WorldWideScience

Sample records for clay loam soil

  1. [Effects of Different Residue Part Inputs of Corn Straws on CO2 Efflux and Microbial Biomass in Clay Loam and Sandy Loam Black Soils].

    Science.gov (United States)

    Liu, Si-yi; Liang, Ai-zhen; Yang, Xue-ming; Zhang, Xiao-ping; Jia, Shu-xia; Chen, Xue-wen; Zhang, Shi-xiu; Sun, Bing-jie; Chen, Sheng-long

    2015-07-01

    The decomposed rate of crop residues is a major determinant for carbon balance and nutrient cycling in agroecosystem. In this study, a constant temperature incubation study was conducted to evaluate CO2 emission and microbial biomass based on four different parts of corn straw (roots, lower stem, upper stem and leaves) and two soils with different textures (sandy loam and clay loam) from the black soil region. The relationships between soil CO2 emission, microbial biomass and the ratio of carbon (C) to nitrogen (N) and lignin of corn residues were analyzed by the linear regression. Results showed that the production of CO2 was increased with the addition of different parts of corn straw to soil, with the value of priming effect (PE) ranged from 215. 53 µmol . g-1 to 335. 17 µmol . g -1. Except for corn leaves, the cumulative CO2 production and PE of clay loam soil were significantly higher than those in sandy loam soil. The correlation of PE with lignin/N was obviously more significant than that with lignin concentration, nitrogen concentration and C/N of corn residue. The addition of corn straw to soil increased the contents of MBC and MBN and decreased MBC/MBN, which suggested that more nitrogen rather than carbon was conserved in microbial community. The augmenter of microbial biomass in sandy loam soil was greater than that in clay loam soil, but the total dissolved nitrogen was lower. Our results indicated that the differences in CO2 emission with the addition of residues to soils were primarily ascribe to the different lignin/N ratio in different corn parts; and the corn residues added into the sandy loam soil could enhance carbon sequestration, microbial biomass and nitrogen holding ability relative to clay loam soil. PMID:26489342

  2. Assessment of fate of thiodicarb pesticide in sandy clay loam soil

    International Nuclear Information System (INIS)

    in present study the fate of thiodicarb pesticide in sandy clay loam soil was investigated through its adsorption and leaching using hplc. Experimental results revealed that thiodicarb follows first order kinetic with rate constant value of 0.711 h-1 and equilibrium study showed that freundlich model was best fitted with multilayer adsorption capacity 3.749 mol/g and adsorption intensity 1.009. Therefore, adsorption of thiodicarb was multilayer, reversible and non-ideal. Leaching study has indicated intermediate mobility of thiodicarb with water due to its solubility, while field study showed the non-leacher nature. However both adsorption and leaching were heavily affected by soil characteristics. As the soil taken was sandy clay loam hence due to clay texture adsorption was higher because of vacant sites existing and greater surface area. For this the pesticide has remained adsorbed in above 20 cm soil layer as clearly seen from field study, minor amount was recorded in third layer of soil having 21-30 cm depth. The leached amount of thiodicarb in first and last part of water was 1.075 and 0.003 ng/ mu l. The general trend observed for adsorption in column and field soil was decreased downwards from 2.027 to 0.618 and 5.079 to 0.009 ng/mu l. (author)

  3. Assessment of Fate of Thiodicarb Pesticide in Sandy Clay Loam Soil

    Directory of Open Access Journals (Sweden)

    M. A. Bajeer

    2015-06-01

    Full Text Available In present study the fate of thiodicarb pesticide in sandy clay loam soil was investigated through its adsorption and leaching using HPLC. Experimental results revealed that thiodicarb follows first order kinetic with rate constant value of 0.711 h-1 and equilibrium study showed that Freundlich model was best fitted with multilayer adsorption capacity 3.749 mol/g and adsorption intensity 1.009. Therefore, adsorption of thiodicarb was multilayer, reversible and non-ideal. Leaching study has indicated intermediate mobility of thiodicarb with water due to its solubility, while field study showed the non-leacher nature. However both adsorption and leaching were heavily affected by soil characteristics. As the soil taken was sandy clay loam hence due to clay texture adsorption was higher because of vacant sites existing and greater surface area. For this the pesticide has remained adsorbed in above 20 cm soil layer as clearly seen from field study, minor amount was recorded in third layer of soil having 21-30 cm depth. The leached amount of thiodicarb in first and last part of water was 1.075 and 0.003 ng/µl. The general trend observed for adsorption in column and field soil was decreased downwards from 2.027 to 0.618 and 5.079 to 0.009 ng/µl.

  4. Influence of crop residues on trifluralin mineralization in a silty clay loam soil.

    Science.gov (United States)

    Farenhorst, Annemieke

    2007-01-01

    Trifluralin is typically applied onto crop residues (trash, stubble) at the soil surface, or onto the bare soil surface after the incorporation of crop residues into the soil. The objective of this study was to quantify the effect of the type and amount of crop residues in soil on trifluralin mineralization in a Wellwood silty clay loam soil. Leaves and stubble of Potato (Solanum tuberosum) (P); Canola (Brassica napus) (C), Wheat (Triticum aestivum) (W), Oats (Avena sativa), (O), and Alfalfa (Medicago sativa) (A) were added to soil microcosms at rates of 2%, 4%, 8% and 16% of the total soil weight (25 g). The type and amount of crop residues in soil had little influence on the trifluralin first-order mineralization rate constant, which ranged from 3.57E-03 day(-1) in soil with 16% A to 2.89E-02 day(-1) in soil with 8% W. The cumulative trifluralin mineralization at 113 days ranged from 1.15% in soil with 16% P to 3.21% in soil with 4% C, again demonstrating that the observed differences across the treatments are not of agronomic or environmental importance. PMID:17454379

  5. Reactive Clay Minerals in a land use sequence of disturbed soils of the Belgian Loam Belt

    Science.gov (United States)

    Barao, Lucia; Vandevenne, Floor; Ronchi, Benedicta; Meire, Patrick; Govers, Gerard; Struyf, Eric

    2014-05-01

    Clay minerals play a key role in soil biogeochemistry. They can stabilize organic matter, improve water storage, increase cation exchange capacity of the soil (CEC) and lower nutrient leaching. Phytoliths - the biogenic silica bodies (BSi) deposited in cell walls of plants - are important Si pools in soil horizons due to their higher solubility compared to minerals. They provide the source of Si for plant uptake in short time scales, as litter dissolves within soils. In a recent study, we analyzed the BSi pool differences across a set of different land uses (forests, pastures, croplands) in 6 long-term disturbed (multiple centuries) soil sites in the Belgium Loam Belt. Results from a simultaneous chemical extraction in 0.5M NaOH of Si and Al, showed that soils were depleted in the BSi pool while showing high levels of reactive secondary clay minerals, mainly in the deeper horizons and especially in the forests and the croplands. During the extraction, clays were similar in reactivity to the biogenic pool of phytoliths. In order to study the kinetics in a more natural environment, batch dissolution experiments were conducted. Samples from different soil depths for each land use site (0.5 g) were mixed with 0.5 L of demineralised water modified to pH 4, 7 and 10. Subsamples of 2 ml were taken during 3 months. In the end of the period, results for pH 7 showed that in the pastures, where reactive clays were almost absent, the ratio Si/RSi (defined as the Si concentration in the end of the batch experiment divided by the reactive silica extracted from the soil with the alkaline extraction) was lower than 0.005%. The same ratio was higher in the mineral horizons of forests (Si/RSi>0.01%) and croplands (0.005% < Si/RSi <0.01%) where clay minerals were the dominant fraction. These preliminary results highlight the clay minerals' strong potential for Si mobilization. More attention should be paid to this important fraction as it can contribute strongly to Si availability

  6. Changes in the sorption-desorption of fungicides over time in an amended sandy clay loam soil under laboratory conditions

    OpenAIRE

    Marín Benito, Jesús María; Andrades, M. S.; Rodríguez-Cruz, M. S.; Sánchez Martín, M. J.

    2012-01-01

    Purpose The aim of this work was to study the temporal changes in the sorption–desorption of fungicides in a sandy clay loam soil amended with spent mushroom substrate (SMS) under controlled laboratory conditions and the influence that fungicides properties and soil characteristics have on these processes. Soil amendment with SMS is becoming a widespread management practice since it can effectively solve the problems of uncontrolled SMS accumulation and disposal and improve soil quality...

  7. Short-Term Effects of Land Leveling on Irrigation-Related Some Soil Properties in a Clay Loam Soil

    OpenAIRE

    Öztekin, Tekin

    2013-01-01

    There are few studies conducted on the short-term effects of land leveling on soil water holding capacity. The objectives of this study were to analyze the short-term effects of land leveling on the magnitudes, variances, spatial variability, and distributions of surface (0–20 cm) and subsurface (20–40 cm) soil properties of bulk density, field capacity, permanent wilting point, water holding capacity and particle size fractions. The study was conducted in a 1.2 ha field with clay loam soil l...

  8. Performance Evaluation of Different Tillage Systems in a Clay Loam Soil

    International Nuclear Information System (INIS)

    Field experiments were conducted to assess the performance of different tillage systems in a clay loam soil. A completely randomized block design with four treatments i.e., conventional tillage (CT), minimum tillage (MT), zero tillage (ZT) and controlled traffic farming (CTF) was carried out to evaluate the performance of tillage systems. Results indicated that the soil pulverization was higher (P<0.05) under MT and lower under CT treatments while, it was non-significant between MT and CTF treatments. Similarly, soil volume disturbed and effective ploughing depth was maximum (P<0.05) under CT followed by MT, CTF and minimum under ZT. Similarly the operating speed was significantly higher (P<0.05) under CTF and lower under CT whereas, wheel slippage/travel reduction was significantly minimum (P<0.05) under CTF and maximum under CT. Significantly, higher field capacity was recorded under CTF and lower (P<0.05) under CT. The maximum fuel consumption (P<0.05) was recorded under CT while it was minimum under ZT. Almost similar trends were observed for all parameters in 2012 and 2013. The results suggested that the control traffic system was more efficient tillage system in terms of soil pulverization, operating speed, travel reduction and over all field capacity. While, zero tillage had minimum fuel consumption and conventional tillage had higher working depth hence, more soil volume was disturbed under this treatment. (author)

  9. THE EFFECT OF MIXING WITH ORGANIC SOIL ON CHANGES IN SOME PHYSICAL PROPERTIES OF A COMPACTED CLAY LOAM SOIL

    Directory of Open Access Journals (Sweden)

    Abdullah BARAN

    1996-01-01

    Full Text Available In this research, the effect of organic soil on changes in total pore space, aeration porosity, available water content and hydraulic conductivity of a compacted clay loam were investigated. By adding organic soil at rates of 0 %, 1 %, 2 % and 4 % to soil, mixtures were compacted at compaction levels of 0 kg/cm2, 0.21 kg/cm2, 1.98 kg/cm2 and 3.95 kg/cm2 Some physical properties of compacted soil were determined. Compaction decreased total pore space, areation porosity, available water content and hydraulic conductivity, but in samples with the mixing rate of 4 %, all properties inspected were affected positively in all compaction levels, except available water content

  10. Short-term effects of land leveling on irrigation-related some soil properties in a clay loam soil.

    Science.gov (United States)

    Öztekin, Tekin

    2013-01-01

    There are few studies conducted on the short-term effects of land leveling on soil water holding capacity. The objectives of this study were to analyze the short-term effects of land leveling on the magnitudes, variances, spatial variability, and distributions of surface (0-20 cm) and subsurface (20-40 cm) soil properties of bulk density, field capacity, permanent wilting point, water holding capacity and particle size fractions. The study was conducted in a 1.2 ha field with clay loam soil located on the low terraces of Yesilirmak River, Tokat, Turkey. According to the paired t-test results, water holding capacity, and bulk density significantly increased, while permanent wilting point (P ≤ 0.001) and field capacity (P ≤ 0.05) significantly decreased for surface soil due to land leveling. The reasons for the increases in WHC values in both cut and fill areas (29%, and 12%, resp.) of surface soil are look like the much more decreases in PWP values than those of FC values and the increases in BD values. The moderate positive linear relationship between the surface soil clay contents and cut depths through cut areas (r = 0.64) was also determined in this study. PMID:23843730

  11. The Effect of Chloride and Sulfate Ions on the Adsorption of Cd2+ on Clay and Sandy Loam Egyptian Soils

    OpenAIRE

    EL-Hefnawy, Mohamed E.; Selim, Elmetwaly M.; Assaad, Faiz F.; Ismail, Ali I.

    2014-01-01

    Adsorption of Cd2+ on two types of Egyptian soils: clay (alluvial) and sandy loam (calcareous), was studied. Effect of changing the matrix electrolyte type and concentration was used to mimic the natural soil salts. Kinetics and thermodynamic parameters of the adsorption were calculated at two different electrolyte concentrations: 0.05 N and 0.15 N. The adsorption was described by Langmuir and Freundlich isotherms. Results showed that lower concentration of the NaCl or Na2SO4 electrolytes (0....

  12. Water Retention and Structure Stability in Smectitic or Kaolinitic Loam and Clay Soils Affected by Polyacrylamide Addition

    Science.gov (United States)

    Mamedov, Amirakh; Levy, Guy

    2015-04-01

    Studying the effects of polyacrylamide (PAM) on soil aggregate and structure stability is important in developing effective soil and water conservation practices and in sustaining soil and water quality. Five concentrations of an anionic PAM (0, 25, 50, 100 and 200 mg L-1) with a high molecular weight were tested on loam and clay soils having either a predominant smectitic or kaolinitic clay mineralogy. The effects of the PAM and of soil texture on soil water retention at near saturation and on aggregate and structure stability were investigated using the high energy moisture characteristic (HEMC) method. The S-shaped water retention curves obtained by the HEMC method were characterized by the modified van Genuchten (1980) model that provided: (i) the model parameters α and n, which represent the location of the inflection point and the steepness of the water retention curve, respectively; and (ii) the soil structure index, SI =VDP/MS, where VDP is the volume of drainable pores, an indicator of the quantity of water released by a soil over the range of applied suctions (0-5 J kg-1), and MS is the modal suction representing the most frequent pore sizes (> 60 μm). In general, the treatments tested (clay mineralogy, soil type and PAM concentration) resulted in: (i) a considerable modification of the shape of the water retention curves as indicated by the changes in the α and n values; and; (ii) substantial effects on the stability indices and other model parameters. The contribution of PAM concentration to soil structure stability depended on the clay mineralogy, being more effective in the smectitic soils than in the kaolinitic ones. Although kaolinitic soils are usually more stable than smectitic soils, when the latter were treated with PAM (25-200 mg L-1) the opposite trend was observed. In the loam soils, increasing the PAM concentration notably decreased the differences between values of the stability indices of the smectitic and kaolinitic samples. The

  13. Soil moisture distribution over time in a clay loam soil in Kosovo

    OpenAIRE

    Abdullah Nishori; Besnik Gjongecaj; Deme Abazi

    2013-01-01

    Studying the soil moisture distribution over time in a given soil profile is the object of the present study. The way the soil moisture gets distributed over soil profile depends particularly on the soil texture and on the soil suction gradients developed. However, it changes continuously over time for a given soil depth. The method of determining the soil moisture distribution over time is based on the measuring of soil moisture suctions developed and the soil moisture contents in various ti...

  14. Influence of Compost and Compost Leachate on Growth and Chemical Composition of Barley and Bioavailability of Some Nutrients in Calcareous Clay Loam Soil and Sandy Soil

    OpenAIRE

    Z. Hatam; A. Ronaghi

    2012-01-01

    Application of compost and compost leachate as organic fertilizers can improve plant growth, nutrients uptake and increase phytoavailability of nutrients in soil. A factorial experiment (4×4×2) was conducted in a completely randomized design to evaluate the effect of compost and compost leachate on growth and chemical composition of barley and bioavailability of some nutrients in calcareous clay loam soil and sandy soil under greenhouse conditions. Treatments consisted of four levels of compo...

