塌陷破坏问题,恢复塌陷地水田隔水层的持水能力,重构土壤水田隔水层,利用探地雷达和高密度电法2种手段进行现场探测,并结合地域特点,调查水田塌陷地的破坏特点,总结西南地区采煤塌陷地水田破坏形式及漏水特征,并分析了其漏水机理。结果表明:西南地区采煤塌陷导致地下水位下降、地表裂缝生成等;塌陷区水田的破坏形式主要有塌陷田、漏水田、裂缝田3种。通过现场调查和探测认为采煤塌陷影响了水田隔水层的保水作用是导致塌陷地水田漏水的主要原因。%In order to solve the paddy field subsidence and failure caused by the coal mining subsidence in the southwest part of China, to recovery the water holding capacity of the water insolated stratum for the paddy fields in the mining subsidence area and to reconstruct the water insolated stratum in the soil, ground radar and high density electric method were applied to the site exploration. In combination with the regional features, the failure features of the paddy field subsidence area were investigated. The paddy field failure way and the wa- ter leakage features of the paddy field in the mining subsidence of Southwest China were summarized. The water leakage mechanism was analyzed. The results showed that the mining subsidence in Southwest China would cause the underground water dropping, the surface ground cracking and others. The paddy field failures in the mining subsidence area would have the subsidence field, water leakage field and land cracking field. The site investigation and the exploration held the coal mining subsidence affected to the water keeping function of the paddy field insolated stratum would be the main reason to cause the paddy field water leakage in the subsidence area.

  8. Biodiversity Conservation in Rice Paddies in China: Toward Ecological Sustainability

    Directory of Open Access Journals (Sweden)

    Yufeng Luo

    2014-09-01

    Full Text Available Rice paddies are artificial wetlands that supply people with food and provide wildlife with habitats, breeding areas, shelters, feeding grounds and other services, and rice paddies play an important part in agricultural ecological systems. However, modern agricultural practices with large-scale intensive farming have significantly accelerated the homogenization of the paddy field ecosystem. Modern agriculture mostly relies on chemically-driven modern varieties and irrigation to ensure high production, resulting in the deterioration and imbalance of the ecosystem. Consequently, outbreaks of diseases, insects and weeds have become more frequent in paddy fields. This paper describes the current situation of rice paddy biodiversity in China and analyzes the community characteristics of arthropods and weedy plants. Meanwhile, we discuss how biodiversity was affected by modern agriculture changes, which have brought about a mounting crisis threatening to animals and plants once common in rice paddies. Measures should be focused to firstly preventing further deterioration and, then, also, promoting restoration processes. Ecological sustainability can be achieved by restoring paddy field biodiversity through protecting the ecological environment surrounding the paddy fields, improving paddy cropping patterns, growing rice with less agricultural chemicals and chemical fertilizers, constructing paddy systems with animals and plants and promoting ecological education and public awareness.

  9. The availabilities of arsenic and cadmium in rice paddy fields from a mining area: The role of soil extractable and plant silicon.

    Science.gov (United States)

    Yu, Huan-Yun; Ding, Xiaodong; Li, Fangbai; Wang, Xiangqin; Zhang, Shirong; Yi, Jicai; Liu, Chuanping; Xu, Xianghua; Wang, Qi

    2016-08-01

    Adequate silicon (Si) can greatly boost rice yield and improve grain quality through alleviating stresses associated with heavy metals and metalloids such as arsenic (As) and cadmium (Cd). The soil plant-available Si is relatively low in South China due to severe desilicification and allitization of the soils in this region. Conversely, pollution of heavy metals and metalloids in the soils of this region occurs widely, especially As and Cd pollution in paddy soil. Therefore, evaluating the plant availability of Si in paddy soil of South China and examining its correlation with the availability of heavy metals and metalloids are of great significance. Accordingly, in our study, 107 pairs of soil and rice plant samples were collected from paddy fields contaminated by As and Cd in South China. Significantly positive correlations between Si in rice plants and Si fractions in soils extracted with citric acid, NaOAc-HOAc buffer, and oxalate-ammonium oxalate buffer suggest that these extractants are more suitable for use in extracting plant-available Si in the soils of our present study. Significantly negative correlations between different Si fractions and As or Cd in rice plant tissues and negative exponential correlations between the molar ratios of Si to As/Cd in rice roots, straws, husks or grains and As/Cd in rice grains indicate that Si can significantly alleviate the accumulation of As/Cd from soils to the rice plants. Finally, a contribution assessment of soil properties to As/Cd accumulation in rice grains based on random forest showed that in addition to Si concentrations in soil or rice plants, other factors such as Fe fractions and total phosphorus also contributed largely to As/Cd accumulation in rice grains. Overall, Si exhibited its unique role in mitigating As or Cd stress in rice, and our study results provide strong field evidence for this role.

  10. Geographical variation in inorganic arsenic in paddy field samples and commercial rice from the Iberian Peninsula.

    Science.gov (United States)

    Signes-Pastor, Antonio J; Carey, Manus; Carbonell-Barrachina, Angel A; Moreno-Jiménez, Eduardo; Green, Andy J; Meharg, Andrew A

    2016-07-01

    This study investigated total arsenic and arsenic speciation in rice using ion chromatography with mass spectrometric detection (IC-ICP-MS), covering the main rice-growing regions of the Iberian Peninsula in Europe. The main arsenic species found were inorganic and dimethylarsinic acid. Samples surveyed were soil, shoots and field-collected rice grain. From this information soil to plant arsenic transfer was investigated plus the distribution of arsenic in rice across the geographical regions of Spain and Portugal. Commercial polished rice was also obtained from each region and tested for arsenic speciation, showing a positive correlation with field-obtained rice grain. Commercial polished rice had the lowest i-As content in Andalucia, Murcia and Valencia while Extremadura had the highest concentrations. About 26% of commercial rice samples exceeded the permissible concentration for infant food production as governed by the European Commission. Some cadmium data is also presented, available with ICP-MS analyses, and show low concentration in rice samples.

  11. PHYLOGENETICAL CHARACTERIZATION OF CYANOBACTERIA FROM PADDY FIELD OF CHHATTISGARH (PART I

    Directory of Open Access Journals (Sweden)

    Pankaj Bajpai

    2013-03-01

    Full Text Available ABSTRACT: With respect to Chhattisgarh, rice is the principal crop of the state. India Covers 66% of cultivable land and mostly grown under kharif cropping season. To increase sustained productivity without decreasing soil quality, algal bio fertilizers are used widely now days in the state. Use of local isolates as algal inoculants is being stressed due to their competitiveness in the field for establishment of better ecological adaptability for developing composite starter. Culture of algal bio fertilizer program on a regional basis, survey, isolation and screening of stress-tolerant cyanobacteria has been started at various parts of India. The soils of Chhattisgarh state comprise mostly of iron- rich red soil, laterite soil, and red and yellow soil and brown forest soil. So the above study comprises the characterization of physical and chemical properties collected from 4 districts of Chhattisgarh state.

  12. The effects of rape residue mulching on net global warming potential and greenhouse gas intensity from no-tillage paddy fields.

    Science.gov (United States)

    Zhang, Zhi-Sheng; Cao, Cou-Gui; Guo, Li-Jin; Li, Cheng-Fang

    2014-01-01

    A field experiment was conducted to provide a complete greenhouse gas (GHG) accounting for global warming potential (GWP), net GWP, and greenhouse gas intensity (GHGI) from no-tillage (NT) paddy fields with different amounts of oilseed rape residue mulch (0, 3000, 4000, and 6000 kg dry matter (DM) ha(-1)) during a rice-growing season after 3 years of oilseed rape-rice cultivation. Residue mulching treatments showed significantly more organic carbon (C) density for the 0-20 cm soil layer at harvesting than no residue treatment. During a rice-growing season, residue mulching treatments sequestered significantly more organic C from 687 kg C ha(-1) season(-1) to 1654 kg C ha(-1) season(-1) than no residue treatment. Residue mulching significantly increased emissions of CO2 and N2O but decreased CH4 emissions. Residue mulching treatments significantly increased GWP by 9-30% but significantly decreased net GWP by 33-71% and GHGI by 35-72% relative to no residue treatment. These results suggest that agricultural economic viability and GHG mitigation can be achieved simultaneously by residue mulching on NT paddy fields in central China.

  13. Novel Approach for Estimating Nitrogen Content in Paddy Fields Using Low Altitude Remote Sensing System

    Science.gov (United States)

    Saberioon, M. M.; Gholizadeh, A.

    2016-06-01

    Concerns over the use of nitrogen have been increasing due to the high cost of fertilizers and environmental pollutions caused by excess nitrogen application in agricultural fields. Several methods are available to assess the amount of nitrogen in crops, however, they are expensive, time-consuming, inaccurate, and/or require specialists to operate the tools. Researcher recently suggested remote sensing and specifically Low Altitude Remote Sensing (LARS) system of chlorophyll content in crop canopies as a low-cost alternative to estimate plant nitrogen status. The main objective of this study was to develop and test a new Vegetation Index (VI) to determine the status of nitrogen and chlorophyll content in rice leaf by analysing and considering all Visible (Vis) bands. Besides, capability of introduced VI has compared with all known VIs in both Vis and Near Infrared (NIR) bands in canopy scale. To develop the VI, images from 6-pannel leaf colour chart were acquired using Basler Scout scA640-70fc under light-emitting diode lighting, in which principal component analysis was used to retain the lower order principal component to develop a new index called IPCA. A conventional digital camera mounted to an Unmanned Aerial Vehicle (UAV) was also used to acquire images over the rice canopy in Vis bands. Simultaneously, Tetracam agriculture digital camera was employed to acquire rice canopy image in Vis-NIR bands. The results indicated that the proposed index at canopy (r = 0.78) scale could be used as a sensor to determine the status of chlorophyll content consequently for monitoring nitrogen in rice plant through different growth stages. Moreover, results confirmed that a lowcost LARS system would be suited for high spatial and temporal resolution images and data analysis for proper assessment of key nutrients in crop farming in a fast, inexpensive and non-destructive way.

  14. External Costs and Optimum Use of Nitrogen Fertilizer Based on the Balance of Economic and Ecological Benefits in the Paddy Field System of the Dongting Lake Area, China

    Institute of Scientific and Technical Information of China (English)

    XIANG Ping-an; ZHOU Yan; JIANG Ju-ao; ZHENG Hua; YAN Hui-min; HUANG Huang

    2007-01-01

    The external costs and the optimum use of nitrogen fertilizer based on the balance of economic and ecological benefits was studied with the paddy field system of Dongting Lake area, one of the main food production regions in China. The environmental impact was economically evaluated using methods of the environmental impact economical evaluation.The optimum use of nitrogen fertilizer was calculated based on the exterior diseconomy theory and by using the production function model. Both ecological benefits and farmers' economic benefits were considered. It was calculated on the data from 2002 that the losses caused by inappropriate utilization of nitrogen fertilizer in the process of food production were fishery, 0.1 × 107 RMB yuan; water treatment, 1.02 × 108 RMB yuan; tour business, 0.11 × 108 RMB yuan, and habitation environment, 0.3 × 107 RMB yuan, totally equivalent to 0.41 RMB yuan kg-1 N. The economically satisfactory and the ecological agronomic nitrogen fertilizer dose for current production was 138 and 137 kg ha-1, respectively. The research showed that the actual nitrogen fertilizer application amount in the paddy field system of the Dongting Lake area already reached or exceeded the farmers' economic satisfaction and the ecological agronomic nitrogen fertilizer dose for current production. An environmental tax is suggested to impose on over-use of nitrogen fertilizer.

  15. Trace analysis of pesticides in paddy field water by direct injection using liquid chromatography-quadrupole-linear ion trap-mass spectrometry.

    Science.gov (United States)

    Pareja, Lucía; Martínez-Bueno, M J; Cesio, Verónica; Heinzen, Horacio; Fernández-Alba, A R

    2011-07-29

    A multiresidue method was developed for the quantification and confirmation of 70 pesticides in paddy field water. After its filtration, water was injected directly in a liquid chromatograph coupled to a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). The list of target analytes included organophosphates, phenylureas, sulfonylureas, carbamates, conazoles, imidazolinones and others compounds widely used in different countries where rice is cropped. Detection and quantification limits achieved were in the range from 0.4 to 80 ng L(-1) and from 2 to 150 ng L(-1), respectively. Correlation coefficients for the calibration curves in the range 0.1-50 μg L(-1) were higher than 0.99 except for diazinon (0.1-25 μg L(-1)). Only 9 pesticides presented more than 20% of signal suppression/enhancement, no matrix effect was observed in the studied conditions for the rest of the target pesticides. The method developed was used to investigate the occurrence of pesticides in 59 water samples collected in paddy fields located in Spain and Uruguay. The study shows the presence of bensulfuron methyl, tricyclazole, carbendazim, imidacloprid, tebuconazole and quinclorac in a concentration range from 0.08 to 7.20 μg L(-1). Copyright © 2011 Elsevier B.V. All rights reserved.

  16. The paddy field of laser grader system based on Matlab simulation%基于Matlab的水田激光平地机系统模拟仿真

    Institute of Scientific and Technical Information of China (English)

    叶娟; 陈君梅

    2014-01-01

    通过对水田激光平地机平地铲工作原理的分析和数学推算,建立水田激光平地机平地铲液压伺服系统(电磁阀)传递函数模型。采用Matlab软件对传递函数模型进行计算机仿真验证,以求达到理想控制效果。通过记录、对比实验数据,不断改进和完善水平控制系统,直至达到最优控制效果。%In paddy field laser grader flat shovel working principle analysis and mathematical calculation, establish a paddy field laser grader flat shovel(solenoid valve)transfer function model for hydraulic servo system.Using Matlab software to computer simulation verify the transfer function model,in order to achieve ideal control effect.By recording,comparing the experimental data,continuous improvement and improve the level of control system,until reach the optimal control effect.

  17. Prompt Proxy Mapping of Flood Damaged Rice Fields Using MODIS-Derived Indices

    Directory of Open Access Journals (Sweden)

    Youngjoo Kwak

    2015-11-01

    Full Text Available Flood mapping, particularly hazard and risk mapping, is an imperative process and a fundamental part of emergency response and risk management. This paper aims to produce a flood risk proxy map of damaged rice fields over the whole of Bangladesh, where monsoon river floods are dominant and frequent, affecting over 80% of the total population. This proxy risk map was developed to meet the request of the government on a national level. This study represents a rapid, straightforward methodology for estimating rice-crop damage in flood areas of Bangladesh during the large flood from July to September 2007, despite the lack of primary data. We improved a water detection algorithm to achieve a better discrimination capacity to discern flood areas by using a modified land surface water index (MLSWI. Then, rice fields were estimated utilizing a hybrid rice field map from land-cover classification and MODIS-derived indices, such as the normalized difference vegetation index (NDVI and enhanced vegetation index (EVI. The results showed that the developed method is capable of providing instant, comprehensive, nationwide mapping of flood risks, such as rice field damage. The detected flood areas and damaged rice fields during the 2007 flood were verified by comparing them with the Advanced Land Observing Satellite (ALOS AVNIR-2 images (a 10 m spatial resolution and in situ field survey data with moderate agreement (K = 0.57.

  18. Environmental profile of paddy rice cultivation with different straw management.

    Science.gov (United States)

    Fusi, Alessandra; Bacenetti, Jacopo; González-García, Sara; Vercesi, Annamaria; Bocchi, Stefano; Fiala, Marco

    2014-10-01

    Italy is the most important European country in terms of paddy rice production. North Italian districts such as Vercelli, Pavia, Novara, and Milano are known as some of the world's most advanced rice cultivation sites. In 2013 Italian rice cultivation represented about 50% of all European rice production by area, and paddy fields extended for over 216,000 ha. Cultivation of rice involves different agricultural activities which have environmental impacts mainly due to fossil fuels and agrochemical requirements as well as the methane emission associated with the fermentation of organic material in the flooded rice fields. In order to assess the environmental consequences of rice production in the District of Vercelli, the cultivation practices most frequently carried out were inventoried and evaluated. The general approach of this study was not only to gather the inventory data for rice production and quantify their environmental impacts, but also to identify the key environmental factors where special attention must be paid. Life Cycle Assessment methodology was applied in this study from a cradle-to-farm gate perspective. The environmental profile was analyzed in terms of seven different impact categories: climate change, ozone depletion, human toxicity, terrestrial acidification, freshwater eutrophication, marine eutrophication, and fossil depletion. Regarding straw management, two different scenarios (burial into the soil of the straw versus harvesting) were compared. The analysis showed that the environmental impact was mainly due to field emissions, the fuel consumption needed for the mechanization of field operations, and the drying of the paddy rice. The comparison between the two scenarios highlighted that the collection of the straw improves the environmental performance of rice production except that for freshwater eutrophication. To improve the environmental performance of rice production, solutions to save fossil fuel and reduce the emissions from

  19. Dynamic modeling of leveling system of paddy field laser leveler%水田激光平地机调平系统动力学建模

    Institute of Scientific and Technical Information of China (English)

    陈嘉琪; 赵祚喜; 施垒; 可欣荣; 吴志伟; 刘雄

    2015-01-01

    为实现基于动态过程模型的控制,提高平地机调平控制系统控制精度和稳定性,该文建立平地机调平系统动力学模型。水田激光平地机调平系统是一种典型的机械电控液压一体化结构,该文建立其从比例阀输入电流至平地铲水平倾角的动力学模型。首先根据平地机调平物理系统结构与工作原理,在简化和假定条件下,建立平地机调平系统受力分析图,以此分析和建立基于微分-代数方程的动力学模型,即DAE(differential-algebraic equations)模型。通过求解DAE模型,得出输入电流与输出平地铲角度的仿真结果,并用试验方法将仿真结果与实际结果对比来验证模型。结果表明该文提出的系统模型能较好地描述平地机调平系统动态响应。该文提出的研究方法不仅对不同机型的平地机机械设计与控制系统设计有指导意义,还对其他机电液一体的农机作业机械动力学建模与试验验证提供参考。%Modern paddy rice planting requires the field with high smoothness since it is conducive to reducing water consumption and improving the crop yields. A paddy land leveler is a complex mechanical system connected to the tractor by hanging. With both plow leveling and working height adjustment mechanisms, the paddy land leveler can automatically adjust the height and leveling of the land-leveling plow to attain high paddy field flatness. In order to improve the control precision, stability and responsiveness of a laser leveler in varying paddy field environment, a dynamic model of the leveling system is proposed in this paper. Considering that the leveling system of paddy field laser leveler is a typical electro-hydro-mechanical system, the dynamic model takes the proportional valve’s solenoid current as the input, and the tilt of the plow as the output. Firstly, based on the electro-hydro-mechanical structure and the working principle of the

  20. 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.

  1. Methane mitigation in transplanting and direct-wet seeding rice fields treated with fertilizers under condition of alternately flooding and soil aerating

    Directory of Open Access Journals (Sweden)

    Sanwangsi, M.

    2006-05-01

    Full Text Available Rice is main staple crop of the world. Growing rice in flooded water entails methane (CH4 emission. CH4 is one of greenhouse gases contributing to global warming. The experiment aimed to clarify the influence of fertilizer and water management on total methane emission (TME, methane mitigation and rice yields (RY. The experimental design was a split - split plot with 3 replications taking 2 cultivation in main plots, transplanting (TP rice and direct-wet seeding (DWS rice fields; 2 basal fertilizers, 16-16-8, 20 kg/rai and chicken manure pallet (CMP, 105 kg/rai in sub plots; and 3 top dressing fertilizers 1 none, 2 urea (46% N, 15 kg/rai and 3 ammonium sulfate (AS, 21% N, 30 kg/rai in sub-sub plots. It also examined relationship between quantity of paddy-soil water, TME and RY of both cultivations. Methane emission rate (MER occurred during the whole growth period and was characterized by 2 large peaks: one from after transplanting or broadcasting to maximum tillering stage and the other from flowering to yellow ripening stage. Rapid declines of MER were dictated by soil aeration recognized as 3-5 days cracks. In TP rice plot based with CMP, 105 kg/rai, topped with AS, 30 kg/rai, TME decreased to 73.0% and RY increased to 14.7% over that of untreated plots with top dressing fertilizer, while in that topped with urea, 15 kg/rai, TME decreased to 68.9% and RY increased to 16.9%. In all of DWS rice plots which were topped with AS or urea, declines of TME ranged from 27.3 to 56.4% and increase of RY ranged from 31.3 to 47.9% over those without top dressing. In both TP and DWS plots, TMEs were closely correlated with the quantity of paddy-soil water (r = 0.83 and 0.86, respectively and with submergence days (r = 0.94 and 0.89, respectively. Hence, saturated condition in paddy soil is a primary factor for methanogenesis. Moreover, for TP rice, the relationship between TME and RY was weakly positive (r = 0.16, whereas that for DWS rice was obviously

  2. Quantifying Nitrogen Loss From Flooded Hawaiian Taro Fields

    Science.gov (United States)

    Deenik, J. L.; Penton, C. R.; Bruland, G. L.; Popp, B. N.; Engstrom, P.; Mueller, J. A.; Tiedje, J.

    2010-12-01

    In 2004 a field fertilization experiment showed that approximately 80% of the fertilizer nitrogen (N) added to flooded Hawaiian taro (Colocasia esculenta) fields could not be accounted for using classic N balance calculations. To quantify N loss through denitrification and anaerobic ammonium oxidation (anammox) pathways in these taro systems we utilized a slurry-based isotope pairing technique (IPT). Measured nitrification rates and porewater N profiles were also used to model ammonium and nitrate fluxes through the top 10 cm of soil. Quantitative PCR of nitrogen cycling functional genes was used to correlate porewater N dynamics with potential microbial activity. Rates of denitrification calculated using porewater profiles were compared to those obtained using the slurry method. Potential denitrification rates of surficial sediments obtained with the slurry method were found to drastically overestimate the calculated in-situ rates. The largest discrepancies were present in fields greater than one month after initial fertilization, reflecting a microbial community poised to denitrify the initial N pulse. Potential surficial nitrification rates varied between 1.3% of the slurry-measured denitrification potential in a heavily-fertilized site to 100% in an unfertilized site. Compared to the use of urea, fish bone meal fertilizer use resulted in decreased N loss through denitrification in the surface sediment, according to both porewater modeling and IPT measurements. In addition, sub-surface porewater profiles point to root-mediated coupled nitrification/denitrification as a potential N loss pathway that is not captured in surface-based incubations. Profile-based surface plus subsurface coupled nitrification/denitrification estimates were between 1.1 and 12.7 times denitrification estimates from the surface only. These results suggest that the use of a ‘classic’ isotope pairing technique that employs 15NO3- in fertilized agricultural systems can lead to a drastic

  3. 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...

  4. Changes in Grain Yield of Rice and Emission of Greenhouse Gases from Paddy Fields after Application of Organic Fertilizers Made from Maize Straw

    Institute of Scientific and Technical Information of China (English)

    MA Yi-hu; GU Dao-jian; LIU Li-jun; WANG Zhi-qin; ZHANG Hao; YANG Jian-chang

    2014-01-01

    A field experiment was conducted at the farm of Yangzhou University, Yangzhou, China, to study the effects of organic fertilizers made from maize straw on rice grain yield and the emission of greenhouse gases. Four organic fertilizer treatments were as follows:maize straw (MS), compost made from maize straw (MC), methane-generating maize residue (MR), and black carbon made from maize straw (BC). These organic fertilizers were applied separately to paddy fields before rice transplanting. No organic fertilizer was applied to the control (CK). The effects of each organic fertilizer on rice grain yield and emission of greenhouse gases were investigated under two conditions, namely, no nitrogen (N) application (0N) and site-specific N management (SSNM). Rice grain yields were significantly higher in the MS, MC and MR treatments than those in CK under either 0N or SSNM. The MS treatment resulted in the highest grain yield and agronomic N use efficiency. However, no significant difference was observed for these parameters between the BC treatment and CK. The changes in the emissions of methane (CH4), carbon dioxide (CO2), or nitrous oxide (N2O) from the fields were similar among all organic fertilizer treatments during the entire rice growing season. The application of each organic fertilizer significantly increased the emission of each greenhouse gas (except N2O emission in the BC treatment) and global warming potential (GWP). Emissions of all the greenhouse gases and GWP increased under the same organic fertilizer treatment in the presence of N fertilizer, whereas GWP per unit grain yield decreased. The results indicate that the application of organic fertilizer (MS, MC or MR) could increase grain yield, but also could enhance the emissions of greenhouse gases from paddy fields. High grain yield and environmental efficiency could be achieved by applying SSNM with MR.

  5. Desorption of dieldrin from field aged sediments: simulating flood events

    NARCIS (Netherlands)

    Smit, M.P.J.; Grotenhuis, J.T.C.; Bruning, H.; Rulkens, W.H.

    2008-01-01

    Background, Aim and Scope With the predicted climate change, it is expected that the chances of flooding may increase. During flood events, sediments will resuspend and when the sediments are polluted, contaminants can be transferred to the surrounding water. Mass transfer of organic compounds like

  6. 吡虫啉在稻田水环境中的残留动态%Dynamics of Imidacloprid Residue in Paddy-field Water Environment

    Institute of Scientific and Technical Information of China (English)

    郑岚; 王梅; 段劲生; 胡本进; 孙明娜; 张勇; 高同春

    2011-01-01

    [ Objective] The dynamics of imidacloprid residue in paddy-field water environment by HPLC was studied in this paper. [ Method]Imidacloprid in the samples was extracted with dichloromethane and detected by HPLC with UV. [ Result ] The average of recoveries were ranged from 89.69% to 92.06%, the standard deviations were from 3.01% to 3.73%, and the coefficients of variation were from 3.79% to 4.46%. The minmium detectable amount of imidacloprid was 1.0 × 10-9 g, and the minimum detectable concentrations in paddy-field water was 0.005 mg/L. The test in Anhui province indicated that the half-lives of imidacloprid was 4.4 days. [ Conclusion] 10% EC imidacloprid was applied in paddy-field; imidacloprid in water was more quickly degradated%[目的]研究了稻田水环境中吡虫啉的残留动态.[方法]田水样品采用二氯甲烷萃取,HPLC-UV测定不同田水样品中的吡虫啉残留量.[结果]田水中吡虫啉的平均添加回收率为89.69%~92.06%、标准偏差为3.01%~3.73%、变异系数为3.79%~4.46%,吡虫啉的最小检出量为1.0×10g,在田水中最低检测浓度为0.005 mg/L.在安徽的试验结果表明,吡虫啉在碍水中降解半衰期为4.4 d.[结论]10%吡虫啉乳油在稻田使用后,在田水中降解较快.

  7. [Effects of different organic manure sources and their combinations with chemical fertilization on soil nematode community structure in a paddy field of East China].

    Science.gov (United States)

    Liu, Ting; Ye, Cheng-Long; Chen, Xiao-Yun; Ran, Wei; Shen, Qi-Rong; Hu, Feng; Li, Hui-Xin

    2013-12-01

    A comparative study was conducted to investigate the effects of different fertilization modes on the soil nematode community structure in a paddy field with paddy rice and wheat rotation in Jintan County (31 degrees 39'41.8" N, 119 degrees 28'23.5" E) of Jiangsu Province, East China. Six treatments were installed, i. e., no fertilization (CK), 100% chemical NPK fertilization (F), pig manure compost plus 50% chemical fertilization (PF), straw returning plus 100% chemical fertilization (SF), pig manure compost and straw returning plus 50% chemical fertilization (PSF), and application of commercial pig manure-inorganic complex fertilizer (PMF). The soil samples were collected from the field after the paddy rice harvested in autumn. The two continuous years study showed that the soil nematode community structure varied with fertilization treatments and years. The combined application of chemical fertilizers and organic manures increased the total number of soil nematodes, decreased the abundance of soil bacterivorous nematodes, and made the abundance of predator- and omnivore nematodes increased significantly. No significant differences were observed in the abundance of soil fungivorous nematodes among all the treatments. Chemical fertilization alone and the application of commercial pig manure-inorganic complex fertilizer had no obvious suppression effect on the soil phytophagous nematodes. The abundance of soil bacteriavorous nematodes under the combined application of chemical fertilizers and organic manures was relatively increased in the second year, as compared with that in the first year, while the abundance of soil phytophagous nematodes (Hirschmanniella) was relatively decreased in the second year. From the aspect of nematode ecological indices, the Margalef diversity index (H) under the combined application of chemical fertilizers and organic manures in the second year had an increasing trend, while the NCR index had less change. The Wasilewka index had a

  8. Emissions of CH4 and N2O under different tillage systems from double-cropped paddy fields in Southern China.

    Science.gov (United States)

    Zhang, Hai-Lin; Bai, Xiao-Lin; Xue, Jian-Fu; Chen, Zhong-Du; Tang, Hai-Ming; Chen, Fu

    2013-01-01

    Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NT

  9. Design and Simulation Analysis of Vertical Weed Control Device Between Seedlings in Paddy Field%水田株间立式除草装置的设计

    Institute of Scientific and Technical Information of China (English)

    杨松梅; 王金武; 刘永军; 王金峰; 赵佳乐

    2014-01-01

    Mechanical weed control is the best method to solve serious environmental pollution , weed resistance and other hazards caused by large use of herbicide .As the weeds between seedlings were difficult to control , a kind of vertical intra-row weed control device in paddy field was designed and its structure and working principle were described .Its 3 D model was constructed using PRO/E and kinematics simulation was carried by using ADAMS , obtaining weeding trajecto-ry of weeding spring tooth .The simulation results were analyzed , gainingλ2=1 .65 , k=8 and optimal parameter values , which provides the theoretical basis of the key components for the development of weeding machine for paddy fields .%机械除草是解决除草剂大量使用而造成环境严重污染、杂草抗药性增强等危害的最佳方法。针对株间杂草难以控制的问题,设计了一种水田株间立式除草装置,并对其结构及工作原理进行了阐述。运用 Pro/E 软件建立了三维模型,并通过ADAMS软件对株间立式除草刀盘进行运动学仿真,获得株间立式除草弹齿的除草轨迹。对仿真结果进行分析,得出了最佳速比为1.65、齿数k=8时最接近各参数要求的结论,为水田除草机整机关键部件的研制提供了理论依据。

  10. Using DET and DGT probes (ferrihydrite and titanium dioxide) to investigate arsenic concentrations in soil porewater of an arsenic-contaminated paddy field in Bangladesh.

    Science.gov (United States)

    Garnier, Jean-Marie; Garnier, Jérémie; Jézéquel, Didier; Angeletti, Bernard

    2015-12-01

    Arsenic concentration in the pore water of paddy fields (Csoln) irrigated with arsenic-rich groundwater is a key parameter in arsenic uptake by rice. Pore water extracts from cores and in situ deployment of DET and DGT probes were used to measure the arsenic concentration in the pore water. Ferrihydrite (Fe) and titanium dioxide (Ti) were used as DGT binding agents. Six sampling events during different growing stages of the rice, inducing different biogeochemical conditions, were performed in one rice field. A time series of DGT experiments allow the determination of an in situ arsenic diffusion coefficient in the diffusive gel (3.34×10(-6) cm(2) s(-1)) needed to calculate the so-called CDGT(Fe) and CDGT(Ti) concentrations. Over 3 days of a given sampling event and for cores sampled at intervals smaller than 50 cm, great variability in arsenic Csoln concentrations between vertical profiles was observed, with maxima of concentrations varying from 690 to 2800 μg L(-1). Comparisons between arsenic measured Csol and CDET and calculated CDGT(Fe) and CDGT(Ti) concentrations show either, in a few cases, roughly similar vertical profiles, or in other cases, significantly different profiles. An established iron oxyhydroxide precipitation in the DET gel may explain why measured arsenic CDET concentrations occasionally exceeded Csoln. The large spread in results suggests limitations to the use of DET and type of DGT probes used here for similarly representing the spatio-temporal variations of arsenic content in soil pore water in specific environmental such as paddy soils.

  11. Mapping paddy rice with multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China

    Institute of Scientific and Technical Information of China (English)

    Hua-sheng SUN; Jing-feng HUANG; Alfredo R. HUETE; Dai-liang PENG; Feng ZHANG

    2009-01-01

    The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer (MODIS) data in China. Paddy rice fields were extracted by identifying the unique characteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization. The characteristic could be reflected by the enhanced vegetation index (EVI) and the land surface water index (LSWI) derived from MODIS sensor data. Algorithms for single, early, and late rice identification were obtained from selected typical test sites. The algorithms could not only separate early rice and late rice planted in the same fields, but also reduce the uncertainties. The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics, and the spatial matching was examined by ETM+ (enhanced thematic mapper plus) images in a test region. Major factors that might cause errors, such as the coarse spatial resolution and noises in the MODIS data, were discussed. Although not suitable for monitoring the inter-annual variations due to some inevitable factors, the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale, and they might provide reference for further studies.