  15. Investigating the Effect of Three Nitrate Fertilizers on Nitrate Leaching under the Root Zone in Clay Loam Soil

    Directory of Open Access Journals (Sweden)

    Thamer A. Mohammed

    2009-01-01

    Full Text Available Problem statement: Nitrogen fertilizer is recognized as an important factor in crop’s yield level, however more application of N fertilizers in the soil have some adverse effects on environment and especially on ground water contamination. Perception and recognition the factors influencing nitrate transport through soil profile is helpful for fertilizer management to minimize adverse impacts on environment and nitrate leaching below the root zone. Approach: In this study, 9 large cylindrical lysimeters with 1 m height and 0.5 m diameter were filled with clay loam soil and planted with maize to investigate nitrate leaching under different types of N-fertilizer, chemical fertilizer, activated sludge and organic manure. Nitrate concentration in the soil and drainage water samples were analyzed by spectrophotometer method and the mass of nitrate was calculated in soil and drainage water. Crop productions for different treatments were compared too. Results: Results showed that cumulative mass of nitrate leaching from organic fertilizer was greater than the other treatments (229 kg ha-1. Organic manure had the greatest nitrate accumulation in soil (15.17 mg kg-1, which was significantly greater than chemical fertilizer. Conclusions/Recommendations: experimental results showed that manure application could result in NO3--N accumulation increase in the deeper soil profiles compared with activated sludge. Results showed that maize production was significantly higher under activated sludge fertilizer. Observations made in the current study suggested activated sludge fertilizer due to a higher crop production with same level of ground water contamination, especially in clay loam soils.

  16. Short-term Effects of Tillage Practices on Organic Carbon in Clay Loam Soil of Northeast China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A tillage experiment, consisting of moldboard plow (MP), ridge tillage (RT), and no-tillage (NT), was performed in a randomized complete block design with four replicates to study the effect of 3-year tillage management on SOC content and its distribution in surface layer (30 cm) of a clay loam soil in northeast China. NT did not lead to significant increase of SOC in topsoil (0-5 cm) compared with MP and RT; however, the SOC content in NT soil was remarkably reduced at a depth of 5-20 cm. Accordingly, short-term (3-year) NT management tended to stratify SOC concentration, but not necessarily increase its storage in the plow layer for the soil.

  17. Soil moisture distribution over time in a clay loam soil in Kosovo

    Directory of Open Access Journals (Sweden)

    Abdullah Nishori

    2013-02-01

    Full Text Available Studying the soil moisture distribution over time in a given soil profile is the object of the present study. The way the soil moisture gets distributed over soil profile depends particularly on the soil texture and on the soil suction gradients developed. However, it changes continuously over time for a given soil depth. The method of determining the soil moisture distribution over time is based on the measuring of soil moisture suctions developed and the soil moisture contents in various times, but in a given soil depth (internal drainage method [7]. The soil depths under investigation are four, starting from 0cm to 60cm, which means that the most important depth of soil profile is considered. Such measurements are supposed to be done over soil profile when the soil water flow is already ceased, in the conditions of preventing the evaporation [1, 7, and 9]. Therefore, to determine the soil moisture distribution over time, a plot of 8m x 6m or 48 m2 with no plants was set. The tensiometers and the electronic devices for soil moisture content measurements were installed in four soil depths. The plot was previously wetted and covered by a plastic to prevent the evaporation. In this way, it was made sure that the only possibility for water is to move internally, which gave us the opportunity to measure the changes in soil water content and in soil water suction over time. The final result showed that the dependency of soil water suction and soil moisture content over time is a power function (expressed as a semi logarithmic function, basically.

  18. Contamination Time Effect on Plant Available Fractions of Cadmium and Zinc in a Mexican Clay Loam Soil

    Science.gov (United States)

    Ehsan, Muhammad; Augustine Molumeli, Polile; Espinosa Hernandez, Vicente; Baeza Reyes, Alejandro; Perez Moreno, Jesus; Hernandez, Marcos Soto; Ojeda Trejo, Enrique; Jaen Contreras, David; Ruiz Bello, Alejandrina; Robledo Santoyo, Edmundo

    Knowledge of plant available fractions of heavy metals in soil can assist directing phytoremediation efforts for contaminated soils. For this reason different doses of ZnCl2 (0, 200, 400 and 600 mg kg-1) and CdCl2, 2½ H2O (0, 9, 18 and 27 mg kg-1) were applied to an uncontaminated slightly acidic clay loam soil from Sate of Mexico, Mexico incubated under ambient temperature and humidity for 90 days. Both the metals were extracted with a DTPA-TEA-CaCl2 mixture after 1, 5, 15, 25, 60 and 90 days and analyzed using atomic absorption spectroscopy. The results showed that DTPA extractable contents of Zn and Cd followed a decreasing trend with increase in incubation time. Maximum contents were found at day 01 in all the treatments. After 15 days of incubation, the variation in extractable contents was non-significant. The rapid adsorption of the metals might be due to elevated clay content (34%) of the incubated soil.

  19. Crop uptake and leaching losses of 15N labelled fertilizer nitrogen in relation to waterlogging of clay and sandy loam soils

    International Nuclear Information System (INIS)

    Ammonium nitrate fertilizer, labelled with 15N, was applied in spring to winter wheat growing in undisturbed monoliths of clay and sandy loam soil in lysimeters; the rates of application were respectively 95 and 102 kg N ha-1 in the spring of 1976 and 1975. Crops of winter wheat, oilseed rape, peas and barley grown in the following 5 or 6 years were treated with unlabelled nitrogen fertilizer at rates recommended for maximum yields. During each year of the experiments the lysimeters were divided into treatments which were either freely drained or subjected to periods of waterlogging. Another labelled nitrogen application was made in 1980 to a separate group of lysimeters with a clay soil and a winter wheat crop to study further the uptake of nitrogen fertilizer in relation to waterlogging. In the first growing season, shoots of the winter wheater at harvest contained 46 and 58% of the fertilizer nitrogen applied to the clay and sandy loam soils respectively. In the following year the crops contained a further 1-2% of the labelled fertilizer, and after 5 and 6 years the total recoveries of labelled fertilizer in the crops were 49 and 62% on the clay and sandy loam soils respectively. In the first winter after the labelled fertilizer was applied, less than 1% of the fertilizer was lost in the drainage water, and only about 2% of the total nitrogen (mainly nitrate) in the drainage water from both soils was derived from the fertilizer

  20. Effect of blade vibration on mulch tillage performance under silt clay loam soil

    Directory of Open Access Journals (Sweden)

    B Goudarzi

    2015-09-01

    Full Text Available Introduction: Mulch tillage system is an intermediate system which covers some of disadvantages of no tillage and conventional tillage systems. In farms in which tillage is done with a chisel plow, runoff and soil erosion have a less important relation to moldboard and disk plow and naturally absorption of rainfall will be developed. Thus, the mulch tillage system is an appropriate alternative to conventional tillage and no tillage (Backingham and Pauli, 1993. The unwanted vibration in machinery and industry mainly processes most harmful factors, for example: bearing wear, cracking and loosening joints. And noise is produced in electrical systems by creating a short circuit (Wok, 2011. Self-induced and induced vibration are used in tillage systems. Induced vibration is created by energy consumption and self-induced vibration is created by collision among the blades and soil at the shank (Soeharsono and Setiawan, 2010. A study by Mohammadi-gol et al. (2005 was conducted. It was found that on the disk plow, plant residues maintained on the soil are more than that of moldboard plow. 99% frequency and amplitude, speed and rack angle of blade directly affect soil inversion and indirectly affect preservation of crop residue on the soil. The effect of vibration frequency and rack angle of blade to reduce the tensile strength is also clear. Moreover, in contrast to previous studies when speed progressing is less than (λ, not only the relative speed (λ, but also frequency can reduce the tensile strength (Beiranvand and Shahgoli, 2010; Awad-Allah et al., 2009. Therefore, aim of this study was to determine the effect of vibration and the speed of tillage on soil parameters and drawbar power in using electric power. Materials and Methods: To perform this test, three different modes of vibration (fixed, variable and induced vibration and two levels of speed in real terms at a depth of 20 cm were used for farming. The test was performed with a split plot

  1. Effects of Different Factors on Water Flow and Solute Transport Investigated by Time Domain Reflectometry in Sandy Clay Loam Field Soil.

    Science.gov (United States)

    Merdun, Hasan

    2012-09-01

    Factors affecting preferential flow and transport in the vadose zone need to be investigated by experiments and simulations to protect groundwater against surface applied chemicals. The objectives of this study were to investigate the effects of several factors (soil structure, initial soil water content (SWC), and application rate) and their interactions on the extent of preferential flow and transport in a sandy clay loam field soil using the time domain reflectometry (TDR) for measuring SWC and electrical conductivity (EC) in 12 treatments, modeling (by HYDRUS-1D and VS2DTI) the measured SWC and EC, and conducting statistical tests for comparing the means of the measured and modeled SWC and EC and solute transport parameters (pore water velocity and dispersion coefficient) obtained by inversely fitting in the CXTFIT program. The study results showed that the applied solution moved faster in the undisturbed, wet initial SWC, and higher application rate experimental conditions than in the disturbed, dry initial SWC, and lower application rate, respectively, based on the analysis of the changes in TDR measured SWC and EC with depth at 1, 2, 5, and 15 h of the experiments. However, the effects of interactive factors or treatments on water flow and solute transport were not clear enough. The modeling results showed that HYDRUS-1D was better than VS2DTI in the estimation of EC and especially SWC, but overall the models had relatively low performances in the simulations. Statistical test results also showed that the treatments had different flow and transport characteristics because they were divided into different groups in terms of the means of SWC and EC and solute transport parameters. These results suggest that similar experiments with more distinct interactions and modeling studies with different approaches need to be considered for better understanding the complex flow and transport processes in the vadose zone. PMID:23002311

  2. Response of Soybean [Glycine Max (L. Merrill] to Lime Based Integrated Nutrient Management and Mulching on Nodulation, Nutrient Contents and Yield in Clay Loam Soil.

    Directory of Open Access Journals (Sweden)

    R.C. Jain

    2015-08-01

    Full Text Available The present experiment was laid out in a randomized block design consisted of 6 treatments viz. (T1-Absolute control,(T2 -Farmer practice (50kg DAP/ha,(T3 RDF+ ZnSO4@25 kg/ha+ Ammonium Molybdate 1.0g/kg seed+ slacked lime@25Kg Ca(OH 2 /ha,(T4-RDF+ ZnSO4@25 kg/ha+ slacked lime@25Kg Ca(OH 2 /ha +Rhizobium+PSB (@Each 5g/kg seed +Ammonium Molybdate 1.0g/kg seed,(T5-50%RDF+ ZnSO4@25 kg/ha +FYM 2.5 t/ha+ slacked lime@25Kg Ca(OH 2 /ha + Rhizobium+PSB (@Each 5g/kg seed + Ammonium Molybdate 1.0g/kg seed + Mulching and(T6-50% RDF + ZnSO4@25 kg/ha+ slacked lime@25 Kg Ca(OH 2 + Vermicompost 1.5t/ha + Rhizobium + *PSB (@Each 5g/kg seed + Ammonium Molybdate1.0g/kg seed + Mulching. Variety JS 95-60 was used under experimentation which was conducted in clay loam soil during kharif seasons of 2010, 2011 and 2012 at ZARS Khargone (M.P The effect of lime based integrated nutrient management and mulching on nodulation, its dry weight, nutrient contents in straw & seed at maturity and grain yield(kg/ha were found to increase significantly and beneficial due to the application of 50% RDF + ZnSO4@25 kg/ha+ slacked lime@25Kg Ca(OH 2 /ha + V.C. 1.5t/ha + B.F.+ A.M. + Mulching(T6 followed by treatment T4 and T5 ( Table 1 over other treatments.

  3. Polyacrylamide and water quality effects on infiltration in sandy loam soils

    OpenAIRE

    Ajwa, Husein A; Trout, T J

    2006-01-01

    Slow infiltration rates constrain effective and economical irrigation in some sandy loam soils in California. Polyacrylamide (PAM) has increased soil infiltration in some areas, especially in soils high in clay or silt. Field trials near Fresno, CA, with PAM failed to show improved infiltration. Laboratory experiments were conducted to investigate PAM effect on infiltration of various quality waters in sandy loam soils. Two formulations of a high molecular weight PAM, a liquid emulsion and a ...

  4. The influence of clay-to-carbon ratio on soil physical properties in a humid sandy loam soil with contrasting tillage and residue management

    DEFF Research Database (Denmark)

    Getahun, Gizachew Tarekegn; Munkholm, Lars Juhl; Schjønning, Per

    2016-01-01

    × SOC according to Dexter et al. (2008). NCC was a better predictor of dispersible clay than total clay and SOC at all depths in natural aggregates, while tensile strength and derived parameters were generally better explained by the total amount of clay in remoulded aggregates. Remoulded aggregates had...

  5. Phosphorus leaching from loamy sand and clay loam topsoils after application of pig slurry

    OpenAIRE

    Liu, Jian; Aronsson, Helena; Bergström, Lars; Sharpley, Andrew

    2012-01-01

    Appropriate management of animal waste is essential for guaranteeing good water quality. A laboratory leaching study with intact soil columns was performed to investigate the risk of phosphorus (P) leaching from a clay loam and a loamy sand. The columns (0.2 m deep) were irrigated before and after application of pig slurry on the surface or after incorporation, or application of mineral P, each at a rate of 30 kg P ha-1. The two soils had different initial P contents (i.e. the ammonium lactat...

  6. Gardening in Clay Soils

    OpenAIRE

    Wagner, Katie; Kuhns, Michael; Cardon, Grant

    2015-01-01

    This fact sheet covers the basics of clay, silt and sand soils with an emphasis on gardening in soils with a high clay content. It includes information on the composition of clay soils, gardening tips for managing clay soils, and the types of plants that grow best in clay soils.

  7. The aeration of clay soils in cricket

    OpenAIRE

    Parsons, Simon A.

    2012-01-01

    In the game of cricket good ball-surface interactions are essential and require a hard, flat surface. To achieve this the clay loam soil comprising the pitch is compressed and compacted using a smooth wheeled roller, which when combined with the drying action of the grass plant roots, causing the clay minerals within the soil to shrink, creates a high bulk density, hard surface on which to play. High bulk density soils present difficult growing conditions for plants due to h...

  8. New way of measurement of thermophysical properties of clay loam materials by transient methods

    Science.gov (United States)

    Boháč, Vlastimil; Dieška, Peter; Vretenár, Viliam; Lukáč, Vladimír

    2016-07-01

    The problem of the measurement of clay loam materials in plastic consistency is more or less difficult as they can change the shape during the long time measurements. The specimen thickness is expected as the constant during all the experiment measured by transient pulse method. In a case of plastic clay loam, it can change the form during the measurement because of the squeeze of the material even under the gravity condition. Thus the specimen surface wall should be reinforced by special dimensionally well-defined thin wall container. In this paper the special container in a form of thin tube rings bounded by central annular ring was constructed and used for the measurements. The heat source was inserted into the tube rings through the nozzle in the middle part and the thermocouple was inserted through the drilled openings at defined distance from the heat source. System clamped the heat source together with the rings at desired distance from the thermocouple. This distance represents the thickness of tested specimen. The soft plastic material fill the inner space of tube rings in such a way to fulfill the geometry conditions for this method. The need of soft clay loam material measurement is to test its thermal properties because of the interest to use it as the heat storage material below the buildings. The measured clay loam containing some moisture has quite high values of specific heat and thus the use of it as the heat storage material is promising.

  9. Surface Runoff of Pesticides from a Clay Loam Field in Sweden.

    Science.gov (United States)

    Larsbo, Mats; Sandin, Maria; Jarvis, Nick; Etana, Ararso; Kreuger, Jenny

    2016-07-01

    Pesticides stored at or close to the soil surface after field application can be mobilized and transported off the field when surface runoff occurs. The objective of our study was to quantify the potential pesticide losses in surface runoff from a conventionally managed agricultural field in a Swedish climate. This was achieved by measuring surface runoff volumes and concentrations in runoff of six spring-applied pesticides and autumn-applied glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Measurements were performed for 3 yr both during the growing seasons and during intervening winter snowmelt periods on a clay loam field close to Uppsala. During growing seasons, surface runoff was generated on only five occasions during one 25-d period in 2012 when the infiltration capacity of the soil may have been reduced by structural degradation due to large cumulative rainfall amounts after harrowing. Concentrations in surface runoff exceeded Swedish water quality standards in all samples during this growing season for diflufenican and pirimicarb. Surface runoff was generated during three snowmelt periods during the winter of 2012-2013. All of the applied pesticides were found in snowmelt samples despite incorporation of residues by autumn plowing, degradation, and leaching into the soil profile during the period between spraying and sampling. Concentrations of glyphosate ranged from 0.12 to 7.4 μg L, and concentrations of AMPA ranged from 0 to 2.7 μg L. Our results indicate that temporal changes in hydraulic properties during the growing season and when the soil freezes during winter affect pesticide losses through surface runoff. PMID:27380086

  10. Long-term copper availability and adsorption in a sludge-amended Davidson clay loam

    OpenAIRE

    Anderson, Martha Ann

    1997-01-01

    A single application of aerobically digested sewage sludge was applied by Rappaport et al. (1988) in 1984 at rates up to 210 dry Mt ha-1 on a Davidson clay loam (clayey, kaolinitic, thermic, Rhodic KandiuduIts). The heavily contaminated sludge supplied up to 760 kg Cu and 620 kg Zn haha-1, which are below current cumulative limits, but above annual loading limits for these metals (USEPA, 1993). Rappaport et al. (1988) reported an increase in DTPA extractable Cu and Zn with incr...

  11. The effects of treading by two breeds of dairy cow with different live weights on soil physical properties, poaching damage and herbage production on a poorly drained clay-loam soil

    OpenAIRE

    Tuohy, P.; Fenton, O; Holden, N. M.; Humphreys, J.

    2014-01-01

    SUMMARY There is little empirical evidence to indicate that dairy cow live weight affects the extent of soil damage at the hoof-soil interface during grazing on poorly drained permanent grassland. In the present study the impact of Holstein-Friesian (HF) dairy cows with a mean (±standard deviation) live weight of 570 (±61) kg were compared with Jersey × Holstein-Friesian (JX) with a mean live weight of 499 (±52) kg each at two stocking densities: mean 2·42 ± (0·062) and 2·66 (±0·079) cows/ha....

  12. Distribución de la porosidad de un suelo franco arcilloso (alfisol en condiciones semiáridas después de 15 años bajo siembra directa Soil porosity distribution of a clay loam soil (alfisol in semi-arid conditions after 15 years under direct drilling

    Directory of Open Access Journals (Sweden)

    Cecilia Isabel Cerisola

    2005-12-01

    Full Text Available A partir de un estudio más amplio sobre evolución de las propiedades físicas de un suelo sometido a tres sistemas de labranza, se realizó, en dos campañas consecutivas, un seguimiento de la distribución de la porosidad del suelo según su origen, en parcelas cultivadas bajo siembra directa continua durante 15 años. En el ensayo se consideró un trayecto de 2 metros de longitud, perpendicular a la dirección de las labores, donde se realizaron mediciones de densidad aparente seca y contenido de humedad. El cultivo extensivo de secano (cereal, en cada una de las dos campañas, fue cebada de ciclo corto y de ciclo largo. El calendario de la toma de datos de las variables medidas se fijó en 5 fechas por campaña. La porosidad estructural del suelo, debida principalmente a la alternancia de ciclos de humectación - desecación, fue calculada cada 5 cm y hasta 35 cm de profundidad. Este proceso de fisuración natural resulta suficiente para asegurar un buen drenaje y facilitar el desarrollo radicular de las plantas, siempre y cuando el contenido de humedad se mantenga dentro de la capacidad de retención de agua.On a long-term essay under direct drilling, the evolution of the physical properties of a clay loam soil, such as distribution by origin of soil porosity, has been assessed during two growing seasons. The cereal crops in each growing seasons were spring barley and winter barley, respectively. Soil physical properties were measured on a 2 m length transect located in a perpendicular line to the direction of vehicular traffic for field operations. Five sampling opportunities, within crop cycle, were used to measure the variables. Structural soil porosity, due principally to shrinkage and swelling cycles, was assessed in the 0 to 35 cm depth soil profile. This natural process seemed to be sufficient to guarantee good drainage and normal crop development, unless in the moisture content range included in field capacity.

  13. Aggregate water stability of sandy and clayey loam soils differently compacted with and without wheat plants

    OpenAIRE

    Bazzoffi P.; Balashov E.

    2003-01-01

    The objectives of our studies were to: 1) estimate the effects of compaction of sandy loam and clayey loam soils on growth parameters of winter wheat plants, 2) evaluate the resilien- ce capacity of the root system for the water-stable aggregation of compacted soils. Soil samples at field capacity were placed into pots with an initial bulk density of 1.2 Mg m-3 and compacted with ground contact pressures of 51, 103 and 154 kPa using a hydraulic compressor. Five plants in each pot were allowed...

  14. Rheological properties of different minerals and clay soils

    Directory of Open Access Journals (Sweden)

    Dolgor Khaydapova

    2015-07-01

    Full Text Available Rheological properties of kaolinite, montmorillonite, ferralitic soil of the humid subtropics (Norfolk island, southwest of Oceania, alluvial clay soil of arid subtropics (Konyaprovince, Turkey and carbonate loess loam of Russian forest-steppe zone were determined. A parallel plate rheometer MCR-302 (Anton Paar, Austria was used in order to conduct amplitude sweep test. Rheological properties allow to assess quantitatively structural bonds and estimate structural resistance to a mechanical impact. Measurements were carried out on samples previously pounded and capillary humidified during 24 hours. In the amplitude sweep method an analyzed sample was placed between two plates. The upper plate makes oscillating motions with gradually extending amplitude. Software of the device allows to receive several rheological parameters such as elastic modulus (G’, Pa, viscosity modulus (G", Pa, linear viscoelasticity range (G’>>G”, and point of destruction of structure at which the elastic modulus becomes equal to the viscosity modulus (G’=G”- crossover. It was found out that in the elastic behavior at G '>> G " strength of structural links of kaolinite, alluvial clay soil and loess loam constituted one order of 105 Pa. Montmorillonit had a minimum strength - 104 Pa and ferrallitic soil of Norfolk island [has] - a maximum one -106 Pa. At the same time montmorillonite and ferralitic soil were characterized by the greatest plasticity. Destruction of their structure (G '= G" took place only in the cases when strain was reaching 11-12%. Destraction of the kaolinite structure happened at 5% of deformation and of the alluvial clay soil and loess loam - at 4.5%.

  15. Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

    OpenAIRE

    Schjønning, P.; de Jonge, L. W.; Munkholm, L.J.; P. Moldrup; B. T. Christensen; Olesen, J.E.

    2011-01-01

    Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

  16. Soil resistance and resilience to mechanical stresses for three differently managed sandy loam soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Schjønning, Per; Møldrup, Per;

    2012-01-01

    immediately after compaction, prior to removal of the load, was greatest for the high organic soil. Physical resilience after natural recovery followed the organic carbon gradient (MFC > MCC > CCC). After wet–dry cycles, the MFC soil showed a significantly greater resilience for all three indicators (ka, e......To improve our understanding of how clay-organic carbon dynamics affect soil aggregate strength and physical resilience, we selected three nearby soils (MFC, Mixed Forage Cropping; MCC, Mixed Cash Cropping; CCC, Cereal Cash Cropping) with identical clay content and increasing contents of organic...... carbon (CCC < MCC < MFC). The objective was to assess the resistance and resilience of the three soils to compaction using air permeability (ka), void ratio (e) and air-filled porosity (ε) as functional indicators and to characterise aggregate stability, strength and friability. Aggregate tensile...

  17. Overall assessment of soil quality on humid sandy loams: Effects of location, rotation and tillage

    DEFF Research Database (Denmark)

    Abdollahi, Lotfollah; Hansen, Elly Møller; Rickson, J.M.;

    2015-01-01

    .e. visual evaluation of soil structure (VESS), overall visual structure (OVS) and overall soil structure (OSS)) were employed to differentiate the effects of these alternative management practices on soil structural quality and relative crop yield (RY). A Pearson correlation was also employed to find the......Conservation tillage and diversified crop rotations have been suggested as appropriate alternative soil management systems to sustain soil quality. The purpose of this study was to quantify the effect of implementing three crop rotations (R2–R4) on soil structural changes and the “productivity...... each rotation: mouldboard ploughing to a depth of 20 cm (MP); harrowing to a depth of 8–10 cm (H); and direct drilling (D) at two experimental sites with a sandy loam soil and different water budgets in Denmark. The Muencheberg soil quality rating (M-SQR) method and simpler soil quality indices (i...

  18. Advance of Wetting Front in Silt Loam Soil

    Directory of Open Access Journals (Sweden)

    Mohamed Mahmood

    2013-04-01

    Full Text Available Under drip irrigation , the plant's root is concentrated inside the wetted bulb (region. Thus, the development of these roots and the plant production are greatly affected by the wetting pattern. Therefore, the wetting pattern of soil under drip irrigation must be taken into consideration in the design of drip irrigation system for both single dripping source or multi-overlapping wetting patterns of dripping water sources.2The aim of this study is to evaluate the effect of initial water content of the soil and spacing between two adjacent dripping sources with different flow rate on the movement of the wetting front.This study included 16 tests for monitoring the advancement of the wetting front with time during and after the water application phase. The water advance and water distribution measurement are carried out for two cases of the soil profile: for the first case with initial volumetric water content of 4.08% and for the second case with initial volumetric water content of 12.24%. Two spacing between the emitter were tested 25cm and 50 cm using application flow rates of 0.606, 1.212, 1.818, and 2.424 cm3 /min/cm to show the combined effect of spacing and flow rate on the performance of two adjacent emitter.The study proposed a method for determining the spacing between the two emitting sources , the water application rate and watering time. The proposed method depends on a wetted zone whose depth is equal to the root zone depth with a values equals to the maximum vertical advance of the wetting front underneath the drip line at time when this depth is equal to the depth of wetting at mid­point between the drip line. the study revealed that both the vertical water advance in soil underneath the emitter and the horizontal advance of the wetting front is larger than those in the case of single emitter.Furthermore, the vertical water advance increases with the decrease spacing between the two drip lines. Also, the horizontal advance of the

  19. Effect of biochar on aerobic processes, enzyme activity, and crop yields in two sandy loam soils

    DEFF Research Database (Denmark)

    Sun, Zhencai; Bruun, Esben; Arthur, Emmanuel;

    2014-01-01

    Biochar added to agricultural soils may sequester carbon and improve physico-chemical conditions for crop growth, due to effects such as increased water and nutrient retention in the root zone. The effects of biochar on soil microbiological properties are less certain. We addressed the effects of...... in reference and biochar-amended soil plots.......Biochar added to agricultural soils may sequester carbon and improve physico-chemical conditions for crop growth, due to effects such as increased water and nutrient retention in the root zone. The effects of biochar on soil microbiological properties are less certain. We addressed the effects of...... wood-based biochar on soil respiration, water contents, potential ammonia oxidation (PAO), arylsulfatase activity (ASA), and crop yields at two temperate sandy loam soils under realistic field conditions. In situ soil respiration, PAO, and ASA were not significantly different in quadruplicate field...

  20. Effect of Injecting Hydrogen Peroxide into Heavy Clay Loam Soil on Plant Water Status, NET CO2 Assimilation, Biomass, and Vascular Anatomy of Avocado Trees Efecto de la Inyección de Peróxido de Hidrógeno en Suelo Franco Arcilloso Pesado, sobre el Estado Hídrico, Asimilación Neta de CO2, Biomasa y Anatomía Vascular de Paltos

    Directory of Open Access Journals (Sweden)

    Pilar M Gil M

    2009-03-01

    Full Text Available In Chile, avocado (Persea americana Mill. orchards are often located in poorly drained, low-oxygen soils, situation which limits fruit production and quality. The objective of this study was to evaluate the effect of injecting soil with hydrogen peroxide (H2O2 as a source of molecular oxygen, on plant water status, net CO2 assimilation, biomass and anatomy of avocado trees set in clay loam soil with water content maintained at field capacity. Three-year-old ‘Hass’ avocado trees were planted outdoors in containers filled with heavy loam clay soil with moisture content sustained at field capacity. Plants were divided into two treatments, (a H2O2 injected into the soil through subsurface drip irrigation and (b soil with no H2O2 added (control. Stem and root vascular anatomical characteristics were determined for plants in each treatment in addition to physical soil characteristics, net CO2 assimilation (A, transpiration (T, stomatal conductance (gs, stem water potential (SWP, shoot and root biomass, water use efficiency (plant biomass per water applied [WUEb]. Injecting H2O2 into the soil significantly increased the biomass of the aerial portions of the plant and WUEb, but had no significant effect on measured A, T, gs, or SWP. Xylem vessel diameter and xylem/phloem ratio tended to be greater for trees in soil injected with H2O2 than for controls. The increased biomass of the aerial portions of plants in treated soil indicates that injecting H2O2 into heavy loam clay soils may be a useful management tool in poorly aerated soil.En Chile, los huertos de palto (Persea americana Mill. se ubican comúnmente en suelos pobremente drenados con bajo contenido de oxígeno, lo que limita producción y calidad de fruta. El objetivo de este estudio fue evaluar el efecto de la inyección de peróxido de hidrógeno (H2O2 al suelo como fuente de O2, sobre el estado hídrico, asimilación de CO2, biomasa y anatomía de paltos en suelo franco arcilloso con

  1. A Bioassay Technique to Study Clomazone Residues in Sandy Loam Soil

    Directory of Open Access Journals (Sweden)

    Jelena Gajić Umiljendić

    2013-01-01

    Full Text Available A bioassay test was conducted to evaluate the sensitivity of maize, sunflower and barley toclomazone residues in sandy loam soil. Clomazone was applied at different rates from 0.12 to12 mg a.i./kg of soil. The parameters measured 14 days after treatment were: shoot height, freshand dry weight, and content of pigments (carotenoids, chlorophyll a and chlorophyll b. Theresults showed that the lowest clomazone concentration caused a significant reduction in allmeasured parameters for barley and sunflower shoots. Fresh weight of maize shoots was notsensitive to clomazone residual activity in soil while the other parameters were highly inhibited.Nomenclature: clomazone (2-(2-chlorbenzyl-4,4-dimethyl-1,2-oxazolidin-3-one, maize(Zea mays L., sunflower (Helianthus annuus L., barley (Hordeum vulgare L.

  2. Tillage Effects on Bulk Density and Hydraulic Properties of a Sandy Loam Soil in the Mon-Dak Region, USA

    Science.gov (United States)

    We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density (BD), water content (MC), infiltration rate (Ir) and hydraulic conductivity (Ks) in a Lihen sandy loam soil. Soil cores were collected from each plot at 0 to 10 and 10 to 30 cm depths under each tillage pr...

  3. Bulk density, water content and hydraulic properties of a sandy loam soil following conventional or strip tillage

    Science.gov (United States)

    We evaluated the effects of conventional (CT) and strip (ST) tillage practices on bulk density ('b), water content ('w), infiltration rate (Ir) and hydraulic conductivity (Ks) of plots in a Lihen sandy loam soil during the 2007 and 2008 growing seasons. We measured 'b and 'w using soil cores collect...