  12. Imazethapyr and imazapic, bispyribac-sodium and penoxsulam: Zooplankton and dissipation in subtropical rice paddy water

    Energy Technology Data Exchange (ETDEWEB)

    Reimche, Geovane B., E-mail: geovane_reimche@yahoo.com.br [Department of Plant Protection, Federal University of Santa Maria (UFSM), 97105-900 Santa Maria, RS (Brazil); Machado, Sérgio L.O. [Department of Plant Protection, Federal University of Santa Maria (UFSM), 97105-900 Santa Maria, RS (Brazil); Oliveira, Maria Angélica [Department of Biology, Federal University of Santa Maria, Santa Maria, RS (Brazil); Zanella, Renato; Dressler, Valderi Luiz; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, Santa Maria, RS (Brazil); Gonçalves, Fábio F. [School of Chemistry and Food, Federal Foundation University of Rio Grande (FURG), 95500-000 Santo Antônio da Patrulha, RS (Brazil); Donato, Filipe F.; Nunes, Matheus A.G. [Department of Chemistry, Federal University of Santa Maria, Santa Maria, RS (Brazil)

    2015-05-01

    Herbicides are very effective at eliminating weed and are largely used in rice paddy around the world, playing a fundamental role in maximizing yield. Therefore, considering the flooded environment of rice paddies, it is necessary to understand the side effects on non-target species. Field experiment studies were carried out during two rice growing seasons in order to address how the commonly-used herbicides imazethapyr and imazapic, bispyribac-sodium and penoxsulam, used at recommended dosage, affect water quality and the non-target zooplankton community using outdoor rice field microcosm set-up. The shortest (4.9 days) and longest (12.2 days) herbicide half-life mean, estimated of the dissipation rate (k) is shown for imazethapyr and bispyribac-sodium, respectively. Some water quality parameters (pH, conductivity, hardness, BOD{sub 5}, boron, potassium, magnesium, phosphorus and chlorides) achieved slightly higher values at the herbicide treatment. Zooplankton community usually quickly recovered from the tested herbicide impact. Generally, herbicides led to an increase of cladocera, copepods and nauplius population, while rotifer population decreased, with recovery at the end of the experiment (88 days after herbicide treatment). - Highlights: • Selective herbicides in paddy rice fields, do not affect water quality. • Zooplankton communities show good response with herbicide dissipation. • The use of commercial herbicide mixture has strong effects on freshwater Rotifers.

  13. The biology of Gynnidomorpha permixtana (Lepidoptera, Tortricidae on Sagittaria trifolia L. (Alismataceae in paddy fields in Iran

    Directory of Open Access Journals (Sweden)

    Atousa Farahpour Haghani

    2014-09-01

    Full Text Available While testing the efficacy of herbicides on paddy weeds at the Rice Research Institute of Iran (RRII in 2008, we encountered the failure of arrowhead (Sagittaria sagittifolia L., Alismataceae seeds to germinate. Detailed investigation revealed physical damage of seeds caused by the larvae of Gynnidomorpha permixtana (Denis & Schiffermüller, 1775 (Tortricidae, Tortricinae, Cochylina. Further studies showed that larvae feed on the seeds and flowers of the host plant and destroy the achenes. Under laboratory conditions G. permixtana required 23–30 days to complete its life cycle. Arrowhead is a new host record for this moth species; furthermore, this is the first detailed record of a tortricid feeding on this plant.

  14. Bioaccumulation of organochlorine pesticides and polychlorinated biphenyls by loaches living in rice paddy fields of Northeast China.

    Science.gov (United States)

    Zhang, Haijun; Lu, Xianbo; Zhang, Yichi; Ma, Xindong; Wang, Shuqiu; Ni, Yuwen; Chen, Jiping

    2016-09-01

    The concentrations of 21 organochlorine pesticide (OCP) residues and 18 polychlorinated biphenyl (PCB) congeners were measured in two loach species (Misgurnus mohoity and Paramisgurnus dabryanus) and the soils of their inhabiting rice paddies from three typical rice production bases of Northeast China to explore the main factors influencing the bioaccumulation. The concentrations of ∑18PCBs and ∑21OCPs in loaches were determined to be in the ranges of 0.14-0.76 ng g(-1) wet weight (ww) and 1.19-78.53 ng g(-1) ww, respectively. Most of loaches showed the considerably high contamination levels of dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), which accounted for over 97% of the total OCPs. The much lower maximum allowable loach consumption rates (bioaccumulation potential. The comparisons of BSAF values and the results of multivariate analysis indicated that habitat-specific environmental conditions, mainly the paddy soil contamination levels and average temperature, decisively affected the bioaccumulation of organochlorine contaminants. When the influence of lipid contents was offset, M. mohoity loaches were found to have a higher potential to accumulation PCBs and OCPs than P. dabryanus loaches, while the bioaccumulation potentials did not exhibit significant differences between juvenile and adult loaches and between male and female loaches. The octanol-water partition coefficient (KOW) was the main chemical factor influencing bioaccumulation potentials. The BSAF values presented an increasing tendency with increasing log KOW values from 6.0 to approximately 7.0, followed by a decreasing tendency with a continuous increase in log KOW values. Moreover, loaches exhibited an isomeric-selective bioaccumulation for p,p'-chlorinated DDTs, α-HCH, β-HCH, δ-HCH and cis-chlordane.

  15. THE FLOOD RISK IN THE LOWER GIANH RIVER: MODELLING AND FIELD VERIFICATION

    Directory of Open Access Journals (Sweden)

    NGUYEN H. D.

    2016-03-01

    Full Text Available Problems associated with flood risk definitely represent a highly topical issue in Vietnam. The case of the lower Gianh River in the central area of Vietnam, with a watershed area of 353 km2, is particularly interesting. In this area, periodically subject to flood risk, the scientific question is strongly linked to risk management. In addition, flood risk is the consequence of the hydrological hazard of an event and the damages related to this event. For this reason, our approach is based on hydrodynamic modelling using Mike Flood to simulate the runoff during a flood event. Unfortunately the data in the studied area are quite limited. Our computation of the flood risk is based on a three-step modelling process, using rainfall data coming from 8 stations, cross sections, the topographic map and the land-use map. The first step consists of creating a 1-D model using Mike 11, in order to simulate the runoff in the minor river bed. In the second step, we use Mike 21 to create a 2-D model to simulate the runoff in the flood plain. The last step allows us to couple the two models in order to precisely describe the variables for the hazard analysis in the flood plain (the water level, the speed, the extent of the flooding. Moreover the model is calibrated and verified using observational data of the water level at hydrologic stations and field control data (on the one hand flood height measurements, on the other hand interviews with the community and with the local councillors. We then generate GIS maps in order to improve flood hazard management, which allows us to create flood hazard maps by coupling the flood plain map and the runoff speed map. Our results show that: the flood peak, caused by typhoon Nari, reached more than 6 m on October 16th 2013 at 4 p.m. (its area was extended by 149 km². End that the typhoon constitutes an extreme flood hazard for 11.39%, very high for 10.60%, high for 30.79%, medium for 31.91% and a light flood hazard for 15

  16. Organic matter and water management strategies to reduce methane and nitrous oxide emissions from rice paddies in Vietnam

    DEFF Research Database (Denmark)

    Pandey, Arjun; Mai, Van Trinh; Duong, Quynh Vu

    2014-01-01

    The reduction of CH4 and N2O emissions from rice paddies is of utmost importance in minimizing the impact of rice production on global warming. A field experiment was therefore conducted in farmers' field in Hanoi, Vietnam to examine whether the use of straw compost or straw biochar, in combination.......05) between any of the treatments. These results indicated that the straw compost incorporation might not reduce the global warming potential (GWP) and yield-scaled GWP of rice production, whereas biochar in combination with AWD has the potential to maintain the GWP and yield-scaled GWP of rice production...... with the safe alternate wetting and drying (AWD) has the potential to suppress both CH4 and N2O emissions from rice paddies while maintaining the rice yield. The study compared the proposed strategies with local farmers' practice of permanent flooding (PF) and farmyard manure (FYM) incorporation, respectively...

  17. Study on Intermittent Irrigation for Paddy Rice: II. Crop Responses

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Effect of intermittent irrigation on the production of paddy rice was studied in a well-puddled paddy field with four treatments and 2 replicates: continuous flooding irrigation (CFI), and intermittent irrigation II-0, II-1 and II-2, in which plants were re-irrigated when the soil water potential fell below 0, -10, and -20 kPa, respectively, at soil depth of about 5 cm. Results showed that the reduction in soil water potential to about -10 or -20 kPa did not significantly affect the number of grains and the percentage of ripened grains. While, a lower crop growth rate (CGR) resulted from a decrease in the net assimilation rate (NAR) during intermittent irrigation II-1 and II-2, and there was also a reduction in the leaf area index (LAI) during intermittent irrigation II-2. Senescence of lower leaves on stems was promoted in treatments II-1 and II-2 at the ripening stage. Early senescence at ripening stage and water stress around midday decreased the rate of photosynthesis in leaves, causing the lower NAR. These physiological responses of the plants were responsible for the reduction in the dry matter production and grain yield in the intermittent irrigation treatments.

  18. A review on improvement and utilization of southern cold-waterlogged paddy fields in China%江南冷浸田治理利用研究进展

    Institute of Scientific and Technical Information of China (English)

    王飞; 林诚; 李清华; 林新坚; 余广兰

    2016-01-01

    AbstractCold-waterlogged (CW) paddy fields are the main low-yield paddy fields in South China. CW paddy fields have attracted close attention as they belong to common derelict lands with huge potential for crop productivity and good ecological conditions. CW paddy fields are the products of the complex interaction of climate, topography, hydrology and anthropogenic activity. Influenced by years of surface water and groundwater dip, soil physicochemical and biological properties of CW paddy fields have shown huge variations in the degree of coldness, rottenness, toxicity and infertility. CW paddy fields have low-temperature waters, soils and immersed bulk density, excessive reducing substances and soil organic carbon, but also low active organic carbon, microflora and available nutrients or unbalanced nutrients. Soil quality of CW paddy fields can be diagnosed and assessed by gley horizons, soil reducing substances and groundwater levels. This study summarized the integrated management and utilization of CW paddy fields, including engineering, agronomic and biological measures. This included open ditch and hidden drainage tubes, suitable rice varieties, paddy-upland crop rotation, ridge cultivation, balanced fertilization, soil conditioning, etc. In addition to traditional rice cultivation, it was an effective measure to comprehensively improve production capacity by adapting local conditions to the utilization of CW paddy fields. Finally, there was clear need to put future research emphasis on the administration and utilization of CW paddy fields based on sustainable agricultural development. This include 1) studying the differences in soil structure and the composition of organic matter under different gleyic states and the alternation of drying and wetting; 2) Strengthening research on methane emission characteristics under long-term gleyic state in CW paddy fields; 3) Strengthening research on ecological processes of anaerobic microbes and production enzymes

  19. Investigating flood susceptible areas in inaccessible regions using remote sensing and geographic information systems.

    Science.gov (United States)

    Lim, Joongbin; Lee, Kyoo-Seock

    2017-03-01

    Every summer, North Korea (NK) suffers from floods, resulting in decreased agricultural production and huge economic loss. Besides meteorological reasons, several factors can accelerate flood damage. Environmental studies about NK are difficult because NK is inaccessible due to the division of Korea. Remote sensing (RS) can be used to delineate flood inundated areas in inaccessible regions such as NK. The objective of this study was to investigate the spatial characteristics of flood susceptible areas (FSAs) using multi-temporal RS data and digital elevation model data. Such study will provide basic information to restore FSAs after reunification. Defining FSAs at the study site revealed that rice paddies with low elevation and low slope were the most susceptible areas to flood in NK. Numerous sediments from upper streams, especially streams through crop field areas on steeply sloped hills, might have been transported and deposited into stream channels, thus disturbing water flow. In conclusion, NK floods may have occurred not only due to meteorological factors but also due to inappropriate land use for flood management. In order to mitigate NK flood damage, reforestation is needed for terraced crop fields. In addition, drainage capacity for middle stream channel near rice paddies should be improved.

  20. Emergent insect production in post-harvest flooded agricultural fields used by waterbirds

    Science.gov (United States)

    Moss, Richard C.; Blumenshine, Steven C.; Yee, Julie; Fleskes, Joseph P.

    2009-01-01

    California’s Tulare Lake Basin (TLB) is one of the most important waterbird areas in North America even though most wetlands there have been converted to cropland. To guide management programs promoting waterbird beneficial agriculture, which includes flooding fields between growing periods, we measured emergence rates of insects, an important waterbird food, in three crop types (tomato, wheat, alfalfa) in the TLB relative to water depth and days flooded during August–October, 2003 and 2004. We used corrected Akaike’s Information Criterion values to compare a set of models that accounted for our repeated measured data. The best model included crop type and crop type interacting with days flooded and depth flooded. Emergence rates (mg m−2 day−1) were greater in tomato than wheat or alfalfa fields, increased with days flooded in alfalfa and tomato but not wheat fields, and increased with water depth in alfalfa and wheat but not tomato fields. To investigate the relationship between the range of diel water temperatures and insect emergence rates, we rearedChironomus dilutus larvae in environmental chambers under high (15–32°C) and low fluctuation (20–26°C) temperature regimes that were associated with shallow and deep (respectively) sampling sites in our fields. Larval survival (4×) and biomass (2×) were greater in the low thermal fluctuation treatment suggesting that deeply flooded areas would support greater insect production.

  1. Temporal patterns and source apportionment of nitrate-nitrogen leaching in a paddy field at Kelantan, Malaysia.

    Science.gov (United States)

    Hussain, Hazilia; Yusoff, Mohd Kamil; Ramli, Mohd Firuz; Abd Latif, Puziah; Juahir, Hafizan; Zawawi, Mohamed Azwan Mohammed

    2013-11-15

    Nitrate-nitrogen leaching from agricultural areas is a major cause for groundwater pollution. Polluted groundwater with high levels of nitrate is hazardous and cause adverse health effects. Human consumption of water with elevated levels of NO3-N has been linked to the infant disorder methemoglobinemia and also to non-Hodgkin's disease lymphoma in adults. This research aims to study the temporal patterns and source apportionment of nitrate-nitrogen leaching in a paddy soil at Ladang Merdeka Ismail Mulong in Kelantan, Malaysia. The complex data matrix (128 x 16) of nitrate-nitrogen parameters was subjected to multivariate analysis mainly Principal Component Analysis (PCA) and Discriminant Analysis (DA). PCA extracted four principal components from this data set which explained 86.4% of the total variance. The most important contributors were soil physical properties confirmed using Alyuda Forecaster software (R2 = 0.98). Discriminant analysis was used to evaluate the temporal variation in soil nitrate-nitrogen on leaching process. Discriminant analysis gave four parameters (hydraulic head, evapotranspiration, rainfall and temperature) contributing more than 98% correct assignments in temporal analysis. DA allowed reduction in dimensionality of the large data set which defines the four operating parameters most efficient and economical to be monitored for temporal variations. This knowledge is important so as to protect the precious groundwater from contamination with nitrate.

  2. Field Testing of Energy-Efficient Flood-Damage-Resistant Residential Envelope Systems Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Aglan, H.

    2005-08-04

    The primary purpose of the project was to identify materials and methods that will make the envelope of a house flood damage resistant. Flood damage resistant materials and systems are intended to be used to repair houses subsequent to flooding. This project was also intended to develop methods of restoring the envelopes of houses that have been flooded but are repairable and may be subject to future flooding. Then if the house floods again, damage will not be as extensive as in previous flood events and restoration costs and efforts will be minimized. The purpose of the first pair of field tests was to establish a baseline for typical current residential construction practice. The first test modules used materials and systems that were commonly found in residential envelopes throughout the U.S. The purpose of the second pair of field tests was to begin evaluating potential residential envelope materials and systems that were projected to be more flood-damage resistant and restorable than the conventional materials and systems tested in the first pair of tests. The purpose of testing the third slab-on-grade module was to attempt to dry flood proof the module (no floodwater within the structure). If the module could be sealed well enough to prevent water from entering, then this would be an effective method of making the interior materials and systems flood damage resistant. The third crawl space module was tested in the same manner as the previous modules and provided an opportunity to do flood tests of additional residential materials and systems. Another purpose of the project was to develop the methodology to collect representative, measured, reproducible (i.e. scientific) data on how various residential materials and systems respond to flooding conditions so that future recommendations for repairing flood damaged houses could be based on scientific data. An additional benefit of collecting this data is that it will be used in the development of a standard test

  3. Study of Dynamics of Floodwater Nitrogen and Regulation of Its Runoff Loss in Paddy Field-Based Two-Cropping Rice with Urea and Controlled Release Nitrogen Fertilizer Application

    Institute of Scientific and Technical Information of China (English)

    JI Xiong-hui; ZHENG Sheng-xian; LU Yan-hong; LIAO Yu-lin

    2007-01-01

    The article deals with the effects of urea and controlled release nitrogen fertilizer (CRNF) on dynamics of pH, electronic conductivity (EC), total nitrogen (TN), NH4+-N and NO3--N in floodwater, and the regulation of runoff TN loss from paddy field-based two-cropping rice in Dongting Lake, China, and probes the best fertilization management for controlling N loss. Studies were conducted through modeling alluvial sandy loamy paddy soil (ASP) and purple calcareous clayey paddy soil (PCP) using lysimeter, following the sequence of the soil profiles identified by investigating soil profile. After application of urea in paddy field-based two-cropping rice, TN and NH4+-N concentrations in floodwater reached peak on the 1st and the 3rd day, respectively, and then decreased rapidly over time; all the floodwater NO3--N concentrations were very low; the pH of floodwater gradually rose in case of early rice within 15 d (late rice within 3 d) after application of urea,and EC remained consistent with the dynamics of NH4+-N. The applied CRNF, especially 70% CRNF, led to significantly lower floodwater TN and NH4+ concentrations, pH, and EC values compared with urea within 15 d after application. The monitoring result for N loss due to natural rainfall runoff indicated that the amount of TN lost in runoff from paddy fieldbased two-cropping rice with urea application in Dongting Lake area was 7.47 kg ha-1, which accounted for 2.49% of ureaN applied, and that with CRNF and 70% CRNF application decreased 24.5 and 27.2% compared with urea application,respectively. The two runoff events, which occurred within 20 d after application, contributed significantly to TN loss from paddy field. TN loss due to the two runoffs in urea, CRNF, and 70% CRNF treatments accounted for 72, 70, and 58% of the total TN loss due to runoff over the whole rice growth season, respectively. And the TN loss in these two CRNF treatments due to the first run-off event at the 10th day after application to early

  4. Hydrological adjustment and flooding control of wetlands in the Liaohe Delta

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The function of estuary wetland on hydrological adjustment and flooding control is studied in this paper.It is estimated that theevapotranspiration in the reed field during growth season(June to October) is 722.9 mm, which is 37.5% higher than large water body(E601:525.9 mm).The water replacement rate in the reed field can reach 95 % only when the rains continuously for 11 days and the precipitationreached 912 mm.For the water balance in the paddy field, the total water requirement ranges between 1920 and 1860 mm, among which,31% is from precipitation, and the left is provided by reservoirs.The water usage efficiency is 0.35 at present productivity.Based on thelandscape characteristics and functionalities on flooding control, 5 functional zones are designed for the Liaohe Delta: key protected area;underground storage area; flooding discharge area; flood diversion area in emergency; and flood control drainage area.

  5. Effects of cultivation patterns on rice yield and soil properties in cold waterlogged paddy fields%耕作模式对冷浸田水稻产量和土壤特性的影响

    Institute of Scientific and Technical Information of China (English)

    王思潮; 曹凑贵; 李成芳; 熊又升; 汪金平

    2014-01-01

    为探明不同耕作模式对冷浸田的影响机制,挖掘冷浸田的生产潜力,以冷浸田为研究对象,通过田间试验,以常规平作模式为对照,研究了垄作和稻鱼共作模式对冷浸田水稻产量以及土壤团聚体、温度、pH及有机质和还原性物质含量以及酶活性的影响。结果表明:相比对照(CK),垄作模式(T1)能显著降低土壤微团聚体(1 mm) and organic matter content increased respectively by 67.6%and 28.0%at rice maturity stage. Treatment T2 had less effect on soil physical and chemical properties in cold waterlogged paddy fields. However, it significantly increased soil available nutrients (mainly available potassium and phosphorus) contents. Soil available potassium content increased 18.2% and 69.2% at booting and mature stages, compared with CK. It provided good soil environment and nutrition for rice growth, promoted rice growth and development, and improved rice yield. Further analysis showed that treatments T1 and T2 significantly improved rice yield in cold waterlogged paddy fields and increased yield in the range of 8.8%-25.8%. The effect of T1 on increasing rice production was the most significant, with actual output reaching 7 623 kg·hm-2. In conclusion, treatment T1 effectively improved soil properties in cold waterlogged paddy fields and increased rice yield. The effect of increasing production of treatment T2 was mainly drived by increased water and soil available nutrients in cold paddy waterlogged fields.

  6. [Effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions and their global warming potentials in paddy fields with double-rice cropping].

    Science.gov (United States)

    Wang, Cong; Shen, Jian-Lin; Zheng, Liang; Liu, Jie-Yun; Qin, Hong-Ling; Li, Yong; Wu, Jin-Shui

    2014-08-01

    A field experiment was carried out to study the effects of combined applications of pig manure and chemical fertilizers on CH4 and N2O emissions, which were measured using the static chamber/gas chromatography method, and their global warming potentials in typical paddy fields with double-rice cropping in Hunan province. The results showed that the combined applications of pig manure and chemical fertilizers did not change the seasonal patterns of CH4 and N2O emissions from paddy soils, but significantly changed the magnitudes of CH4 and N2O fluxes in rice growing seasons as compared with sole application of chemical fertilizers. During the two rice growing seasons, the cumulative CH4 emissions for the pig manure and chemical nitrogen (N) fertilizer each contributing to 50% of the total applied N (1/2N + PM) treatment were higher than those for the treatments of no N fertilizer (ON), half amount of chemical N fertilizer (1/2N) and 100% chemical N fertilizer (N) by 54.83%, 33.85% and 43.30%, respectively (P fertilizers in paddy fields would increase the GWP of CH4 and N2O emissions during rice growing seasons and this effect should be considered in regional greenhouse gases emissions inventory.

  7. Effect of moisture regime on the redistribution of heavy metals in paddy soil.

    Science.gov (United States)

    Zheng, Shunan; Zhang, Mingkui

    2011-01-01

    Sequential extraction procedure was applied to assess the dynamics of solid-phase transformation of added Cu, Pb, Cd, and Hg in a typical Chinese paddy soil incubated under three moisture regimes (75% field capacity, wetting-drying cycle, and flooding). The heavy metals spiked in the soil were time-dependently transferred from the easily extractable fraction (the exchangeable fraction) into less labile fractions (Fe-Mn oxide- and organic matter-bound fractions), and thus reduced lability of the metals. No significant changes were found for the carbonate-bound and residual fractions of the heavy metals in the soil during the whole incubation. Change rate of the mobility factor (MF), a proportion of weakly bound fractions (exchangeable and carbonate-bound) in the total metal of soil, reflected the transformation rate of metal speciation from the labile fractions toward stable fractions. It was found that soil moisture regime did not change the direction and pathways of transformation of metal speciation, but it significantly affected the transformation rate. In general, the paddy soil under flooding regime had higher metal reactivity compared with 75% field capacity and wetting-drying cycle regimes, resulting in the more complete movement of metals toward stable fractions. This might be related to the increased pH, precipitation of the metals with sulfides and higher concentration of amorphous Fe oxides under submerged condition.

  8. Effect of moisture regime on the redistribution of heavy metals in paddy soil

    Institute of Scientific and Technical Information of China (English)

    Shunan Zheng; Mingkui Zhang

    2011-01-01

    Sequential extraction procedure was applied to assess the dynamics of solid-phase transformation of added Cu, Pb, Cd, and Hg in a typical Chinese paddy soil incubated under three moisture regimes (75% field capacity, wetting-drying cycle, and flooding).The heavy metals spiked in the soil were time-dependently transferred from the easily extractable fraction (the exchangeable fraction) into less labile fractions (Fe-Mn oxide- and organic matter-bound fractions), and thus reduced lability of the metals.No significant changes were found for the carbonate-bound and residual fractions of the heavy metals in the soil during the whole incubation.Change rate of the mobility factor (MF), a proportion of weakly bound fractions (exchangeable and carbonate-bound) in the total metal of soil, reflected the transformation rate of metal speciation from the labile fractions toward stable fractions.It was found that soil moisture regime did not change the direction and pathways of transformation of metal speciation, but it significantly affected the transformation rate.In general, the paddy soil under flooding regime had higher metal reactivity compared with 75% field capacity and wetting-drying cycle regimes, resulting in the more complete movement of metals toward stable fractions.This might be related to the increased pH, precipitation of the metals with sulfides and higher concentration of amorphous Fe oxides under submerged condition.

  9. Transformation of marine sediment to paddy soil: Primary marine, lacustrine, and land plant lipids

    Science.gov (United States)

    Mueller-Niggemann, Cornelia; Cao, Zhihong; Schwark, Lorenz

    2010-05-01

    More than fifty percent of the world's population feeds on rice. The continuous population increase and urban sprawl leads to an ever-increasing demand for new rice cultivation area, in particular China. For centuries suitable coastal areas in China have been exploited for land reclamation, i.e. conversion of coastal marine and lacustrine marshlands into rice paddy fields. Flooded rice paddies are considered one of the major biogenic sources of methane into the atmospheric. Methane is thought to be about 30 times more efficient as greenhouse gas, when compared to carbon dioxide. Overall, rice fields are assumed to contribute app. 10-25% to global CH4 production. It is thus paramount importance to study the effects of increasing rice cultivation and land reclamation in China. For global carbon cycle investigation, it is crucial whether paddy soils, due to their large extent and higher carbon turnover, serve as carbon (CO2) sinks or sources. Here we present results from a chronosequence study of paddy soils with different and well known starting dates of cultivation, in the Zhejiang province (Yangtze River delta) by land reclamation through the building of protective dikes over the past 2000 years. Two end members of natural sediments subjected to land reclamation, a marine tidal mudflat in the Yangtze delta and a coastal lake, represent the substrate on which the paddy soil evolution started. Dike systems were constructed 2000, 1000, 700, 300, 100, and 50 years before present. We are thus able to follow the evolution of rice paddy soils developed on marine sediments using eight well defined tie-points. This chronosequence is then used for assessing the relative proportion of primary marine or lacustrine organic matter preserved in present day soils and to identify the amount and composition of organic matter added since cultivation started. Paddy soil management introduces rice plants debris and exudates as well as rice-associated microbial biomass (covered in a

  10. Sulfur and molybdenum fractionation in marine and riverine alluvium paddy soils

    Directory of Open Access Journals (Sweden)

    Hamed Zakikhani

    2016-10-01

    Full Text Available Intermittently submergence and drainage status of paddy fields can cause alterations in morphological and chemical characteristics of soils. We conducted a sequential fractionation study to provide an insight into solubility of Sulfur (S and Molybdenum (Mo in flooded alluvial paddy soils. The samples (0–15 and 15–30 cm were taken from marine and riverine alluvial soils in Kedah and Kelantan areas, respectively, and were sequentially extracted with NaHCO3, NaOH, HCl, and HClO4–HNO3. Total S in upper and lower layers of Kedah and Kelantan ranged between 273 and 1121 mg kg−1, and 177 to 1509 mg kg−1, respectively. In upper layers and subsoil of Kedah, average total Mo were 0.34 and 0.27 mg kg−1, respectively. Average total Mo in Kelantan were 0.25 mg kg−1 (surface layer and 0.28 mg kg−1 (subsoil. Cation exchange capacity (CEC was positively correlated with plant available amounts of Mo in upper layers of Kedah area. Also, total and medium-term plant-available S was correlated with total carbon (C at lower layers of Kelantan soil series. But in surface layers of Kelantan soil series, CEC was strongly correlated with total and medium-term plant-available S. Our results indicates that the influence of flooding conditions on soil S and Mo contents in paddy fields may cause long-term changes in S and Mo chemical reactivities.

  11. TEMPORAL AND SPATIAL VARIATIONS OF PADDY FIELDS AND ITS CARBON SEQUESTRATION EFFECT IN WESTERN JILIN%吉林西部水田时空变化与固碳效应研究

    Institute of Scientific and Technical Information of China (English)

    徐小明; 汤洁; 李昭阳; 韩维峥; 廉宏宇

    2011-01-01

    通过解译吉林西部1989年、1996年、2000年、2004年和2008年等5个年份的土地利用/覆被变化(LUCC)数据,获取吉林西部水田面积变化及其空间分布情况.设置了38个典型采样单元,各单元分别采集3~5个土样,测试不同土地利用类型的有机碳含量,分析水田开发所引起的LUCC变化对水田有机碳储量的影响.结果显示:1989~2008年间由于LUCC变化使得水田表层(0~30cm)土壤有机碳储量增加了874.16x107kg;研究区较大面积的水田表层土有机碳汇位于在白城市与镇赉县交界处及镇赉县东北部,而碳源则主要分布在前郭县北部与松原市境内.研究成果可以为研究全球气候变化提供局地基础数据支持.有助于探索全球及区域尺度的碳循环状况,同时在缓解该区当前严峻的土地问题、为土地开发提供决策依据等方面也具有积极意义.%At present,carbon cycle in terrestrial ecosystems became a hot issue in studying global change because of the widespread concerning about the global warming. Land use/cover change ( LUCC) was one of the most important factor among all the impact ones. It was a typical responding area to global changing in middle latitude areas in Western Jilin province of China which have a complex environment and intricate LUCC status. In this paper,in order to interpret the TM remote sensing images of Western Jilin in the years of 1989, 1996, 2000, 2004 and 2008.the LUCC data of the five years were achieved,as well as the area of paddy fields and spatial distributions.Moreover,according to the LUCC maps in different years,123 soil samples were collected to obtain average soil organic carbon ( SOC ) contents of different LUCC types and different stages of paddy development. Then the organic matter contents of these samples were measured by the potassium dichromate oxidation-outer heating method. Based on the LUCC data and soil data above , the amount of SOC sequestrated by the

  12. Diversity of bacteriophages infecting Xanthomonas oryzae pv. oryzae in paddy fields and its potential to control bacterial leaf blight of rice.

    Science.gov (United States)

    Chae, Jong-Chan; Hung, Nguyen Bao; Yu, Sang-Mi; Lee, Ha Kyung; Lee, Yong Hoon

    2014-06-28

    Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

  13. Molecular differentiation of the microgastrine species commonly found in paddy fields from Southeast Asia,with additional data on their phylogeny (Hymenoptera:Braconidae)

    Institute of Scientific and Technical Information of China (English)

    MINSHI; XUE-XINCHEN

    2005-01-01

    Partial DNA sequences of three genes, that is, mitochondrial large ribosomal subunit (16S), nuclear large ribosomal subunit (28S D2) and mitochondrial NADH1 dehydrogenase (NADH1) gene, were sequenced from different microgas trine species(Braconidae: Microgastrinae) collected fresh from paddy fields. The DNA sequences were used to determine the extent of sequence variation among species in order to evaluate the specific status of each species. Cladistic analysis was also used to infer a phylogenetic relationship among these species. The results showed that sequence divergence among species of the same genus Cotesia was much lower than those among different genera, such as Cotesia, Exoryza and Apanteles; the sequence similarity of 16S rDNA and NADH 1 genes between Cotesia sp. and C. chilonis was higher than that between C. sp. and C. ruficrus.Phylogenetic analyses suggested that four species of Cotesia were always grouped in the same clade regardless of using different analysis methods; Cotesia sp. and C. chilonis are more closely related to each other than to C. ruficrus, different from previous morphological results. Additionally, sequence analyses indicated that NADH1 gene has more parsimony informative characters than 28S rDNA D2 and 16S rDNA at the species-level analysis,indicating that NADH1 gene might be a useful marker for species-level analysis.

  14. Control Effects of Two-Batch-Duck Raising with Rice Framing on Rice Diseases, Insect Pests and Weeds in Paddy Field

    Directory of Open Access Journals (Sweden)

    Kai-ming Liang

    2012-10-01

    Full Text Available Rice-duck farming system is one of the means of organic rice farming, in which the weeds, diseases and insects could be effectively controlled with minimal or no pesticide and herbicide application. Whereas in conventional rice-duck farming system the controlling effect on diseases, insect pests and weeds was slowly disappeared after the rice heading stage at which ducks were driven out of the paddy field. To fill up the blank period of pasture activities of ducks, this study put forward two new rice-duck farming systems innovated from the conventional rice-duck farming system, in these new systems, two batches of ducks were raised with rice within one rice planting season. The results revealed that the overall controlling effect of ducks on rice diseases, insect pest and weeds was significantly enhanced in the two new rice-duck farming systems without agrochemicals application. It might be suggested that these two new systems have potential application as biocontrol agent for the organic rice agriculture.

  15. Suppressive effect of magnesium oxide materials on cadmium accumulation in winter wheat grain cultivated in a cadmium-contaminated paddy field under annual rice-wheat rotational cultivation

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Tetsuro, E-mail: tetsu-k@hino.meisei-u.ac.jp [Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Okazaki, Masanori, E-mail: masaok24@cc.tuat.ac.jp [Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Motobayashi, Takashi, E-mail: takarice@cc.tuat.ac.jp [Field Science Center for Education and Research, Tokyo University of Agriculture and Technology, 3-7-1 Hommachi, Fuchu, Tokyo 183-0027 (Japan)

    2009-08-30

    The effectiveness of two kinds of magnesium oxide (MgO) materials, commercial MgO (2250 kg ha{sup -1}) and a material derived from MgO and magnesium silicate minerals named 'MgO-SH-A' (2250 and 4500 kg ha{sup -1}1), in suppression of uptake and accumulation of cadmium (Cd) into grain of winter wheat (Triticum aestivum L. cv. Ayahikari) was examined in a Cd-contaminated alluvial paddy field under annual rice-wheat rotational system. The MgO materials were mixed into the plough-layer soil only once prior to the preceding rice cultivation. Cadmium concentration in wheat grain produced from the non-amendment control exceeded the maximum limit of Cd in wheat grain adopted by FAO/WHO (0.2 mg kg{sup -1}). All of the treatments with the MgO materials significantly lowered plant available Cd fraction in the plough-layer soil. However, only the treatment with the commercial MgO at 2250 kg ha{sup -1} produced wheat grain whose Cd concentration was not only significantly lower than that from the control but also less than 0.2 mg kg{sup -1}. It is suggested that the significant suppressive effect of the commercial MgO on Cd accumulation in wheat grain would be mainly attributed to its high soil neutralizing capacity as compared to that of MgO-SH-A.

  16. Evaluation of Leaf Total Nitrogen Content for Nitrogen Management in a Malaysian Paddy Field by Using Soil Plant Analysis Development Chlorophyll Meter

    Directory of Open Access Journals (Sweden)

    A. Gholizadeh

    2009-01-01

    Full Text Available Problem statement: Laboratory plant testing is usually time-consuming and high-costing. Hence, plant nutrient variability must be measured rapidly and the information made known to the farmers before the new season starts. Site-specific crop management, well-established in some developed countries, is now being considered in other places such as Malaysia. Approach: The application of site-specific management principles and techniques to diverse crops and small-scale farming systems in Malaysia will present new challenges. Describing within-field variability in typical Malaysian production settings is a fundamental first step toward determining the size of management zones and the inter-relationships between limiting factors, for establishment of site-specific management strategies. Results: Measurements of rice SPAD readings and nitrogen content were obtained in a Malaysian rice paddy field. SPAD reading data was manually collected on 80DAT and measured using a Minolta SPAD 502. Leaf samples were collected at 60 points at the same time to compare results from sampling with SPAD reading values. Samples nitrogen content was analyzed in a laboratory. Analysis of variance, variogram and kriging were conducted to determine the variability of the measured parameters and also their relationship. SPAD reading and nitrogen content maps were created on the interpretation of the data was investigated. Conclusion/Recommendations: Finally the research indicated that SPAD readings are closely related to leaf N content which means the potential for technology of precision farming to understand and control variation in Malaysian production fields and also SPAD chlorophyll meter ability to monitor the N status of rice and recommend the amount of N fertilization. Additional research is needed to confirm the results with data from other fields and crops.

  17. Research on Vertical Distribution Pattern and Reserve of Organic Carbon in Paddy Field Soil of Qianguo, Jilin%吉林前郭水田土壤有机碳垂向分布规律和储量研究

    Institute of Scientific and Technical Information of China (English)

    汤洁; 张雯辉; 李昭阳; 张楠; 胡猛

    2013-01-01

    Taking Qianguo paddy field of Jilin Province as investigation object, based on the soil test data of 7 different periods developed for 4 to 55 years, the vertical distribution of SOC content in the 1 m paddy field section was studied adopting the space scale method instead of time scale.The paddy soil carbon sink in last 20 years was discussed and the organic carbon storage of Qianguo paddy field soil was estimated.According to the second soil census data, the characteristics of soil SOC used in fields of different type were comparatively analyzed.The results showed that the paddy field SOC decreased from top to bottom by layer, which showed an increasing trend with the increase of development age; the organic carbon content in the surface soil layer (0-30 cm) (1 820.79 t)was 46.87% of the total organic carbon storage in deep soil (3 885.05 t), and the soil SOCD content was highly different depending on the type of field,ranked in descending order as paddy field,dry land,and saline field.The development of paddy field is a SOC accumulating carbon sink process,which is conducive to the transfer of organic carbon from the surface soil layer to the bottom soil layer.%以吉林省前郭水田区为研究对象,空间尺度代替时间尺度方法,采用开发时间4~55 a共7个不同年限的土壤实测数据,研究1 m水田剖面土壤有机碳含量(SOC)的垂向分布规律,探讨近20年来水田土壤碳源、汇,估算了前郭水田土壤有机碳库储量,并结合吉林西部第二次土壤普查数据,进行不同土地利用类型土壤SOC的差异特征对比分析.结果表明,水田SOC自上而下逐层递减,随着开发年限的增加总体呈增长趋势,表土层(0 ~30 cm)有机碳储量(1 820.79t)占1 m深土壤总有机碳储量(3 885.05 t)的46.87%,不同土地利用类型的土壤有机碳密度(SOCD)差异很大,从大到小依次为水田、旱田、盐碱地,水田开发是一个SOC积累的碳汇过程,有利于实现有机碳由表土层向底土层的转移.

  18. Microprofiling of nitrogen patches in paddy soil: Analysis of spatiotemporal nutrient heterogeneity at the microscale

    Science.gov (United States)

    Li, Yilin; Kronzucker, Herbert J.; Shi, Weiming

    2016-06-01

    Flooded paddy soil ecosystems in the tropics support the cultivation of the majority of the world’s leading crop, rice, and nitrogen (N) availability in the paddy-soil rooting zone limits rice production more than any other nutritional factor. Yet, little is known about the dynamic response of paddy soil to N-fertiliser application, in terms of horizontal and vertical patchiness in N distribution and transformation. Here, we present a microscale analysis of the profile of ammonium (NH4+) and nitrate (NO3‑), nitrification, oxygen (O2water and O2soil), and pH (pHwater and pHsoil) in paddy soils, collected from two representative rice-production areas in subtropical China. NH4+ and NO3‑ exhibited dramatic spatiotemporal profiles within N patches on the microscale. We show that pHsoil became constant at 1.0–3.5 mm depth, and O2soil became undetectable at 1.7–4.0 mm. Fertiliser application significantly increased pH, and decreased O2, within N patches. Path analysis showed that the factors governing nitrification scaled in the order: pHwater > pHsoil > NH4+ > O2water > NO3‑ > O2soil. We discuss the soil properties that decide the degree of nutrient patchiness within them and argue that such knowledge is critical to intelligent appraisals of nutrient-use efficiencies in the field.

  19. Effect of rice husk gasification residue application on herbicide behavior in micro paddy lysimeter.

    Science.gov (United States)

    Ok, Junghun; Pisith, Sok; Watanabe, Hirozumi; Thuyet, Dang Quoc; Boulange, Julien; Takagi, Kazuhiro

    2015-06-01

    Effects of rice husk gasification residues (RHGR) application on the fate of herbicides, butachlor and pyrazosulfuron-ethyl, in paddy water were investigated using micro paddy lysimeters (MPLs). The dissipation of both herbicides in paddy water was faster in the RHGR treated MPL than in the control MPL. The average concentrations of butachlor and pyrazosulfuron-ethyl in paddy water in the lysimeter treated with RHGR during 21 days were significantly reduced by 51% and 48%, respectively, as compared to those in the lysimeter without RHGR application. The half-lives (DT50) of butachlor in paddy water for control and treatment were 3.1 and 2.3 days respectively, and these values of pyrazosulfuron-ethyl were 3.0 and 2.2 days, respectively. Based on this study, RHGR application in rice paddy environment is an alternative method to reduce the concentration of herbicide in paddy field water and consequently to reduce potential pollution to aquatic environment.

  20. Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N₂O emission in forage rice paddy fields fertilized with liquid cattle waste.

    Science.gov (United States)

    Riya, Shohei; Zhou, Sheng; Kobara, Yuso; Sagehashi, Masaki; Terada, Akihiko; Hosomi, Masaaki

    2015-04-01

    Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and N2O emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha(-1) (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha(-1)) and three LCW topdressings (each 57-284 kg N ha(-1)). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH4 (+) concentration in the pore water at a depth of 20 cm was less than 1 mg N L(-1) in N100, N250, and N500 throughout the cultivation period, while the NH4 (+) concentration in N750 increased to 3 mg N L(-1) after the third topdressing. Cumulative N2O emissions ranged from -0.042 to 2.39 kg N ha(-1); the highest value was observed in N750, followed by N500. In N750, N2O emitted during the final drainage accounted for 80 % of cumulative N2O emissions. This study suggested that 100-258 kg N ha(-1) is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and N2O emission.

  1. Interpolation of observed rainfall fields for flood forecasting in data poor areas

    Science.gov (United States)

    Rogelis Prada, M. C.; Werner, M. G. F.

    2010-09-01

    Observed rainfall fields constitute a crucial input for operational flood forecasting, providing boundary conditions to hydrological models for prediction of flows and levels in relevant forecast points. Such observed fields are derived through interpolation from available observed data from rain gauges. The reliability of the derived rainfall field depends on the density of the gauge network within the basin, as well as on the variability of the rainfall itself, and the interpolation method. In this paper interpolation methods to estimate rainfall fields under data- poor environments are researched, with the derived rainfall fields being used in operational flood warnings. Methods are applied in a small catchment in Bogotá, Colombia. This catchment has a complex climatology, which is strongly influenced by the inter-tropical convergence zone and orographic enhancement. As is common in such catchments in developing countries, the rainfall gauging network is sparse, while the need for reliable rainfall in flood forecasting is high. The extensive high flood risk zones in the lower areas of the catchment, where urbanization processes are characterized by unplanned occupation of areas close to rivers, is common in developing countries. Results show the sensitivity of interpolated rainfall fields to the interpolation methods chosen, and the importance of the use of indicator variables for improving the spatial distribution of interpolated rainfall. The value of these methods in establishing optimal new gauging sites for augmenting the sparse gauge network is demonstrated.

  2. Characteristics of Soil Fertility of Buried Ancient Paddy at Chuodun Site in Yangtze River Delta, China

    Institute of Scientific and Technical Information of China (English)

    LU Jia; HU Zheng-yi; CAO Zhi-hong; YANG Lin-zhang; LIN Xian-gui; DONG Yuan-hua; DING Jin-long; ZHENG Yun-fei

    2006-01-01

    Field investigation and laboratory analysis of 22 ancient paddy soils excavated at Chuodun site, Kunshan City, JiangsuProvince, China were carried out in 2003 to (1) understand the basic characteristics of ancient paddy soils, (2) compare the difference of soil fertility between ancient paddy soils and recent paddy soils, and (3) inquire into mechanisms of the sustainability of paddy soil. The oldest paddy soils at Chuodun site can be dated back to Neolithic age, around 6 000 aBP. These ancient fields were buried in about 1-m deep from the soil surface and their areas ranged from 0.32 to 12.9 m2 with an average of 5.2 m2. The paddy soils with > 5 000 pellets phytolith g-1 soil were termed intensively cultivated paddy soils (ICPS) and those with < 5 000 pellets phytolith g-1 soil were called weakly cultivated soils (WCPS). The contents of organic carbon (OC), and total N in the former were significantly higher than that in the latter. Ancient paddy soils had higher soil pH and C/N, total and available P, and lower contents of OC, DOC, total N, S, Cu, Fe, and available K, S, Fe, Mn, and Cu compared with recent paddy soils, which were attributed to application of chemical and manure fertilizers, pollution and acidification in recent paddy soils. The variation coefficients of OC and other nutrients in ancient paddy soils with higher PI were greater than that in ancient paddy soils with low PI, which indicated that human activities had a great impact on the spatial variability of soil nutrients. The contents of OC, total N, P and S in ancient paddy soils were higher than that in ancient moss of the same age, which indicated that planting rice during Majiabang culture period was beneficial to the accumulation of those life elements.

  3. Improving the accuracy of flood forecasting with transpositions of ensemble NWP rainfall fields considering orographic effects

    Science.gov (United States)

    Yu, Wansik; Nakakita, Eiichi; Kim, Sunmin; Yamaguchi, Kosei

    2016-08-01

    The use of meteorological ensembles to produce sets of hydrological predictions increased the capability to issue flood warnings. However, space scale of the hydrological domain is still much finer than meteorological model, and NWP models have challenges with displacement. The main objective of this study to enhance the transposition method proposed in Yu et al. (2014) and to suggest the post-processing ensemble flood forecasting method for the real-time updating and the accuracy improvement of flood forecasts that considers the separation of the orographic rainfall and the correction of misplaced rain distributions using additional ensemble information through the transposition of rain distributions. In the first step of the proposed method, ensemble forecast rainfalls from a numerical weather prediction (NWP) model are separated into orographic and non-orographic rainfall fields using atmospheric variables and the extraction of topographic effect. Then the non-orographic rainfall fields are examined by the transposition scheme to produce additional ensemble information and new ensemble NWP rainfall fields are calculated by recombining the transposition results of non-orographic rain fields with separated orographic rainfall fields for a generation of place-corrected ensemble information. Then, the additional ensemble information is applied into a hydrologic model for post-flood forecasting with a 6-h interval. The newly proposed method has a clear advantage to improve the accuracy of mean value of ensemble flood forecasting. Our study is carried out and verified using the largest flood event by typhoon 'Talas' of 2011 over the two catchments, which are Futatsuno (356.1 km2) and Nanairo (182.1 km2) dam catchments of Shingu river basin (2360 km2), which is located in the Kii peninsula, Japan.

  4. A three-season field study on the in-situ remediation of Cd-contaminated paddy soil using lime, two industrial by-products, and a low-Cd-accumulation rice cultivar.

    Science.gov (United States)

    Yan-Bing, He; Dao-You, Huang; Qi-Hong, Zhu; Shuai, Wang; Shou-Long, Liu; Hai-Bo, He; Han-Hua, Zhu; Chao, Xu

    2017-02-01

    To mitigate the serious problem of Cd-contaminated paddy soil, we investigated the remediation potential of combining in-situ immobilization with a low-Cd-accumulation rice cultivar. A three-season field experiment compared the soil pH, available Cd and absorption of Cd by three rice cultivars with different Cd accumulation abilities grown in Cd-contaminated paddy soil amended with lime (L), slag (S), and bagasse (B) alone or in combination. The three amendments applied alone and in combination significantly increased soil pH, reduced available Cd and absorption of Cd by rice with no effect on grain yield. Among these, the LS and LSB treatments reduced the brown rice Cd content by 38.3-69.1% and 58.3-70.9%, respectively, during the three seasons. Combined with planting of a low-Cd-accumulation rice cultivar (Xiang Zaoxian 32) resulted in a Cd content in brown rice that met the contaminant limit (≤0.2mgkg(-1)). However, the grain yield of the low-Cd-accumulation rice cultivar was approximately 30% lower than the other two rice cultivars. Applying LS or LSB as amendments combined with planting a low-Cd-accumulation rice cultivar is recommended for the remediation of Cd-contaminated paddy soil. The selection and breeding of low-Cd-accumulation rice cultivars with high grain production requires further research.

  5. 黑龙江省通河县旱地改水田许可转换度研究%Research on permissive conversion limit of dryland to paddy field in Tonghe county, Heilongjiang province

    Institute of Scientific and Technical Information of China (English)

    向长玉; 周东兴; 宋戈; 赵映慧

    2012-01-01

    由于水稻种植的效益较高,促使有条件地区旱改水现象突出.水田面积增长迅速,导致部分地区人地用水矛盾突出,如何确定一地区水田面积极限值,保证人地用水和谐发展是亟待解决的问题.该文以黑龙江省通河县为研究区,基于GIS技术、考虑农业生态承载力各自然约束条件,应用定量化模型计算通河县的许可最大水田面积,并以许可转换度来表征区域旱地改水田的极限比例.结果表明:通河县旱地改水田许可转换度应控制在0.45以下,即水田面积控制在79311.8 hm2以内,可以保证通河县人地用水的和谐发展.且以2008年农业种植结构数据为基础,计算出通河县旱地改水田的潜力约为2万hm2,目前旱改水的潜力还较大.研究结果可为黑龙江省通河县农业种植结构调整提供量化依据,保证通河县及类似地区农业可持续发展.%It is prominent phenomenon of the conversion of dryland to paddy in the conditional areas because of high benefit on rice cultivation. The areas where the paddy field grows rapidly can lead to the contradiction between human and land. How to determine the maximum area of paddy field and to guarantee the harmonious development between human and land is a urgent problem to be solved. Based on the technology of GIS, taking Tonghe county, Heilogjiang province as research area, considering the nature constraints of the agricultural ecological bearing capacity, this paper calculated the maximum paddy area of permission in Tonghe county by quantified model. The results showed that the permission conversion degree should be controlled less than 0.45, that is, the paddy field area should be controlled within 79311.8 hm2. This limit can guarantee the harmonious development between human and land in Tonghe county. Based on the agricultural circumstances of 2008, the area of dryland converting to paddy field in Tonghe county is about 20 000 hm2 in the future and there is a

  6. Effects of fertilization on microbial abundance and emissions of greenhouse gases (CH4 and N2O) in rice paddy fields.

    Science.gov (United States)

    Fan, Xianfang; Yu, Haiyang; Wu, Qinyan; Ma, Jing; Xu, Hua; Yang, Jinghui; Zhuang, Yiqing

    2016-02-01

    This study is to explore effects of nitrogen application and straw incorporation on abundance of relevant microbes and CH 4 and N2O fluxes in a midseason aerated rice paddy field. Fluxes of CH 4 and N2O were recorded, and abundance of relevant soil microbial functional genes was determined during rice-growing season in a 6-year-long fertilization experiment field in China. Results indicate that application of urea significantly changed the functional microbial composition, while the influence of straw incorporation was not significant. Application of urea significantly decreased the gene abundances of archaeal amoA and mcrA, but it significantly increased the gene abundances of bacterial amoA. CH 4 emission was significantly increased by fresh straw incorporation. Incorporation of burnt straw tended to increase CH 4 emission, while the urea application had no obvious effect on CH 4 emission. N2O emission was significantly increased by urea application, while fresh or burnt straw incorporation tended to decrease N2O emission. The functional microbial composition did not change significantly over time, although the abundances of pmoA, archaeal amoA, nirS, and nosZ genes changed significantly. The change of CH 4 emission showed an inverse trend with the one of the N2O emissions over time. To some extent, the abundance of some functional genes in this study can explain CH 4 and N2O emissions. However, the correlation between CH 4 and N2O emissions and the abundance of related functional genes was not significant. Environmental factors, such as soil Eh, may be more related to CH 4 and N2O emissions.

  7. Microbial ecology on the microcosm level: Activity and population dynamics of methanotrophic bacteria during early succession in a flooded rice field soil

    Science.gov (United States)

    Krause, S.; Frenzel, P.

    2009-04-01

    Methane oxidizing bacteria (methanotrophs) play an important role in natural wetlands and rice fields preventing large amounts of methane from escaping into the atmosphere. The occurrence of both type I and type II methanotrophs in the soil surface layer has been demonstrated in many studies. However, there is no profound understanding which of them are responsible for the oxidizing activity and how they differ ecologically. Hence, a gradient microcosm system was applied simulating oxic-anoxic interfaces of water saturated soils to unravel population dynamics in early succession of methanotrophs in a flooded rice paddy. Additionally, environmental parameters were analyzed to link environment, populations, and their specific activity. We measured pmoA-based (particulate methane monooxygenase) terminal restriction fragment length polymorphism (T-RFLP) profiles both on transcription and population level. DNA T-RFLP patterns showed no major differences in the methanotrophic community structure remaining relatively constant over time. In contrast the active methanotrophic community structure as detected by pmoA mRNA T-RFLP analysis clearly demonstrated a distinct pattern from DNA T-RFLP profiles. While type II represented the most prominent group on the population level it seems to play a minor role on the transcription level. Furthermore there were no clear implications towards a link between soil parameters (e.g. NH4+ concentration) and methanotrophic community structure.

  8. Effects of Long-Term Organic Amendments on Soil Organic Carbon in a Paddy Field:A Case Study on Red Soil

    Institute of Scientific and Technical Information of China (English)

    HUANG Qing-hai; DUAN Ying-hua; ZHANG Wen-ju; LI Da-ming; LIU Kai-lou; YU Xi-chu; YE Hui-cai; HU Hui-wen; XU Xiao-lin; WANG Sai-lian; ZHOU Li-jun

    2014-01-01

    Soil organic carbon (SOC) is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization (CK), nitrogen-phosphorus-potassium fertilization in early rice only (NPK), green manure (Astragalus sinicus L.) in early rice only (OM1), high rate of green manure in early rice only (OM2), combined green manure in early rice and farmyard manure in late rice (OM3), combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter (OM4), combined green manure in early rice and rice straw mulching in winter (OM5). Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a signiifcant difference between OM3 (33.9 t ha-1) and OM4 (31.8 t ha-1), but no difference between NPK fertilization (27 t ha-1) and non-fertilization (28.1 t ha-1). There was a signiifcant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments (0.276-0.344 g kg-1 yr-1) than in chemical fertilizer (0.216 g kg-1 yr-1) and no fertilizer (0.127 g kg-1 yr-1).

  9. Organophosphorus and Carbamate Pesticide Residues Detected in Water Samples Collected from Paddy and Vegetable Fields of the Savar and Dhamrai Upazilas in Bangladesh

    Directory of Open Access Journals (Sweden)

    Nurul Karim

    2012-09-01

    Full Text Available Several types of organophosphorous and carbamate pesticides have been used extensively by the farmers in Bangladesh during the last few decades. Twenty seven water samples collected from both paddy and vegetable fields in the Savar and Dhamrai Upazilas in Bangladesh were analyzed to determine the occurrence and distribution of organo-phosphorus (chlorpyrifos, malathion and diazinon and carbamate (carbaryl and carbofuran pesticide residues. A high performance liquid chromatograph instrument equipped with a photodiode array detector was used to determine the concentrations of these pesticide residues. Diazinon and carbofuran were detected in water samples collected from Savar Upazila at 0.9 μg/L and 198.7 μg/L, respectively. Malathion was also detected in a single water sample at 105.2 μg/L from Dhamrai Upazila. Carbaryl was the most common pesticide detected in Dhamrai Upazila at 14.1 and 18.1 μg/L, while another water sample from Dhamrai Upazila was contaminated with carbofuran at 105.2 μg/L. Chlorpyrifos was not detected in any sample. Overall, the pesticide residues detected were well above the maximum acceptable levels of total and individual pesticide contamination, at 0.5 and 0.1 μg/L, respectively, in water samples recommended by the European Economic Community (Directive 98/83/EC. The presence of these pesticide residues may be attributed by their intense use by the farmers living in these areas. Proper handling of these pesticides should be ensured to avoid direct or indirect exposure to these pesticides.

  10. The rice REDUCED CULM NUMBER11 gene controls vegetative growth under low-temperature conditions in paddy fields independent of RCN1/OsABCG5.

    Science.gov (United States)

    Funabiki, Atsushi; Takano, Sho; Matsuda, Shuichi; Tokuji, Yoshihiko; Takamure, Itsuro; Kato, Kiyoaki

    2013-10-01

    Low temperature tolerance during vegetative growth is an important objective in rice (Oryza sativa L.) breeding programs. We isolated a novel reduced culm number mutant, designated reduced culm number11 (rcn11), by screening under low-temperature condition in a paddy fields. Since the shoot architecture of the rcn11 was very similar to that of the rcn1, we examined whether RCN11 is involved in RCN1/OsABCG5-associated vegetative growth control. The rcn11 mutant has no mutation in the RCN1/OsABCG5 gene and rcn11 has no effect on RCN1/OsABCG5 gene expression. In the rcn1 mutant, RCN1/OsABCG5 was upregulated showing that RCN1/OsABCG5 is controlled by negative feedback regulation. Absence of an effect of rcn11 on RCN1/OsABCG5 feedback regulation supported that RCN11 is not involved in the RCN1/OsABCG5-associated transport system. A genetic allelism test and molecular mapping study showed that rcn11 is independent of rcn1 on rice chromosome 3 and located on chromosome 8. The rcn1 rcn11 phenotype suggests that RCN11 acts on vegetative growth independent of RCN1/OsABCG5. A root development comparison between rcn1 and rcn11 in young seedlings represented that rcn11 reduced crown root number and elongation, whereas rcn1 reduced lateral root density and elongation. Thus, rcn11 will shed new light on vegetative growth control under low temperature.

  11. Increased spring flooding of agricultural fields will exhibit altered production of greenhouse gases

    Science.gov (United States)

    Paul, R. F.; Smith, C. M.; Smyth, E. M.; Kantola, I. B.; DeLucia, E. H.

    2013-12-01

    The U.S. Corn Belt currently is a net source of carbon dioxide and nitrous oxide to the atmosphere, but is also a sink of methane. Among the proposed effects of climate change in the North American Midwest region is an increase in the frequency and duration of spring flooding events. This would cause ponding in fields which may change the greenhouse gas balance of the region, especially by providing a suitable anoxic environment for the proliferation of methanogens, increasing methane emissions. To determine whether methanogenesis occurs in flooded agricultural soils of the Midwest and how other gas fluxes are affected, we installed collars into the ground of a research field located in central Illinois. The control group was maintained at the same conditions as the surrounding field. Two groups of collars were sustained with water flooding the headspaces via a drip irrigation system; one treatment was analyzed for gas fluxes of CH4, N2O, and CO2 evolving from the collars, and a separate treatment of flooded collars was used for soil sampling. Comparing flooded soils versus control we measured reduced N2O fluxes (-3.12 x 10-6 × 6.8 x 10-7 g N m-2 min-1), reduced CO2 fluxes (-6.13 x 10-3 × 9.3 x 10-4 g CO2 m-2 min-1), and increased methane fluxes (+2.72 x 10-6 × 5.8 x 10-7 g CH4 m-2 min-1). After only one week of treatment the flooded soils switched from being sinks to sources of methane, which continued across the duration of the experiment. These preliminary results indicate that methanogenesis occurs in flooded agricultural fields, and suggest including regional modeling into further study. Although the global warming potential of methane is 25 times greater than CO2, our measured rates of methane production were compensated by reductions in nitrous oxide and CO2 fluxes, reducing the total 100-year horizon global warming potential of the flooded soils we studied by 64.8%. This indicates that accounting for more frequent seasonal ponding would significantly

  12. Water treatment by aquatic ecosystem: Nutrient removal by reservoirs and flooded fields

    Science.gov (United States)

    Reddy, K. R.; Sacco, P. D.; Graetz, D. A.; Campbell, K. L.; Sinclair, L. R.

    1982-05-01

    Potential use of reservoirs and flooded fields stocked with aquatic plants for reduction of the nutrient levels of organic soil drainage water was evaluated. The treatment systems include 1) a large single reservoir (R1) stocked with waterhyacinth ( Eichhornia crassipes), elodea ( Egeria densa), and cattails ( Typha sp.) in series; 2) three small reservoirs in series with waterhyacinth (R2), elodea (R3), and cattails (R4), grown in independent reservoirs; 3) a control reservoir (R5) with no cultivated plants; 4) a large single flooded field planted to cattails; 5) three small flooded fields in a series planted to cattails; and 6) a flooded field with no cultivated plants. Drainage water was pumped daily (6 hours a day, and 6 days a week) into these systems for a period of 27 months at predetermined constant flow rates. Water samples were collected at the inlet and outlet of each treatment system and analyzed for N and P forms. The series of reservoirs stocked with aquatic plants functioned effectively in the removal of N and P from agricultural drainage water, compared to a single large reservoir. Allowing the water to flow through the reservoir stocked with waterhyacinth plants with a residence time of 3.6 days was adequate to remove about 50% of the incoming inorganic N. Allowing the water to flow through a series of two small reservoirs, R2 and R3, with a residence time of 7.3 days was necessary to remove about 60% of the incoming ortho-P. Flooded fields were effective in the removal of inorganic N, but showed poor efficiency in the removal of ortho-P.

  13. Improvement of seedling establishment under flood condition by seed coating with molybdenum compounds for wheat and barley

    Directory of Open Access Journals (Sweden)

    Yoshitaka Hara

    2016-04-01

    Full Text Available Wheat and barley are often cultivated also in paddy fields in winter in Japan. The drainage of paddy fields is often poor. The seedling establishment of wheat and barley is more prone to become poor if it rains heavily after sowing. The flooding damage on seedling establishment is thought to be caused by many factors. The generation of sulfide ions in flooded and reduced soil is thought to be one factor of the flooding damage. In this study, the effect of seed coating with molybdenum compounds, which suppress the generation of sulfide ions, on the flooding damage of wheat and barley seedling establishment. Two poorly soluble molybdenum compounds were coated on wheat or barley seeds at different amounts. Coated seeds were sown in soil and soon flooded for 2 d at 20 °C. When seeds were not coated with molybdenum compounds, rates of seedling establishment were no more than 32%. However, when any molybdenum compounds of .05–.5 mol-Mo kg−1 were coated, seedling establishment was significantly improved and rates of seedling establishment were no less than 54%. However, when sown seed were not flooded, the establishment rates of the seeds, which were coated with a molybdenum compound of no less than .1 or .2 mol-Mo kg-1, were significantly decreased. Accordingly, coating of molybdenum compounds could improve the seedling establishment of coated seeds under flooded condition, but might impair the seedling establishment of coated seeds under unflooded condition.

  14. H2-Producing Bacterial Community during Rice Straw Decomposition in Paddy Field Soil: Estimation by an Analysis of [FeFe]-Hydrogenase Gene Transcripts.

    Science.gov (United States)

    Baba, Ryuko; Asakawa, Susumu; Watanabe, Takeshi

    2016-09-29

    The transcription patterns of [FeFe]-hydrogenase genes (hydA), which encode the enzymes responsible for H2 production, were investigated during rice straw decomposition in paddy soil using molecular biological techniques. Paddy soil amended with and without rice straw was incubated under anoxic conditions. RNA was extracted from the soil, and three clone libraries of hydA were constructed using RNAs obtained from samples in the initial phase of rice straw decomposition (day 1 with rice straw), methanogenic phase of rice straw decomposition (day 14 with rice straw), and under a non-amended condition (day 14 without rice straw). hydA genes related to Proteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, and Thermotogae were mainly transcribed in paddy soil samples; however, their proportions markedly differed among the libraries. Deltaproteobacteria-related hydA genes were predominantly transcribed on day 1 with rice straw, while various types of hydA genes related to several phyla were transcribed on day 14 with rice straw. Although the diversity of transcribed hydA was significantly higher in the library on day 14 with rice straw than the other two libraries, the composition of hydA transcripts in the library was similar to that in the library on day 14 without rice straw. These results indicate that the composition of active H2 producers and/or H2 metabolic patterns dynamically change during rice straw decomposition in paddy soil.