  4. Aggregate-associated carbon and nitrogen in reclaimed sandy loam soils

    Energy Technology Data Exchange (ETDEWEB)

    Wick, A.F.; Stahl, P.D.; Ingram, L.J. [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States)

    2009-11-15

    Minimal research has been conducted on aggregate, C, and N in coarse-textured soils used to reclaim surface coal mine lands. Furthermore, little is known about the contribution different plant communities make to the recovery of aggregation in these soils. Two chronosequences of semiarid reclaimed sites with sandy loam soils were sampled under shrub- and grass-dominated communities. Aggregation, aggregate fractions, and associated C and N were measured. No definitive trends of increasing macroaggregates between sites were observed undershrubs; however, macro- and microaggregation was greater in the 16-yr-old (0.20 and 0.23 kg aggregate kg{sup -1} soil, respectively) than in the 5-yr-old soils (0.02 and 0.08 kg aggregate kg{sup -1} soil, respectively) under grasses. Although C and N concentrations were drastically reduced (50-75%) with mining activity between the <1-yr-old and native soils, aggregate C and N concentrations tinder shrubs and grasses were similar to each other and to the native soils in the 5-yr-old site. Sods under grass in the 16-yr-old site had lower available and aggregate-occluded C and N concentrations than the 5-yr-old site, while C and N concentrations did not change between 5- and 16-yr-old soils under shrubs. Conversely, aggregate C and N pool sizes under shrubs and grasses both increased with site age to conditions similar to those observed in the native soil. Reclaimed shrub site soils had consistently higher C concentrations in the older reclaimed sites (10 and 16 yr old) than the soils under grasses, indicating greater accumulation and retention of C and N in organic material under shrub than grass communities in semiarid reclaimed sites.

  5. Clay Dispersibility and Soil Friability - Testing the Soil Clay-to-Carbon Saturation Concept

    DEFF Research Database (Denmark)

    Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl;

    2012-01-01

    either air-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor......Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates...

  6. A short-term comparison of organic v. conventional agriculture in a silty loam soil using two organic amendments

    OpenAIRE

    Herencia, Juan F.; Ruiz Porras, J. C.; Melero Sánchez, Sebastiana; García Galavís, P. A.; Maqueda Porras, Celia

    2008-01-01

    The transition from conventional to organic farming is accompanied by changes in soil chemical properties and processes that could affect soil fertility. The organic system is very complex and the present work carries out a short-term comparison of the effects of organic and conventional agriculture on the chemical properties of a silty loam soil (Xerofluvent) located in the Guadalquivir River Valley, Seville, Spain, through a succession of five crop cycles over a 3-year period. Crop rotation...

  7. Radionuclides sorption in clay soils

    International Nuclear Information System (INIS)

    The sorption behaviour of clay soils is examined through a parametric study of the distribution coefficient (Kd) for the radionuclides of interest, Cs and Sr. This work is a preliminary stage of the migration studies of these nuclides in a porous medium (ground of Ezeiza, Argentina) and the evaluation of radiologic impact of the removal of low and intermediate activity wastes in shallow trenches. The determination of Kd is performed by a static technique or batch. The phases are separated by centrifugation at 20000 g during 1 hour. The activity of supernatant solution of Cs-137 and Sr-85 is measured in a detecting system of I Na(Tl) well-type. Two types of parameters were changed: a) those related to the determination method: phase separation (centrifugation vs. centrifugation plus filtration); equilibrium period, ratio solid/liquid; b) those related to the geochemical system: pH of contact solution, carrier concentration, competitive ions, ionic strength, desorption. It was observed that the modification of parameters in the Kd-measurement does not change the order of magnitude of results. (Author)

  8. USE OF THE “ROTHC” MODEL TO SIMULATE SOIL ORGANIC CARBON DYNAMICS ON A SILTY-LOAM INCEPTISOL IN NORTHERN ITALY UNDER DIFFERENT FERTILIZATION PRACTICES

    Directory of Open Access Journals (Sweden)

    Rosa Francaviglia

    2014-01-01

    Full Text Available We evaluated the efficiency of the RothC model to simulate Soil Organic Carbon (SOC dynamics after 12 years of organic and mineral fertilization practices in a study area located in northern Italy, on a silty-loam Inceptisol with a rotation including tomato, maize and alfalfa. The model performance was assessed by RMSE and EF coefficients. RothC simulated well observed SOC decreases in 71 samples (RMSE=7.42; EF=0.79, while performed with less accuracy when considering all samples (96 samples; RMSE=12.37; EF=0.58, due to the fact that the model failed in case of measured SOC increases (25 samples; RMSE=20.77; EF=-0.038. The model was used to forecast the SOC dynamics over a 50 year period under the same pedoclimatic conditions. Only clay contents >15% allowed to predict increasing levels of SOC respect to the starting values.

  9. Transport and transformation of sulfadiazine in soil columns packed with a silty loam and a loamy sand

    Science.gov (United States)

    Unold, M.; Kasteel, R.; Groeneweg, J.; Vereecken, H.

    2009-01-01

    Concerning the transport of the veterinary antibiotic sulfadiazine (SDZ) little is known about its possible degradation during transport. Also its sorption behaviour is not yet completely understood. We investigated the transport of SDZ in soil columns with a special emphasis on the detection of transformation products in the outflow of the soil columns and on modelling of the concentration distribution in the soil columns afterwards. We used disturbed soil columns near saturation, packed with a loamy sand and a silty loam. SDZ was applied as a 0.57 mg L - 1 solution at a constant flow rate of 0.25 cm h - 1 for 68 h. Breakthrough curves (BTC) of SDZ and its transformation products 4-(2-iminopyrimidin-1(2 H)-yl)aniline and 4-hydroxy-SDZ were measured for both soils. For the silty loam we additionally measured a BTC for an unknown transformation product which we only detected in the outflow samples of this soil. After the leaching experiments the 14C-concentration was quantified in different layers of the soil columns. The transformation rates were low with mean SDZ mass fractions in the outflow samples of 95% for the loamy sand compared to 97% for the silty loam. The formation of 4-(2-iminopyrimidin-1(2 H)-yl)aniline appears to be light dependent and did probably not occur in the soils, but afterwards. In the soil columns most of the 14C was found near the soil surface. The BTCs in both soils were described well by a model with one reversible (kinetic) and one irreversible sorption site. Sorption kinetics played a more prominent role than sorption capacity. The prediction of the 14C -concentration profiles was improved by applying two empirical models other than first order to predict irreversible sorption, but also these models were not able to describe the 14C concentration profiles correctly. Irreversible sorption of sulfadiazine still is not well understood.

  10. Uncertainty of Deardorff’s soil moisture model based on continuous TDR measurements for sandy loam soil

    Directory of Open Access Journals (Sweden)

    Brandyk Andrzej

    2016-03-01

    Full Text Available Knowledge on soil moisture is indispensable for a range of hydrological models, since it exerts a considerable influence on runoff conditions. Proper tools are nowadays applied in order to gain in-sight into soil moisture status, especially of uppermost soil layers, which are prone to weather changes and land use practices. In order to establish relationships between meteorological conditions and topsoil moisture, a simple model would be required, characterized by low computational effort, simple structure and low number of identified and calibrated parameters. We demonstrated, that existing model for shallow soils, considering mass exchange between two layers (the upper and the lower, as well as with the atmosphere and subsoil, worked well for sandy loam with deep ground water table in Warsaw conurbation. GLUE (Generalized Likelihood Uncertainty Estimation linked with GSA (Global Sensitivity Analysis provided for final determination of parameter values and model confidence ranges. Including the uncertainty in a model structure, caused that the median soil moisture solution of the GLUE was shifted from the one optimal in deterministic sense. From the point of view of practical model application, the main shortcoming were the underestimated water exchange rates between the lower soil layer (ranging from the depth of 0.1 to 0.2 m below ground level and subsoil. General model quality was found to be satisfactory and promising for its utilization for establishing measures to regain retention in urbanized conditions.

  11. Nitrogen Mineralization of a Loam Soil Supplemented with Organic–Inorganic Amendments under Laboratory Incubation

    Science.gov (United States)

    Abbasi, M. Kaleem; Khaliq, Abdul

    2016-01-01

    The quantification of nitrogen (N) supplying capacity of organic amendments applied to a soil is of immense importance to examine synchronization, N release capacity, and fertilizer values of these added materials. The aims of the present study was to determine the potential N mineralization and subsequent nitrification of separate and combined use of poultry manure (PM), wheat straw residues (WSR), and urea N (UN) applied to a loam soil incubated periodically over 140 days period. In addition, changes in total soil N and carbon contents were also monitored during the study. Treatments included: PM100, WSR100, PM50 + WSR50, UN100, UN50 + PM50, UN50 + WSR50, UN50 + PM25 + WSR25, and a control (unfertilized). All the amendments were applied on an N-equivalent basis at the rate of 200 mg N kg-1. Results indicated that a substantial quantity of N had been released from the added amendments into the soil mineral pool and the net cumulative N mineralized varied between 39 and 147 mg N kg-1, lowest in the WSR and highest in the UN50 + PM50. Significant differences were observed among the amendments and the net mineral N derived from a separate and combined use of PM was greater than the other treatments. The net cumulative N nitrified (NCNN) varied between 16 and 126 mg kg-1, highest in UN50 + PM50 treatment. On average, percentage conversion of added N into available N by different amendments varied between 21 and 80%, while conversion of applied N into NO3-–N ranged between 9 and 65%, and the treatment UN50 + PM50 displayed the highest N recovery. Urea N when applied alone showed disappearance of 37% N (N unaccounted for) at the end while application of PM and WSR with UN reduced N disappearance and increased N retention in the mineral pool for a longer period. Organic amendments alone or in combination with UN improved organic matter buildup and increased soil N concentration. These results demonstrate the existence of substantial amounts of N reserves present in PM

  12. Biochar effects on wet and dry regions of the soil water retention curve of a sandy loam

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Sun, Zhencai;

    2014-01-01

    Reported beneficial effects of biochar on soil physical properties and processes include decreased soil density, and increased soil water transport, water holding capacity and retention (mainly for the wet region). Research is limited on biochar effects on the full soil water retention curve (wet...... and dry regions) for a given soil and biochar amendment scenarios. This study evaluates how biochar applied to a sandy loam field at rates from 0 to 50 Mg ha−1 yr–1 in 2011, 2012, or both years (2011+2012) influences the full water retention curve. Inorganic fertilizer and pig slurry were added to all...... treatments. Six months after the last biochar application, intact and disturbed soil samples were collected for analyses. Soil water retention was measured from −1 kPa to −100 kPa using tension tables and ceramic plates and from −10 MPa to −480 MPa using a Vapor Sorption Analyzer. Soil specific area was...

  13. Phosphorus application to cotton enhances growth, yield, and quality characteristics on a sandy loam soil

    International Nuclear Information System (INIS)

    Phosphorus (P) is the second most limiting nutrient in cotton (Gossypium hirsutum L.) production after nitrogen. Under wheat-cotton cropping system of Pakistan most of the farmers apply P fertilizer only to wheat crop. A field experiment was conducted to evaluate the effect of fertilizer P on the growth, yield and fibre quality of cotton on a sandy loam calcareous soil at farmer's field in cotton growing area of district Khanewal, Punjab. Five levels of P (0, 17, 26, 34 and 43 kg P ha /sup -1/) along with 120 kg N and 53 kg K ha/sup -1/ were applied. The response of cotton growth parameters was greater than quality components to P addition in calcareous soil. There was significant increase in the growth and yield parameters with each additional rate of P. The response of number of bolls per plant, boll weight and seed cotton yield was to the tune of 88.23, 16.82 and 42%, respectively at P application rate of 34 kg ha/sup -1/. Cotton quality components (lint %age, fiber length and fiber strength) improved from 2 to 5% where 43 kg P ha/sup -1/ was added. The lint and seed P concentration was little affected by P application as compared to stem and leaves showing its essentiality for cell division and development of meristematic tissue. Phosphorus use, thus not only valuable for wheat crop but also its application to cotton crop is of vital importance in improving both lint yield and quality. (author)

  14. Phosphorus speciation in Swedish agricultural clay soils

    OpenAIRE

    Eriksson, Ann Kristin

    2016-01-01

    Phosphorus (P) is an important element for crop production, but build-up of excess soil P can promote P leaching and eutrophication of surface waters. To better understand the dynamics of P release from soil to waters, more knowledge is needed about sorption patterns and P speciation in agricultural soils. Two new indices were developed to assess the importance of P sorption to hydroxy-interlayered clay minerals, and to evaluate the amount of hydroxy-interlayering and hydroxy-interlayer ...

  15. Quick clay and landslides of clayey soils.

    Science.gov (United States)

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology. PMID:19905837

  16. Nitrogen Amendment Stimulated Decomposition of Maize Straw-Derived Biochar in a Sandy Loam Soil: A Short-Term Study

    OpenAIRE

    Weiwei Lu; Weixin Ding; Junhua Zhang; Huanjun Zhang; Jiafa Luo; Nanthi Bolan

    2015-01-01

    This study examined the effect of nitrogen (N) on biochar stability in relation to soil microbial community as well as biochar labile components using δ13C stable isotope technology. A sandy loam soil under a long-term rotation of C3 crops was amended with biochar produced from maize (a C4 plant) straw in absence (BC0) and presence (BCN) of N and monitored for dynamics of carbon dioxide (CO2) flux, phospholipid fatty acids (PLFAs) profile and dissolved organic carbon (DOC) content. N amendmen...

  17. Seasonal fluctuations in water repellency and infiltration in a sandy loam soil after a forest fire in Galicia (NW Spain)

    OpenAIRE

    M. Rodríguez-Alleres; M.E. Varela; Benito, E.

    2013-01-01

    The aim of this work was to analyze, after a wildfire of moderate severity, the temporal fluctuations in water repellency and infiltration in a sandy loam soil under a mixed plantation of pine and eucalyptus and the comparison with an adjacent area not affected by the fire. In the burnt area and in a neighboring area not affected by the fire were collected during one year (1, 4, 6, 8 and 12 months after the fire) 10 soil samples along a transect of 18 m at four depths: 0-2, 2-5, 5-10 and 10-2...

  18. Soil Microbes and soil microbial proteins: interactions with clay minerals

    International Nuclear Information System (INIS)

    Bacterial enumeration in soil environments estimates that the population may reach approximately 1010 g-1 of soil and comprise up to 90% of the total soil microbial biomass. Bacteria are present in soils as single cells or multicell colonies and often strongly adsorb onto mineral surfaces such as sand and clay. The interactions of microbes and microbial biomolecules with these minerals have profound impacts on the physical, chemical and biological properties of soils. (Author)

  19. Evaluation of Soil Quality Indicators in Sugarcane Management in Sandy Loam Soil

    Institute of Scientific and Technical Information of China (English)

    S.A.C.SANT'ANNA; M.F.FERNANDES; W.M.P.M.IVO; J.L.S.COSTA

    2009-01-01

    An important factor for the sustainability of soils highly susceptible to degradation is the use of monitoring tools that promptly and realistically reflect changes imposed on soil by different cropping systems.To select soil quality indicator variables in sugarcane (Saccharum offcinarum L.) production areas that fulfill the criteria of sensitivity to management practices and between-season consistency in the management discrimination,ten composite soil samples (0-10 cm) were collected in July 2005 (rainy season) and again in March 2006 (dry season) from areas under cultivation of organic sugarcane (OS),green sugarcane (GS),burned sugarcane (BS) and from an adjacent native forest (NF) area at Usina Triunfo,Boca da Mata,Alagoas,Brazil.Microbial biomass-C (MBC),total organic C (TOC),soil enzyme activity expressed as the rate of fluorescein diacetate (FDA) hydrolysis,mean weight diameter of water-stable soil aggregates (MWD),and percentage of water-stable macroaggregates (PWSA) were analyzed.Although MBC and TOC were higher in NF than in the cultivated areas,no differences were observed in these C pools between the three sugarcane systems.The response of FDA to the site management was dependent on the sampling time.In the rainy period,the activity followed the order:NF > OS > GS > BS,whereas in the dry season,only NF differed from the other treatments.Irrespective of the sampling time,MWD and PWSA decreased in the order NF > OS = GS > BS.The variables MWD and PWSA are quite sensitive for discriminating between site management histories regardless the sampling season.