  15. Differential assemblage of functional units in paddy soil microbiomes.

    Directory of Open Access Journals (Sweden)

    Yongkyu Kim

    Full Text Available Flooded rice fields are not only a global food source but also a major biogenic source of atmospheric methane. Using metatranscriptomics, we comparatively explored structural and functional succession of paddy soil microbiomes in the oxic surface layer and anoxic bulk soil. Cyanobacteria, Fungi, Xanthomonadales, Myxococcales, and Methylococcales were the most abundant and metabolically active groups in the oxic zone, while Clostridia, Actinobacteria, Geobacter, Anaeromyxobacter, Anaerolineae, and methanogenic archaea dominated the anoxic zone. The protein synthesis potential of these groups was about 75% and 50% of the entire community capacity, respectively. Their structure-function relationships in microbiome succession were revealed by classifying the protein-coding transcripts into core, non-core, and taxon-specific transcripts based on homologous gene distribution. The differential expression of core transcripts between the two microbiomes indicated that structural succession is primarily governed by the cellular ability to adapt to the given oxygen condition, involving oxidative stress, nitrogen/phosphorus metabolism, and fermentation. By contrast, the non-core transcripts were expressed from genes involved in the metabolism of various carbon sources. Among those, taxon-specific transcripts revealed highly specialized roles of the dominant groups in community-wide functioning. For instance, taxon-specific transcripts involved in photosynthesis and methane oxidation were a characteristic of the oxic zone, while those related to methane production and aromatic compound degradation were specific to the anoxic zone. Degradation of organic matters, antibiotics resistance, and secondary metabolite production were detected to be expressed in both the oxic and anoxic zones, but by different taxonomic groups. Cross-feeding of methanol between members of the Methylococcales and Xanthomonadales was suggested by the observation that in the oxic zone

  16. The Extraction Model of Paddy Rice Information Based on GF-1 Satellite WFV Images.

    Science.gov (United States)

    Yang, Yan-jun; Huang, Yan; Tian, Qing-jiu; Wang, Lei; Geng, Jun; Yang, Ran-ran

    2015-11-01

    In the present, using the characteristics of paddy rice at different phenophase to identify it by remote sensing images is an efficient way in the information extraction. According to the remarkably properties of paddy rice different from other vegetation, which the surface of paddy fields is with a large number of water in the early stage, NDWI (normalized difference water index) which is used to extract water information can reasonably be applied in the extraction of paddy rice at the early stage of the growth. And using NDWI ratio of two phenophase can expand the difference between paddy rice and other surface features, which is an important part for the extraction of paddy rice with high accuracy. Then using the variation of NDVI (normalized differential vegetation index) in different phenophase can further enhance accuracy of paddy rice information extraction. This study finds that making full advantage of the particularity of paddy rice in different phenophase and combining two indices (NDWI and NDVI) associated with paddy rice can establish a reasonable, accurate and effective extraction model of paddy rice. This is also the main way to improve the accuracy of paddy rice extraction. The present paper takes Lai'an in Anhui Province as the research area, and rice as the research object. It constructs the extraction model of paddy rice information using NDVI and NDWI between tillering stage and heading stage. Then the model was applied to GF1-WFV remote sensing image on July 12, 2013 and August 30, 2013. And it effectively extracted out of paddy rice distribution in Lai'an and carried on the mapping. At last, the result of extraction was verified and evaluated combined with field investigation data in the study area. The result shows that using the extraction model can quickly and accurately obtain the distribution of rice information, and it has the very good universality.

  17. Estimate of CH4 Emissions from Year-Round Flooded Rice Fields During Rice Growing Season in China

    Institute of Scientific and Technical Information of China (English)

    CAI Zu-Cong; KANG Guo-Ding; H. TSURUTA; A. MOSIER

    2005-01-01

    A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China.The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66Mha were estimated to be 2.44 Tg CH4 year-1. The uncertainties of these estimations are discussed as well. However,the emissions during the non-rice growing season could not be estimated because of limited available data. Nevertheless,methane emissions from rice fields that were flooded year-round could be several times higher than those from the rice fields drained in the non-rice-growing season. Thus, the classification of "continuously flooded rice fields" in the IPCC(International Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories is suggested to be revised and divided into "continuously flooded rice fields during the rice growing season" and "year-round flooded rice fields".

  18. 适宜深泥脚田的2行插秧机试验研究%Study on Two-row Rice Transplanter Suitable for Deep Mud Feet Paddy Field

    Institute of Scientific and Technical Information of China (English)

    易文裕; 应婧; 庹洪章; 熊昌国; 谢祖琪

    2014-01-01

    针对深泥脚田的泥脚深度30 cm以上、田面积水层深浅不一致,以及土壤的硬底层较深、表层土壤流变性大、剪切应力小和运动阻力大等特点,设计研制了一种适应深泥脚田的 SNJ 2行插秧机,并在田间进行了机插秧试验,对SNJ 2行插秧机的秧苗栽插质量(包括漂秧率、漏插率、伤秧率)、插秧效率和产量进行了分析。%This paper research on deep mud feet paddy field when the depth of the mud feet is above 30cm, surface wa-ter layer depth is inconsistent , the substratum of soil is deep , surface of soil rheology is big、shear stress is small and the movement resistance is large , a two-row SNJ rice transplanter adapting to deep mud feet paddy field was designed .On the basis of taking a great number of producing experiments by the two-row SNJ rice transplanter verified that the two-row SNJ rice transplanter is suitable for deep mud feet paddy field .In the meanwhile , this paper analyze transplanting quality which means seedling floating rate , sowing leakage rate and seedling injury rate , transplanting efficiency and rice yields .

  19. Characterizations of purple non-sulfur bacteria isolated from paddy fields, and identification of strains with potential for plant growth-promotion, greenhouse gas mitigation and heavy metal bioremediation.

    Science.gov (United States)

    Sakpirom, Jakkapan; Kantachote, Duangporn; Nunkaew, Tomorn; Khan, Eakalak

    2017-04-01

    This study was aimed at selecting purple non-sulfur bacteria (PNSB) isolated from various paddy fields, including Cd- and Zn-contaminated paddy fields, based on their biofertilizer properties. Among 235 PNSB isolates, strain TN110 was most effective in plant growth-promoting substance (PGPS) production, releasing 3.2 mg/L of [Formula: see text] , 4.11 mg/L of 5-aminolevulinic acid (ALA) and 3.62 mg/L of indole-3-acetic acid (IAA), and reducing methane emission up to 80%. This strain had nifH, vnfG and anfG, which are the Mo, V and Fe nitrogenase genes encoded for key enzymes in nitrogen fixation under different conditions. This strain provided 84% and 55% removal of Cd and Zn, respectively. Another isolate, TN414, not only produced PGPS (1.30 mg/L of [Formula: see text] , 0.94 mg/L of ALA and 0.65 mg/L of IAA), but was also efficient in removing both Cd and Zn at 72% and 74%, respectively. Based on 16S rDNA sequencing, strain TN110 was identified as Rhodopseudomonas palustris, while strain TN414 was Rubrivivax gelatinosus. A combination of TN110 and TN414 could potentially provide a biofertilizer, which is a greener alternative to commercial/chemical fertilizers and an agent for bioremediation of heavy metals and greenhouse gas mitigation in paddy fields. Copyright © 2016 Institut Pasteur. All rights reserved.

  20. Remote-Sensing-Based Evaluation of Relative Consumptive Use Between Flood- and Drip-Irrigated Fields

    Science.gov (United States)

    Martinez Baquero, G. F.; Jordan, D. L.; Whittaker, A. T.; Allen, R. G.

    2013-12-01

    Governments and water authorities are compelled to evaluate the impacts of agricultural irrigation on economic development and sustainability as water supply shortages continue to increase in many communities. One of the strategies commonly used to reduce such impacts is the conversion of traditional irrigation methods towards more water-efficient practices. As part of a larger effort by the New Mexico Interstate Stream Commission to understand the environmental and economic impact of converting from flood irrigation to drip irrigation, this study evaluates the water-saving effectiveness of drip irrigation in Deming, New Mexico, using a remote-sensing-based technique combined with ground data collection. The remote-sensing-based technique used relative temperature differences as a proxy for water use to show relative differences in crop consumptive use between flood- and drip-irrigated fields. Temperature analysis showed that, on average, drip-irrigated fields were cooler than flood-irrigated fields, indicating higher water use. The higher consumption of water by drip-irrigated fields was supported by a determination of evapotranspiration (ET) from all fields using the METRIC Landsat-based surface energy balance model. METRIC analysis yielded higher instantaneous ET for drip-irrigated fields when compared to flood-irrigated fields and confirmed that drip-irrigated fields consumed more water than flood-irrigated fields planted with the same crop. More water use generally results in more biomass and hence higher crop yield, and this too was confirmed by greater relative Normalized Difference Vegetation Index for the drip irrigated fields. Results from this study confirm previous estimates regarding the impacts of increased efficiency of drip irrigation on higher water consumption in the area (Ward and Pulido-Velazquez, 2008). The higher water consumption occurs with drip because, with the limited water supplies and regulated maximum limits on pumping amounts, the

  1. 江川灌区旱田改水田加剧水体氮磷污染%Changing from dry field to paddy field intensifying water pollution by nitrogen and phosphorus loads in Jiangchuan irrigation area

    Institute of Scientific and Technical Information of China (English)

    樊庆锌; 孟婷婷; 李金梦; 邱微

    2014-01-01

    After changing from upland farming to paddy field in Jiangchuan irrigation area, the grain production continues to increase, but problem of the non-point source pollution occurs predominantly with total nitrogen and total phosphorus. Both paddy fields and upland fields can experience surface runoff of chemical fertilizers and pesticides, but which land use can cause more surface runoff remains largely unknown. There are many point source pollution researches in water systems in China, and the technology and methods are relatively mature. But for agricultural non-point source pollution, most research is done in the south, and less in the northeast of China. Therefore, it is needed for research on surface nutrient or pesticide runoff when changing from upland farming to paddy fields. With the use of GIS and SWAT model, the spatial database and attribute database of the model for the research area were established. The spatial database included digital elevation map (DEM), land use map and soil map. The attribute database basically included the meteorological, soil property, and agricultural management data. Based on the feature of natural rivers distribution on the edge of the irrigation area, we used“burn-in”algorithm to make the artificial canal system network as the water system, and set up the threshold watershed area to delimit sub basin in the river basin. Next, we used LH-OAT method of SWAT model to analyze parameter sensitivity, and selected the important factors for the model output. We then used the measured data of runoff, total nitrogen and total phosphorus from the years of 2008 to 2009 as the calibration period, and years of 2010 to 2013 as validation period to explore the model applicability in the research area. Finally, the nitrogen and phosphorus pollution load in the study area under different scenarios were simulated. These scenarios were: no change of the existing farmland area, 70%, or 50% of land converted to paddy field. The results showed

  2. The Reasons for Tillage Layer Shallowing in Paddy Fields and Its Control Strategies%临安市稻田耕作层变浅的原因与治理措施

    Institute of Scientific and Technical Information of China (English)

    陈丁红; 胡国成

    2011-01-01

    从1982年第二次土壤普查、1997年的水稻田土壤养分复查及2008年的标准农田地力调查的三次结果可以发现,临安市稻田耕作层呈现了变浅的趋势.通过对历年来生产情况的研究,笔者对稻田耕作层变浅的原因进行了综合分析,得出长期浅耕或免耕是造成稻田耕作层变浅的主要原因,并针对性地提出了治理措施.%The data of the second general soil survey in 1982, the soil nutrients of rice fields review in1997 and the fertility of farmland survey in 2008 were analyzed, we find that the tillage layer of paddy fields showed a trend of shallowing in Lin'an City. By studying production situation over the years, this article synthetically analyzed the shallowing reasons, drew a conclusion that the long-time shallow tillage and no-tillage is the major reason causing the shallowing of tillage layer of paddy fields, and several improvement countermeasures were proposed.

  3. Nonlinear Analysis and Optimization of Paddy Fields Self-walking Device%水田自行走机构梁的几何非线性分析及优化

    Institute of Scientific and Technical Information of China (English)

    段锴; 张海亮

    2012-01-01

    设计一款水田自行走机构,其中承重梁的设计直接影响整个机构的工作效果。利用ANSYS有限元分析软件对承重梁进行非线性分析以及优化设计,以实现水田作业的最优效果。%Paddy fields Self-walking device is a kind of auxiliary institutions, which can finish the task more effective, convenient and rapidly. Paddy field work environment is complexity and has big resistance, which is not easy to control, inorder to solve these problems, we designed this self-walking device. The design of spandrel girder directly influence the effect of the self-walking device, Based on ANSYS this paper completed the analysis and optimization design of spandrel girder, and realize the optimal operation effect of the pad- dy fields.

  4. 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

  5. Constraining the onset of flood volcanism in Isle of Skye Lava Field, British Paleogene Volcanic Province

    Science.gov (United States)

    Angkasa, Syahreza; Jerram, Dougal. A.; Svensen, Henrik; Millet, John M.; Taylor, Ross; Planke, Sverre

    2016-04-01

    In order to constrain eruption styles at the onset of flood volcanism, field observations were undertaken on basal sections of the Isle of Skye Lava Field, British Paleogene Volcanic Province. This study investigates three specific sections; Camus Ban, Neist Point and Soay Sound which sample a large area about 1500 km2 and can be used to help explain the variability in palaeo-environments at the onset of flood volcanism. Petrological analysis is coupled with petrophysical lab data and photogrammetry data to create detailed facies models for the different styles of initiating flood basalt volcanism. Photogrammetry is used to create Ortho-rectified 3D models which, along with photomontage images, allow detailed geological observations to be mapped spatially. Petrographic analyses are combined with petrophysical lab data to identify key textural variation, mineral compositions and physical properties of the volcanic rocks emplaced during the initial eruptions. Volcanism initiated with effusive eruptions in either subaerial or subaqueous environments resulting in tuff/hyaloclastite materials or lava flow facies lying directly on the older Mesozoic strata. Volcanic facies indicative of lava-water interactions vary significantly in thickness between different sections suggesting a strong accommodation space control on the style of volcanism. Camus Ban shows hyaloclastite deposits with a thickness of 25m, whereas the Soay Sound area has tuffaceous sediments of under 0.1m in thickness. Subaerial lavas overly these variable deposits in all studied areas. The flood basalt eruptions took place in mixed wet and dry environments with some significant locally developed water bodies (e.g. Camus Ban). More explosive eruptions were promoted in some cases by interaction of lavas with these water bodies and possibly by local interaction with water - saturated sediments. We record key examples of how palaeotopography imparts a primary control on the style of volcanism during the

  6. Study on Intermittent Irrigation for Paddy Rice:I.Water Use Efficiency

    Institute of Scientific and Technical Information of China (English)

    LUJUN; T.HIRASAWA

    2001-01-01

    A field experiment was conducted in a well-puddled paddy field developed on the Tama River alluvial soil in the Farm of Tokyo University of Agriculture and Technology,Japan,to study the effect of intermittent irrigation on water use efficiency of paddy rice,Four treatments were arranged with 2 replicates:continuous flooding irrigation treatments(CFI),and three intermittent irrigation treatments Ⅱ-0,Ⅱ-1 and Ⅱ-2,in which plants were re-irrigated when the soil water potential.fell below 0,-10,and -20 kPa,respectively,at soil depth of about 5 cm,Water consumption wa lower in treatment Ⅱ-0 than in treatment CFI because the percolation rate was reduced by the reduction in the hydraulic head of ponded water .Intermittent irrigation led to soil repeated shrinking and swelling in Ⅱ-1 and Ⅱ-2 plots and ,therefore,soil cracks developed rapidly.Since they became the major routes of water percolation,the soil cracks increased waer consumption in treatments Ⅱ-1 and Ⅱ-2.there were no significant differenes in dry matter production and grain yields between treatment Ⅱ-0 and treatment CFI,but the dry matter production and grain yields in treatments Ⅱ-0 and CFI were significantly higher than those in treatments Ⅱ-1 and Ⅱ-2,Therefore,the eater use efficiency in the treatments was in the order of Ⅱ-0>CFI>Ⅱ-2>Ⅱ-1.

  7. Remote sensing identification method for paddy field in hilly region based on object-oriented analysis%面向对象的丘陵区水田遥感识别方法

    Institute of Scientific and Technical Information of China (English)

    易凤佳; 李仁东; 常变蓉; 邱娟

    2015-01-01

    Identification of paddy fields in the hilly regions is important for policy making of food self-sufficiency in China. However, extracting image information using current image analysis techniques is difficult because of the unique terrain of hilly regions. The traditional pixel-based analysis of remotely sensed data is usually affected by pixel heterogeneity, mixed pixels, and spectral similarity, thus leading to the inaccurate identification of paddy fields in hilly regions. This study aimed to find other methods for accurate paddy field identification in hilly regions. The study area was Xiangtan City located in the mid-east of Hunan province, a good representative of hilly regions. In Xiangtan city, the land use change markedly increases with rapid economic development, leading to gradual decline of cultivated land. The Chinese environment and disaster mitigation satellite (i.e., HJ-1A/1B) image of the region was data source for land use map. The HJ-1A star was equipped with a charge-coupled device (CCD) camera and a hyperspectral imager, whereas the HJ-1B star was equipped with CCD and infrared (IR) cameras. The satellite observes the ground in widths of 700 km with a ground pixel resolution of 30 m by four multispectral imaging steps. The object-oriented image analysis technique is a new type of automatic technique under a computer environment. The information carrier used was multi-scale objects composed of multiple adjacent pixels containing rich semantic information. Image segmentation is an important classification step because high-precision remote sensing (RS) image classification depends on good segmentation. The multi-scale image segmentation algorithm was applied in the preliminary object extraction to fully interpret the RS images with the different spectral features, shape, and textural features of real ground targets. The configuration of multi-scale segmentation thresholds directly affected the integrity of features extracted from RS images. In

  8. Design of High-ground-clearance Narrow-rubber-pedrail-type Running System for Paddy Field and Upland%高地隙窄形橡胶履带式水旱兼用行走系统设计

    Institute of Scientific and Technical Information of China (English)

    邢全道; 何瑞银; 何彦平; 安波; 刘天星; 王媛媛; 邢艳红; 徐高明

    2013-01-01

    A high-ground-clearance narrow -rubber-pedrail-type running system for paddy field and dry upland was de-veloped, which was especially suitable for plant protection work of paddy field .The working principle of this running system was an-alyzed.The pedrail, driving wheel or guiding wheel , supporting bearing and other key parts were designed and calculated .The per-formance tests showed that the system had stable working property with the ground clearance of 1 m, and prevented the wheels from sinking into the deep earth, so that few seedlings were squashed .%  研制了一种高地隙水旱兼用行走系统,特别适用于水稻田植保作业,分析了其工作原理,并对履带、驱动轮或导向轮、支撑轴承座等关键部件进行了设计计算,通过性能试验表明:该行走系统工作性能稳定,地隙达1 m,防陷深,压苗少。

  9. 沟渠及塘堰湿地系统对稻田氮磷污染的去除试验%Experiments on Removal Effects of Ditch-Pond Wetland System on N and P Pollutants from Paddy Field

    Institute of Scientific and Technical Information of China (English)

    何军; 崔远来; 吕露; 易帆; 段中德

    2011-01-01

    In order to study removal effect and laws of irrigation area ditch-pond wetlands system to paddy drainage water nitrogen and phosphorus pollutants under natural condition, three typical drainage ditches and one pond at the scale from field ditch to lateral ditch were selected in Zhanghe Irrigation System, Hubei Province. Water samples at inlet and outlet of the ditches and pond were collected for nitrogen and phosphorus analysis during the whole rice growing season from May to September in 2009 and 2010. The results show that the average total removal rates from field ditch to lateral ditch on total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus in drainage water from paddy field were 44.6%, 9.9%, 37.3% and 35.1%, respectively; and the average removal rates of typical pond on total nitrogen, nitrate nitrogen, ammonium nitrogen, total phosphorus in drainage water were 15.2%, 15.6%, 30.2% and -6.5%, respectively. The experiment also showed certain anti-impact and self-repairing effects of the wetland system to nitrogen and phosphorus pollutants. Generally the removal rate was significant in the earlier growing stage of paddy rice, then decreased or even appeared negative value in the middle, and finally recovers in the later growing stage. In natural condition, the hydraulic retention time( HRT) of each ditch was not long enough, which made the difference of removal effect on nitrogen and phosphorus pollutants between different ditches not significant. The pond's removal effect on paddy drainage water nitrogen and phosphorus pollutants in 2009 when it was planted with pollen typhae were better than that in 2010 without pollen typhae in the pond. The cultivation of vegetation and its management of ditches-pond wetland system is of great significance to remove drainage water nitrogen and phosphorus pollutants from paddy field.%为研究原位状态下灌区沟渠及塘堰湿地系统对稻田氮磷污染的去除效应和规律,在湖北省漳河灌

  10. 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

  11. Simulation and measurement of leaf wetness formation in paddy rice crops.

    NARCIS (Netherlands)

    Luo Weihong,

    1996-01-01

    The study described in this thesis focuses on a quantification of leaf wetness formation in paddy rice crops based on insight in the physical processes of the formation of leaf wetness. For this purpose, experimental research was conducted in a tropical paddy rice field.A shielding (nocturnal net ra

  12. Simulation and measurement of leaf wetness formation in paddy rice crops

    NARCIS (Netherlands)

    Luo, W.

    1996-01-01


    The study described in this thesis focuses on a quantification of leaf wetness formation in paddy rice crops based on insight in the physical processes of the formation of leaf wetness. For this purpose, experimental research was conducted in a tropical paddy rice field.

    A

  13. [Effects of Tillage on Distribution of Heavy Metals and Organic Matter Within Purple Paddy Soil Aggregates].

    Science.gov (United States)

    Shi, Qiong-bin; Zhao, Xiu-lan; Chang, Tong-ju; Lu, Ji-wen

    2016-05-15

    A long-term experiment was utilized to study the effects of tillage methods on the contents and distribution characteristics of organic matter and heavy metals (Cu, Zn, Pb, Cd, Fe and Mn) in aggregates with different sizes (including 1-2, 0.25-1, 0.05-0.25 mm and tillage methods including flooded paddy field (FPF) and paddy-upland rotation (PR). The relationship between heavy metals and organic matter in soil aggregates was also analyzed. The results showed that the aggregates of two tillage methods were dominated by 0.05-0.25 mm and tillage methods did not significantly affect the contents of heavy metals in soils, but FPF could enhance the accumulation and distribution of aggregate, organic matter and heavy metals in aggregates with diameters of 1-2 mm and 0.25-1 mm. Correlation analysis found that there was a negative correlation between the contents of heavy metals and organic matter in soil aggregates, but a positive correlation between the amounts of heavy metal and organic matter accumulated in soil aggregates. From the slope of the correlation analysis equations, we could found that the sensitivities of heavy metals to the changes of soil organic matters followed the order of Mn > Zn > Pb > Cu > Fe > Cd under the same tillage. When it came to the same heavy metal, it was more sensitive in PR than in FPF.

  14. Study on Intermittent Irrigation for Paddy Rice:Ⅱ.Crop Responses

    Institute of Scientific and Technical Information of China (English)

    LUJUN; T.HIRASAWA; 等

    2001-01-01

    Effect of intermittent irrigation on the production of paddy rice was studied in a well-puddled paddy field with four treatments and 2 replicates:continuou flooding irrigation(CFI),and intermittent irrigation Ⅱ-0,Ⅱ-1 and Ⅱ-2,in which plants were re-irrigated when the soil water potential fell below 0,-10,and -20 to about -10 or -20 kPa did not significantly affect the number of grains and the percentage of ripened grains .While,a lower crop growth rate(CGR) resulted from a decrease in the net assimilation rate (NAR) during intermittent irrigation Ⅱ-1 and Ⅱ-2,and there was also a reduction in the leaf area index (LAI) durin indtermittent irrigation Ⅱ-2.Senescence of lower leaves on stems was promoted in treatments Ⅱ-1 and Ⅱ-2 at the ripening stage .Early senescence at ripening stage and water stress around midday decreased the rate of photosynthesis in leaves,causing the lower NAR,These physiological responses of the plants were responsible for the reduction in the dry matter production and grain yield in the intermmittent irrigation treatments.

  15. 10%氰氟草酯EC防除水稻直播田禾本科杂草的效果研究%Control Effect of 10% Cyhalofop-butyl on Grassy Weeds in Direct Seeding Paddy Fields

    Institute of Scientific and Technical Information of China (English)

    朱文达; 魏守辉; 张宏军; 李林; 张文君

    2011-01-01

    To provide guidance for chemical weed management in direct seeding paddy fields, two-year field trials were conducted to evaluate the control effect of 10% cyhalofop-butyl EC on grassy weeds and application safety of it. The results showed that cyhalofop-butyl had good control effects on grassy weed Echinochloa crusgalli and Leptochloa chinensis in direct seeding paddy fields, the overall control effects for grassy weeds all reached 99% when applying 80~100 g/lun2 of effective components of cyhalofop-butyl, which can reach the highest by 99%; the control effect of cyhalofop-butyl on Echinochloa crusgalli was equivalent to that of control (quinclorac); the control effect of cyhalofopbutyl on Leptochloa chinensis was significantly higher than that of control; the overall control effect of cyhalofop-butyl on grassy weeds was also significantly higher than that of control; the application of cyhalofop-butyl significantly increased the rice yield by 18.79% to 26.99%. Therefore, cyhalofop-butyl is an excellent candidate herbicide especially for controlling Leptochloa chinensis in direct seeding paddy fields.%通过2a田间试验研究了10%氰氟草酯EC对禾本科杂草的控制效果和应用安全性,为水稻直播田草害的化学防控提供依据.结果表明,氰氟草酯对水稻直播田禾本科杂草稗草和千金子具有良好的防除效果,有效成分用量80~100g/hm2对禾本科杂草的综合防效均在90%以上,最高可达99.59%.氰氟草酯对稗草的防效与对照药剂二氯喹啉酸相当,对千金子的防效显著优于二氯喹啉酸,对禾本科杂草的综合防效也显著优于二氯喹咻酸.施用氰氟草酯能显著提高水稻产量,增产幅度一般为18.79%~26.99%.氰氟草酯可作为水稻直播田防除千金子的特效药剂.

  16. The Infectious and Noninfectious Dermatological Consequences of Flooding: A Field Manual for the Responding Provider.

    Science.gov (United States)

    Bandino, Justin P; Hang, Anna; Norton, Scott A

    2015-10-01

    Meteorological data show that disastrous floods are increasingly frequent and more severe in recent years, perhaps due to climatic changes such as global warming. During and after a flood disaster, traumatic injuries, communicable diseases, chemical exposures, malnutrition, decreased access to care, and even mental health disorders dramatically increase, and many of these have dermatological manifestations. Numerous case reports document typical and atypical cutaneous infections, percutaneous trauma, immersion injuries, noninfectious contact exposures, exposure to wildlife, and exacerbation of underlying skin diseases after such disasters as the 2004 Asian tsunami, Hurricane Katrina in 2005, and the 2010 Pakistan floods. This review attempts to provide a basic field manual of sorts to providers who are engaged in care after a flooding event, with particular focus on the infectious consequences. Bacterial pathogens such as Staphylococcus and Streptococcus are still common causes of skin infections after floods, with atypical bacteria also greatly increased. Vibrio vulnificus is classically associated with exposure to saltwater or brackish water. It may present as necrotizing fasciitis with hemorrhagic bullae, and treatment consists of doxycycline or a quinolone, plus a third-generation cephalosporin and surgical debridement. Atypical mycobacterial infections typically produce indolent cutaneous infections, possibly showing sporotrichoid spread. A unique nontuberculous infection called spam has recently been identified in Satowan Pacific Islanders; combination antibiotic therapy is recommended. Aeromonas infection is typically associated with freshwater exposure and, like Vibrio infections, immunocompromised or cirrhotic patients are at highest risk for severe disease, such as necrotizing fasciitis and sepsis. Various antibiotics can be used to treat Aeromonas infections. Melioidosis is seen mainly in Southeast Asia and Australia, particularly in rice farmers, and

  17. Estimation of Global Warming Potential in the Saline-alkali Paddy Fields of Western Jilin%吉林西部盐碱水田区全球变暖潜势研究

    Institute of Scientific and Technical Information of China (English)

    汤洁; 方天儒; 赵仁竹; 梁爽

    2014-01-01

    O 略有优势,CO2所占比例恢复至95%。这主要与水稻生长期间土壤条件的变化有关,生长旺盛期,淹水层为土壤中微生物提供了良好的厌氧条件,使得 CH4贡献率增加。而成熟期水层浅,后期排水落干的条件不利于 CH4排放,N2O相比于成熟后植物呼吸作用大于光合作用产生的较多CO2来说基本属于痕量气体。研究区GWP产生总量持续增加,且增长幅度与水田面积增加趋势一致。新开发水田对温室效应的贡献很大,这与本研究区近20年来大力发展水稻种植业有直接关系。说明吉林西部盐碱水田面积大规模的开发对区域变暖做出了一定贡献。%In order to explore the western Jilin land consolidation project's contribution to regional-wide warming, based on the measured data of paddy soil greenhouse gases, the analysis of regional greenhouse gas emissions, a scientific basis for assessing the impact of paddy development on global warming had been provided. With the method of combining field sampling and region experiments, taking saline-alkali paddy field of Jilin province as an investigation object, of 0~30 cm surface soil samples of paddy were collected back to the experiments field. Pits with the size of 100 cm × 100 cm × 50 cm were digged in the field, after laying plastic sheeting at the bottom of the pits, the soil taking back from the sampling points were filled into the pits, watering, planting rice. Six plots were filled with different developed age soil, their disposal model was the same as QianGuo's local water and fertilizer management, drainage.was digged around the plots To research the greenhouse gas emission and contribution in the paddy, estimate GWP in the area, CH4, CO2 and N2O that released by soil during rice growth period were monitored by Static box - gas chromatography. combine The greenhouse gas GWP contribution was analysised combined with thirty years paddy area change. The results show

  18. Modeling of basin-wide water management for dry-season paddy irrigation with large reservoirs in the Mekong River Basin

    Science.gov (United States)

    Kudo, R.; Masumoto, T.; Horikawa, N.; Yoshida, T.

    2012-12-01

    . Irrigation and crop patterns are set as agricultural conditions in each mesh, and then irrigation water and actual evapotranspiration can be estimated according to crop stage and soil moisture. We also modeled water management of 160 reservoirs (10 large reservoirs and 150 medium reservoirs) and water allocation process of 10 large irrigated areas in the basin. The results obtained in this study are as follows: 1) The reservoir operation model reproduced water management such as impoundment of flood discharge during rainy seasons and release of irrigation water controlled by water requirement in downstream irrigation area during dry seasons. 2) The paddy water use and the water allocation models estimated water withdrawals at diversion weirs and water supply in paddy fields depending on water demands in large irrigation areas. 3) Based on the difference in water use patterns between rainy and dry seasons, the cropping model represented the actual conditions of rice planting pattern in both seasons. These results show that the interaction among the sub-models (reservoir operation, paddy water use, water allocation and so on) enables this hydrological model to represent the detailed processes of paddy water use and to evaluate the interaction between hydrological cycle and agricultural activities through anthropogenic water management for paddy irrigation.

  19. Azolla-Anabaena as a Biofertilizer for Rice Paddy Fields in the Po Valley, a Temperate Rice Area in Northern Italy

    Directory of Open Access Journals (Sweden)

    Stefano Bocchi

    2010-01-01

    Full Text Available Azolla is a floating pteridophyte, which contains as endosymbiont the nitrogen-fixing cyanobacterium Anabaena azollae (Nostocaceae family. Widely cultivated in the Asian regions, Azolla is either incorporated into the soil before rice transplanting or grown as a dual crop along with rice. To examine the feasibility of its use in flooded rice fields sited in the Temperate European Areas, we carried out a series of experiments in PVC tanks during 2000–2002 in Po Valley (northern Italy conditions, to study the growth-development dynamics and the resistance/tolerance to low temperatures and to commonly used herbicides of several different Azolla strains. Three out of five strains tested survived the winter, with an increase in biomass from March to May producing approximately 30–40 kg ha−1 of nitrogen. One of these strains, named “Milan”, emerged as the most resistant to herbicide and the most productive. Of the herbicides tested, Propanil permitted the survival of growing Azolla.

  20. HYMEX-SOPI the field campaign dedicated to heavy precipitation and flash flooding in the Northwestern Mediterranean

    OpenAIRE

    Ducrocq, V; Braud, I.; S. Davolio; Ferretti, R.; Flamant, C; Jansa, A.; Kalthoff, N.; Richard, E.; Taupier-Letage, I.; Ayral, P. A.; Belamari, S.; A. Berne; Borga, M; Boudevillain, B.; Bock, O.

    2014-01-01

    The Mediterranean region is frequently affected by heavy precipitation events associated with flash floods, landslides, and mudslides that cause hundreds of millions of euros in damages per year and, often, casualties. A major field campaign was devoted to heavy precipitation and flash floods from 5 September to 6 November 2012 within the framework of the 10-yr international Hydrological Cycle in the Mediterranean Experiment (HyMeX) dedicated to the hydrological cycle and related high-impact ...

  1. Evaluation of crop yield loss of floods based on water turbidity index with multi-temporal HJ-CCD images

    Science.gov (United States)

    Gu, Xiaohe; Xu, Peng; Wang, Lei; Wang, Xiuhui

    2015-12-01

    Paddy is one of the most important food crops in China. Due to the intensive planting in the surrounding of rivers and lakes, paddy is vulnerable to flooding stress. The research on predicting crop yield loss derived from flooding stress will help the adjustment of crop planting structure and the claims of agricultural insurance. The paper aimed to develop a method of estimating yield loss of paddy derived from flooding by multi-temporal HJ CCD images. At first, the water pixels after flooding were extracted, from which the water line (WL) of turbid water pixels was generated. Secondly, the water turbidity index (WTI) and perpendicular vegetation index (PVI) was defined and calculated. By analyzing the relation among WTI, PVI and paddy yield, the model of evaluating yield loss of flooding was developed. Based on this model, the spatial distribution of paddy yield loss derived from flooding was mapped in the study area. Results showed that the water turbidity index (WTI) could be used to monitor the sediment content of flood, which was closely related to the plant physiology and per unit area yield of paddy. The PVI was the good indicator of paddy yield with significant correlation (0.965). So the PVI could be used to estimate the per unit area yield before harvesting. The PVI and WTI had good linear relation, which could provide an effective, practical and feasible method for monitoring yield loss of waterlogged paddy.

  2. 电晕场处理三层水稻种子对其活力的影响%Effect of corona discharge field processing on vigor of three layers of paddy seeds

    Institute of Scientific and Technical Information of China (English)

    徐江; 郭守志; 贾国梁; 张宁; 宋占华; 许光虎; 张春庆; 李法德

    2015-01-01

    为提高电晕场处理水稻种子的效率,该文利用弧形芒刺电极阵列与平板电极构建了正脉冲电晕电场,研究了电晕场对铺放在平板电极上的3层水稻种子活力的影响。试验结果显示,在相同的处理时间(4 min)和电压(18、20和22 kV)条件下,脉冲电晕场对不同位置的种子有不同的影响:18 kV(root mean square, RMS)处理3层水稻种子时,上层种子的活力指标较对照有显著的提高(P<0.01或0.05),中层和下层种子较对照无明显差别;20 kV(RMS)处理3层水稻种子时,上、中、下3层种子的活力指标较对照有显著的提高(P<0.01或0.05),层与层之间不存在显著差异;22 kV(RMS)处理3层水稻种子时,除发芽势外下层种子的其余活力指标较对照有显著提高(P<0.01或0.05),上层和中层种子较对照无明显差别。并且,18 kV处理时的上层种子、20 kV处理时的所有种子和22 kV处理时的中层和下层种子的发芽数峰值较对照组均提前1 d,这与活力指标的提高是一致的。试验结果表明,利用电晕场处理多层种子以提高其活力指标是可行的,但电晕场所释放的电磁能必须在适当范围内,即利用电晕场处理种子时,电场处理条件(电场强度与处理时间)必须在优化范围内。脉冲电晕场能够提高种子活力,其机理可能是脉冲电晕场在种子内部引起的脉冲极化力使得种子内部细胞膜重新排列,但这有待于进一步研究。%In order to increase the efficiency of a corona discharge field processing aged paddy seeds, a positive pulse corona discharged field consisting of an arc-shaped prick electrode array and a plate electrode (as the grounding electrode) was developed in this research. The gap between the arc-shaped electrode array and the plate was 50 mm. After adjusted with an AC transformer and converted into the positive pulse DC voltage

  3. Impact of triazophos insecticide on paddy soil environment

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A laboratory incubation study was carried out to elucidate the dynamic response of insecticide (triazophos) on a paddy field soil health under controlled moisture (flooded soil) and temperature (25℃).The insecticide was applied at five levels that were 0.0 (control),0.5 field rate (FR),1.0 FR,5.0 FR,and 10.0 FR,where FR was 1500 ml/hm2,and the parameters were studied at 1,4,7,14,and 21days after treatments' addition.The electron transport system (ETS)/dehydrogenase activity exhibited a negative correlation with insecticide concentrations,and the activity affected adversely as the concentration increased.The higher doses of 5 and 10 field rates significantly reduced the ETS activity,while lower rates failed to produce any significant inhibiting effect against the control.The toxicity of insecticide decreased towards decreasing the ETS activity with the advancement of incubation period.The insecticide caused an improvement in the soil phenol content and it increased with increasing concentration of insecticide.The insecticide incorporation applied at various concentrations did not produce any significant change in soil protein content and it remained stable throughout the incubation period of 21 - days.The response of biomass phospholipid content was nearly similar to ETS activity.The phospholipid content was decreased with the addition of insecticide and the toxicity was in the order:10 FR (field rate) > 5 FR > 1.0 FR > 0.5 FR > control and it also decreased with incubation period.

  4. Potential effects of earthworm activity on C and N dynamics in tropical paddy soil

    Science.gov (United States)

    John, Katharina; Zaitsev, Andrey S.; Wolters, Volkmar

    2016-04-01

    Earthworms are involved in key ecosystem processes and are generally considered important for sustainable crop production. However, their provision of essential ecosystem services and contribution to tropical soil carbon and nitrogen balance in rice-based agroecosystems are not yet completely understood. We carried out two microcosm experiments to quantify the impact of a tropical earthworm Pheretima sp. from the Philippines on C and N turnover in rice paddy soils. First one was conducted to understand the modulation impact of soil water saturation level and nitrogen fertilizer input intensity on C and N cycles. The second one focused on the importance of additional organic matter (rice straw) amendment on the earthworm modulation of mineralization in non-flooded conditions. We measured CO2, CH4 (Experiments 1 and 2) and N2O evolution (Experiment 2) from rice paddy soil collected at the fields of the International Rice Research Institute (Philippines). Further we analysed changes in soil C and N content as well as nutrient loss via leaching induced by earthworms (Experiment 2). Addition of earthworms resulted in the strong increase of CH4 release under flooded conditions as well as after rice straw amendment. Compared to flooded conditions, earthworms suppressed the distinct CO2 respiration maximum at intermediate soil water saturation levels. In the first few days after the experiment establishment (Experiment 1) intensive nitrogen application resulted in the suppression of CO2 emission by earthworms at non-flooded soil conditions. However, at the longer term perspective addressed in the second experiment (30 days) earthworm activity rather increased average soil respiration under intensive fertilization or rice straw amendment. The lowest N2O release rates were revealed in the microcosms with earthworm and straw treatments. The combined effect of N fertilizer and straw addition to microcosms resulted in the increased leachate volume due to earthworm bioturbation

  5. 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

  6. Kinematics Analysis and Experimental Study on Grid Inter-row Weed Control Device for Paddy Field%栅条式水田行间除草装置运动学分析与试验研究

    Institute of Scientific and Technical Information of China (English)

    刘永军; 王金武; 陶桂香; 张春凤

    2015-01-01

    为解决化学药剂控制水田杂草所带来的环境污染及杂草抗药性增强等危害,设计了一种栅条式水田行间除草装置。同时,对其工作原理进行了阐述,通过运动学分析,推导了栅条的运动轨迹方程,并在试验台上进行试验研究。试验结果表明,该装置可一次性完成对杂草的压、翻、埋等作业,且在栅条个数为10个、栅条宽度为30 mm、除草深度为50 mm时,除草效果最佳,除草率可达81%,满足水田作业除草性能的要求。%To solve the problems of environmental pollution , increasement of weed resistance brought by heavily using herbicide to control weed for paddy field , a grid inter-row weed control device for paddy field was designed and its kine-matics was analyzed ,obtaining the kinematic trajectory equation .Grid, which made weeds pressed , turned and buried in the soil in the process of weeding , is the key part of the device , the results of test in soil bin showed that when the num-ber of grid was 10, the width of grid was 25 mm and weeding depth was 50mm, the effect of weed control was best , and weeding rate could reach 81%.

  7. Geostatistics applied to the study of the spatial distribution of Tibraca limbativentris in flooded rice fields

    Directory of Open Access Journals (Sweden)

    Juliano de Bastos Pazini

    2015-06-01

    Full Text Available Tibraca limbativentris (rice stem bug is an insect highly injurious to the rice crop in Brazil. The aim of this research was to define the spatial distribution of the T. limbativentris and improve the sampling process by means of geostatistical application techniques and construction of prediction maps in a flooded rice field located in the "Planalto da Campanha" Region, Rio Grande do Sul (RS, Brazil. The experiments were conducted in rice crop in the municipality of Itaqui - RS, in the crop years of 2009/10, 2010/11 and 2011/12, counting fortnightly the number of nymphs and adults in a georeferenced grid with points spaced at 50m in the first year and in 10m in the another years. It was performed a geostatistical analysis by means adjusting semivariogram and interpolation of numeric data by kriging to verify the spatial dependence and the subsequent mapping population. The results obtained indicated that the rice stem bug, T. limbativentris, has a strong spatial dependence. The prediction maps allow estimating population density of the pest and visualization of the spatial distribution in flooded rice fields, enabling the improvement of the traditional method of sampling for rice stem bug

  8. Field, experimental and numerical model developments in outburst flood understanding and opportunities for future work

    Science.gov (United States)

    Carrivick, Jonathan

    2015-04-01

    Local-scale risks to society from a rapidly changing cryosphere include a range of mass flows and floods. Most of these slides, slumps, falls and flow events have been attributed to climatically-induced permafrost degradation, to glaciological mass loss and consequent meltwater production and sudden drainage of glacier lakes, or to volcano-ice interactions. This presentation will firstly overview outburst flood research and knowledge to date and it will do this from a field, experimental and numerical modeling perspective. Fieldwork examples from around the world and including Iceland, New Zealand, Greenland, and the European Alps will be argued to underpin all understanding but to be severely limited in spatiotemporal coverage. Laboratory experiments will be argued to be overly generalised and narrowly-focussed. Numerical models will be argued to be omitting or over-generalising major processes; particularly sediment transport and morphodynamics. This presentation will then look forwards, by placing an emphasis on several recent and major technological advances that should be enabling much improved monitoring and measurement in both the field and the laboratory. The opportunity for new numerical modelling approaches will be discussed from two viewpoints; that of the researcher interested in process mechanisms, and that of the natural hazard manager wishing for real-time information.

  9. Floods and Flash Flooding

    Science.gov (United States)

    Floods and flash flooding Now is the time to determine your area’s flood risk. If you are not sure whether you ... If you are in a floodplain, consider buying flood insurance. Do not drive around barricades. If your ...

  10. Distribution characteristics of soil profile nitrous oxide concentration in paddy fields with different rice-upland crop rotation systems%不同水旱轮作体系稻田土壤剖面N2O的分布特征

    Institute of Scientific and Technical Information of China (English)

    刘平丽; 张啸林; 熊正琴; 黄太庆; 丁敏; 王金阳

    2011-01-01

    To investigate the dynamic distribution patterns of nitrous oxide (N2O) in the soil pro-files in paddy fields with different rice-upland crop rotation systems, a special soil gas collection de-vice was adopted to monitor the dynamics of N2O at the soil depths 7, 15, 30, and 50 cm in the paddy fields under both flooding and drainage conditions. Two rotation systems were installed, i. e. , wheat-single rice and oilseed rape-double rice, each with or without nitrogen (N) applica-tion. Comparing with the control, N application promoted the N2O production in the soil profiles significantly (P<0.01) , and there existed significant correlations in the N2O concentration among the four soil depths during the whole observation period (P<0.01). In the growth seasons of winter wheat and oilseed rape under drainage condition and with or without N application, the N2O con-centrations at the soil depths 30 cm and 50 cm were significantly higher than those at the soil depths 7 cm and 15 cm; whereas in the early rice growth season under flooding condition and without N ap-plication, the N2O concentrations at the soil depth 7 cm and 15 cm were significantly higher than those at the soil depths 30 cm and 50 cm (P<0.05). No significant differences were observed in the N2O concentrations at the test soil depths among the other rice cropping treatments. The soil N2 0 concentrations in the treatments without N application peaked in the transitional period from the upland crops cropping to rice planting, while those in the treatments with N application peaked right after the second topdressing N of upland crops. Relatively high soil N2O concentrations were ob-served at the transitional period from the upland crops cropping to rice planting.%通过原位采集淹水和排水状态下土壤剖面4个层次的气体,研究氧化亚氮(N2O)在水旱轮作体系稻田土壤剖面中的动态分布特征.试验设置小麦-单季稻和油菜-双季稻两种轮作体系,包括施N和不施N两

  11. Characterization and risk assessment of polychlorinated biphenyls in soils and rice tissues in a suburban paddy field of the Pearl River Delta, South China.

    Science.gov (United States)

    Li, Qilu; Wang, Yan; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-08-01

    We investigated the concentration and composition of polychlorinated biphenyls (PCBs) in paddy soils and rice tissues and the associated potential health risks in the urban agricultural areas of the Pearl River Delta (PRD), South China. The results indicated that highly chlorinated PCBs were more prominent in soil when the concentrations of low-molecular-weight PCBs were relatively high in rice plants. There was a trend of decreasing PCB concentrations with soil depth and a significant correlation between PCBs and the total organic carbon or total nitrogen concentration in section soils. The PCB concentrations followed the order of root > leaf > stem > grain. Although the dioxin toxicity equivalency values and estimated daily intake levels (based direct and indirect consumption) were lower than in other seriously contaminated regions, there is still a need to monitor PCB pollution in urban agriculture because of the PCB emissions from capacitor storage following the rapid urbanization experienced in the PRD.

  12. An in-house protocol for improved flood field calibration of TrueBeam FFF cine imaging.

    Science.gov (United States)

    Faught, Austin M; Yin, Fang-Fang; Adamson, Justus

    2017-01-01

    TrueBeams equipped with the 40 × 30 cm(2) Electronic Portal Imaging Devices (EPIDs) are prone to image saturation at the image center when used with flattening filter free (FFF) photon energies. While cine imaging during treatment may not saturate because the beam is attenuated by the patient, the flood field calibration is affected when the standard calibration procedure is followed. Here, we describe the hardware and protocol to achieve improved image quality for this model of TrueBeam EPID. A stainless steel filter of uniform thickness was designed to have sufficient attenuation to avoid panel saturation. The cine imaging flood field calibration was acquired with the filter in place for the FFF energies under the standard calibration geometry (SID = 150 cm). Image quality during MV cine was assessed with & without the modified flood field calibration using a low contrast resolution phantom and an anthropomorphic phantom. When the flood field is acquired without the filter in place, a pixel gain artifact is clearly present in the image center which may be mis-attributed to panel saturation in the subject image. At the image center, the artifact obscured all low contrast inserts and was also visible on the anthropomorphic phantom. Using the filter for flood field calibration eliminates the artifact. TrueBeams equipped with the 40 × 30 cm(2) IDU can utilize a modified flood field calibration procedure for FFF photon energies that improves image quality for cine MV imaging. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  13. Emission of Greenhouse Gases from Paddy Fields of Rice-wheat Rotation System in Chongming Island, China%崇明岛稻麦轮作系统稻田温室气体排放研究

    Institute of Scientific and Technical Information of China (English)

    侯玉兰; 王军; 陈振楼; 王东启; 许世远

    2012-01-01

    During rice growth season and the fallow period(from June 2011 to November 2011 ), static chamber technique was used to investigate the emission and consumption of CO2, CH4 and N2O at paddy field in Chongming Island, and the greenhouse effect of there three gases were assessed using global warming potentials(GWPs). Results showed that the fluxes of greenhouse gases had obvious difference in different period of rice growth. Except ripening stage, paddy fields were sources of CH4 emission through the whole study period, and the peak appeared at tillering stage. Rice field was the sink of atmospheric N2O in seedling stage, but changed into the sources in other stages and the peak of N2O emission was observed at elongation stage. According to the analysis of the greenhouse effect, CH4 and N2O were the major greenhouse gases from rice fields. The GWPs of CH4 and N2O was 3.255×l03 kgCO2·hm‐2. The whole rice field acted as a sink of atmospheric CO2 due to photosynthesis(2.462×l03 kgCO2·hm‐2). Total GWPs of there three greenhouse gases from rice fields in Chongming Island was 793 kgC02·hm‐2. Paddy field in Chongming Island is a solid source of greenhouse gases.%通过静态箱-气相色谱法,研究了崇明岛稻麦轮作地水稻生长季及收割后休耕期(2011年6月至2011年11月)温室气体CO2、CH4和N2O的排放、吸收规律及交换量,并运用增温潜势进行了温室效应估算.3种温室气体通量在水稻不同生长阶段有明显差异:稻田除成熟收割期外,其他期均表现为CH4排放源,并在分蘖期达到最大值;N2O除幼苗期表现为汇,其他期均为排放源,并在拔节期达到最大值.温室效应分析得出:水稻田温室气体以CH4和N2O排放为主,二者对全球温室效应的贡献为3.255×103kgCO2·hm-2;由于光合作用,稻田表现为对CO2固定,固定量为2.462× 103kgCO2· hm-2;崇明水稻生长季排放温室气体综合GWP值为793 kgCO2·hm-2,为温室气体排放源.

  14. 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.

  15. Speciation and release kinetics of zinc in contaminated paddy soils.

    Science.gov (United States)

    Khaokaew, Saengdao; Landrot, Gautier; Chaney, Rufus L; Pandya, Kaumudi; Sparks, Donald L

    2012-04-03

    Zinc is an important nutrient for plants, but it can be toxic at high concentrations. The solubility and speciation of Zn is controlled by many factors, especially soil pH and Eh, which can vary in lowland rice culture. This study determined Zn speciation and release kinetics in Cd-Zn cocontaminated alkaline and acidified paddy soils, under various flooding periods and draining conditions, by employing synchrotron-based techniques and a stirred-flow kinetic method. Results showed almost no change in Zn speciation and release kinetics in the two soils, although the soils were subjected to different flooding periods and draining conditions. The mineral phases in which Zn is immobilized in the soil samples were constrained by linear least squares fitting (LLSF) analyses of bulk X-ray absorption fine structure (XAFS) spectra. Only two main phases were identified by LLSF, i.e., Zn-layered double hydroxides (Zn/Mg-hydrotalcite-like, and ZnAl-LDH) and Zn-phyllosilicates (Zn-kerolite). Under all soil pHs, flooding, and draining conditions, less than 22% of Zn was desorbed from the soil after a two-hour desorption experiment. The information on Zn chemistry obtained in this study will be useful in finding the best strategy to control Cd and Zn bioavailability in the Cd-Zn cocontaminated paddy soils.

  16. On-site field test on groundwater re-flooding (2)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-02-01

    A mini-dome (an underground structure to be closed; ground level: - 50 m to - 82.5 m) situated on a diluvium along the Sagami River, Kanagawa prefecture, Japan, was used to perform an on-site field tests on groundwater re-flooding for 11 months after the mini-dome was filled up with sand, mortar, and fluidized soil consisting of cement and mudwater. The present report includes monitoring data of the environmental groundwater at the surrounding bed rocks and of the groundwater in the deep mudstone beneath the site. Change with time at various test points in water pressure, water temperature, pH, electric conductivity, and the temperature of the wall of the structure making the mini-dome is reported. Furthermore, some isotopic abundance and the monitoring results on chemical analysis were also included. (S. Ohno)

  17. Field evidence for the potential of Rhodobacter capsulatus as Biofertilizer for flooded rice.

    Science.gov (United States)

    Gamal-Eldin, Hosny; Elbanna, Khaled

    2011-02-01

    In a previous study, we evaluated the effects of inoculating rice plants with the phototrophic purple nonsulfur bacterium Rhodobacter capsulatus (Rc) on growth and yield of rice in pots and lysimeter experiments and the results obtained have been highly encouraging. In this study, we carried out two field experiments: one in the experimental farm of the Faculty of Agriculture, Fayoum University, and the second in a farmer's field in Kafr El-sheikh, to assess the effects of Rc on growth and yield of rice in comparison and in combination with chemical nitrogen fertilizer (CNF) and farmyard manure. The results indicated that both biological and grain yields in all the Rc inoculated treatments were significantly higher than those in the uninoculated corresponding treatments in both fields. With regard to grain yield, the major factor for determining the effectiveness of any agricultural treatment, inoculation with Rc in combination with 50% of the recommended CNF rate gave a grain yield that was statistically equivalent to that obtained with 100% of the recommended CNF rate. These results provide a clear evidence for the potential of Rc as biofertilizer for flooded rice under field conditions.

  18. Flooding and Flood Management

    Science.gov (United States)

    Brooks, K.N.; Fallon, J.D.; Lorenz, D.L.; Stark, J.R.; Menard, Jason; Easter, K.W.; Perry, Jim

    2011-01-01

    Floods result in great human disasters globally and nationally, causing an average of $4 billion of damages each year in the United States. Minnesota has its share of floods and flood damages, and the state has awarded nearly $278 million to local units of government for flood mitigation projects through its Flood Hazard Mitigation Grant Program. Since 1995, flood mitigation in the Red River Valley has exceeded $146 million. Considerable local and state funding has been provided to manage and mitigate problems of excess stormwater in urban areas, flooding of farmlands, and flood damages at road crossings. The cumulative costs involved with floods and flood mitigation in Minnesota are not known precisely, but it is safe to conclude that flood mitigation is a costly business. This chapter begins with a description of floods in Minneosta to provide examples and contrasts across the state. Background material is presented to provide a basic understanding of floods and flood processes, predication, and management and mitigation. Methods of analyzing and characterizing floods are presented because they affect how we respond to flooding and can influence relevant practices. The understanding and perceptions of floods and flooding commonly differ among those who work in flood forecasting, flood protection, or water resource mamnagement and citizens and businesses affected by floods. These differences can become magnified following a major flood, pointing to the need for better understanding of flooding as well as common language to describe flood risks and the uncertainty associated with determining such risks. Expectations of accurate and timely flood forecasts and our ability to control floods do not always match reality. Striving for clarity is important in formulating policies that can help avoid recurring flood damages and costs.

  19. One millimetre makes the difference: high-resolution analysis of methane-oxidizing bacteria and their specific activity at the oxic-anoxic interface in a flooded paddy soil.

    Science.gov (United States)

    Reim, Andreas; Lüke, Claudia; Krause, Sascha; Pratscher, Jennifer; Frenzel, Peter

    2012-11-01

    Aerobic methane-oxidizing bacteria (MOB) use a restricted substrate range, yet >30 species-equivalent operational taxonomical units (OTUs) are found in one paddy soil. How these OTUs physically share their microhabitat is unknown. Here we highly resolved the vertical distribution of MOB and their activity. Using microcosms and cryosectioning, we sub-sampled the top 3-mm of a water-saturated soil at near in situ conditions in 100-μm steps. We assessed the community structure and activity using the particulate methane monooxygenase gene pmoA as a functional and phylogenetic marker by terminal restriction fragment length polymorphism (t-RFLP), a pmoA-specific diagnostic microarray, and cloning and sequencing. pmoA genes and transcripts were quantified using competitive reverse transcriptase PCR combined with t-RFLP. Only a subset of the methanotroph community was active. Oxygen microprofiles showed that 89% of total respiration was confined to a 0.67-mm-thick zone immediately above the oxic-anoxic interface, most probably driven by methane oxidation. In this zone, a Methylobacter-affiliated OTU was highly active with up to 18 pmoA transcripts per cell and seemed to be adapted to oxygen and methane concentrations in the micromolar range. Analysis of transcripts with a pmoA-specific microarray found a Methylosarcina-affiliated OTU associated with the surface zone. High oxygen but only nanomolar methane concentrations at the surface suggested an adaptation of this OTU to oligotrophic conditions. No transcripts of type II methanotrophs (Methylosinus, Methylocystis) were found, which indicated that this group was represented by resting stages only. Hence, different OTUs within a single guild shared the same microenvironment and exploited different niches.

  20. Value of Ecosystem Services in Conventional and Organic Rice Paddies: A Case Study in Wannian,Jiangxi,China

    Institute of Scientific and Technical Information of China (English)

    Zhang Dan; Min Qingwen; He Lu; Cheng Shengkui; Fang Jianmin

    2010-01-01

    In the current study,the ecosystem services(ES)of conventional and organic rice paddies in Wannian,Jiangxi Province,China are investigated.First,the ES at the field level under organic and conventional paddies were investigated.Total economic value of ES in organic rice paddies was 30093.08yuan RMB/ha per year and that of conventional rice paddies was22 793.31 yuan RMB/ha per year.The total indirect value of ES was 14 813.7 yuan RMB/ha per year in organic rice paddies and12 424.56 yuan RMB/ha per year in conventional ones.There were significant differences between organic and conventional rice paddies for the economic values.Then,this economic information was used to extrapolate and to calculate the total and indirect value of ES from rice paddies in Wangnian.The total and indirect economic values of ES from conventional rice paddies in Wannian were6791 million and 3702 million yuan RMB per year respectively,and the total and indirect economic values of ES from organic rice paddies in Wannian were 1311 million and 646 million yuan RMB per year.If half the area had being converted to organic farming in Wannian,the total and indirect economic values of ES from conventional rice paddies were 3397 million and 1851 million yuan RMB per year,and the total and indirect economic values of ES from organic rice paddies were 5794 million and 2852 million yuan RMB per year.Finally,the total economic value of ES in rice paddies in Wannian was demonstrated through geographic information system techniques.

  1. 仿生非光滑水田犁壁的设计及田间应用试验%Design and Applying Experiments of the Bionic Non-smooth Plow Moldboard for Paddy Field

    Institute of Scientific and Technical Information of China (English)

    金俊; 李建桥; 张广权; 李英日; 朴明哲; 黄晗

    2015-01-01

    Soil adhesion which exists between soil and plow moldboard in the field work of paddy field plough , not only increases the working resistance and energy consumption of these machines , but also decreases the quality of work and the productivity .It was found that the non-smooth surfaces of the typical soil animal-dung beetle had the characteristics of anti-adhesion , anti-resistance and desorption by lots of tests and observations .Based on these researchers , bionic non-smooth plow moldboards were developed .In this paper , we analyzed the plowing resistance impact of dimention and distribution of bionic non-smooth structural units , then optimized parameters ( dimention and distribution ) , developed bionic non-smooth paddy field plow moldboard that had better properties of anti-adhesion and anti-resistance .The plo-wing resistances , oil consumption and plowing productivity of bionic plow and common plow were tested in paddy field . The results showed that, compared with common smooth plough, the bionic plow moldboard could reduce plowing resistance to 15.9%~18.0%, could save the fuel consumption to 11.9%, and could raise the plowing productivity to 20 .5%.Meanwhile , the bionic non-smooth plow , not only with the advantages of soil-turning , but also has highly effi-ciency of clod crushing and has a good application prospect .%水田犁田间作业时土壤对犁壁的严重粘附,将导致犁耕阻力增加、油耗增大、耕作质量和生产效率降低。经过大量的试验研究,已发现典型土壤动物蜣螂体表的减粘降阻和脱附效应,并据此开发了仿生犁壁。在前期研究基础上,考察仿生非光滑水田犁壁面上几何非光滑结构单元的尺寸和分布对犁耕阻力的影响,进行了设计参数优化,研制出具有减粘降阻性能的仿生非光滑水田犁壁。田间对比测试表明:仿生非光滑水田犁壁与普通光滑水田犁壁相比,降低犁耕阻力15.9%~18.0

  2. Effects of NBPT urease inhibitor on ammonia volatilization in paddy fields with wheat straw application%添加脲酶抑制剂NBPT对麦秆还田稻田氨挥发的影响

    Institute of Scientific and Technical Information of China (English)

    彭玉净; 田玉华; 尹斌

    2012-01-01

    While ammonia volatilization is the main mode of nitrogen loss in paddy fields,urease inhibitors are known to effectively inhibit urease activity,delay urea hydrolysis and reduce ammonia emission.Urease inhibitors have,however,not been widely applied in paddy fields.In this study,the effects of NBPT urease inhibitor on the dynamic changes in urea hydrolysis and ammonia volatilization in wheat-straw incorporated gley paddy soils in Taihu Lake region were investigated via the dynamic chamber method.Results showed that ammonia volatilization mainly occurred during basal and tillering fertilization periods.While the highest ammonia volatilization was at basal fertilization stage,the lowest was at booting fertilization stage.Ammonia volatilization mainly occurred within three days after fertilization.Applying NBPT one day before fertilization significantly retarded urea hydrolysis,delayed occurring time and decreased value of NH+-N peak and reduced rate and amount of ammonia volatilization of surface water.After basal and tillering fertilization,urea hydrolysis ended within 2~3 days after fertilization,NH4+-N and ammonia volatilization peaks occurred on the second day under non-NBPT treatment.Peak values of NH/-N of basal and tillering fertilization were 132.3 mg·L-1 and 66.3 mg·L-1,respectively.Also ammonia volatilization peak values were 15.6 kg·hm-2·d-1 and 10.4 kg·hm-2·d-1,respectively.Under NBPT treatment,however,the peak of NH/-N occurred 4 days after fertilization after which it dropped to 70.7 mg·L--1 and then to 51.6 mg-L-1.After 4 days of fertilization,ammonia volatilization peak dropped to 4.7 kg·hm-2·d-1 and then to 2.6 kg-hm-2·d-1.Total ammonia volatilization dropped from 73.3 kg(N)hm-2 (24.4% of applied N) to 34.5 kg(N)-hm-2 (11.5% of applied N) after NBPT application,a drop of 53%.NBPT application in wheat-straw incorporated paddy fields significantly reduced ammo-nia volatilization by delaying urea hydrolysis.It was recommended that NBPT

  3. 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.

  4. 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.

  5. Tracing remobilization of nutrients and toxic elements after application of rice straw or derived ash / biochar in paddy soils

    Science.gov (United States)

    Schaller, Jörg; Wang, Jiajia; Planer-Friedrich, Britta

    2017-04-01

    More than 600 million tons of rice straw are produced each year as byproduct of rice grain production. As an increasing application, besides e.g. composting or fodder for animals, the straw remains on the field for decomposition and nutrient supply. A central concern during rice cultivation is accumulation of arsenic, but it is currently unclear how the application of rice straw or derived ash or biochar to paddy soils will influence arsenic uptake by the next generation of rice plants. Consequently, we assessed the element mobilization via soil microcosm incubations with straw or derived ash or biochar or without those amendments under flooding (40 days) and subsequent drainage (14 days). We focused on elements potentially influencing the uptake of arsenic by the next generation of rice plants (e.g. silicon, phosphorus, iron), or which are nutrients but toxic themselves at higher levels (sulfur, sulfide, iron, iron(II), manganese, copper, and zinc). We found significant differences in the release of arsenic, iron(II), sulfide, total sulfur, DOC, manganese, copper, and zinc . For example highest pore water Mn and As concentrations were found for soil amended with straw, whereas the straw amendment reduced S mobilization, possibly due to sulfate reduction by straw decomposing microbes. For P, we found highest pore water concentrations for straw, followed by biochar, ash and control. In summary, application of rice straw or derived ash or biochar strongly affect the element availability in paddy soil.

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

    OpenAIRE

    Deepmala Satpathy; M. Vikram Reddy; Soumya Prakash Dhal

    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...