  20. Influence of salinity on bioremediation of oil in soil

    International Nuclear Information System (INIS)

    Spills from oil production and processing result in soils being contaminated with oil and salt. The effect of NaCl on degradation of oil in a sandy-clay loam and a clay loam soil was determined. Soils were treated with 50 g kg-1 non-detergent motor oil (30 SAE). Salt treatments included NaCl amendments to adjust the soil solution electrical conductivities to 40, 120, and 200 dS m-1. Soils were amended with nutrients and incubated at 25oC. Oil degradation was estimated from the quantities of CO2 evolved and from gravimetric determinations of remaining oil. Salt concentrations of 200 dS m-1 in oil amended soils resulted in a decrease in oil mineralized by 44% for a clay loam and 20% for a sandy-clay loam soil. A salt concentration of 40 dS m-1 reduced oil mineralization by about 10% in both soils. Oil mineralized in the oil amended clay-loam soil was 2-3 times greater than for comparable treatments of the sandy-clay loam soil. Amending the sandy-clay loam soil with 5% by weight of the clay-loam soil enhanced oil mineralization by 40%. Removal of salts from oil and salt contaminated soils before undertaking bioremediation may reduce the time required for bioremediation. (author)

  1. Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar

    Science.gov (United States)

    Cely, P.; Tarquis, A. M.; Paz-Ferreiro, J.; Méndez, A.; Gascó, G.

    2014-06-01

    The effect of biochar on the soil carbon mineralization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on physicochemical properties and CO2 emissions of a sandy loam soil. For this purpose, soil was amended with three different biochars (BI, BII and BIII) at a rate of 8 wt% and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coefficients (r2) greater than 0.97. Results show a negative priming effect in the soil after addition of BI and a positive priming effect in the case of soil amended with BII and BIII. These results can be related to different biochar properties such as carbon content, carbon aromaticity, volatile matter, fixed carbon, easily oxidized organic carbon or metal and phenolic substance content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

  2. Seasonal fluctuations in water repellency and infiltration in a sandy loam soil after a forest fire in Galicia (NW Spain

    Directory of Open Access Journals (Sweden)

    M. Rodríguez-Alleres

    2013-05-01

    Full Text Available The aim of this work was to analyze, after a wildfire of moderate severity, the temporal fluctuations in water repellency and infiltration in a sandy loam soil under a mixed plantation of pine and eucalyptus and the comparison with an adjacent area not affected by the fire. In the burnt area and in a neighboring area not affected by the fire were collected during one year (1, 4, 6, 8 and 12 months after the fire 10 soil samples along a transect of 18 m at four depths: 0-2, 2-5, 5-10 and 10-20 cm. Soil water repellency was determined using the water drop penetration time test (WDPT test and the infiltration was measured with a mini-disc infiltrometer (pressure head h0 = -2 cm.The results show a temporal pattern of soil water repellency in the burnt and unburnt areas. Significant correlations between water repellency and soil moisture were observed, with higher correlation coefficients in the unburned area and in the surface soil layer.Soil water infiltration was significantly lower than would be expected by the coarse texture of the soil in both burnt and unburnt areas. Temporal fluctuations in unburnt soil infiltration seem to be clearly related to the transient nature of the soil water repellency, with no infiltration in samples extremely repellent. In the burned area, the soil infiltration showed much more variability and temporal fluctuations appear to be less dependent on the persistence of water repellency and more dependent on environmental conditions.The unburnt area show significant and negative correlations of soil water repellency with hydraulic conductivity and sorptivity and positive of these two parameters with soil moisture. These relationships were not observed in the burnt area. The temporal fluctuations of soil water repellency have an evident impact on soil infiltration and seem to be more influent than the effects of fire.

  3. Clay mineral type effect on bacterial enteropathogen survival in soil.

    Science.gov (United States)

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. PMID:24035982

  4. Changes to soil water content and biomass yield under combined maize and maize-weed vegetation with different fertilization treatments in loam soil

    Directory of Open Access Journals (Sweden)

    Lehoczky Éva

    2016-06-01

    Full Text Available Especially during early developmental stages, competition with weeds can reduce crop growth and have a serious effect on productivity. Here, the effects of interactions between soil water content (SWC, nutrient availability, and competition from weeds on early stage crop growth were investigated, to better understand this problem. Field experiments were conducted in 2013 and 2014 using long-term study plots on loam soil in Hungary. Plots of maize (Zea mays L. and a weed-maize combination were exposed to five fertilization treatments. SWC was observed along the 0–80 cm depth soil profile and harvested aboveground biomass (HAB was measured.

  5. Estimation of soil clay content from hygroscopic water content measurements

    OpenAIRE

    Wuddivira, Mark N.; Robinson, David A.; Lebron, Inma; Brechet, Laëtitia; Atwell, Melissa; De Caires, Sunshine; Oatham, Michael; Jones, Scott B.; Abdu, Hiruy; Verma, Aditya K.; Tuller, Markus

    2012-01-01

    Soil texture and the soil water characteristic are key properties used to estimate flow and transport parameters. Determination of clay content is therefore critical for understanding of plot-scale soil heterogeneity. With increasing interest in proximal soil sensing, there is the need to relate obtained signals to soil properties of interest. Inference of soil texture, especially clay mineral content, from instrument response from electromagnetic induction and radiometric methods is of subst...

  6. An Experimental Study of Heavy Metal Extraction, Using Various Concentration of EDTA in a Sandy Loam Soils

    OpenAIRE

    D. Naghipoor Khalkhaliani; A.R. Mesdaghinia; a.h Mahvi; J. Nouri; F Vaezi

    2006-01-01

    This study provides an evaluation of EDTA solution for the removal of lead, zinc and cadmium from a contaminated soil. The field soil contained 68% sand, 12% clay and 20% silt. The performance of EDTA for the treatment of soil contaminated with heavy metals was evaluated in this study. Soil samples containing variable levels of Pb, Zn, Cd were subjected to Ethylene Diamin Tetra-acetic Acid (EDTA) treatment and the extraction of heavy metals was found to vary, ranging from 54.5 to 100%. Thus t...

  7. Studies of fertilizer nitrogen transformation in soil with special regard to ammonium fixation in clay minerals

    International Nuclear Information System (INIS)

    Transformation of 15N is investigated by means of nitrogen analyses of the soil and analyses for nitrogen uptake by plants after 15(NH4)2SO4 or K15NO3 fertilization. Under conditions of nitrogen deficiency, winter wheat utilizes 50-60% of the fertilizer nitrogen. Nitrogen uptake is higher with K15NO3 fertilization. This is due to higher immobilization and additional fixation after fertilization with ammonium. Nitrogen fixation under plant cover amounts to 12 kg N·ha-1 in loess soil and 4.5 kg N·ha-1 in heavily loamed clay soil. Remobilization and plant availability of these reserves cannot be discerned within one growing season. (author)

  8. Structural classification of clay soils and its application in classifying Tehran City clays

    International Nuclear Information System (INIS)

    The behaviour of all reconstituted and natural clays is determined by their fabric and bonding. A new classification of clays is proposed in this paper on the basis of standard penetration test (Spt), the geological history and the one-dimensional compression of the clay in the 1v-σv plane. Although the eighth clay types defined in the classification have different origins, fabric and bonding, they all have either a syn-sedimentation or a post-sedimentation structure. The definition of these clay types is taken as a starting point for the construction of a general framework of behaviour of clays. In this research results of laboratory and field investigations of a very stiff Tehran silty clay in the natural and reconstituted states including Spt, Odometer, Scanning Electron Microscopy and polarizing microscopy are presented. The structure of the Tehran silty clay is strongly influenced by bonding, calcium carbonate content and weathering intensity. This soil is a very stiff to hard clay which geologically is over-consolidated. Consolidation curve of soils lies close to the Icl line. Hence the Tehran silty clay is a type 4 clay but, at certain depths where the yield stress ratio is greater than 1, the Tehran silty clay becomes a type 7 clay

  9. Dynamics of parameters of Cs137 and Sr90 accumulation by agricultural crops on sod-podzolic sandy loam soil

    International Nuclear Information System (INIS)

    In the conditions of the Republic of Belarus there was realized the determination of the parameters of Cs137 and Sr90 accumulation by green mass of winter rape (Brassica napus), lupine (Lupinus), pea (Pisum) and corn (Zea mays), as well as dynamics of coefficients of radionuclide transfer from soil into plant products in the after-Chernobyl period. Research results showed that in the conditions of sod-podzolic sandy loam soil the indexes of the coefficients of Cs137 and Sr90 radionuclide transfer from soil into rape green mass were on 1,67 and 1,15 times lower than the standard indexes fixed the green mass of sprig rape in the conditions of the same agronomic indexes. Over the time after the Chernobyl disaster there was the substantial lowering of indexes of Cs137 transfer from soil into plants. For the green mass of pea it lowered in 7,5 times, for maize – 15 times. The values of Sr90 transfer indexes did not substantially change. At present the values of Cs137 and Sr90 do not undergo essential changes as there was developed the dynamic equilibrium between the radionuclide forms in soil

  10. Clay Mineralogy of Various Marginal Soils in Vietnam

    OpenAIRE

    Nguyen, Quang Hai; Egashira, Kazuhiko

    2008-01-01

    Various marginal soils derived from different parent materials were collected from different landforms and agro-ecological regions in Vietnam and were subjected to clay mineral analysis in addition to particle-size analysis. The result showed that the particle-size distribution of the soils had a close relationship with the landform. The clay content was highest for the soils from the meander floodplain and inland valley, followed by the soil from the hill and lowest for the soils from the ...

  11. STABILISATION OF SILTY CLAY SOIL USING CHLORIDE

    Directory of Open Access Journals (Sweden)

    TAMADHER T. ABOOD

    2007-04-01

    Full Text Available The object of this paper is to investigate the effect of adding different chloride compounds including (NaCl, MgCl2, CaCl2 on the engineering properties of silty clay soil. Various amounts of salts (2%, 4%, and 8% were added to the soil to study the effect of salts on the compaction characteristics, consistency limits and compressive strength. The main findings of this study were that the increase in the percentage of each of the chloride compounds increased the maximum dry density and decrease the optimum moisture content. The liquid limit, plastic limit and plasticity index decreased with the increase in salt content. The unconfinedcompressive strength increased as the salt content increased.

  12. Effect of nutrients and plant growth regulators on growth and yield of black gram in sandy loam soils of Cauvery new delta zone, India

    OpenAIRE

    Marimuthu, S.; U. Surendran

    2015-01-01

    Pulse productivity is very low in some of the sandy soil areas where, soils are having poor water and nutrient holding capacity. To improve the pulse productivity, field experiments were conducted at Agricultural Research Station, Tamil Nadu for two consecutive years to study the effect of phosphorus sources (mono- and diammonium phosphate) with brassinolide and salicylic acid on growth and yield of black gram in sandy loam soils. The experiment was carried out in a randomized block design wi...

  13. Differences in physical properties of two clay soils

    OpenAIRE

    Alakukku, Laura; Ristolainen, Antti; nuutinen, Visa

    2008-01-01

    We studied the physical properties of two clay soils (J1 and J2) having relatively similar texture but differing cultivation properties J2 being more sensitive to dry and wet conditions. The general assumption that the productivity of heavy clay soils is mainly threatened by excessive wetness holds in both fields.

  14. Removal of non aqueous phase liquid liquid (NAPL) from a loam soil monitored by time domain reflectometry (TDR) technique

    Science.gov (United States)

    comegna, alessandro; coppola, Antonio; dragonetti, giovanna; ajeel, ali; saeed, ali; sommella, angelo

    2016-04-01

    Non-aqueous phase liquids (NAPLs) are compounds with low or no solubility with water. These compounds, due to the several human activities, can be accidentally introduced in the soil system and thus constitute a serious geo-environmental problem, given the toxicity level and the high mobility. The remediation of contaminated soil sites requires knowledge of the contaminant distribution in the soil profile and groundwater. Methods commonly used to characterize contaminated sites are coring, soil sampling and the installation of monitoring wells for the collection of groundwater samples. The main objective of the present research is to explore the potential application of time domain reflectometry (TDR) technique in order to evaluate the effect of contaminant removal in a loam soil, initially contaminated with NAPL and then flushed with different washing solutions. The experimental setup consist of: i) a Techtronix cable tester; ii) a three-wire TDR probe with wave guides 14.5 cm long inserted vertically into the soil samples; iii) a testing cell of 8 cm in diameter and 15 cm high; iv) a peristaltic pump for upward injection of washing solution. In laboratory, soil samples were oven dried at 105°C and passed through a 2 mm sieve. Known quantities of soil and NAPL (corn oil, a non-volatile and non-toxic organic compound) were mixed in order to obtain soil samples with different degrees of contamination. Once a soil sample was prepared, it was repacked into a plastic cylinder and then placed into the testing cell. An upward injection of washing solution was supplied to the contaminated sample with a rate q=1.5 cm3/min, which corresponds to a darcian velocity v=6.0 cm/h. The out coming fluid, from the soil column was collected, then the washing solution and oil was separated. Finally both the amount of oil that was remediated and the dielectric permittivity (measured via TDR) of the contaminated soil sample were recorded. Data collected were employed to implement a

  15. Wave liquefaction in soils with clay content

    DEFF Research Database (Denmark)

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

  16. Effect of wheat and rice straw biochars on pyrazosulfuron-ethyl sorption and persistence in a sandy loam soil.

    Science.gov (United States)

    Manna, Suman; Singh, Neera

    2015-01-01

    The objective of this research was to investigate the effect of wheat and rice biochars on pyrazosulfuron-ethyl sorption in a sandy loam soil. Pyrazosulfuron-ethyl was poorly sorbed in the soil (3.5-8.6%) but biochar amendment increased the herbicide adsorption, and the effect varied with the nature of the feedstock and pyrolysis temperature. Biochars prepared at 600°C were more effective in adsorbing pyrazosulfuron-ethyl than biochars prepared at 400°C. Rice biochars were better than wheat biochars, and higher herbicide adsorption was attributed to the biochar surface area/porosity. The Freundlich constant 1/n suggested nonlinear isotherms, and nonlinearlity increased with increase in the level of biochar amendment. Desorption results suggested sorption of pyrazosulfuron-ethyl was partially irreversible, and the irreversibility increased with increase in the level of biochar. Both sorption and desorption of pyrazosulfuron-ethyl correlated well with the content of biochars. The free energy change (ΔG) indicated that the pyrazosulfuron-ethyl sorption process was exothermic, spontaneous and physical in nature. Persistence studies indicated that biochar (0.5%) amendment did not have significant effect on herbicide degradation, and its half-life values in the control, 0.5% WBC600- and RBC600-amended rice planted soils were 7, 8.6, and 10.4 days, respectively. PMID:25996810

  17. Seasonal dynamics in wheel load-carrying capacity of a loam soil in the Swiss Plateau

    DEFF Research Database (Denmark)

    Gut, S.; Chervet, A.; Stettler, Matthias;

    2015-01-01

    ) is defined as the maximum wheel load for a specific tyre and inflation pressure that does not result in soil stress in excess of soil strength. The soil strength and hence WLCC is strongly influenced by soil matric potential (h). The aim of this study was to estimate the seasonal dynamics in WLCC......, demonstrating the potential of tyre equipment in reducing compaction risks. The NTD varied between years and generally decreased with increasing wheel load of the machinery. The WLCC simulations presented here provide a useful and easily interpreted tool to guide the avoidance of soil compaction.......Subsoil compaction is a major problem in modern agriculture caused by the intensification of agricultural production and the increase in weight of agricultural machinery. Compaction in the subsoil is highly persistent and leads to deterioration of soil functions. Wheel load-carrying capacity (WLCC...