  7. Field Demonstration of Carbon Dioxide Miscible Flooding in the Lansing-Kansas City Formation, Central Kansas

    Energy Technology Data Exchange (ETDEWEB)

    Alan Byrnes; G. Paul Willhite; Don Green; Richard Pancake; JyunSyung Tsau; W. Lynn Watney; John Doveton; Willard Guy; Rodney Reynolds; Dave Murfin; James Daniels; Russell Martin; William Flanders; Dave Vander Griend; Eric Mork; Paul Cantrell

    2010-03-07

    A pilot carbon dioxide miscible flood was initiated in the Lansing Kansas City C formation in the Hall Gurney Field, Russell County, Kansas. The reservoir zone is an oomoldic carbonate located at a depth of about 2900 feet. The pilot consists of one carbon dioxide injection well and three production wells. Continuous carbon dioxide injection began on December 2, 2003. By the end of June 2005, 16.19 MM lb of carbon dioxide was injected into the pilot area. Injection was converted to water on June 21, 2005 to reduce operating costs to a breakeven level with the expectation that sufficient carbon dioxide was injected to displace the oil bank to the production wells by water injection. By March 7,2010, 8,736 bbl of oil were produced from the pilot. Production from wells to the northwest of the pilot region indicates that oil displaced from carbon dioxide injection was produced from Colliver A7, Colliver A3, Colliver A14 and Graham A4 located on adjacent leases. About 19,166 bbl of incremental oil were estimated to have been produced from these wells as of March 7, 2010. There is evidence of a directional permeability trend toward the NW through the pilot region. The majority of the injected carbon dioxide remains in the pilot region, which has been maintained at a pressure at or above the minimum miscibility pressure. Estimated oil recovery attributed to the CO2 flood is 27,902 bbl which is equivalent to a gross CO2 utilization of 4.8 MCF/bbl. The pilot project is not economic.

  8. Effects of 10 % Metamifop WP on Gramineous Weeds Control in Direct Seeding Paddy Field%(口恶)唑酰草胺WP对水稻直播田禾本科杂草的防效

    Institute of Scientific and Technical Information of China (English)

    朱文达; 何燕红; 李林

    2011-01-01

    为明确10%(口恶)唑酰草胺WP在湖北省水稻直播田的应用前景,建立水稻直播田的杂草管理体系,研究了其对水稻直播田稗草和千金子的防除效果,并研究了杂草防除对杂草养分含量变化和水稻增产效果的影响.结果表明,施用10%(口恶)唑酰草胺WP对直播稻田中杂草的防除效果显著,对稗草、千金子的综合密度防除效果和综合鲜重防除效果分别保持在91.79%~99.44%和96.42% ~99.90%,极显著优于人工除草的防除效果.施用10%(口恶)唑酰草胺WP防除田间杂草,降低了杂草对田间养分的吸收,从而显著提高了水稻的产量,增产效果显著.%The weed control effects for Echinochloa crusgalli and Leptochloa chinensis ,the influence on the change of weed nutrient content and rice yield potential were studied to evaluate the application prospect of 10% metamifop WP and establish a weed management system in direct seeding paddy field in Hubei province. The results showed that 10% metamifop WP presented superior effects for weed control compared with the manual control. Overall quantity control effect for Echinochloa crusgalli and Leptochloa chinensis was from 91. 79% to 99. 44% and the overall fresh control effect was from 96.42% to 99.90%. Application of 10% metamifop WP in direct seeding paddy field significantly reduced the weeds absorption of nutrition resulting in a significant yield enhancing.

  9. Mapping paddy fields of Dongting Lake area by fusing Landsat and MODIS data%基于多时相Landsat数据融合的洞庭湖区水稻面积提取

    Institute of Scientific and Technical Information of China (English)

    张猛; 曾永年

    2015-01-01

    洞庭湖区作为中国重要的商品粮基地,水稻种植面积的变化对国家粮食安全有重要的影响,准确获取水稻面积及其变化显得十分重要。为解决数据缺失问题,该文利用STARFM(spatial and temporal adaptive reflectance fusion model)模型融合高时间分辨率的MODIS数据与中等空间分辨率的Landsat数据,得到时序Landsat NDVI数据,并利用时序Landsat NDVI数据对水稻种植面积进行提取。结果显示,该方法能够有效地提取水稻种植面积,总体分类精度94.52%, Kappa系数为0.9128。水稻分布几乎覆盖整个研究区,水稻种植总面积达7.88×105hm2。双季稻种植面积为7.75×105hm2,主要集中于湖区北部及西北部,且分布较连续。一季稻种植面积为1.3×104hm2,分布相对零散,有小范围集中于湖区中部及西北部。%The Dongting Lake area is one of the important commodity grain bases in the middle and lower reaches of Yangtze River, China, so we selected the Dongting Lake area as an example to extract the paddy area using Landsat data. But it was hard to get the time series Landsat data of the study area due to the rainy weather and return cycle of the satellite. In order to solve the problem of data missing in mapping paddy fields, we used STARFM (spatial and temporal adaptive reflectance fusion model) algorithm to blend MODIS and Landsat data, and got the high-frequency temporal information from MODIS and high-resolution spatial information from Landsat. Then the Savitzky-Golay(S-G), Gaussian and Double logistic filter were used to smooth the time series Landsat NDVI (normalized difference vegetation index) data. Through the comparative analysis, we found that the overall fidelity of Savitzky-Golay was the best. On one hand, the correlation coefficient between original NDVI value and fitting value was higher than the other 2 methods which were used to smooth the time series Landsat NDVI data. On the other hand

  10. Fertilization increases paddy soil organic carbon density

    Institute of Scientific and Technical Information of China (English)

    Shao-xian WANG; Xiao-jun LI; Xin-qiang LIANG; Qi-xiang LUO; Fang FAN; Ying-xu CHEN; Zu-zhang LI; Huo-xi SUN; Tian-fang DAI; Jun-nan WAN

    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.

  11. 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.

  12. Composition of Humus and Structure of Humic Acid as a Function of Age of Paddy Field%开垦年限对稻田土壤腐殖质组成和胡敏酸结构特征的影响

    Institute of Scientific and Technical Information of China (English)

    刘鑫; 窦森; 李长龙; 王培宇

    2016-01-01

    Relative to dry land,paddy field originally referred to artificially irrigated fields,where either paddy rice or upland crops were planted. Now only the field where paddy rice or some other aquatic plants are planted is called paddy field,or rice field. Different from the orginal paddy field,it has ridges to store water. In South China,paddy fields are not only long in cultivation history but also be vast in area and studies on such paddy fields started quite earlier and are great in volume both at home and abroad,but only a few has been reported on paddy soil in North China. Rice is the main grain crop in China. A large proportion of the total grain output in this country comes from Northeast China,where the paddy fields reach over 66.7 billion hm2(including 53.3 billion hm2 in Heilongjiang,and 6.6 billion hm2 each in Jilin and Liaoning) and occupy an important position in the rice cultivation area of the country. However,the rice fields are mostly short in cultivation history and most of the paddy fields were turned from upland fields,and what's more,some of the paddy fields were turned back into upland fields again due to incomplete water conservancy facilities. During this kind of irregular changes,the soils in the fields would certain change in carbon fixation capacity,soil fertility and CO2 emission. But little has been done at home and abroad on how they evolve. Therefore,the study on paddy soils in Northeast China is of great significance. Rice yield depends mainly on soil fertility,of which soil organic matter is an important component. Soil humus,being an important component of the soil solid phase material,plays a huge role in the genesis and development of soil fertility, and hence is also an important indicator for soil fertility. It does not only influence productivity of the farmland ecosystem,but also have a great impact on CO2 concentration in the atmosphere through decomposition of soil organic matter. The study on how soil organic matter in the

  13. Fly ash application in nutrient poor agriculture soils: impact on methanotrophs population dynamics and paddy yields.

    Science.gov (United States)

    Singh, Jay Shankar; Pandey, Vimal Chandra

    2013-03-01

    There are reports that the application of fly ash, compost and press mud or a combination thereof, improves plant growth, soil microbial communities etc. Also, fly ash in combination with farmyard manure or other organic amendments improves soil physico-chemical characteristics, rice yield and microbial processes in paddy fields. However, the knowledge about the impact of fly ash inputs alone or in combination with other organic amendments on soil methanotrophs number in paddy soils is almost lacking. We hypothesized that fly ash application at lower doses in paddy agriculture soil could be a potential amendment to elevate the paddy yields and methanotrophs number. Here we demonstrate the impact of fly ash and press mud inputs on number of methanotrophs, antioxidants, antioxidative enzymatic activities and paddy yields at agriculture farm. The impact of amendments was significant for methanotrophs number, heavy metal concentration, antioxidant contents, antioxidant enzymatic activities and paddy yields. A negative correlation was existed between higher doses of fly ash-treatments and methanotrophs number (R(2)=0.833). The content of antioxidants and enzymatic activities in leaves of higher doses fly ash-treated rice plants increased in response to stresses due to heavy metal toxicity, which was negatively correlated with rice grain yield (R(2)=0.944) and paddy straw yield (R(2)=0.934). A positive correlation was noted between heavy metals concentrations and different antioxidant and enzymatic activities across different fly ash treated plots.The data of this study indicate that heavy metal toxicity of fly ash may cause oxidative stress in the paddy crop and the antioxidants and related enzymes could play a defensive role against phytotoxic damages. We concluded that fly ash at lower doses with press mud seems to offer the potential amendments to improving soil methanotrophs population and paddy crop yields for the nutrient poor agriculture soils.

  14. Immobilization of Cd in a paddy soil using moisture management and amendment.

    Science.gov (United States)

    Li, Jianrui; Xu, Yingming

    2015-03-01

    To offer basis for remediation of Cd-polluted paddy soil under reasonable water condition, pot experiment was conducted to study the effects of moisture management and amendment on the immobilization of Cd in paddy soil. Application of sepiolite in combination with phosphate fertilizer reduced exchangeable Cd by 18.2%, 13.7% and 12.5%, brown rice Cd by 52.3%, 46.0% and 46.8%, under continuous flooding, conventional irrigation and wetting irrigation, respectively, compared to the control groups. Under no amendments, the content of Fe(II) in root coating in the continuous flooding treatment was 2.3 and 3.6 times of that in the conventional and wetting irrigation treatments, but Cd content in root coating in the continuous flooding treatment was only 82.6% and 73.8% of that in the conventional and wetting irrigation treatments. Amendments application increased Fe(II) in root coating by 40.1%, 70.2% and 78.0%, but reduced the Cd content in root coating by 35.3%, 42.4% and 38.6% under continuous flooding, conventional irrigation and wetting irrigation, respectively. The lower availability of Cd in soil and the competition for adsorption sites in root coating of rice plant between Cd(2+) and Fe(2+) etc. reduced form bivalent ions in paddy soil resulted in lower Cd concentrations in brown rice in amended soil treatments.

  15. Simulation and measurement of leaf wetness formation in paddy rice crops

    OpenAIRE

    Luo, W.

    1996-01-01


    The study described in this thesis focuses on a quantification of leaf wetness formation in paddy rice crops based on insight in the physical processes of the formation of leaf wetness. For this purpose, experimental research was conducted in a tropical paddy rice field.

    A shielding (nocturnal net radiative loss) experiment was designed to investigate the dependence of dew formation on nocturnal net radiative loss. A simple method was developed to estimate dew amount and du...

  16. Optimization design of laser receiver amplification circuit of laser leveler for paddy field%水田激光平地机激光接收放大电路的优化设计

    Institute of Scientific and Technical Information of China (English)

    可欣荣; 罗锡文

    2014-01-01

    为解决水田激光平地机平地铲高程定位稳定性问题,该文采用试验方法研究了激光接收器的光电转换特征,对光电转换电路和放大电路参数进行了优化设计。并对影响激光接收器光电转换信号幅值的接收距离、太阳辐照度噪声、振动噪声与有效激光信号幅值频率等因素开展了相关性试验。试验结果表明,随着激光接收距离增加,接收到激光能量减小,激光光电转换信号幅值随接收距离增加按负指数衰减;随着阳光辐照度增加,光电转换硅光电池背景电流增加,光电转换效率降低,激光光电转换信号幅值按负指数衰减,而光电转换噪声按指数规律显著增加;机械振动噪声频率相对固定在低频段。在试验分析基础上,该文采用硅光电池内部等效电容和外接电感的直接光电转换电路,将激光脉冲电流信号调制为交流电压信号,优化带通放大电路参数,降低放大电路带宽对阳光辐照噪声和振动噪声的衰减,以提高激光接收器放大电路的信噪比。进一步田间试验表明,当采用定制的福田KF308发射器旋转频率为600 r/min,设计优化后的激光接收器可满足水田激光平地机的高程可靠定位检测要求。%Because of its high efficiency and leveling precision, the laser leveler for paddy fields has received widespread attention in the mechanization of rice planting. The laser receiver is the elevation sensor component of a laser leveler for paddy fields, and the effective distances of the laser leveler for paddy fields are mainly decided by the noise-rejection performance of the photoelectric conversion and amplifier circuit. In extension work, due to strong solar irradiance and vibration the laser receiver may output wrong height position information, reducing leveling precision and work efficiency. In order to improve the reliability of elevation measurements, the

  17. Paddy Rice Identification by Blending Time-series SAR and Optical Data

    Science.gov (United States)

    Oyoshi, K.; Sobue, S.

    2014-12-01

    In Asia, rice is a staple cereal crop and Asian countries are responsible for approximately 90% of the world rice production and consumption. Asian space and agriculture related agencies launched an Asia-Rice Crop Estimation & Monitoring (Asia-RiCE) component for the GEOGLAM initiative. However, there are some difficulties to monitor rice crop by satellite imagery, which is different from other crops: 1) rice is mainly cultivated in rainy season and a large amount of cloud cover limits rice crop monitoring by the optical sensors; 2) adequate rainfall and temperature enable to cultivate rice two or three times a year in the tropics; 3) each field size is small compared to croplands in Western countries; and 4) water related agricultural disasters such as flood and drought are frequently occurred. To overcome these issues, C-band backscattering coefficient from RADARSAT-2 and reflectance data from MODIS were blended to estimate rice planted area over the West Java, Indonesia. By blending SAR and optical data, roughness and spectral information can be effectively used to differentiate paddy rice from other landcovers. The methodology using multi-wavelength data including optical (visible to thermal infrared) and SAR (X/C/L) would be a promising way for monitoring paddy rice in terms of the accuracy improvement and also the operational use to meet the requirement of observing the whole country with high-revisit frequency. In particular, the combining C-band SAR with other frequency SAR data such as L-band SAR onboard the ALOS-2 would be a challenge.

  18. Big Muddy Field Low-Tension Flood Demonstration Project. Sixth annual report, April 1983-March 1984

    Energy Technology Data Exchange (ETDEWEB)

    1984-10-01

    The Big Muddy low-tension flood is a commercial-size demonstration project consisting of nine 10-acre injection patterns in the heart of the Big Muddy Oil Field located 15 miles east of Casper, Wyoming. The main goal of the project is to provide data for commercialization of the process for the Big Muddy Field and similar Wyoming and Colorado fields. Other objectives are discussed in previous annual reports. This report discusses the project performance during the polymer drive phase with emphasis on the analyses of oil cut, pattern balance, and early tracer response. The oil rate increased only slightly during 1983 and began to flatten near year-end at about 210 barrels per day or 12% of the injection rate. The injection rate was increased in late 1982 and early 1983 but simply resulted in a net input (influx plus injection) greater than production with only slight improvement in oil rate. In fact, the imbalance is suspected of contributing to the early flattening in oil production. Though the project oil rate flattened, an increased cut was observed in the north row of wells, indicating an oil response to slug injection in all wells except Well 54. Also during 1983, the polymer drive volume increased to about 10% of pore volume or to the midpoint of the polymer drive. Tracer and slug components have still appeared in only a few wells, even after 20% pore volume injection. Oil treating was becoming more troublesome but was relieved when the new treating facility was put into use. 5 references, 91 figures, 7 tables.

  19. Field Observation on Seed Arrival into Surface Layers of Sand Bars after Several Floods in Kinugawa River

    Science.gov (United States)

    Miyamoto, Hitoshi; Oishi, Tetsuya; Ohtsuki, Kazuaki; Ohmura, Sohei; Iimura, Hayata

    2017-04-01

    This presentation gives the results of field observation on seed arrival into surface layers of sand bars after several floods during 2016 in Kinugawa River, Japan. The seed arrival could be an onset of secondary succession on sand bars, leading to their well-vegetated states after several decades that cause river management issues both on flood disaster prevention and riverine ecosystem alteration. Kinugawa River had the largest record flood in September 9-10, 2015. It resulted in the levee failure and the corresponding flood disaster in Joso City located in the downstream part of Kinugawa River. It also had the large impact on the riverine vegetation environment, resulting in making many sand bars and gravel beds be bare surface states. In order to investigate the very initial state of the seed arrival into the created bare surfaces by small to medium flood events, 3 channel sections with 6 observation points in total were chosen and observed during the rainy season in 2016. A steel ling with a pile was used for measuring the depth of active surface layers on the sand bars during the flood events. The sediments in the active surface layers were sampled for making the grain size accumulation curve as well as for counting the number of seeds within the sample sediments. The results showed that the sample sediments with the smaller mean diameters, ranging around 0.1 - 6.4 mm, kept much more seeds than those with the larger mean diameters over 12 mm. The number of seeds decreases with the small percentile (around 10-20th) in particle diameter rather than the mean diameter. Furthermore, relationships were discussed in detail between the number of seeds, the depth of the active layers, and bed shear stresses calculated by a numerical simulation model.

  20. 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

  1. Influence of pH on the redox chemistry of metal (hydr)oxides and organic matter in paddy soils

    NARCIS (Netherlands)

    Pan, Y.; Koopmans, G.F.; Bonten, L.T.C.; Song, J.; Luo, Y.; Temminghoff, E.J.M.; Comans, R.N.J.

    2014-01-01

    The primary purpose of this study was to determine how flooding and draining cycles affect the redox chemistry of metal (hydr)oxides and organic matter in paddy soils and how the pH influences these processes. Our secondary purpose was to determine to what extent a geochemical thermodynamic

  2. Influence of pH on the redox chemistry of metal (hydr)oxides and organic matter in paddy soils

    NARCIS (Netherlands)

    Pan, Y.; Koopmans, G.F.; Bonten, L.T.C.; Song, J.; Luo, Y.; Temminghoff, E.J.M.; Comans, R.N.J.

    2014-01-01

    The primary purpose of this study was to determine how flooding and draining cycles affect the redox chemistry of metal (hydr)oxides and organic matter in paddy soils and how the pH influences these processes. Our secondary purpose was to determine to what extent a geochemical thermodynamic equilibr

  3. Reduction of nitrogen, phosphorous and runoff by coordination controlled drainage with basin and ditch in paddy field%水稻沟田协同控制灌排模式的节水减污效应

    Institute of Scientific and Technical Information of China (English)

    朱成立; 郭相平; 刘敏昊; 汤树海

    2016-01-01

    Heavy rains occur frequently in South China during rice growth stages. The large amount of discharge from paddy field combined with high fertilization has caused serious environmental problems. The present controlled drainage methods pay much attention to holding more water in basins and reducing pollutant from basins, however, how to control runoff from field ditches and non-cultivated areas are often ignored. Coordinated Controlled Drainage (CCD) was proposed in the paper to solve the problem above by making most use of the wetland effects of both paddy field and field ditches that were widely distributed in the farmland in South China. The CCD technique tries to store rainwater in basins as much as possible by using rain-catching and controlled irrigation (RCCI) technique that maintains lower irrigation limit and higher water depth after rain depending on the waterlogging-tolerant and drought-tolerant ability of rice so as to reduce runoff from basins. Furthermore, it also impouned runoff from basins and non-cultivation lands such as roads, ditches and canals by a construction at the outlet of the field ditch. Field experiments were conducted in 2013 to verify the feasibility of the model. Controlled and uncontrolled drainages treatments were designed in rice field. Each controlled field of 4.5 hm2. Three replicates were designed. During the experiment, the drainage from field and trench were collected for determination of total nitrogen and phosphorus (TN and TP). Rice yield was measured. The results showed that at field scale, CCD could reduce evaportanspiration and water consumption by 18.8% and 15.3%, compared with frequent and shallow irrigation technique (FSI) respectively. Irrigation quote, drainage quote and irrigation frequency declined 28%, 60.6% and 4 times while TN and TP loss reduced 58.6% and 58.8%. At field control scale, surface drainage volume, the TN and TP burden from controlled ditch decreased by 55.9%, 59.7% and 66.7%, respectively under CCD

  4. Carbon Dioxide Flooding Technology Research and Field Test in Liuzan North Block

    Science.gov (United States)

    Zhang, Hanshi; Luo, Pingya; Sun, Lei; Fu, Zhijun

    2014-12-01

    The fault roots of Liuzan north block in Jidong oilfield of China have been long-term explored by solution gas drive. Recently, oil production declined rapidly because of shortage of formation energy and needing high water injection pressure. Carbon dioxide injection pressure is found to be generally low, and CO2 has good solubility in crude oil to supply formation energy and achieve high oil recovery efficiency. In this work, a pilot program of CO2 EOR technology was carried out. The slim tube test results showed that the minimal miscible pressure of Liuzan north block was 28.28 MPa. The injection parameters were optimized by numerical simulation method: the injection method was continuous, the slug size was 0.2 HCPV and the EOR efficiency was 7.23%. After two months of gas injection field test, the formation pressure of two gas injectors just increased by 14.02 MPa and 2.98 MPa, respectively, indicating that carbon dioxide could supply the formation energy effectively. 16 months after gas injection, the CO2 injection amount was 14640 t, and the oil increment was 16424 t. The present work demonstrates the potential applicability of CO2 flooding technology from high water injection reservoirs.

  5. Reducing nitrogen leaching losses from paddy field under water-saving irrigation by water table control%控制地下水位减少节水灌溉稻田氮素淋失

    Institute of Scientific and Technical Information of China (English)

    和玉璞; 张展羽; 徐俊增; 杨士红; 洪大林

    2014-01-01

    Effects of controlled drainage (CD) on nitrogen leaching losses from paddy field under controlled irrigation (CI) were investigated. Water table control levels were managing with the use of a lysimeter equipped with an automatic water table control system. Three drainage treatments were implemented, namely, controlled water table 1, controlled water table 2, and controlled water table 3. For controlled water table 1, the water table control levels were adjusted daily based on the actual water table depths that were measured by using a water table observation well. Water table control levels in controlled water table 2 were controlled based on the rice root zone depths in different stages according to the water table management that was tested in the humid regions of Eastern Canada and Midwestern United States. For controlled water table 3, the water table control levels in different stages were selected based on previous studies in paddy field of Southeast China. The water table control levels in the later tillering stage and milk stage were also adjusted depending on the characteristics of rice growth and cultivation needs. Experiments were conducted in nine drainage type lysimeters with a mobile shelter and gallery. Each lysimeter had an area of 2.5 m × 2 m and a depth of 1.3 m. Influence of rainfall was avoided using the mobile shelter to strictly regulate the soil moisture in CI. Each lysimeter was individually irrigated and drained using a pipe installed with a water meter and a tube (40 mm in inner diameter) installed at 1.2 m below the soil surface, respectively. Subsurface drainage was conducted based on the water table control levels by using an automatic water table control system, which was installed on each drain tube in the gallery. Subsurface drainage water were collected twice at 2d intervals after each fertilizer application followed by 4d intervals. A 7d sampling interval was used during the rest time. NH4+–N and NO3−–N concentrations in the

  6. Effect of Pesticides On Certain Soil Biological and Biochemical Indices of a Paddy Soil

    Institute of Scientific and Technical Information of China (English)

    LIAO Min; XIE Xiao-mei; HUANG Chang-yong

    2003-01-01

    A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (Triazophos, Butaehlor and Jinggangmycin) on a paddy field soil health under controlled moisture (flooded soil) and temperature (25℃ ) conditions. The electron transport system (ETS)/dehydrogenase activity displayed a negative correlation with pesticides concentrations, and the activity was affected adversely as the concentration of the pesticides increased. The higher doses of pesticides,5 and 10 folds field rates, significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect against the control. The relative toxicity level of pesticides in decreasing the ETS activity was in the following order:Triazophos>Jinggangmycin>Butachlor, irrespective of their rates of application. The pesticides caused an improvement in the soil phenol content and it increased with increasing the concentration of agrochemicals. The pesticide incorporation did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of pesticides in the given order of Triazophos>Jinggangmycin>Butachlor; and the toxicity was in the order: 10 FR (times of field rate)>5 FR>1.0 FR>0.5 FR>control.

  7. Alteration of certain soil microbiological and biochemical indices of a paddy soil under anthropogenic stress

    Institute of Scientific and Technical Information of China (English)

    AbidSubhani; 廖明; 黄昌勇; 谢正苗

    2002-01-01

    A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (insecticide, herbicide, fungicide) on paddy field soil health under omatrolld moisture (flooded soil) and tem-perature (25℃ ) environment. The electron system (ETS)/Dehydrogenase activity showed negative correlation with pesticides concentrations, decreased with increase of pesticide ooncentration. The higher doses (5 to 10 times field rates) of pesticides significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect on the control. The toxicity of pesticides in decreasing the ETS activity was in the order: insectidde > fungicide > herbicide, irrespective of their rates of application. The pasticides increased the soil phenol content, which increased with increasing concentration of agrochemicals. The pesticide applieatkm did not produce any significant change in soil protein content. The response of biomamess phospholipid content was nearly similar to that of ETS activity. The phospholipid content decreased with the addition of pesficides in the order insecfidde > furgicide > herbicide and the maidty was in the order: 10 FR (field rate) > 5FR> 1.0 FR > 0.5 FR >control.

  8. Alteration of certain soil microbiological and biochemical indices of a paddy soil under anthropogenic stress

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A 21-day laboratory incubation experiment was conducted to investiga t e the impact of pesticides (insecticide, herbicide, fungicide) on paddy field so il health under controlled moisture (flooded soil) and temperature (25 ℃) envir onment. The electron transport system (ETS)/Dehydrogenase activity showed negati ve correlation with pesticides concentrations, decreased with increase of pesti cide concentration. The higher doses(5 to 10 times field rates) of pesticides si gnificantly inhibited ETS activity, while lower rates failed to produce any sign ificant reducing effect on the control. The toxicity of pesticides in decreasing the ETS activity was in the order: insecticide > fungicide > herbicide, irrespe ctive of their rates of application. The pesticides increased the soil phenol co ntent, which increased with increasing concentration of agrochemicals. The pesti cide application did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to that of ETS activity. The phospholipid content decreased with the addition of pesticides in the order insecticide > fungicide > herbicide and the toxicity was in the order: 10 FR (field rate) > 5 FR > 1.0 FR > 0.5 FR > control.

  9. Design and experiment on critical component of cultivator for straw returning in paddy field and dry land%水旱两用秸秆还田耕整机关键部件设计与试验

    Institute of Scientific and Technical Information of China (English)

    张秀梅; 张居敏; 夏俊芳; 张顺; 翟建波; 吴昊

    2015-01-01

    As the main producing area of rice, the Yangtze River basin usually had various multiple cropping systems, such as rape-rice, wheat-rice, green manure-rice, the double cropping of rice, triple-cropping. Rice is planted immediately after the harvest of the previous crop. So the straws are buried in the field in a busy harvesting and planting season. Crop residues incorporated in farmland by mechanical technique can improve soil physics properties and fertility, increase the yield and farm income. Straw returning to field practice can reduce the problem of crop residue burning and also the amount of chemical fertilizer application. Based on our previous research on the 1GMC-70, the cultivator for high stubble returning in paddy field, a new roller of cultivator for straw returning both in paddy field and dry land was designed. The helical rotary blades, bent blades and the IIT245 rotary blade were the main tillage parts of the machine, and its power consumption was an important technical parameter to consider for the overall performance. The former two types of blade are used to cut soil, while the latter one to bury straw. In this study, based on the roller structural and working principle of the main parts of the cultivator, the parameters of key components were tested for the rotary blades IIT245 and spiral blades. Furthermore, their interrelationships and interactions were analyzed in detail. An advisable arrangement of rotary blades IIT245 fixed on the rotor was provided. The tillage width was 2 000 mm. The rotor speed was 335 rev/min. The forward velocity was 0.7 to 1.1 m/s. The lower forward velocity was used in dry land, while the higher forward velocity was for wet land tillage. Experiments of crop straw burying rotary tillage were conducted repeatedly both in wet land and dry land. The field test showed when tillage in fields of soil compaction value under 1260 kPa at about 150 mm depth, the cultivator could realize the straw mulching and returning, soil

  10. 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.

  11. [Dimensional fractal of post-paddy wheat root architecture].

    Science.gov (United States)

    Chen, Xin-xin; Ding, Qi-shuo; Li, Yi-nian; Xue, Jin-lin; Lu, Ming-zhou; Qiu, Wei

    2015-06-01

    To evaluate whether crop rooting system was directionally dependent, a field digitizer was used to measure post-paddy wheat root architectures. The acquired data was transferred to Pro-E, in which virtual root architecture was reconstructed and projected to a series of planes each separated in 10° apart. Fractal dimension and fractal abundance of root projections in all the 18 planes were calculated, revealing a distinctive architectural distribution of wheat root in each direction. This strongly proved that post-paddy wheat root architecture was directionally dependent. From seedling to turning green stage, fractal dimension of the 18 projections fluctuated significantly, illustrating a dynamical root developing process in the period. At the jointing stage, however, fractal indices of wheat root architecture resumed its regularity in each dimension. This wheat root architecture recovered its dimensional distinctness. The proposed method was applicable for precision modeling field state root distribution in soil.

  12. AUTOMATIC PADDY RICE MAPPING INTERFACE USING ARCENGINE AND LANDSAT8 IMAGERY (CASE STUDY IN NORTH PART OF IRAN

    Directory of Open Access Journals (Sweden)

    Sh. Bahramvash Shams

    2014-10-01

    Full Text Available Recognition of paddy rice boundaries is an essential step for many agricultural processes such as yield estimation, cadastre and water management. In this study, an automatic rice paddy mapping is proposed. The algorithm is based on two temporal images: an initial period of flooding and after harvesting. The proposed method has several steps include: finding flooded pixels and masking unwanted pixels which contain water bodies, clouds, forests, and swamps. In order to achieve final paddy map, indexes such as Normalized Difference Vegetation Index (NDVI and Land Surface Water Index (LSWI are used. Validation is performed by rice paddy boundaries, which were drawn by an expert operator in Google maps. Due to this appraisal good agreement (close to 90% is reached. The algorithm is applied to Gilan province located in the north part of Iran using Landsat 8 date 2013. Automatic Interface is designed based on proposed algorithm using Arc Engine and visual studio. In the Interface, inputs are Landsat bands of two time periods including: red (0.66 μm, blue (0.48 μm, NIR (0.87 μm, and SWIR (2.20 μm, which should be defined by user. The whole process will run automatically and the final result will provide paddy map of desire year.

  13. Study on the occurrence characteristics and chemical control techniques of Murdannia triquetra in wheat and paddy fields%麦稻田水竹叶发生特点及其化学防除技术研究

    Institute of Scientific and Technical Information of China (English)

    田志慧; 沈国辉; 芦芳; 顾士光; 温广月

    2015-01-01

    The occurrence characteristics and chemical control techniques of Murdannia triquetra were stud-ied in wheat and paddy fields.The results showed that the seeds of Murdannia triquetra in wheat fields began to germinate in mid-March,and the sprout reached the peak in mid-April.The creeping stems were left in the field after wheat harvest in mid-to-late May,and began the asexual reproduction by ploughing into paddy field.Mur-dannia triquetra entered the growth period 3 weeks after planting rice,and generated a large amount of primary and secondary branches.The generation of branches reached two peaks respectively in late July and mid-Septem-ber.Murdannia triquetra bloomed in early September and seeded in late September.Murdannia triquetra comple-ted its whole life cycle after seeds matured in early October and then fall in the field after natural cracking.The whole growth period was about 210 days.Control of Murdannia triquetra should stick to rely mainly on wheat field control while paddy field control subsidiary.(1 )Bensulfuron-methyl WP for preemergence treatment with spra-ying or toxic soil method were used in the growth period of wheat and before the germination of Murdannia triquetra.Fluroxypyr EC or MCPA +bentazon AS for postemergence treatment with spraying method were used in the 2—4 leaves stage of Murdannia triquetra.(2)Fluroxypyr EC or MCPA-Na AS for postemergence treatment with spraying method were used in the japonica rice growing period or 2—3 branches stage of Murdannia triquetra.These herbicides not only had good weeding efficacy and fast pesticide effect,but also were safe to the growth of wheat and japonica rice.%对麦稻田水竹叶发生特点及其化学防除技术进行了研究。结果表明:麦田中的水竹叶种子3月上中旬开始萌发,4月中旬出苗达到高峰,5月中下旬麦子收割后匍匐茎留于田间,并随耕翻进入稻田开始无性繁殖;水稻种植3周后水竹叶进入生长旺期,并产

  14. EVALUATION OF THE FLOOD POTENTIAL OF THE SOUTH HOUSE (BLINEBRY) FIELD, LEA COUNTY, NEW MEXICO

    Energy Technology Data Exchange (ETDEWEB)

    L. Stephen Melzer

    2000-12-01

    /11 respectively. Production of oil and gas has been established with several months of production now available to make a reserve analysis. Production histories and reserves estimation are provided. An assessment of the flood potential for the South House project area has been completed with work concentrated on South House rock property and pay thickness characterization and analog studies. For the analogs, the North Robertson area, located twenty miles to the northeast, and the Teague Field, located 20 miles to the south, have been utilized due to their readily available database and previous waterflood studies. The South House area does appear to merit further examination as the rock quality compares favorably with both analog Fields; however, current well spacings of 40-acres will provide only marginal economics based upon $23.00/barrel oil prices. Permeability and porosity relationships are provided as a conditional demonstration that rock quality may be sufficient for successful waterflooding of the project area. Further rock property work and pay continuity studies are recommended.