  18. No favorable effect of reduced tillage on microbial communities in a silty loam soil (Belgium)

    OpenAIRE

    Degrune, Florine; Theodorakopoulos, Nicolas; Dufrêne, Marc; Taminiau, Bernard; Colinet, Gilles; Bodson, Bernard; Hiel, Marie-Pierre; Daube, Georges; Vandenbol, Micheline

    2015-01-01

    To date, only a few studies have applied metagenomics to investigate the influence of different tillage regimes and types of crop residue management on soil microbial communities. These studies were conducted under specific climates on soils characterized by particular land-use histories. A very different ecological context is to be found in certain areas of Western Europe, such as central Belgium, whose loess-derived soils are among the most fertile in the world and have long been used for i...

  19. Clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils.

    Science.gov (United States)

    Colman, Steven M.

    1982-01-01

    Weathering rinds on volcanic clasts in Quaternary deposits in the western US contain only very fine-grained and poorly crystalline clay minerals. Rinds were sampled from soils containing well-developed argillic B horizons in deposits approx 105 yr old or more. The clay-size fraction of the rinds is dominated by allophane and iron hydroxy-oxides, whereas the B horizons contain abundant well-crystallized clay minerals. The contrast between the clay mineralogy of the weathering rinds, in which weathering is isolated from other soil processes, and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic B horizons. It seems that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in Middle to Late Pleistocene soil.-A.P.

  20. Main Clay Minerals in Soils of Fujian Province,China

    Institute of Scientific and Technical Information of China (English)

    WANGGUO; ZHANGWEIMING; 等

    1996-01-01

    The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution.Montmorillonite was found in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit,and some lateritic red soil,red soil and yellow soil with a low weathering degree.Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit.1.4nm intergradient mineral appeared frequently in yellow soil,red soil and lateritic red soil.The content of 1.4nm intergradient mineral increased with the decrease of weathering degree from lateritic red soil to red soil to yellow soil.Hydrous micas were more in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit.and puple soil from purple shale than in other soils.Kaolinte was the most important clay mineral in the soils iun this province.The higher the soil weathering degree,the more the kaolinite existed.From yellow soil to red soil to lateritic red soil,kaolinite increased gradually,Kaolinite was the predominant clay mineral accompanied by few other minerals in typical lateritic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities.The soil derived from the paent rocks rich in feldspar contained more tubular halloysite.Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt gibbsite in the soils in this district was largely“primary gibbsite” which formed in the early weathering stage.Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to lateritic red soil.Goethite also decreased in the same sequence while hematite increased.

  1. Bacterial and fungal taxon changes in soil microbial community composition induced by short-term biochar amendment in red oxidized loam soil.

    Science.gov (United States)

    Hu, Liao; Cao, Lixiang; Zhang, Renduo

    2014-03-01

    To take full advantage of biochar as a soil amendment, the objective of this study was to investigate the effects of biochar addition on soil bacterial and fungal diversity and community composition. Incubation experiments with a forest soil (a red oxidized loam soil) with and without biochar amendment were conducted for 96 days. The culture-independent molecular method was utilized to analyze soil bacterial and fungal species after the incubation experiments. Results showed that bacteria and fungi responded differently to the biochar addition during the short-term soil incubation. Twenty four and 18 bacterial genara were observed in the biochar amended and unamended soils, respectively, whereas 11 and 8 fungal genera were observed in the biochar amended and unamended soils, respectively. Microbial taxa analysis indicated that the biochar amendment resulted in significant shifts in both bacterial and fungal taxa during the incubation period. The shift for bacteria occurred at the genus and phylum levels, while for fungi only at the genus level. Specific taxa, such as Actinobacteria of bacteria and Trichoderma and Paecilomyces of fungi, were enriched in the biochar amended soil. The results reveal a pronounced impact of biochar on soil microbial community composition and an enrichment of key bacterial and fungal taxa in the soil during the short time period. PMID:24136343

  2. Physical and hydraulic properties of a sandy loam soil under zero, shallow and deep tillage practices

    Science.gov (United States)

    Over the centuries, tillage has been an important agronomic practice that has been used to mechanically alter soil properties and enhance the soil ecosystem for growth of crops. A 4-yr study investigated the impact of no-tillage (NT), shallow tillage at a 10-cm depth (ST), and deep tillage at a 30-c...

  3. Nitrogen Amendment Stimulated Decomposition of Maize Straw-Derived Biochar in a Sandy Loam Soil: A Short-Term Study.

    Science.gov (United States)

    Lu, Weiwei; Ding, Weixin; Zhang, Junhua; Zhang, Huanjun; Luo, Jiafa; Bolan, Nanthi

    2015-01-01

    This study examined the effect of nitrogen (N) on biochar stability in relation to soil microbial community as well as biochar labile components using δ13C stable isotope technology. A sandy loam soil under a long-term rotation of C3 crops was amended with biochar produced from maize (a C4 plant) straw in absence (BC0) and presence (BCN) of N and monitored for dynamics of carbon dioxide (CO2) flux, phospholipid fatty acids (PLFAs) profile and dissolved organic carbon (DOC) content. N amendment significantly increased the decomposition of biochar during the first 5 days of incubation (P < 0.05), and the proportions of decomposed biochar carbon (C) were 2.30% and 3.28% in BC0 and BCN treatments, respectively, during 30 days of incubation. The magnitude of decomposed biochar C was significantly (P < 0.05) higher than DOC in biochar (1.75%) and part of relatively recalcitrant biochar C was mineralized in both treatments. N amendment increased soil PLFAs concentration at the beginning of incubation, indicating that microorganisms were N-limited in test soil. Furthermore, N amendment significantly (P < 0.05) increased the proportion of gram-positive (G+) bacteria and decreased that of fungi, while no noticeable changes were observed for gram-negative (G-) bacteria and actinobacteria at the early stage of incubation. Our results indicated that N amendment promoted more efficiently the proliferation of G+ bacteria and accelerated the decomposition of relatively recalcitrant biochar C, which in turn reduced the stability of maize straw-derived biochar in test soil. PMID:26192282

  4. Nitrogen Amendment Stimulated Decomposition of Maize Straw-Derived Biochar in a Sandy Loam Soil: A Short-Term Study.

    Directory of Open Access Journals (Sweden)

    Weiwei Lu

    Full Text Available This study examined the effect of nitrogen (N on biochar stability in relation to soil microbial community as well as biochar labile components using δ13C stable isotope technology. A sandy loam soil under a long-term rotation of C3 crops was amended with biochar produced from maize (a C4 plant straw in absence (BC0 and presence (BCN of N and monitored for dynamics of carbon dioxide (CO2 flux, phospholipid fatty acids (PLFAs profile and dissolved organic carbon (DOC content. N amendment significantly increased the decomposition of biochar during the first 5 days of incubation (P < 0.05, and the proportions of decomposed biochar carbon (C were 2.30% and 3.28% in BC0 and BCN treatments, respectively, during 30 days of incubation. The magnitude of decomposed biochar C was significantly (P < 0.05 higher than DOC in biochar (1.75% and part of relatively recalcitrant biochar C was mineralized in both treatments. N amendment increased soil PLFAs concentration at the beginning of incubation, indicating that microorganisms were N-limited in test soil. Furthermore, N amendment significantly (P < 0.05 increased the proportion of gram-positive (G+ bacteria and decreased that of fungi, while no noticeable changes were observed for gram-negative (G- bacteria and actinobacteria at the early stage of incubation. Our results indicated that N amendment promoted more efficiently the proliferation of G+ bacteria and accelerated the decomposition of relatively recalcitrant biochar C, which in turn reduced the stability of maize straw-derived biochar in test soil.

  5. Mobility of Arsenic and Heavy Metals in a Sandy-Loam Textured and Carbonated Soil

    Institute of Scientific and Technical Information of China (English)

    GARCIA; M.DIEZ; F.MARTIN; M.SIMóN; C.DORRONSORO

    2009-01-01

    The continued effect of the pyrite-tailing oxidation on the mobility of arsenic,lead,zinc,cadmium,and copper was studied in a carbonated soil under natural conditions,with the experimcntal plot preserved with a layer of tailing covering the soil during three years.The experimental area is located in Southern Spain and was affected by a pyrite-mine spill.The climate in the area is typically Mediterranean,which determines the rate of soil alteration and element mobility.The intense alteration processes that occurred in the soil during three years caused important changes in its morphology and a strong degradation of the main soil properties.In this period,lead concentrated in the first 5 mm of the soil,with concentrations higher than 1500 mg kg-1,mainly associated to the neoformation of plumbojarosite.Arsenic was partially leached from the first 5 mm and mainly concentrated between 5-10 mm in the soil,with maximum values of 1 239 mg kg-1;the retention of arsenates was related to the neoformation of iron hydroxysulfates (jarosite,schwertmannite) and oxyhydroxides (goethite,ferrihydrite),both with a variable degree of crystallinity.The mobility of Zn,Cd,and Cu was highly affected by pH,producing a stronger leaching in depth;their retention was related to the forms of precipitated aluminium and,in the case of Cu,also to the neoformation of hydroxysulfate.

  6. The effect of primary soil tillage methods on ugar beet growth on a light loam luvisol

    OpenAIRE

    Romaneckas, Kęstutis; Romaneckienė, Regina; Šarauskis, Egidijus

    2006-01-01

    Different primary soil tillage methods intended for sugar beet were investigated at the Experimental Station of the Lithuanian University of Agriculture during the period 2001-2005. The aim of the trial was to ascertain the influence of reduced soil tillage intensity on soil physical properties, sugar beet yield and quality. Treatments of the trial: 1. conventional (22-25 cm) ploughing with a mouldboard plough (CP); 2. shallow (12-15 cm) ploughing with a mouldboard plough (SP); 3. deep (25-30...

  7. Effect of industrial, municipal and agricultural wastes on peanut in lateritic sandy loam soil

    International Nuclear Information System (INIS)

    Modern agriculture, worldwide, depends upon the external application of plant nutrients supplied mostly through chemical fertilizer to meet the crop needs. The natural recycling cannot provide the very large amount of nutrients needed year after year in an intensive cropping system and nutrients being a major constraint harvesting the nutrient energy from biological and industrial waste are of prime importance for maximizing the food grain production in the world. A number of industrial wastes like fly ash from thermal power plants, paper factory sludge from paper factory, sewage sludge from municipal source and farmyard manure from livestock farming are the important waste resources, having potentiality in recycling in agricultural land. When these wastes are recycled through soil for crop production, due to the degradative and assimilative capacity of soil, the pollution hazards of these wastes can be minimized to a greater extent as compared to direct disposing of at the site. Fly ash is a waste product residue resulting from the combustion of pulverised coal in coal-fired power generating station. Physico - chemical analysis of fly ash has revealed the presence of both macro-micro nutrients, which can sustain plant growth. Its application in the agricultural land acts as a liming material and improves crop growth by neutralizing the soil acidity, increasing the water availability for the plants and supplement of nutrients (Adriano et al, 1980, Molliner and Street, 1982, Schnappinger et al, 1975). Application of paper factory sludge has been reported to increase the organic carbon content in soil and nutrient content like P, K, Ca, Mg and micronutrients (Guerini et al, 1994, Muse and Mitchell, 1995). Sludge application also improves the organic carbon content of the soil and availability of nutrients like Ca, K and Mg besides improvement of physical properties (Pitchel and Hayes, 1990). Much is known regarding crop performance and changes in physical and

  8. Optimization method for quantitative calculation of clay minerals in soil

    Indian Academy of Sciences (India)

    Libo Hao; Qiaoqiao Wei; Yuyan Zhao; Zilong Lu; Xinyun Zhao

    2015-04-01

    Determination of types and amounts for clay minerals in soil are important in environmental, agricultural, and geological investigations. Many reliable methods have been established to identify clay mineral types. However, no reliable method for quantitative analysis of clay minerals has been established so far. In this study, an attempt was made to propose an optimization method for the quantitative determination of clay minerals in soil based on bulk chemical composition data. The fundamental principles and processes of the calculation are elucidated. Some samples were used for reliability verification of the method and the results prove the simplicity and efficacy of the approach.

  9. Charge Properties and Clay Mineral Composition of Tianbao Mountains Soils

    Institute of Scientific and Technical Information of China (English)

    HEJI-ZHENG; LIXUE-YUAN; 等

    1992-01-01

    The clay mineral association,oxides of clay fraction and surface charge properties of 7 soils,which are developed from granite,located at different altitudesof the Tianbao Mountains were studied.Results indicate that with the increase in altitude,1) the weathering process and desilicification of soil clay minerals became weaker,whereas the leaching depotassication and the formation process of hydroxy-aluminum interlayer got stronger;2)the contents of amorphous and complex aluminum and iron,and the activity of aluminum and iron oxides for soil clay fraction increased;and 3) the amount of variable negarive charge,anion exchange capacity and the values of PZC and PZNC also increased.The activity of aluminum and iron oxides,the accumulation of aluminum,and surface charge characteristics and their relation to clay oxides of the vertical zone soils were observed and recorded.

  10. Soil C dynamics in a 26-year CRP chronosequence on an Amarillo fine sandy loam

    Science.gov (United States)

    The Conservation Reserve Program (CRP) sequesters more carbon (C) on private lands than any other federally administered program, but the rate and maximum amount of sequestered SOC is dependent on inherent soil properties (e.g. texture), local climate, and initial restoration efforts. We estimated t...

  11. Effects of biochar and manure amendments on water vapor sorption in a sandy loam soil

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per;

    2015-01-01

    Over the last decade, the application of biochar (BC) as a soil amendment to sequester carbon and mitigate global climate change has received considerable attention. While positive effects of biochar on plant nutrition are well documented, little is known about potential impacts on the physical...

  12. Predicting Saturated Hydraulic Conductivity from Percolation Test Results in Layered Silt Loam Soils

    Science.gov (United States)

    The size of on-site waste disposal systems is usually determined by one or more percolation tests performed on the proposed site. The objectives of this study were to develop an empirical relationship between the saturated hydraulic conductivity (Ks) of layered soils and their percolation times (PT)...

  13. Relationship Between Soil Apparent Electrical Conductivity and Cassava Plant (TMS 98/0505) Growth at Early Stages on Sandy Loam Soil

    OpenAIRE

    Emmanuel Olugbemi Joshua; Olanrewaju Adewunmi Mokuolu

    2014-01-01

    A thorough study of major soil properties such as soil Apparent Electrical Conductivity (ECa) which influences plant productivity is of utmost importance if losses in output and input cost from a farm are to be minimized. Soil ECa is a measure of the soil’s ability to conduct electric current as well as its nutrient contents. It is affected by a combination of several soil properties such as soil water content, organic matter, clay and mineralogy, bulk density, soluble salts etc. This study d...

  14. Modeling Tractive Force Requirements of Wheel tractors For Disc Ploughing in Sandy Loam Soil

    Directory of Open Access Journals (Sweden)

    S O Nkakini

    2012-10-01

    Full Text Available Tractive force models at different tillage speeds were developed using dimensional analysis, describing the tractor tyre - soil interaction. In this research study, disc ploughing on an experimental plot at twenty different soil moisture levels in loamy sand soil was carried out using trace tractor techniques. The independent variables: drawbar pull force, rolling (motion resistance, wheel slip, moisture content, cone index, wheel numeric, contact pressure, speed, width of plough, depth of plough, and dependent variable (Tractive force were measured and compared to computed values. High coefficients of determination R2 = 0.9492, 0.9555 and 0.9447 for ploughing at tillage speeds of 1.94m/s, 2.22m/s and 2.5m/s were obtained respectively. Standard errors of 0.3672552, 0.8628 and 0.8047 and the percentage (% errors of -2.272608059 and 2.45655144,-2.304946155 and 2.523126085,-1.424947801 and 2.020155232 at minimum and maximum values, were obtained. These results are clear evidence of the test of goodness of fit of the models between predictive and measured parameters for ploughing at different tillage speeds. The models were verified and validated by comparing the predicted with the measured tractive forces, and shown to closely followed the experimental results.