  15. Research on carbon dioxide miscible flooding by Technology Research Center of Japan National Oil Corporation. Current status of CO/sub 2/ flooding field application, Work honored with the 31st JAPT award

    Energy Technology Data Exchange (ETDEWEB)

    Tanakadate, Tadao

    1988-03-01

    The application examples in world on carbon dioxide miscible flooding which is an enhanced oil recovery method and the outline of field pilot test in Japan which will start from fiscal 1989 were reported. In the USA, there are fifty three examples on carbon dioxide miscible flooding and thirty one examples on carbon dioxide immiscible flooding. The enhanced rates of oil recovery by carbon dioxide miscible flooding are 7 to 13 %. In Hungary, the oil reservior pressures were increased rapidly due to the carbon dioxide injection and the push by water, and the recovery rates of 24 % and more were achieved. In Turkey, carbon dioxide immiscible flooding is in a trial stage. In these countries, carbon dioxide can be provided comparatively easily owing to the existences of the carbon dioxide fields, and the advantageous conditions are utilized. In Japan, the pilot tests are carried out with main research subjects on the phase behavior of carbon dioxide-oil system, prospect for performance of carbon dioxide miscible flooding by oil reservior simulation. (10 figs, 2 tabs, 5 refs)

  16. Residue decline study of ethiprole in paddy field soil and water%乙虫腈在水稻土壤和田水中的残留及消解动态研究

    Institute of Scientific and Technical Information of China (English)

    尚子帅; 吴慧明; 秦丽; 马新生; 刘菲菲; 朱国念

    2011-01-01

    In order to study the safety of ethiprole to paddy soil ecosystem,residue decline of ethiprole in soil and water were investigated under field and field-simulated condition. The samples were extracted by acetic-acetonitrile (1: 99, V: V), cleaned up with primary secondary amine ( PSA), and analyzed by UPLC-MS/MS. External reference method was used for quantitative determination. The linearity was satisfied (r > 0. 98) in the concentration range of 0. 001 - 0. 1 mg/L . The limit of detection(LOD) was 2. 2 x 10~13 g,and the limit of quantification (LOQ) in paddy soil and water were 0. 001 mg/kg(L). The average fortification recoveries varied from 80. 2% to 119. 5% with relative standard deviation (RSD) of3.1% -9.0% when ethiprole was spiked at 0.002 -1.0 mg/kg level in soil matrix, the average fortification recoveries varied from 94. 2% - 108. 2% with relative standard deviation (RSD) of 1.6% -13.2% when ethiprole was spiked at 0.001 -1.0 mg/L level in water matrix. The decline study of ethiprole residue in paddy field soil and water were carried out,the decline curves accorded with the first-order kinetics equation, and the half-lives of ethiprole in soil andwater under field-simulated and field condition were of 3. 2 -2. 8 d and 3. 5 - 1. 8 d, respectively.Ethiprole belongs to the easily degradable pesticide.%为研究乙虫腈对淹水稻田土壤生态环境的安全性,在田间和室内模拟试验条件下,定期取样检测了乙虫腈在土壤和田水中的消解动态.样品采用醋酸-乙腈(1∶99,体积比)提取,经N-丙基乙二胺(PSA)净化,超高效液相色谱-串联质谱(UPLC-MS/MS)检测,外标法(ESTD)定量.结果表明,在0.001 ~0.1 mg/L质量浓度范围内,乙虫腈的仪器响应值与质量浓度呈良好的线性关系,相关系数均在0.98以上.方法的最小检出量(LOD)为2.2×10-13 g,乙虫腈在稻田土壤和田水中的最低检测浓度(LOQ)为0.001 mg/kg(L).当土壤中的添加水平为0.002~ 1.0 mg

  17. 广东省东南部菜地水田砷含量空间分布%Spatial distribution of As in vegetable field and paddy in southeast of Guangdong province

    Institute of Scientific and Technical Information of China (English)

    姜晓璐; 邹滨; 汤景文; 涂宇龙

    2016-01-01

    The soil As pollution in agricultural land has received increasing attention globally due to its significant potential harm to the environment and human health. Knowing the source as well as the characteristics of pollutants is the premise for their control and treatment. But now, sampling for understanding pollutants in soil is difficult and costly resulting in limited number of soil samples from the As contaminated land. For the problem that it is hard to accurately and efficiently map the spatial distribution of soil As concentration based on limited soil samples. In this study, we collected a total of 104 top soil samples (0~20cm) from agricultural land, in a southeast of Guangdong province. A combined approach of spatial analysis and multiple regression modeling was developed to recognize the statistical characteristic of As concentration in sampling soil, and to reveal their formation causes of spatial variation and associated spatial patterns in vegetable field, paddy and orchard. Results showed that in general, As concentration of soil samples was largely not exceeding the national standard in the agricultural land of the studied area. However, As concentration of few soil samples was still exceeding the National Environment Quality Standard for soil (GB15618-1995), with the maximum value was 137.80 mg/kg. Among three different types of agricultural lands, the soil As concentration in vegetable field was the highest, followed by the paddy and orchard, with mean values of 11.04, 9.89 and 2.54 mg/kg, respectively. The sources of soil As contamination were variable in different agricultural land. In vegetable field, soil As concentration was closely interrelated with shortest distances between samples and chimneys and rivers, and the slope of sample sites. Significance value of the soil As concentration simulation model in vegetable field was 0.010 (P0.05) in this study. The results suggested that the soil As contamination in vegetable field mainly was

  18. Effects of Conversion of Paddy Field into Vineyard on Soil Nitrogen Transformation in the Taihu Lake Region of China%太湖地区稻麦轮作农田改葡萄园对土壤氮转化过程的影响

    Institute of Scientific and Technical Information of China (English)

    王敬; 张金波; 蔡祖聪

    2016-01-01

    In response to the growing demand for fruits,farmers in the Taihu Lake region are rushing to convert paddy fields into fruit orchards in recent years. Changes in land-use and management may affect or alter physico-chemical properties of the soil,and hence cycling of soil N and fate of N fertilizer. Up to date, little has been reported on quantification of effects of changes in land use on soil N gross transformation rate, besides some works that have been mainly focused on effects of the conversion of non-agricultural land into agricultural land,and rarely on the effects of the conversion from one type to another type of agricultural land use. In the Taihu Lake region,paddy fields under rice-wheat crop rotation and orchards coverted from paddy fields are the two typical types of agricultural land-use,which differ sharply in water regimes(periodically waterlogged for paddy fields and water-unsaturated for orchards)and fertilizer management (no input of organic manure for paddy fields and combined application of chemical fertilizer and organic manure for orchards). Therefore,gross N processes(e.g.,nitrification and denitrification)in the soils under the two types of land use also differ sharply,as affected by their different aeration conditions and fertilizer managements. The paddy field under rice-wheat crop rotation and the vineyard converted from paddy field under study are located in the upper-streams of the Zhushan Bay Catchment in the Taihu Lake Region of China. Gross transformation rates of soil N under the two types of land use were measured using the15N tracing technique combined with the Markov Chain Monte Carlo(MCMC)algorithm-based numerical optimization model,and effects of the conversion on soil N supply and N retention capacity were investigated. Results show that the conversion reduced soil pH(from 5.74 in paddy field to 5.14 in vineyard,on average) and contents of soil organic C and total N,though not much. In the soils of the paddy field and vineyard

  19. Clomazone dissipation, adsorption and translocation in four paddy topsoils.

    Science.gov (United States)

    Li, Lian-fang; Li, Guo-xue; Yang, Ren-bin; Guo, Zheng-yuan; Liao, Xiao-yong

    2004-01-01

    Laboratory experiments about the dissipation, adsorption and translocation in four paddy topsoils were conducted in this paper. From the results it can be concluded as follows: the dissipation rate of clomazone differed greatly in different paddy soil derived from different parent materials. The half-lives for clomazone degradation in paddy soils ranged from 5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy soil > alluvial sandy paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Clomazone sorption quantity was significantly correlated with organic carbon (R2 = 0.62) and clay content(R2 = 0.67) in the tested paddy soils. Positive correlation was found between apparent Kd value and cation exchange content(CEC). The consequences for the adsorption of different soils were purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm through four different unsaturated soil lysimeters over 24 h, clomazone was readily to be leached into lower surface soil and there was about 2.6%--4.2% of applied clomazone leached out of 20 cm cultivated soil layer. Translocation experiments showed that the order of clomazone leaching ability was: alluvial sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Simple regression results manifested that factors like CEC, organic carbon, clay, and adsorption rate constant had been negatively correlated with the percentage of clomazone loss from soil lysimeters.

  20. Positive feedback of crop residue incorporation on dissolved organic carbon contents under anaerobic conditions in temperate rice paddy soils

    Science.gov (United States)

    Said-Pullicino, Daniel; Sodano, Marcella; Bertora, Chiara; Lerda, Cristina; Sacco, Dario; Celi, Luisella

    2016-04-01

    Rice paddy soils are generally characterized by large concentrations and fluxes of DOC in comparison to other ecosystems. Our recent studies have shown that the combination of relatively high pore-water DOC concentrations under anoxic soil conditions (>10-20 mg C l-1) and important percolation fluxes of water during field flooding may contribute significant organic C inputs into the subsoil (18-51 g C m-2) over the cropping season. Crop residues incorporated into the soil after harvest represent the main input of organic C into paddy soils, returning about 200-300 g C m-2 y-1 in single-cropped rice paddies. The anaerobic decomposition of these residues may supply important amounts of DOC to soil pore waters. Moreover, the supply of electron donors with the input of residue-derived labile OM may further increase DOC contents by stimulating the microbially-catalyzed reductive dissolution of Fe and Mn oxyhydroxides under anoxic conditions, and release of DOC previously stabilized on the mineral matrix (i.e. positive feedback). This could have important implications on organic C inputs into the subsoil as well as substrate availability for methane production. We therefore hypothesized that crop residue management practices that influence the amount of labile organic matter present in the soil at the time of field flooding may strongly influence soil solution DOC concentrations as well as the positive feedback on the release of soil-derived DOC. We tested this hypothesis at field-scale by evaluating variations in the contents and quality of DOC above and beneath the plough pan over the cropping season as a function of crop residue management practices involving: tillage and crop residue incorporation in spring (SPR), tillage and crop residue incorporation in spring, dry seeding and 1 month delayed flooding (DRY), tillage and crop residue incorporation in autumn (AUT), and straw removal after harvest and tillage in spring (REM). Moreover, we linked changes in DOC

  1. Organic carbon stratification and size distribution of three typical paddy soils from Taihu Lake region, China

    Institute of Scientific and Technical Information of China (English)

    PAN Genxing; WU Laosheng; LI Lianqing; ZHANG Xuhui; GONG Wei; WOOD Yvonne

    2008-01-01

    Developing realistic soil carbon (C) sequestration strategies for China's sustainable agriculture relies on accurate estimates of the amount, retention and turnover rates of C stored in paddy soils. Available C estimates to date are predominantly for the tilled and flood-irrigated surface topsoil (ca. 30 cm). Such estimates cannot be used to extrapolate to soil depths of 100 cm since soil organic carbon (SOC) generally shows a sharp decrease with depth. In this research, composite soil samples were collected at several depths to 100 cm from three representative paddy soils in the Taihu Lake region, China. Soil organic carbon distribution in the profiles and in aggregate-size fractions was determined. Results showed that while SOC decreased exponentially with depth to 100 cm, a substantial proportion of the total SOC (30%-40%) is stored below the 30 cm depth. In the carbon-enriched paddy topsoils, SOC was found to accumulate preferentially in the 2-0.25 and 0.25-0.02 mm aggregate size fractions. d13C analysis of the coarse micro-aggregate fraction showed that the high degree of C stratification in the paddy topsoil was in agreement with the occurrence of lighter d1313C in the upper 30 cm depth. These results suggest that SOC stratification within profiles varies with different pedogenetical types of paddy soils with regards to clay and iron oxyhydrates distributions. Sand-sized fractions of aggregates in paddy soil systems may play a very important role in carbon sequestration and turnover, dissimilar to other studied agricultural systems.

  2. Biogeochemical typing of paddy field by a data-driven approach revealing sub-systems within a complex environment--a pipeline to filtrate, organize and frame massive dataset from multi-omics analyses.

    Directory of Open Access Journals (Sweden)

    Diogo M O Ogawa

    Full Text Available We propose the technique of biogeochemical typing (BGC typing as a novel methodology to set forth the sub-systems of organismal communities associated to the correlated chemical profiles working within a larger complex environment. Given the intricate characteristic of both organismal and chemical consortia inherent to the nature, many environmental studies employ the holistic approach of multi-omics analyses undermining as much information as possible. Due to the massive amount of data produced applying multi-omics analyses, the results are hard to visualize and to process. The BGC typing analysis is a pipeline built using integrative statistical analysis that can treat such huge datasets filtering, organizing and framing the information based on the strength of the various mutual trends of the organismal and chemical fluctuations occurring simultaneously in the environment. To test our technique of BGC typing, we choose a rich environment abounding in chemical nutrients and organismal diversity: the surficial freshwater from Japanese paddy fields and surrounding waters. To identify the community consortia profile we employed metagenomics as high throughput sequencing (HTS for the fragments amplified from Archaea rRNA, universal 16S rRNA and 18S rRNA; to assess the elemental content we employed ionomics by inductively coupled plasma optical emission spectroscopy (ICP-OES; and for the organic chemical profile, metabolomics employing both Fourier transformed infrared (FT-IR spectroscopy and proton nuclear magnetic resonance (1H-NMR all these analyses comprised our multi-omics dataset. The similar trends between the community consortia against the chemical profiles were connected through correlation. The result was then filtered, organized and framed according to correlation strengths and peculiarities. The output gave us four BGC types displaying uniqueness in community and chemical distribution, diversity and richness. We conclude therefore that

  3. Persistence behaviour of thiamethoxam and lambda cyhalothrin in transplanted paddy.

    Science.gov (United States)

    Barik, Suhrid Ranjan; Ganguly, Pritam; Kunda, Samir Kumar; Kole, Ramen Kumar; Bhattacharyya, Anjan

    2010-10-01

    A field study was conducted in Pre-Kharif season 2007 on paddy to determine the persistence of thiamethoxam (12.6%) and lambda cyhalothrin (9.4%) [in a 'Readymix' formulation Alika 247 ZC], following the application of 33 g. a.i. ha⁻¹ (T₁) and 66 g. a.i. ha⁻¹ (T₂). Spraying of insecticide was done during milking stage of the crop (63 days after transplantation). Thiamethoxam and lambda cyhalothrin residues were estimated by HPLC and GLC respectively. The half-life values were 5.2-5.8 and 4.8 days for thiamethoxam and lambda cyhalothrin respectively. No residue was detected in the harvested paddy, straw, grain, and soil samples.

  4. Effects of long-term drainage of stony open deep-narrow drainage ditches on groundwater level, soil chemical characteristics and rice grain quality in cold-waterlogged paddy fields%长期深窄沟排渍对冷浸田地下水位、土壤化学特性及水稻籽粒品质的影响

    Institute of Scientific and Technical Information of China (English)

    王飞; 林诚; 李清华; 方宇; 林新坚; 刘玉洁; 刘启鹏; 林丽红

    2015-01-01

    Cold-waterlogged paddy fields across Jiangnan rice-growing regions belong to low-yield paddy fields. The main characteristics of these paddy fields include low soil temperature, high reducing agents and bad soil structure. However, the fields have the potential to significantly increase paddy rice yields. A 30-year stony open deep-narrow drainage ditch system in Shunchang County, Fujian Province, was investigated for its effects on groundwater level, soil chemical characteristics and rice grain quality in cold-waterlogged paddy fields using a consecutive 3-year monitoring. The results showed that soil conditions in paddy fields 75 m, 25 m, 15 m and 5 m from the ditches were deep-foot mud, shallow-foot mud, blue mud and blue-bottom mud, respectively. The groundwater levels in paddy fields 75 m, 25 m, 15 m and 5 m from the drainage ditches were 5.0 cm, 8.3 cm,−5.4 cm and−16.7 cm, respectively. The highest variation in groundwater level (from−62 cm to 13 cm) was in paddy field 5 m from the drainage ditches. The closer the distance to the drainage ditches, the lower the reducing agents and the higher the contents of available N, P and K. Compared with the field 75 m from the drainage ditches (CK), soil reducing agents content at the field 5 m from the drainage ditches decreased by 62.6%while available N, P and K contents increased respectively by 40.7%, 38.8%and 184.5%. At closer distances to the drainage ditches (e.g., 5 m, 15 m and 25 m sites), amino acids content of rice grain were significantly higher than that of CK. Amino acids content of rice grain was significantly negatively correlated with soil reducing agents content, but positively correlated with soil available N and P contents. Starch content of rice grain was also significantly negatively correlated with soil reducing agents content. Soil physiochemical properties and rice amino acids content were improved by long-term drainage of stony open deep-narrow drainage ditches. Soil improving effect was

  5. 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

  6. [Dynamics of active organic carbon in a paddy soil under different rice farming modes].

    Science.gov (United States)

    Zhan, Ming; Cao, Cou-Gui; Jiang, Yang; Wang, Jin-Ping; Yue, Li-Xin; Cai, Ming-Li

    2010-08-01

    A field experiment was conducted to study the dynamics of dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) in a paddy soil under integrated rice-duck farming (RD), intermittent irrigation (RW), and conventional flooded irrigation (CK), the three rice farming modes typical in southern China. Under these three farming modes, the soil DOC and MBC contents reached the highest during the period from rice booting to heading, while the soil ROC content had less change during the whole rice growth period. Two-factor variance analysis showed that soil MBC was greatly affected by rice growth stage, soil DOC was greatly affected by rice growth stage and farming mode, and soil ROC was mainly affected by farming mode. Comparing with CK, RD significantly increased the soil DOC and ROC contents and their availability, while RW significantly decreased the soil DOC content and its availability but increased the soil ROC content and its availability. No significant differences were observed in the soil MBC and microbial quotient among RD, RW, and CK.

  7. Microbial Community and Greenhouse Gas Fluxes from Abandoned Rice Paddies with Different Vegetation.

    Science.gov (United States)

    Kim, Sunghyun; Lee, Seunghoon; McCormick, Melissa; Kim, Jae Geun; Kang, Hojeong

    2016-10-01

    The area of rice paddy fields has declined continuously in East Asian countries due to abandonment of agriculture and concurrent socioeconomic changes. When they are abandoned, rice paddy fields generally transform into wetlands by natural succession. While previous studies have mainly focused on vegetation shifts in abandoned rice paddies, little information is available about how these changes may affect their contribution to wetland functions. As newly abandoned fields proceed through succession, their hydrology and plant communities often change. Moreover, the relationships between these changes, soil microbial characteristics, and emissions of greenhouse gasses are poorly understood. In this study, we examined changes over the course of secondary succession of abandoned rice paddies to wetlands and investigated their ecological functions through changes in greenhouse gas fluxes and microbial characteristics. We collected gas and soil samples in summer and winter from areas dominated by Cyperaceae, Phragmites, and Sphagnum in each site. We found that CO2 emissions in summer were significantly higher than those in winter, but CH4 and N2O emission fluxes were consistently at very low levels and were similar among seasons and locations, due to their low nutrient conditions. These results suggest that microbial activity and abundance increased in summer. Greenhouse gas flux, soil properties, and microbial abundance were not affected by plant species, although the microbial community composition was changed by plant species. This information adds to our basic understanding of the contribution of wetlands that are transformed from abandoned rice paddy systems.

  8. Modeling Nitrogen Mineralization in Paddy Soils of Shanghai Region

    Institute of Scientific and Technical Information of China (English)

    LI Hui-Lin; HAN Yong; CAI Zu-Cong

    2003-01-01

    Six paddy soils of Shanghai, China, were studied after 120 days of anaerobic incubation at 25 ℃ and 35 ℃. Four models, the effective accumulated temperature model, the one-component first-order exponential model (the one-pool model), the two-component first-order exponential model (the two-pool model), and the two-component first-order plus zero-order exponential model including a constant term (the special model),were fitted to the data of observed mineral-N during incubation using non-linear regression procedures. The two-pool model and the special model gave the best fits amongst the four models, and parameters in the special model were more reasonable than those in the other three. Results showed that the special model gave a better prediction of nitrogen mineralization under flooded conditions than the other three models.

  9. Distribution of mosquito larvae within the paddy and its implication in larvicidal application in Mwea rice irrigation scheme, Central Kenya.

    Science.gov (United States)

    Mwangangi, Joseph M; Muturi, Ephantus J; Shililu, Josephat I; Jacob, Benjamin; Kabiru, Ephantus W; Mbogo, Charles M; Githure, John I; Novak, Robert J

    2008-03-01

    Distribution of mosquito larvae in inundated rice fields is poorly known despite its profound implications in implementation of vector control programs. Based on oviposition behavior of gravid females and biotic and abiotic conditions of the rice field, distribution of mosquito larvae within the paddy may vary greatly. As a guide to implementation of mosquito vector control program targeting the aquatic stages in the rice fields in Mwea, studies were conducted to determine the distribution of mosquito larvae within the paddy. Twenty-eight cages measuring 50 cm3 were distributed randomly within the paddy during the transplanting stage of the rice growth cycle, and were examined twice per week up to the flowering stage to determine mosquito oviposition pattern. A total of 17,218 mosquito larvae were collected at the periphery and a further 17,570 at the center of the paddy. These comprised 7,461 larvae from the genus Anopheles and 27,327 from genus Culex. The number of pupae collected at the periphery was 1,004 and 1.5 times greater than the number collected at the center. Significantly higher counts of Anopheles larvae were collected at the center (1.00 +/- 0.11) than at the periphery (0.55 +/- 0.05) of the paddy during transplanting stage, but the difference was not significant during the tillering stage. In contrast, significantly higher numbers of Culex larvae were collected from the periphery (3.09 +/- 0.39) than at the center (2.81 +/- 0.24) of the paddy. More pupae were also collected at the center than at the periphery of the paddy. These findings indicate the distribution of Anopheles and Culex larvae in rice fields to be nonrandom; however, for successful achievement of an integrated vector control program targeting the diverse mosquito fauna occurring in rice fields, there is need to target the whole paddy for larvicidal application.

  10. HyMeX-SOP1, the field campaign dedicated to heavy precipitation and flash-flooding in the northwestern Mediterranean

    OpenAIRE

    Ducrocq, V; Braud, I.; S. Davolio; Ferretti, R.; Flamant, C; Jansa, A.; Kalthoff, N.; Richard, E.; Taupier Letage, I.; Ayral, P. A.; Belamari, S.; A. Berne; Borga, M; Boudevillain, B.; Bock, O.

    2014-01-01

    The Mediterranean region is frequently affected by heavy precipitation events associated with flash floods, landslides, and mudslides that cause hundreds of millions of euros in damages per year and often, casualties. A major field campaign was devoted to heavy precipitation and flash floods from 5 September to 6 November 2012 within the framework of the 10-year international HyMeX (Hydrological cycle in the Mediterranean Experiment) dedicated to the hydrological cycle and related high-impact...

  11. Flood-Fighting Structures Demonstration and Evaluation Program: Laboratory and Field Testing in Vicksburg, Mississippi

    Science.gov (United States)

    2007-07-01

    actual flood conditions. Log impact tests were conducted at a water elevation of 66 percent levee height to model the impact of waterborne debris...sand. A total of 250 cu yd of sand was delivered to the site. An automatic-speed sandbagger, Model ASB-3 (Hogan Manufacturing, Inc.) was rented...Local Sponsor Mr. Renold Minsky , President, Fifth Louisiana Levee Board Mr. Bump Calloway, Director, Warren County (MS) Civil Defense The

  12. 不同区域稻田土壤复合体有机碳分配及δ13C特征%Distribution and δ13C Characteristics of Organic Carbon in Soil Organo-mineral Complexes of Paddy Fields Located in Different Regions

    Institute of Scientific and Technical Information of China (English)

    朱洁; 慈恩; 杨林章; 马力; 谢德体

    2011-01-01

    Representative paddy fields were selected in five regions(Longjing of Jilin Province, Fengqiu of Henan province, Cixi of Zhejiang province, Jinxian of Jiangxi province and Haikou of Hainan province).Distribution and δ13 C characters of organo-mineral complexes in these paddy soils were studied.The results showed that the content (mass percent) changes of complexes <2 μm and >50 μm were more obvious than other particle-sizes complexes in paddy soils located in different regions.In southern paddy fields, the content of complex <2 μm in the 0-20 cm layer was lower than the 20-40 cm layer, and conversely in soil profiles of northern paddy fields.Distribution of organic carbon content in different particle-sizes complexes <50 μm kept consistent in the 0-20 cm layer and the 20-40 cm layer of paddy fields.Organic carbon content of complexes >50 μm in the 20-40 cm layer of paddy fields declined sharply, and was significantly lower than the topsoil.Soil organic carbon of cropland was mainly accumulated in complexes < 10 μm.Climate conditions, cultivation system and original soil would have significant influence on distribution of organic carbon in soil organo-mineral complexes of cropland, and water culture was propitious to accumulation of coarse organism in the topsoil of paddy fields.In the 0-20 cm layer of paddy fields located in different regions, organic carbon with higher δ13C value and lower activity was contained in smaller particle-size complexes.The rule wasn't strictly followed in the 20-40 cm layer that the activity of organic carbon in coarse complex was higher than fine complex, and especially in coarse complex >50 μm.%选取位于5个不同区域(吉林龙井、河南封丘、浙江慈溪、江西进贤和海南海口)的代表性稻田,对其土壤复合体有机碳分配及δ13C特征进行了研究.结果表明,不同区域稻田土壤中各粒级复合体含量(质量百分比)变化主要体现在<2μm和>50

  13. Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon

    Science.gov (United States)

    Ferns, Mark L.; Streck, Martin J.; McClaughry, Jason D.

    2017-08-09

    The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks are considered part of the La Grande-Owyhee eruptive axis (LOEA), an approximately 300-kilometer-long (185 mile), north-northwest-trending, middle Miocene to Pliocene volcanic belt located along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the (1) flood basalt-dominated Columbia Plateau on the north, (2) bimodal basalt-rhyolite vent complexes of the Owyhee Plateau on the south, (3) bimodal basalt-rhyolite and time-transgressive rhyolitic volcanic fields of the Snake River Plain-Yellowstone Plateau, and (4) the High Lava Plains of central Oregon.This field-trip guide describes a 4-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the Columbia River Basalt Group and coeval and compositionally diverse volcanic rocks associated with the early “Yellowstone track” and High Lava Plains in eastern Oregon. Beginning in Portland, the Day 1 log traverses the Columbia River gorge eastward to Baker City, focusing on prominent outcrops that reveal a distal succession of laterally extensive, large-volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Basalt formations of the CRBG. These “great flows” are typical of the well-studied flood basalt-dominated Columbia Plateau, where interbedded silicic and calc-alkaline lavas are conspicuously absent. The latter part of Day 1 will highlight exposures of middle to late Miocene silicic ash-flow tuffs, rhyolite domes, and

  14. In Situ Dissimilatory Nitrate Reduction to Ammonium in a Paddy Soil Fertilized with Liquid Cattle Waste

    Institute of Scientific and Technical Information of China (English)

    LU Wei-Wei; S.RIYA; ZHOU Sheng; M.HOSOMI; ZHANG Hai-Lin; SHI Wei-Ming

    2012-01-01

    Most studies on dissimilatory nitrate reduction to ammonium (DNRA) in paddy soils were conducted in the laboratory and in situ studies are in need for better understanding of the DNRA process.In this study,in situ incubations of soil DNRA using 15N tracer were carried out in paddy fields under conventional water (CW) and low water (LW) managements to explore the potential of soil DNRA after liquid cattle waste (LCW) application and to investigate the impacts of soil redox potential (Eh) and labile carbon on DNRA.DNRA rates ranged from 3.06 to 10.40 mg N kg -1 dry soil d-1,which accounted for 8.55%-12.36% and 3.88%-25.44% of consunption of added NO3-15N when Eh at 5 cm soil depth ranged from 230 to 414 mV and -225 to -65 mV,respectively.DNRA rates showed no significant difference in paddy soils under two water managements although soil Eh and/or dissolved organic carbon (DOC) were more favorable for DNRA in the paddy soil under CW management 1 d before,or 5 and 7 d after LCW application.Soil DNRA rates were negatively correlated with soil Eh (P < 0.05,n =5) but positively correlated with soil DOC (P < 0.05,n =5) in the paddy soil under LW management,while no significant correlations were shown in the paddy soil under CW management.The potential of DNRA measured in situ was consistent with previous laboratory studies; and the controlling factors of DNRA in paddy soils might be different under different water managements,probably due to the presence of different microfloras of DNRA.

  15. Cadmium (Cd) distribution and contamination in Chinese paddy soils on national scale.

    Science.gov (United States)

    Liu, Xiaojuan; Tian, Guangjin; Jiang, Dong; Zhang, Chi; Kong, Lingqiang

    2016-09-01

    Rice is a staple food by an increasing number of people in China. As more issues have arisen in China due to rice contaminated by cadmium (Cd), Cd contamination in arable soils has become a severe problem. In China, many studies have examined Cd contamination in arable soils on a national scale, but little studies have focused on the distribution of Cd in paddy fields. This study explored the spatial pattern of Cd in paddy soils in China, made a preliminary evaluation of the potential risk, and identified the most critically contaminated regions based on the domestic rough rice trade flow. The results showed that Cd concentrations in paddy soils in China ranged from 0.01 to 5.50 mg/kg, with a median value of 0.23 mg/kg. On average, the highest Cd concentrations were in Hunan (0.73 mg/kg), Guangxi (0.70 mg/kg), and Sichuan (0.46 mg/kg) provinces. Cd concentrations in paddy soils in central and western regions were higher than those in eastern regions, especially the southeastern coastal regions. Of the administrative regions, Cd standard exceedance rate was 33.2 %, and the heavy pollution rate was 8.6 %. Regarding to Cd of paddy soil, soil environmental quality was better in Northeast China Plain than in Yangtze River Basin and southeastern coastal region. Mining activities were the main anthropogenic pollution source of Cd in Chinese paddy soil. Based on rice trade, more of the Chinese population would be exposed to Cd through intake of rice produced in Hunan province. Certain regions that output rice, especially Hunan province, should be given priority in the management and control of Cd contamination in paddy soil.

  16. Design and field test equipment of river water level detection based on ultrasonic sensor and SMS gateway as flood early warning

    Science.gov (United States)

    Sulistyowati, Riny; Sujono, Hari Agus; Musthofa, Ahmad Khamdi

    2017-06-01

    Due to the high rainfall, flood often occurs in some regions, especially in the area adjacent to the river banks that led to the idea to make the river water level detection system as a flood early warning. Several researches have produced flood detection equipment based on ultrasonic sensors and android as flood early warning system. This paper reported the results of a field test detection equipment to measure the river water level of the Bengawansolo River that was conducted in three villages in the district of Bungah, Dukun, and Manyar in Gresik regency. Tests were conducted simultaneously for 21 hours during heavy rainfall. The test results demonstrated the accuracy of the equipment of 97.28% for all categories of observation. The application of AFD (Android Flood Detection) via android smartphone demonstrated its precision in conveying the information of water level as represented by the status of SAFE, STAND, WARNING, and DANGER. Some charts presented from the analysis of data was derived from the data acquisition time of testing that can be used as an evaluation of flooding at some points prone to flood.