  15. Transport of Alachlor, Atrazine, Dicamba, and Bromide through Silt and Loam Soils

    Science.gov (United States)

    Tindall, J. A.

    2015-12-01

    The herbicides alachlor, atrazine, and dicamba, as well as bromide were applied to soils overlying the High Plains aquifer in Nebraska, to both macropore and non-macropore sites. Three of 6 study areas (exhibiting a high percentage of macropores) were used for analysis of chemical transport. Twelve intact soil cores (30 cm diameter; 40 cm height), were excavated (two each from 0-40 cm and 40-80 cm depths). The first three study areas and soil cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties; the remaining cores were treated the same as field macropore sites. Two undisturbed experimental field plots, each with a 1 m2 surface area, were established in each of the three macropore study areas. Each preferential plot was instrumented with suction lysimeters, tensiometers, and neutron access tubes - 10 cm increments to 80 cm - and planted in corn. Three study areas that did not exhibit macropores had alachlor, atrazine, and dicamba and bromide disked into the top 15 cm of soil; concentrations were tracked for 120 days - samples were collected on a grid, distributed within 3 plots measuring 50 m x 50 m each. Core samples were collected prior to and immediately after application, and then at 30, 60, and 120 days after application. Each lab core sample was in 15-cm lengths from 0-15 cm, 15-30 cm, 45-60 cm, and 75-90 cm. For areas exhibiting macropores, herbicides had begun to move between 10-15 days after application with concentrations peaking at various depths after heavy rainfall events. Field lysimeter samples showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of preferential flowpaths. Concentrations of atrazine, alachlor and dicamba exceeding 0.30, 0.30, and 0.05 μg m1-1 respectively were observed with depth (10-30 cm and 50-70 cm) after two months following heavy rainfall events indicating that preferential flowpaths were a significant

  16. Development of methods for multiresidue analysis of rice post-emergence herbicides in loam soil and their possible applications to soils of different composition.

    Science.gov (United States)

    Niell, Silvina; Pareja, Lucia; Asteggiante, Lucía Geis; Roehrs, Rafael; Pizzutti, Ionara R; García, Claudio; Heinzen, Horacio; Cesio, María Verónica

    2010-01-01

    Two simple and straightforward sample preparation methods were developed for the multiresidue analysis of post-emergence herbicides in loam soil that are commonly used in rice crop cultivation. A number of strategic soil extraction and cleanup methods were evaluated. The instrumental analysis was performed by HPLC with a diode array detector. The best compromise between the recoveries (69-98%) and good repeatability (RSD pyrazosulfuron ethyl, propanil, and clomazone were analyzed simultaneously. Quinclorac and bispyribac sodium were also assayed, but their recoveries were below 50%. Both methods had an LOD of 0.7 microg/kg and could accurately determine the residues at the 2 microg/kg level. These two methods could not be applied directly to other soil types as the recoveries strongly depended on the soil composition. The developed methodologies were successfully applied in monitoring 87 real-world soil samples, in which only propanil (6 to 12 microg/kg) and clomazone (15 to 20 microg/kg) residues could be detected. PMID:20480886

  17. Improvement in the Water Retention Characteristics of Sandy Loam Soil Using a Newly Synthesized Poly(acrylamide-co-acrylic Acid/AlZnFe2O4 Superabsorbent Hydrogel Nanocomposite Material

    Directory of Open Access Journals (Sweden)

    Shaukat Ali Shahid

    2012-08-01

    Full Text Available The use of some novel and efficient crop nutrient-based superabsorbent hydrogel nanocomposites (SHNCs, is currently becoming increasingly important to improve the crop yield and productivity, due to their water retention properties. In the present study a poly(Acrylamide-co-acrylic acid/AlZnFe2O4 superabsorbent hydrogel nanocomposite was synthesized and its physical properties characterized using Energy Dispersive X-ray (EDX, FE-SEM and FTIR spectroscopic techniques. The effects of different levels of SHNC were studied to evaluate the moisture retention properties of sandy loam soil (sand 59%, silt 21%, clay 19%, pH 7.4, EC 1.92 dS/m. The soil amendment with 0.1, 0.2, 0.3 and 0.4 w/w% of SHNC enhanced the moisture retention significantly at field capacity compared to the untreated soil. Besides, in a separate experiment, seed germination and seedling growth of wheat was found to be notably improved with the application of SHNC. A delay in wilting of seedlings by 5–8 days was observed for SHNC-amended soil, thereby improving wheat plant growth and establishment.

  18. Mechanical dispersion of clay from soil into water: readily-dispersed and spontaneously-dispersed clay

    Science.gov (United States)

    Czyż, Ewa A.; Dexter, Anthony R.

    2015-01-01

    A method for the experimental determination of the amount of clay dispersed from soil into water is described. The method was evaluated using soil samples from agricultural fields in 18 locations in Poland. Soil particle size distributions, contents of organic matter and exchangeable cations were measured by standard methods. Sub-samples were placed in distilled water and were subjected to four different energy inputs obtained by different numbers of inversions (end-over-end movements). The amounts of clay that dispersed into suspension were measured by light scattering (turbidimetry). An empirical equation was developed that provided an approximate fit to the experimental data for turbidity as a function of number of inversions. It is suggested that extrapolation of the fitted equation to zero inversions enables the amount of spontaneously-dispersed clay to be estimated. This method introduces the possibility of replacing the existing subjective, qualitative method of determining spontaneously-dispersed clay with a quantitative, objective method. Even though the dispersed clay is measured under saturated conditions, soil samples retain a `memory' of the water contents at which they have been stored.

  19. Aggregate stability and associated C and N in a silty loam soil as affected by organic material inputs

    Institute of Scientific and Technical Information of China (English)

    LONG Pan; SUI Peng; GAO Wang-sheng; WANG Bin-bin; HUANG Jian-xiong; YAN Peng; ZOU Juan-xiu; YAN Ling-ling; CHEN Yuan-quan

    2015-01-01

    To make recycling utilization of organic materials produced in various agricultural systems, ifve kinds of organic materials were applied in a ifeld test, including crop straw (CS), biogas residue (BR), mushroom residue (MR), wine residue (WR), pig manure (PM), with a mineral fertilizer (CF) and a no-fertilizer (CK) treatment as a control. Our objectives were:i) to quantify the effects of organic materials on soil C and N accumulation;i ) to evaluate the effects of organic materials on soil aggregate stability, along with the total organic carbon (TOC), and N in different aggregate fractions;and i i) to assess the relationships among the organic material components, soil C and N, and C, N in aggregate fractions. The trial was conducted in Wuqiao County, Hebei Province, China. The organic materials were incorporated at an equal rate of C, and combined with a mineral fertilizer in amounts of 150 kg N ha-1, 26 kg P ha-1 and 124 kg K ha-1 respectively during each crop season of a wheat-maize rotation system. The inputted C quantity of each organic material treatment was equivalent to the total amount of C contained in the crop straw harvested in CS treatement in the previous season. TOC, N, water-stable aggregates, and aggregate-associated TOC and N were investigated. The results showed that organic material incorpora-tion increased soil aggregation and stabilization. On average, the soil macroaggregate proportion increased by 14%, the microaggregate proportion increased by 3%, and mean-weight diameter (MWD) increased by 20%. TOC content fol owed the order of PM>WR>MR>BR>CS>CK>CF;N content fol owed the order WR>PM>MR>BR>CS>CF>CK. No signiifcant correlation was found between TOC, N, and the quality of organic material. Soil silt and clay particles contained the largest part of TOC, whereas the smal macroaggregate fraction was the most sensitive to organic materials. Our results indicate that PM and WR exerted better effects on soil C and N accumulation, fol owed by MR

  20. Cultivos de cobertura: efectos sobre la macroporosidad y la estabilidad estructural de un suelo franco-limoso Cover crops: effects on soil macroporosity and soil structural stability in a silt loam soil

    Directory of Open Access Journals (Sweden)

    María Florencia Varela

    2011-07-01

    Full Text Available Los suelos franco-limosos manejados con siembra directa a menudo poseen porosidad estructural baja e inestable. Con el objetivo de determinar la capacidad de los cultivos de cobertura (CC de mejorar la porosidad y estabilidad estructural de estos suelos se llevaron a cabo experimentos de campo y de invernáculo. Ambos tuvieron tratamientos con y sin CC (avena, Avena sativa L., en rotación con soja (Glicine max L. Merr.. Luego de los CC se midieron densidad aparente (DA, el índice de inestabilidad estructural (IE y en el ensayo de invernáculo además, se midió la evolución de la distribución de tamaño de poros (DTP. En ambos ensayos la introducción de CC no disminuyó la DA, aunque incrementó la estabilidad del suelo (PNo- till (NT silt loam topsoils have often a low and unstable structural porosity. The objective of this study was to determine the capability of cover crops (CC of improving the structural porosity and stability of silt loam soils under NT. Greenhouse and field experiments were carried out on a silt loam soil (Typic Argiudoll with and without CC (oat, Avena sativa L. in crop sequences with soybean (Glicine max L. Merr.. Soil bulk density (DA and aggregate instability index (IE were measured after the CC in both experiments. In the greenhouse experiment, soil pore size distribution (DTP was measured. The use of CC did not change DA, but soil IE was significantly lower in crop sequences with CC (P < 0.05 both under field and greenhouse conditions. Stability increases were likely due to the effect of CC residues and root mass. No differences in DTP were found between treatments, although a significant effect of sampling date was observed (P<0.05. Changes in DTP were due to significant increases in mesopore (517.5% and macropore (52.7% volumes. Such changes occurred in all the treatments, probably due to the soil wetting-drying cycles. The results found in this study agree with other studies carried out on silt loams in the

  1. Biochar increases plant-available water in a sandy loam soil under an aerobic rice crop system

    NARCIS (Netherlands)

    Melo Carvalho, de M.T.; Holanda Nunes Maia, de A.; Madari, B.E.; Bastiaans, L.; Oort, van P.A.J.; Heinemann, A.B.; Soler da Silva, M.A.; Petter, F.A.; Marimon-Junior, B.H.; Meinke, H.B.

    2014-01-01

    The main objective of this study was to assess the impact of biochar rate (0, 8, 16 and 32 Mg ha-1) on the water retention capacity (WRC) of a sandy loam Dystric Plinthosol. The applied biochar was a by-product of slow pyrolysis (~450 °C) of eucalyptus wood, milled to pass through a 2000 µm sieve th

  2. Effect of rainfall and tillage direction on the evolution of surface crusts, soil hydraulic properties and runoff generation for a sandy loam soil

    Science.gov (United States)

    Ndiaye, Babacar; Esteves, Michel; Vandervaere, Jean-Pierre; Lapetite, Jean-Marc; Vauclin, Michel

    2005-06-01

    The study was aimed at evaluating the effect of rainfall and tillage-induced soil surface characteristics on infiltration and runoff on a 2.8 ha catchment located in the central region of Senegal. This was done by simulating 30 min rain storms applied at a constant rate of about 70 mm h -1, on 10 runoff micro-plots of 1 m 2, five being freshly harrowed perpendicularly to the slope and five along the slope (1%) of the catchment. Runoff was automatically recorded at the outlet of each plot. Hydraulic properties such as capillary sorptivity and hydraulic conductivity of the sandy loam soil close to saturation were determined by running 48 infiltration tests with a tension disc infiltrometer. That allowed the calculation of a mean characteristic pore size hydraulically active and a time to ponding. Superficial water storage capacity was estimated using data collected with an electronic relief meter. Because the soil was subject to surface crusting, crust-types as well as their spatial distribution within micro-plots and their evolution with time were identified and monitored by taking photographs at different times after tillage. The results showed that the surface crust-types as well as their tillage dependent dynamics greatly explain the decrease of hydraulic conductivity and sorptivity as the cumulative rainfall since tillage increases. The exponential decaying rates were found to be significantly greater for the soil harrowed along the slope (where the runoff crust-type covers more than 60% of the surface after 140 mm of rain) than across to the slope (where crusts are mainly of structural (60%) and erosion (40%) types). That makes ponding time smaller and runoff more important. Also it was shown that soil hydraulic properties after about 160 mm of rain were close to those of untilled plot not submitted to any rain. That indicates that the effects of tillage are short lived.

  3. Soil, crop and emission responses to seasonal-controlled traffic in organic vegetable farming on loam soil

    NARCIS (Netherlands)

    Vermeulen, G.D.; Mosquera Losada, J.

    2009-01-01

    Some organic arable and vegetable farms in the Netherlands use cm-precise guidance of machinery to restrict wheel traffic to fixed traffic lanes and to achieve non-trafficked cropping zones with optimized soil structure in between the lanes. Contrary to controlled traffic farming (CTF) the traffic l

  4. Potential of Spectroradiometry to Classify Soil Clay Content

    Directory of Open Access Journals (Sweden)

    André Carnieletto Dotto

    2016-01-01

    Full Text Available ABSTRACT Diffuse reflectance spectroscopy (DRS is a fast and cheap alternative for soil clay, but needs further investigation to assess the scope of application. The purpose of the study was to develop a linear regression model to predict clay content from DRS data, to classify the soils into three textural classes, similar to those defined by a regulation of the Brazilian Ministry of Agriculture, Livestock and Food Supply. The DRS data of 412 soil samples, from the 0.0-0.5 m layer, from different locations in the state of Rio Grande do Sul, Brazil, were measured at wavelengths of 350 to 2,500 nm in the laboratory. The fitting of the linear regression model developed to predict soil clay content from the DRS data was based on a R2 value of 0.74 and 0.75, with a RMSE of 7.82 and 8.51 % for the calibration and validation sets, respectively. Soil texture classification had an overall accuracy of 79.0 % (calibration and 80.9 % (validation. The heterogeneity of soil samples affected the performance of the prediction models. Future studies should consider a previous classification of soil samples in different groups by soil type, parent material and/or sampling region.

  5. Natural occurrence and distribution of soil borne entomopathogenic fungi in shahrood region, northeast of Iran

    OpenAIRE

    Derakhshan, Ali

    2009-01-01

    The study investigated the occurrence of soil borne entomopathogenic fungi (EPF) in potato, wheat, sugar beet, alfalfa fields and orchards. A total of 150 soil samples were collected and EPF were isolated using Galleria method. Soil pH was rages from 6.8 to 8.1 and soil texture was sandy, loam, sandy- loam, clay and sandy-loam-clay. Soil borne EPF occurred at 78% of soil samples from which 40% Beauveria bassiana, 21% Metarhizium anisopliae and 17% had both species. Occurrence and ...

  6. Transfer of 137Cs and 90Sr to spring wheat in relation with provision of sod-podzolic loam soil with phosphates and portions of mineral fertilizers

    International Nuclear Information System (INIS)

    The field experiment with fertilizer treatments of spring wheat on four different levels of soil supply with mobile phosphates has been conducted in 2005-2007 on sod-podzolic loam sandy soli contaminated with radionuclides. It was found a damped function decrease of 137Cs and 90Sr transfer to wheat grain up to 1.5 - 1.6 times according to change of mobile P2O5 content in soil from 70 to 393 mg/kg. Increasing the soil phosphate content up to 400 mg/kg with simultaneous application of fertilizers N60+30P60K180 could result in double reduction of 90Sr accumulation in wheat grain

  7. Nitrite and Nitrate Removal Efficiencies of Soil Aquifer Treatment Columns

    OpenAIRE

    GÜNGÖR, Kerem; ÜNLÜ, Kahraman

    2005-01-01

    Bench-scale soil column experiments were performed to examine the effects of soil type and infiltration conditions on the removal efficiencies of wastewater nitrites and nitrates during the biological ripening phase of soil aquifer treatment (SAT) columns. SAT was simulated in three 1-m-high soil columns packed with 3 different natural agricultural soils having sandy clay loam (SCL), loamy sand (LS) and sandy loam (SL) textures. All columns were equipped with tensiometers and soil-wa...