  17. Study on alternative cultivation patterns on nitrous oxide reduction in paddy fields of Fuzhou Plain%栽培方式对福州平原稻田氧化亚氮减排的研究

    Institute of Scientific and Technical Information of China (English)

    林芳; 王纯; 王维奇; 马永跃

    2014-01-01

    采用静态箱-气相色谱法对手插、抛秧、机插和直播的稻田氧化亚氮通量季节变化进行了测定与分析。研究结果表明:观测期内,手插、抛秧、机插和直播样地氧化亚氮季节变化通量分别为-55.67~63.73、-53.03~70.31、-47.41~84.29、-27.38~85.10μg/(m2· h ),平均值分别为7.71、20.98、11.24、37.78μg/(m2· h)。pH和Eh对手插样地氧化亚氮通量具有显著的影响,其他处理样地则是受到多因子的综合作用。从水稻千粒质量看,4种栽培方式由小到大的排序为机插、手插、直播、抛秧,从单丛产量看,4种栽培方式由小到大的排序为手插、抛秧、机插、直播。%In order to clarify the effect of alternative cultivation patterns on paddy field nitrous oxide fluxes ,seasonal nitrous oxide variation of hand transplanting ,seedlings throwing ,machine transplanting and direct seeding is determined by static chamber-gas chromatogram .The results show that the seasonal variations of nitrous oxide fluxes are -55 .67~63 .73 ,-53 .03~70 .31 ,-47 .41~84 .29 and -27 .38~85 .10μg/(m2 · h) ,and the averaged values were 7 .71 ,20 .98 , 11 .24 and 37 .78μg/(m2 · h) ,respectively .Nitrous oxide values are followed the order of hand transplanting < machine transplanting < seedlings throwing

  18. Selectivity of Chinese mitten -handed crab for major weeds in the northern paddy fields%河蟹对北方稻田主要杂草选择性的初步研究

    Institute of Scientific and Technical Information of China (English)

    吕东锋; 王武; 马旭洲; 陈再忠; 白国福; 陈卫新; 于永清

    2011-01-01

    The selection and feeding of weeds and rice were studied in Chinese mitten -handed crab (Eriocheir sinensis) with different body weights of 1 -10, 11 -20, 21 -30 and ≥30 g cultured in net cages disposed in a paddy field. It was found that the crab showed significantly feeding selection of the weeds, the maximal food consumption for wild arrowhead, followed by for Potamogeton and Monochoria grass and the minimal for barnyard grass and rice. The crabs with different sizes were found to have different consumption of the weeds. The crab weighing 20 -30 g had the maximal food consumption of the wild arrowhead, significantly different from the others (P < 0.01 ). The crab over 30 g showed the minimal food consumption of Monochoria vaginalis ,and Echinochloa crusgalli ( P < 0.05 ). The crab weighing 1 - 10 g had the maximal food consumption of the barnyard grass and rice, significantly different from the others( P < 0.01 ).%研究了在稻田中用网箱养殖的不同规格的中华绒螯蟹Eriocheir sinensis对稻田中4种杂草和水稻的选择性及摄食情况.结果表明:中华绒螫蟹对稻田杂草的摄食存在明显的选择性,对野慈姑Sagittaria trifolia var.sinensis的摄食量最大,对鸭舌草Monochoria vaginalis和眼子菜Potamogeton franchetii的摄食量相对较少,对稗草Echinochloa crusgalli和水稻的摄食量最差.不同规格的中华绒螯蟹对杂草的摄食率有所不同,20~30 g的中华绒螯蟹对野慈姑的摄食率最高,与其它3种规格的中华绒螯蟹间存在极显著差异(P<0.01);30g以上的中华绒螯蟹对鸭舌草和眼子菜的摄食率均最低,与其它规格的中华绒螯蟹间存在显著差异(P<0.05);1~10 g的中华绒螯蟹对稗草和水稻的摄食率最高,与其它规格的中华绒螯蟹间存在极显著差异(P<0.01).

  19. Effect of no-tillage and tillage on the ecology of mite, Acarina (Oribatida) in two different farming systems of paddy field in Cachar district of Assam.

    Science.gov (United States)

    Singh, Leimapokpam Amarjit; Ray, D C

    2015-01-01

    The present investigation was carried out in Cachar district of Assam over a period of one year (January 2011 - December 2011) to understand the seasonal ecology of Acarina (Oribatida) in rice (Oryza sativa L.) cultivated fields. Population of Oribatida was found to be maximum during August 2011, both in no-tillage (6.32 ± 0.66 No./m2 x 100(2)) and tillage (5.30 ± 0.71 No./M2 x 100(2)) sites in Dorgakona area whereas the peak was recorded during August 2011, both in no-tillage (5.38 ± 0.75 No./m(2) x 100(2)) and tillage (4.69 ± 0.77 No./m2 x 100(2)) in Durby area of study sites. Least population was encountered during January 2011, in both no-tillage (0.98 ± 0.28 ± No./m2 x 100(2)) and tillage (0.98 ± 0.30 No/m2 x 100(2)) sites in Dorgakona area whereas the same was found during November 2011 in no-tillage (0.57 ± 0.31 No.m/2 x 100(2)) and in February 2011 in tillage (0.45 ± 0.21 No./m2 x 100(2)) sites of Durby area. Linear regression analysis with all the environmental variables showed positive and significant influence on the population dynamics whereas relative humidity (R2 = 0.26 p > 0.05) in Dorgakona no-tillage and tillage (R2 = 0.19 P > 0.05) sites and relative humidity in tillage site (R2 = 0.27 P > 0.05) in Durby area showed no influence. Multiple regression analysis showed that the combined effect of climatic variables having a significant influence (p tillage and tillage systems in both the study sites. Rainfall, relative humidity and temperature facilitated the soil moisture, microbial activity and litter decomposition, which in turn may favour the reproduction and growth rate of the species. Among microclimatic conditions all the parameters showed positive and significant influence (P tillage and tillage system on both the sites except pH which showed negative correlation with the population. One way ANOVA revealed significant difference (F = 6.53, P < 0.01) of the Oribatid population between the systems.

  20. Tolerance of transgenic canola plants (Brassica napus) amended with plant growth-promoting bacteria to flooding stress at a metal-contaminated field site.

    Science.gov (United States)

    Farwell, Andrea J; Vesely, Susanne; Nero, Vincent; Rodriguez, Hilda; McCormack, Kimberley; Shah, Saleh; Dixon, D George; Glick, Bernard R

    2007-06-01

    The growth of transgenic canola (Brassica napus) expressing a gene for the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase was compared to non-transformed canola exposed to flooding and elevated soil Ni concentration, in situ. In addition, the ability of the plant growth-promoting bacterium Pseudomonas putida UW4, which also expresses ACC deaminase, to facilitate the growth of non-transformed and transgenic canola under the above mentioned conditions was examined. Transgenic canola and/or canola treated with P. putida UW4 had greater shoot biomass compared to non-transformed canola under low flood-stress conditions. Under high flood-stress conditions, shoot biomass was reduced and Ni accumulation was increased in all instances relative to low flood-stress conditions. This is the first field study to document the increase in plant tolerance utilizing transgenic plants and plant growth-promoting bacteria exposed to multiple stressors.

  1. Efficient Nitrogen Application Strategy to Hybrid Rice in Chongqing Winter Paddy Field%重庆冬水田地区杂交水稻的高效施氮策略

    Institute of Scientific and Technical Information of China (English)

    姚雄; 李经勇; 文明; 刘代杰; 唐永群

    2015-01-01

    为提高以重庆为代表的西南丘陵山区冬水田水稻的单产水平及氮肥的利用率,实现区域水稻高产高效和生态友好等目标。笔者以大面积水稻生产代表品种‘渝香203’为材料,采用田间试验的方法,研究了氮肥施用量与施用方式对水稻抽穗—成熟期生物产量积累与分配、氮素利用率及稻谷产量的影响。研究结果表明:水稻生物产量、氮积累总量以及稻谷产量均随施氮量增加而增加。氮肥后移作穗肥有利于水稻的生物产量积累和合理分配,在中氮处理(10 kg/666.7 m2)采用底肥:穗肥=5:5的施氮方式下,水稻茎鞘输出率和转换率均较高,分别达到56.59%和48.59%。氮肥后移作穗肥有利于提高氮农学利用效率和表观利用率,适宜的施氮比例受施氮量的影响而不同。氮肥后移作穗肥有利于提高水稻的穗平实粒数、结实率和千粒重,实现大穗高产。兼顾稻谷产量与氮肥高效,重庆冬水田地区杂交水稻的高效施氮策略为纯氮10 kg/666.7 m2,且采用底肥:穗肥=6:4或5:5的施氮方式。稻谷实际产量为9910.68~9940.62 kg/hm2,平均产量为9925.65 kg/hm2。%The study aims to improve per unit yield and nitrogen use efficiency in southwest hilly and mountain area winter paddy fields represented by Chongqing and achieve the target of high yield and high efficiency in regional rice production and an environmental friendly production process. The author selected‘Yuxiang 203’ as material, took the method of field trial and studied the effects of fertilizer application amount and methods on accumulation and distribution of biological yield, nitrogen use efficiency and rice yield in heading to mature stage. The results showed that, rice biological yield, nitrogen accumulation quantity and grain yiel d increased with the increase of nitrogen application rate. Use nitrogen fertilizer as heading fertilizer was conducive to

  2. 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.

  3. Field verification of reconstructed dam-break flood, Laurel Run, Pennsylvania

    Science.gov (United States)

    Chen, Cheng-lung; Armbruster, Jeffrey T.

    1979-01-01

    A one-dimensional dam-break flood routing model is verified by using observed data on the flash flood resulting from the failure of Laurel Run Reservoir Dam near Johnstown, Pennsylvania. The model has been developed on the basis of an explicit scheme of the characteristics method with specified time intervals. The model combines one of the characteristic equations with the Rankine-Hugoniot shock equations to trace the corresponding characteristic backward to the known state for solving the depth and velocity of flow at the wave front. The previous version of the model has called for a modification of the method of solution to overcome the computational difficulty at the narrow breach and at any geomorphological constraints where channel geometry changes rapidly. The large reduction in the computational inaccuracies and oscillations was achieved by introducing the actual "storage width" in the equation of continuity and the imaginary "conveyance width" in the equation of motion. Close agreement between observed and computed peak stages at several stations downstream of the dam strongly suggests the validity and applicability of the model. However, small numerical noise appearing in the computed stage and discharge hydrographs at the dam site as well as discrepancy of attenuated peaks in the discharge hydrographs indicate the need for further model improvement.

  4. Collecting data for quantitative research on pluvial flooding

    NARCIS (Netherlands)

    Spekkers, M.H.; Ten Veldhuis, J.A.E.; Clemens, F.H.L.R.

    2011-01-01

    Urban pluvial flood management requires detailed spatial and temporal information on flood characteristics and damaging consequences. There is lack of quantitative field data on pluvial flooding resulting in large uncertainties in urban flood model calculations and ensuing decisions for investments

  5. Collecting data for quantitative research on pluvial flooding

    NARCIS (Netherlands)

    Spekkers, M.H.; Ten Veldhuis, J.A.E.; Clemens, F.H.L.R.

    2011-01-01

    Urban pluvial flood management requires detailed spatial and temporal information on flood characteristics and damaging consequences. There is lack of quantitative field data on pluvial flooding resulting in large uncertainties in urban flood model calculations and ensuing decisions for investments

  6. Chemical and Microbiological Parameters of Paddy Soil Quality as Affected by Different Nutrient and Water Regimes

    Institute of Scientific and Technical Information of China (English)

    YANG Chang-Ming; YANG Lin-Zhang; YAN Ting-Mei

    2005-01-01

    A field experiment was conducted from 1999 to 2002 to compare and evaluate the effects of nutrient and water regimes on paddy soil quality by investigating soil chemical and microbiological parameters. Four nutrient regimes, a control, chemical fertilizers only (CF), chemical fertilizers with swine manure (SM), and chemical fertilizers with wheat straw (WS), and two soil moisture regimes, continuous waterlogging (CWL) and alternate wetting and drying (AWD),were investigated. With SM and WS total organic carbon and total nitrogen in the paddy soil were significantly higher (P <0.05) than those with CF. A similar effect for organic amendments was observed in the soil light fraction organic C (LFOC), water-soluble carbohydrates (WSC), and water-soluble organic C (WSOC). CWL, in particular when swine manure was incorporated into the paddy soil, markedly decreased soil redox potential (Eh) and increased total active reducing substances (ARS). Meanwhile, as compared to CF, SM and WS significantly (P < 0.05) increased soil microbial biomass C (MBC) and mineralizable carbon, with differences in AWD being higher than CWL. In addition, SM and WS treatments significantly (P < 0.05) improved rice above-ground biomass and grain yield, with AWD being greater than CWL. Thus, for ecologically sustainable agricultural management of paddy soils, long-term waterlogging should be avoided when organic manure was incorporated into paddy soil.

  7. SU-C-202-07: Protocol and Hardware for Improved Flood Field Calibration of TrueBeam FFF Cine Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, J; Faught, A; Yin, F [Duke University Medical Center, Durham, NC (United States)

    2016-06-15

    Purpose: Flattening filter free photon energies are commonly used for high dose treatments such as SBRT, where localization accuracy is essential. Often, MV cine imaging may be employed to verify correct localization. TrueBeam Electronic Portal Imaging Devices (EPIDs) equipped with the 40×30cm{sup 2} Image Detection Unit (IDU) are prone to image saturation at the image center especially for higher dose rates. While saturation often does not occur for cine imaging during treatment because the beam is attenuated by the patient, the flood field calibration is affected when the standard calibration procedure is followed. Here we describe the hardware and protocol to achieve improved image quality for this model of TrueBeam EPID. Methods: A stainless steel filter of uniform thickness was designed to have sufficient attenuation to avoid panel saturation for both 6XFFF and 10XFFF at the maximum dose rates (1400 MU/min & 2400 MU/min, respectively). The cine imaging flood field calibration was then acquired with the filter in place for the FFF energies under the standard calibration geometry (SDD=150cm). Image quality during MV cine was assessed with & without the modified flood field calibration using a low contrast resolution phantom and an anthropomorphic phantom. Results: When the flood field is acquired using the standard procedure (no filter in place), a pixel gain artifact is clearly present in the image center (r=3cm for 10XFFF at 2400 MU/min) which appears similar to and may be mis-attributed to panel saturation in the subject image. The artifact obscured all low contrast inserts at the image center and was also visible on the anthropomorphic phantom. Using the filter for flood field calibration eliminated the artifact. Conclusion: Use of a modified flood field calibration procedure improves image quality for cine MV imaging with TrueBeams equipped with the 40×30cm{sup 2} IDU.

  8. [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.

  9. 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.

  10. Effects of Peanut Shell Biochar on the Adsorption of Cd(II) by Paddy Soil.

    Science.gov (United States)

    Xu, Chao; Wen, Dong; Zhu, Qihong; Zhu, Hanhua; Zhang, Yangzhu; Huang, Daoyou

    2017-03-01

    Soil from an experimental paddy field in southern China was incubated with peanut shell biochar to investigate effects of this additive on the adsorption and desorption characteristics of Cd(II) using batch methods. Incorporation of biochar increased adsorption of Cd(II) by the paddy soil at 20, 25, and 30°C; this trend was apparent both with increasing quantities of biochar and rising temperature. Incorporation of biochar primarily enhanced the non-electrostatic adsorption of Cd(II). In addition, supplementation with biochar decreased the adsorption rate of Cd(II), which decreased with increasing quantities of biochar. The Langmuir constant b and Freundlich constant kf both increased with greater quantities of biochar at different temperatures. Adsorption of Cd(II) was an endothermic process and occurred spontaneously. Incorporation of biochar decreased availability and mobility of Cd(II) to plants primarily through increased non-electrostatic adsorption of Cd(II) by paddy soil.

  11. New piecewise-continuous hydraulic functions for modeling preferential flow in an intermittent-flood-irrigated field

    Science.gov (United States)

    Mohanty, B. P.; Bowman, R. S.; Hendrickx, J. M. H.; van Genuchten, M. T.

    Modeling water flow in macroporous field soils near saturation has been a major challenge in vadose zone hydrology. Using in situ and laboratory measurements, we developed new piecewise-continuous soil water retention and hydraulic conductivity functions to describe preferential flow in tile drains under a flood-irrigated agricultural field in Las Nutrias, New Mexico. After incorporation into a two-dimensional numerical flow code, CHAIN_2D, the performance of the new piecewise-continuous hydraulic functions was compared with that of the unimodal van Genuchten-Mualem model and with measured tile-flow data at the field site during a number of irrigation events. Model parameters were collected/estimated by site characterization (e.g., soil texture, surface/subsurface saturated/unsaturated soil hydraulic property measurements), as well as by local and regional-scale hydrologic monitoring (including the use of groundwater monitoring wells, piezometers, and different surface-irrigation and subsurface-drainage measurement systems). Comparison of numerical simulation results with the observed tile flow indicated that the new piecewise-continuous hydraulic functions generally predicted preferential flow in the tile drain reasonably well following all irrigation events at the field site. Also, the new bimodal soil water retention and hydraulic conductivity functions performed better than the unimodal van Genuchten-Mualem functions in terms of describing the observed flow regime at the field site.

  12. Comparison between wavelet transform and moving average as filter method of MODIS imagery to recognize paddy cropping pattern in West Java

    Science.gov (United States)

    Dwi Nugroho, Kreshna; Pebrianto, Singgih; Arif Fatoni, Muhammad; Fatikhunnada, Alvin; Liyantono; Setiawan, Yudi

    2017-01-01

    Information on the area and spatial distribution of paddy field are needed to support sustainable agricultural and food security program. Mapping or distribution of cropping pattern paddy field is important to obtain sustainability paddy field area. It can be done by direct observation and remote sensing method. This paper discusses remote sensing for paddy field monitoring based on MODIS time series data. In time series MODIS data, difficult to direct classified of data, because of temporal noise. Therefore wavelet transform and moving average are needed as filter methods. The Objective of this study is to recognize paddy cropping pattern with wavelet transform and moving average in West Java using MODIS imagery (MOD13Q1) from 2001 to 2015 then compared between both of methods. The result showed the spatial distribution almost have the same cropping pattern. The accuracy of wavelet transform (75.5%) is higher than moving average (70.5%). Both methods showed that the majority of the cropping pattern in West Java have pattern paddy-fallow-paddy-fallow with various time planting. The difference of the planting schedule was occurs caused by the availability of irrigation water.

  13. Clomazone dissipation,adsorption and translocation in four paddy topsoils

    Institute of Scientific and Technical Information of China (English)

    LI Lian-fang; LI Guo-xue; YANG Ren-bin; GUO Zheng-yuan; LIAO Xiao-yong

    2004-01-01

    Laboratory experiments about the dissipation, adsorption and translocation in four paddy topsoils were conducted in this paper. From the results it can be concluded as follows: the dissipation rate of clomazone differed greatly in different paddy soil derived from different parent materials. The half-lives for clomazone degradation in paddy soils ranged from 5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy soil >alluvial sandy paddy soil > yellow clayey paddy soil > purple sandy paddy soil. Clomazone sorption quantity was significantly correlated with organic carbon ( R2 = 0.62) and clay content ( R2 = 0.67) in the tested paddy soils.Positive correlation was found between apparent Kd value and cation exchange content(CEC). The consequences for the adsorption of different soils were purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm through four different unsaturated soil lysimeters over 24 h, clomazone was readily to be leached into lower surface soil and there was about 2.6%-4.2%of applied clomazone leached out of 20 cm cultivated soil layer. Translocation experiments showed that the order of clomazone leaching ability was: alluvial sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil >purple sandy paddy soil. Simple regression results manifested that factors like CEC, organic carbon, clay, and adsorption rate constant had been negatively correlated with the percentage of clomazone loss from soil lysimeters.

  14. Study on Application Efficiency of Slow/Controlled Release Fertilizer in Paddy Field in South Henan%豫南稻区水稻缓/控释肥应用效果研究

    Institute of Scientific and Technical Information of China (English)

    吕玉虎

    2012-01-01

    为了探讨水稻缓/控释肥在豫南稻区的应用效果,通过田间试验,研究施用水稻缓/控释肥对水稻生长发育、产量和氮素利用率等方面的影响.结果表明,施用等量水稻缓/控释肥比施普通复合肥增加了水稻分蘖数,提高了水稻群体质量;增加了水稻在生育中后期,尤其是水稻灌浆期叶片的叶绿素含量;提高了水稻有效穗、穗实粒数.施用水稻缓/控释肥水稻产量达到9233.3~9725.0 kg/hm2,比施等量普通复合肥增产5.5%~1 1.1%,增产达极显著水平.施用水稻缓/控释肥比施等量普通复合肥氮素利用率、氮素农学效率分别高18.9%~22.9%、2.9%~5.9%.在豫南稻区施用水稻缓/控释肥能增加水稻产量、提高水稻氮素利用效率.%The effects of application of slow/controlled release fertilizer on rice growth, rice grain yield and utilization efficiency of nitrogen were studied through a field experiment. The results showed that, the same amounts of slow/controlled release fertilizer improved tiller number, the population quality of rice and increased the chlorophyll content of rice leaves at middle and late growth phase, especially in the grain filling stage, which resulted in higher effective tiller and filled grain, compared with CK. The rice grain yield was 9233.3-9725.0 kg/hm2 with the application of slow/controlled release fertilizer, which increased by 5.5%-11.1% (P < 0.01), compared with the same amounts of compound fertilizer. Utilization efficiency of nitrogen and agronomic efficiency of nitrogen applied slow/controlled release fertilizer were 18.9%-22.9%, 2.9%-5.9% respectively higher than those with the application of compound fertilizer. In conclusion, higher rice yield and utilization efficiency of nitrogen were obtained when slow/controlled release fertilizer was applied to paddy field in south Henan Province.

  15. Effects of Herbicide Residues in Paddy Field Water on Growth of the Aquatic Plant Pistia stratiotes%稻田除草剂水体残留对水生植物大薸的影响

    Institute of Scientific and Technical Information of China (English)

    王子臣; 朱普平; 郑建初; 盛婧; 陈留根

    2012-01-01

    采用模拟方法研究了稻田3种常用除草剂丁草胺、苄嘧磺隆、2甲4氯钠残留水体对大薸生长的影响.结果显示:(1)3种除草剂水体残留对大薸植株形态影响以苄嘧磺隆处理最为明显,残留浓度大于0.01 mg/L可导致大薸植株大量死亡.4.25 mg/L的丁草胺和3.36 mg/L的2甲4氯钠残留对大薸的生长均有一定的抑制作用,但短期内不能致死.当水体除草剂残留降低至田间常规管理施用浓度的1/8时,即丁草胺0.53 mg/L、苄嘧磺隆0.01 mg/L、2甲4氯钠0.42 mg/L,大薸植株形态的药害影响已经明显减轻.(2)苄嘧磺隆水体残留大于0.01 mg/L时大薸干物质产量显著降低,分株生长受到严重抑制.丁草胺残留浓度为0.53 mg/L时促进大薸干物质积累和分株生长,当残留浓度大于1.06 mg/L时大薸干物质积累和分株生长受到抑制.2甲4氯钠残留浓度低于3.36 mg/L对大薸的干物质产量、分株数及植株含水率影响一般.%Effects of three herbicide (butachlor, bensulfuron - methyl and MCPA - Na) residues in the paddy field water on growth of the aquatic plant Pistia stratiotes were studied by a simulation method. The results showed that: (1) among three herbicides,bensulfuron -methyl residues presented obvious effect on the morphological characters of Pistia stratiotes, and it can lead to Pistia stratiotes large number of death while its concentration reached more than 0.01 mg/L. Both 4.25 mg/L butachlor and 3.36 mg/L MCPA - Na had a certain degree inhibition on the growth of Pistia stratiotes, but can't lead to death during the short period of time. When the concentration of herbicide residues in water reduced to 1/8 of the conventional concentration level applied in the field i. e. 0. S3 mg/L butachlor,0.01 mg/L bensulfuron - methyl,0.42 mg/L MCPA-Na,the influence of herbicide residues on plant morphology of Pistia stratiotes reduced significantly. (2) When the concentration of bensulfuron - methyl residues in

  16. Evolution of regional to global paddy rice mapping methods

    Science.gov (United States)

    Dong, J.; Xiao, X.

    2016-12-01

    Paddy rice agriculture plays an important role in various environmental issues including food security, water use, climate change, and disease transmission. However, regional and global paddy rice maps are surprisingly scarce and sporadic despite numerous efforts in paddy rice mapping algorithms and applications. In this presentation we would like to review the existing paddy rice mapping methods from the literatures ranging from the 1980s to 2015. In particular, we illustrated the evolution of these paddy rice mapping efforts, looking specifically at the future trajectory of paddy rice mapping methodologies. The biophysical features and growth phases of paddy rice were analyzed first, and feature selections for paddy rice mapping were analyzed from spectral, polarimetric, temporal, spatial, and textural aspects. We sorted out paddy rice mapping algorithms into four categories: 1) Reflectance data and image statistic-based approaches, 2) vegetation index (VI) data and enhanced image statistic-based approaches, 3) VI or RADAR backscatter-based temporal analysis approaches, and 4) phenology-based approaches through remote sensing recognition of key growth phases. The phenology-based approaches using unique features of paddy rice (e.g., transplanting) for mapping have been increasingly used in paddy rice mapping. Based on the literature review, we discussed a series of issues for large scale operational paddy rice mapping.

  17. Aerobic biodegradation process of petroleum and pathway of main compounds in water flooding well of Dagang oil field.

    Science.gov (United States)

    Cai, Minmin; Yao, Jun; Yang, Huaijun; Wang, Ruixia; Masakorala, Kanaji

    2013-09-01

    Aerobic biodegradation of crude oil and its pathways were investigated via in vitro culture and GC-MS analysis in water flooding wells of Dagang oil field. The in vitro aerobic culture lasted 90 days when 99.0% of n-alkanes and 43.03-99.9% of PAHs were degraded and the biomarkers and their ratios were changed. The spectra of components in the residual oil showed the similar biodegradation between aerobic process of 90 days and degradation in reservoir which may last for some millions years, and the potential of serious aerobic biodegradation of petroleum in reservoir. 24 Metabolites compounds were separated and identified from aerobic culture, including fatty acid, naphthenic acid, aromatic carboxylic acid, unsaturated acid, alcohols, ketones and aldehydes. The pathways of alkanes and aromatics were proposed, which suggests that oxidation of hydrocarbon to organic acid is an important process in the aerobic biodegradation of petroleum. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. 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

  19. 太湖地区稻田氮肥吸收及其利用的研究%Nitrogen uptake and its utilization by rice in paddy field of Taihu area

    Institute of Scientific and Technical Information of China (English)

    宋勇生; 范晓晖

    2003-01-01

    The effects of different amounts and kinds of nitrogen fertilizer on rice yield and its nitrogen uptake and utiliza-tion were studied on a main paddy soil (Wushan soil) of Taihu area. The results indicated that the optimal amount of nitrogen fertilizer was about 180 kg N· hm-2 for rice production. Applying ammonium sulfate was better than applying urea for increasing rice yield. The efficiency of nitrogen fertilizer in this experiment was about 41.8-48.5%, and its loss was 22.8-38.1% .

  20. Quantitative and qualitative trapping of arsines deployed to assess loss of volatile arsenic from paddy soil.

    Science.gov (United States)

    Mestrot, Adrien; Uroic, M Kalle; Plantevin, Thomas; Islam, Md Rafiqul; Krupp, Eva M; Feldmann, Jörg; Meharg, Andrew A

    2009-11-01

    Arsenic volatilization in the environment is thought to be an important pathway for transfer from terrestrial pools to the atmosphere. However, this phenomenon is not well characterized due to inherent sampling issues in trapping, quantifying and qualifying these arsine gases; including arsine (AsH(3)), monomethyl arsine (MeAsH(2)), dimethyl arsine (Me(2)AsH) and trimethyl arsine (TMAs). To quantify and qualify arsines in air we developed a novel technique based on silver nitrate impregnated silica gel filled tubes. The method was characterized by measuring the recovery of trapped arsines after elution of this chemo-trap with hot boiling diluted nitric acid. Results from three separate experiments, measured by ICP-MS, showed that the method is reproducible and quantitative. Arsine species recovery ranged from 80.1 to 95.6%, with limit of detection as low as 3.8 ng per chemo-trap tube. Moreover, HPLC-ICP-MS analysis of hot boiling water eluted traps showed that the corresponding oxy ions of the arsines were formed with the As-C bonds of the molecule intact, hence, allowing qualification of trapped arsine species. A microcosm study examining volatile arsenic evolution from field contaminated Bangladeshi paddy soils (24.2 mg/kg arsenic) was used to show the application of silver nitrate chemo-trapping approach. Traps were placed on the inlet and the outlet of microcosms containing the soils that were either (cattle derived) manured or not, or flooded or not, in a factorial design. The headspace was purged with air at a flow rate of 12 mL/min. Results showed that as much as 320 ng of arsenic (0.014% of total soil content) could be emitted in a 3 week period for manured and flooded soils and that TMAs was the dominant species evolved, with lesser quantities of Me(2)AsH. No volatile arsenic evolution was observed for nonmanured treatments, and arsine release from the nonflooded, manured treatment was much less than the flooded treatment.

  1. Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

    Science.gov (United States)

    Zhao, Lei; Anderson, Christopher W. N.; Qiu, Guangle; Meng, Bo; Wang, Dingyong; Feng, Xinbin

    2016-04-01

    Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

  2. A comparison of methane emissions following rice paddies conversion to crab-fish farming wetlands in southeast China.

    Science.gov (United States)

    Hu, Zhiqiang; Wu, Shuang; Ji, Cheng; Zou, Jianwen; Zhou, Quansuo; Liu, Shuwei

    2016-01-01

    Rice paddies and aquaculture wetlands are typical agricultural wetlands that constitute one of the important sources of atmospheric methane (CH4). Traditional transplanted rice paddies have been experiencing conversion to pond aquaculture wetlands for pursuing higher economic benefits over the past decades in southeast China. A parallel field experiment was carried out to compare CH4 emissions from a transplanted rice paddy and its converted crab-fish farming wetland in southeast China. Over the rice-growing season, CH4 fluxes averaged 1.86 mg m(-2) h(-1) from rice paddies, and 1.14 and 0.50 mg m(-2) h(-1) for the treatments with or without aquatic vegetation present in the crab-fish farming wetlands, respectively. When averaged across the treatments, seasonal CH4 emissions from crab-fish framing wetlands were 52% lower than those from rice paddies. The CH4 fluxes were negatively related to water dissolved oxygen (DO) concentration but positively related to soil/sediment dissolved organic carbon (DOC) content in crab-fish farming wetlands. Dependence of CH4 fluxes on DO or DOC was intensified by the aquatic vegetation presence. By extrapolating the present CH4 emission rate with the current rice paddy-converted aquaculture cultivation area, the seasonal CH4 emissions from inland aquaculture wetlands during the critical farming stage (20 June to 18 October) were estimated to be 33.6 Gg ha(-1) in southeast China in 2012. Rice paddies conversion to crab-fish farming wetlands might have reduced CH4 emissions by 22-54% in mainland China. Results of this study suggest that the conversion of transplanted rice paddies to crab-fish aquaculture wetlands for higher economic benefits would also lead to a lower ecosystem CH4 release rate.

  3. Development of a complete rice paddy map dataset over Asia using MODIS data

    Science.gov (United States)

    Takeuchi, W.; Oki, T.; Baruah, P. J.; Yasuoka, Y.

    2005-12-01

    Two thirds of the rice-growing areas in the World are in Asian countries and hundreds of millions of people depend on rice as their staple food source. At the same time, paddy fields have been considered to be one of the likely and most important sources of atmospheric methane since the rapid increase in atmospheric methane was recognized in the early 1980's. The improved understanding of paddy field distribution at large spatial scales has increased the interest in deriving crop yield and methane emission estimations. Nevertheless, the collection of such data through field surveys is time-consuming and expensive in Asian regions. Remotely sensing data from satellite images provide an alternative means of obtaining paddy field distribution. In this study, the patterns observed in metrics calculated for one year of MODIS over Asia is examined. Four analytical approached are used; calculation of temporal mean, maximum and minimum layers for selected metrics showing significant spatial variability of channel 1-7, NDXI; linear discriminant for input into the spectral mixture analysis is derived from the same multi-temporal metrics used for the classification product using ASTER; the continuous percentage of paddy field is generated using spectral mixture analysis with the training data derived from the above mentioned ASTER data. The derived metrics are not sensitive to time of year or the seasonal cycle and can limit the inclusion of atmospheric contamination. The comparison of 500m MODIS product with the past efforts on 1km AVHRR derived AARS, BU, JRC, UMD, USGS product shows that the f