  8. Effect of Ionic Soil Stabilizers on Soil-Water Characteristic of Special Clay

    Science.gov (United States)

    Cui, D.; Xiang, W.

    2011-12-01

    The engineering properties of special clay are conventionally improved through the use of chemical additive such as ionic soil stabilizer (ISS). Such special clays are often referred to as stabilized or treated clays. The soil-water characteristic curves (SWCC) of special clays from Henan province and Hubei province were measured both in natural and stabilized conditions using the pressure plate apparatus in the suction range of 0-500 kPa. The SWCC results are used to interpret the special clays behavior due to stabilizer treatment. In addition, relationships were developed between the basic clay and stabilized properties such as specific surface area and pore size distribution. The analysis showed that specific surface area decreases, cumulative pore volume and average pore size diameter decrease, dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. The research data and interpretation analysis presented here can be extended to understand the water film change behaviors influencing the mechanical and physical properties of stabilized special clay soils. KEY WORDS: ionic soil stabilizer, special clay, pore size diameter, specific surface area, soil water characteristic curve, water film

  9. Pesticide leaching in macroporous clay soils: field experiment and modeling

    NARCIS (Netherlands)

    Scorza Júnior, R.P.

    2002-01-01

    Keywords : pesticide leaching, macropores, preferential flow, preferential transport, cracked clay soil, pesticide leaching models, groundwater contamination, inverse modeling, bentazone and imidacloprid. The presence of macropores (i.e. shrinkage c

  10. Clay content evaluation in soils through GPR signal processing

    Science.gov (United States)

    Tosti, Fabio; Patriarca, Claudio; Slob, Evert; Benedetto, Andrea; Lambot, Sébastien

    2013-10-01

    The mechanical behavior of soils is partly affected by their clay content, which arises some important issues in many fields of employment, such as civil and environmental engineering, geology, and agriculture. This work focuses on pavement engineering, although the method applies to other fields of interest. Clay content in bearing courses of road pavement frequently causes damages and defects (e.g., cracks, deformations, and ruts). Therefore, the road safety and operability decreases, directly affecting the increase of expected accidents. In this study, different ground-penetrating radar (GPR) methods and techniques were used to non-destructively investigate the clay content in sub-asphalt compacted soils. Experimental layout provided the use of typical road materials, employed for road bearing courses construction. Three types of soils classified by the American Association of State Highway and Transportation Officials (AASHTO) as A1, A2, and A3 were used and adequately compacted in electrically and hydraulically isolated test boxes. Percentages of bentonite clay were gradually added, ranging from 2% to 25% by weight. Analyses were carried out for each clay content using two different GPR instruments. A pulse radar with ground-coupled antennae at 500 MHz centre frequency and a vector network analyzer spanning the 1-3 GHz frequency range were used. Signals were processed in both time and frequency domains, and the consistency of results was validated by the Rayleigh scattering method, the full-waveform inversion, and the signal picking techniques. Promising results were obtained for the detection of clay content affecting the bearing capacity of sub-asphalt layers.

  11. Ionic migration in soils and clays

    International Nuclear Information System (INIS)

    Migration of ions in soil to plant roots takes place either by the viscous movement of the soil solution through the pore space, or by ionic diffusion. As long as there is drainage viscous flow is possible, but when once the drainage stops ionic diffusion alone migrates the ions. The amount of the nutrient ion that diffuses at a given temperature in a soil depends upon the soil structure and the moisture condition. In free liquids, or in straight uniform channels, the diffusing ions are not obstructed in the course of their migration along the direction of measurement. In such cases the whole fractional area of the cross-section will be effective. But in a bed of soil where the channels bend round corners, forming twists and constrictions, the quantity of the ion diffused falls short of the expected value and the decrease in the ion diffused in such cases should be attributed to the twists and constrictions. The effective fractional areas obtained under different conditions of compaction give a measure of the effect of twists and constrictions on the migration of ions in each case

  12. INFLUENCE OF VERMICOMPOST ON THE PHYSICO-CHEMICAL AND BIOLOGICAL PROPERTIES IN DIFFERENT TYPES OF SOIL ALONG WITH YIELD AND QUALITY OF THE PULSE CROP-BLACKGRAM

    Directory of Open Access Journals (Sweden)

    K. Parthasarathi, M. Balamurugan, L. S. Ranganathan

    2008-01-01

    Full Text Available Field experiments were conducted during 2002-2003 on clay loam, sandy loam and red loam soil at Sivapuri, Chidambaram, Tamil Nadu, to evaluate the efficacy of vermicompost on the physico-chemical and biological characteristics of the soils and on the yield and nutrient content of blackgram - Vigna mungo, in comparison to inorganic fertilizers nitrogen, phosphorous, potassium. Vermicompost had increased the pore space, reduced particle and bulk density, increased water holding capacity, cation exchange capacity, reduced pH and electrical conductivity, increased organic carbon content, available nitrogen, phosphorous, potassium and microbial population and activity in all the soil types, particularly clay loam. The yield and quality (protein and sugar content in seed of blackgram was enhanced in soils, particularly clay loam soil. On the contrary, the application of inorganic fertilizers has resulted in reduced porosity, compaction of soil, reduced carbon and reduced microbial activity.

  13. Sorption of radionuclides on some clays and soils

    International Nuclear Information System (INIS)

    The sorption and desorption properties of radio- cesium, barium and iodine were studied using clay and soil fractions from various regions of Turkey. Clay minerals and soil fractions were identified by X-ray diffraction spectrometry and particle size distribution experiments. The clay minerals were found to be kaolinite, montmorillonite and mixed chlorite-illite types. Grain sizes of all solid particles were all -8 mols/L to 10-3 mols/L. The radionuclides 137Cs, 90Sr, 133Ba and 125I were used as tracers. Batch experiments were performed to determine the distribution ratio, RD, as a function of interaction time, shaking rate, ion concentration, pH, and volume/mass ratio. Cation exchange capacities were obtained using the silver-thiourea method. Kinetic studies indicated initial rapid sorption gradually reaching saturation in several days. The saturation time ranged from 6 to 12 days depending on clay as well as radionuclide types. Inverse S-shaped loading curves were obtained in the studies of RD versus cation concentration on the solid. The curves suggest the presence of at least two types of sorption sites on the clay minerals. The sorption process was observed to be reversible to a large extent in all cases. The distribution ratio was found to increase with increasing volume/mass ratio and with decreasing particle size. The latter observation suggests mainly surface sorption. Generally highest RD values were observed for cesium sorption followed by strontium and barium. Iodine was sorbed very little by clay minerals. (16 refs., 7 figs., 3 tabs.)

  14. Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

    Science.gov (United States)

    Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

    2016-06-01

    Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality. PMID:27022106

  15. Physical-hydraulic properties of a sandy loam typic paleudalf soil under organic cultivation of 'montenegrina' mandarin (Citrus deliciosa Tenore¹

    Directory of Open Access Journals (Sweden)

    Caroline Valverde dos Santos

    2014-12-01

    Full Text Available Citrus plants are the most important fruit species in the world, with emphasis to oranges, mandarins and lemons. In Rio Grande do Sul, Brazil, most fruit production is found on small properties under organic cultivation. Soil compaction is one of the factors limiting production and due to the fixed row placement of this crop, compaction can arise in various manners in the interrows of the orchard. The aim of this study was to evaluate soil physical properties and water infiltration capacity in response to interrow management in an orchard of mandarin (Citrus deliciosa Tenore 'Montenegrina' under organic cultivation. Interrow management was performed through harrowing, logs in em "V", mowing, and cutting/knocking down plants with a knife roller. Soil physical properties were evaluated in the wheel tracks of the tractor (WT, between the wheel tracks (BWT, and in the area under the line projection of the canopy (CLP, with undisturbed soil samples collected in the 0.00-0.15, 0.15-0.30, 0.30-0.45, and 0.45-0.60 m layers, with four replicates. The soil water infiltration test was performed using the concentric cylinder method, with a maximum time of 90 min for each test. In general, soil analysis showed a variation in the physical-hydraulic properties of the Argissolo Vermelho-Amarelo distrófico arênico (sandy loam Typic Paleudalf in the three sampling sites in all layers, regardless of the management procedure in the interrows. Machinery traffic leads to heterogeneity in the soil physical-hydraulic properties in the interrows of the orchard. Soil porosity and bulk density are affected especially in the wheel tracks of the tractor (WT, which causes a reduction in the constant rate of infiltration and in the accumulated infiltration of water in this sampling site. The use of the disk harrow and mower leads to greater harmful effects on the soil, which can interfere with mandarin production.

  16. Land Sliding Analysis on Red Clay soil using Fracture Criteria

    OpenAIRE

    Guthbutheen, Mohamed Riyazdeen Mavaday; ji, Yisho; Ji, Jin

    2012-01-01

    In order to assess the safe and functional design of road ways, buildings, bridges, dams, etc. Also to protect from structural damages and geological disasters. The landslide analysis is to conduct based on force resisting method by applying uniform loads on top of the hill to determine slope stability, instability, for with and without crack on clay soil is to be experimented and evaluate the mechanical properties such as elastic modulus, poison ratio, and shear strength. In addition, the nu...

  17. Field methods for studying soil moisture regimes and irrigation practices in clay soils

    International Nuclear Information System (INIS)

    Characterization of water flow through swelling clay soils with macropores (''cracks'') requires special techniques because these soils are not isotropic and homogeneous as required by standard flow theory. The techniques should preferably be rapid and inexpensive to allow applications in the field. Three experimental techniques, which were recently developed at the Netherlands Soil Survey Institute, are discussed. The measure: (i) vertical and horizontal Ksub(sat) in a gypsum-covered cube of soil which is carved out in situ (the cube method); (ii) the Ksub(unsat) near saturation down to pressure heads of about -15cm by determining fluxes through a series of crusts and the associated negative pressure heads below the crusts (the crusts test); and (iii) short-circuiting, which is the preferential movement of free water along vertical macropores in unsaturated soil, by applying sprinkling irrigation to large, undisturbed cores. In addition, three examples are discussed whereby soil morphological field data are used for simulation models which characterize soil moisture regimes of clay soils. These examples cover: (i) the effect of horizontal cracks on upward unsaturated flow; (ii) infiltration of sprinkling irrigation in a cracked clay soil; and (iii) ponded infiltration of water in a clay soil with worm channels. (author)

  18. Passive Microwave Observation of Soil Water Infiltration

    Science.gov (United States)

    Jackson, Thomas J.; Schmugge, Thomas J.; Rawls, Walter J.; ONeill, Peggy E.; Parlange, Marc B.

    1997-01-01

    Infiltration is a time varying process of water entry into soil. Experiments were conducted here using truck based microwave radiometers to observe small plots during and following sprinkler irrigation. Experiments were conducted on a sandy loam soil in 1994 and a silt loam in 1995. Sandy loam soils typically have higher infiltration capabilities than clays. For the sandy loam the observed brightness temperature (TB) quickly reached a nominally constant value during irrigation. When the irrigation was stopped the TB began to increase as drainage took place. The irrigation rates in 1995 with the silt loam soil exceeded the saturated conductivity of the soil. During irrigation the TB values exhibited a pattern that suggests the occurrence of coherent reflection, a rarely observed phenomena under natural conditions. These results suggested the existence of a sharp dielectric boundary (wet over dry soil) that was increasing in depth with time.

  19. Influence of cracking in the desiccation process of clay soils

    OpenAIRE

    Levatti, Hector Ulises; Prat Catalán, Pere; Ledesma Villalba, Alberto

    2009-01-01

    It is well known that clayey soils undergoing desiccation tend to shrink and eventually crack. Analysis of the behaviour and influence of cracks in these types of soils is very important in several engineering fields such as mine tailing dams, long-term radioactive waste storage, impervious core of earth dams, and in any situation where clay is used as a barrier to fluid flow. Loss of humidity and cracking changes the permeability of such barriers that may no longer work properly and pose pot...

  20. Soil-Water Characteristic Curves of Red Clay treated by Ionic Soil Stabilizer

    Science.gov (United States)

    Cui, D.; Xiang, W.

    2009-12-01

    The relationship of red clay particle with water is an important factor to produce geological disaster and environmental damage. In order to reduce the role of adsorbed water of red clay in WuHan, Ionic Soil Stabilizer (ISS) was used to treat the red clay. Soil Moisture Equipment made in U.S.A was used to measure soil-water characteristic curve of red clay both in natural and stabilized conditions in the suction range of 0-500kPa. The SWCC results were used to interpret the red clay behavior due to stabilizer treatment. In addition, relationship were compared between the basic soil and stabilizer properties such as water content, dry density, liquid limit, plastic limit, moisture absorption rate and stabilizer dosages. The analysis showed that the particle density and specific surface area increase, the dehydration rate slows and the thickness of water film thins after treatment with Ionic Soil Stabilizer. After treatment with the ISS, the geological disasters caused by the adsorbed water of red clay can be effectively inhibited.

  1. Origin of the high sensitivity of Chinese red clay soils to drought : significance of the clay characteristics

    OpenAIRE

    D'Angelo, Benoît; Bruand, Ary; Qin, Jiangtao; Peng, Xihnua; Hartmann, Christian; Bo, Sun; Hao, Hongtao; Rozenbaum, Olivier; Muller, Fabrice

    2014-01-01

    The red clay soils which are widespread in China are known to be highly sensitive to drought during the dry season but the origin of this high sensitivity to drought remains unclear. Several red clay soils were selected in the Hunan province for study. We studied their basic physico-chemical properties and clay mineralogy, their structure and shrinkage properties, as well as their water retention properties. Results show that the amount of water available between -330 and -15 000 hPa water po...

  2. A Preliminary Study on Identification of Clay Minerals in Soils with Reference to Reflectance Spectra

    Institute of Scientific and Technical Information of China (English)

    XUBIN-BIN; LIDE-CHENG; 等

    1995-01-01

    The characteristics of the reflectance spectra of clay minerals and their influences on the reflectance spectra of soils are dealt with in the paper.The results showed that dominant clay minerals in soils could be distinguished in light of the spectral -form parameters of the reflectance spectra of soils,thus making it possible to develop a quick method to determine clay minerals by means of reflectance spectra of soils in the lab.and providing a theoretic basis for remote sensing of clay minerals in soils with a high resolution imaging spectrometer.

  3. Lability of soil organic carbon in tropical soils with different clay minerals

    DEFF Research Database (Denmark)

    Bruun, Thilde Bech; Elberling, Bo; Christensen, Bent Tolstrup

    2010-01-01

    of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 µm by wet sieving...

  4. Effect of nutrients and plant growth regulators on growth and yield of black gram in sandy loam soils of Cauvery new delta zone, India

    Directory of Open Access Journals (Sweden)

    S. Marimuthu

    2015-12-01

    Full Text Available Pulse productivity is very low in some of the sandy soil areas where, soils are having poor water and nutrient holding capacity. To improve the pulse productivity, field experiments were conducted at Agricultural Research Station, Tamil Nadu for two consecutive years to study the effect of phosphorus sources (mono- and diammonium phosphate with brassinolide and salicylic acid on growth and yield of black gram in sandy loam soils. The experiment was carried out in a randomized block design with three replications during kharif season. The treatments include 100% recommended dose of NPK along with foliar application of monoammonium phosphate (MAP, diammonium phosphate (DAP, brassinolide (0.25 ppm, and salicylic acid (100 ppm along with the combination of these treatments. TNAU pulse wonder at 5.0 kg ha−1 and TNAU micronutrient mixture (MN at 5 kg ha−1 were also tried. The results revealed that application of 100% recommended dose of NPK + DAP 2% + TNAU pulse wonder 5.0 kg ha−1 was statistically significant and recorded higher plant growth (37.62 cm, number of pods / plant (37.15, yield of black gram (1162 kg ha−1, and benefit cost ratio (2.98 over the other treatments. The lowest black gram yield (730 kg ha−1 was recorded for control.

  5. Effect of organic amendments on the retention and mobility of imazaquin in soils

    OpenAIRE

    Undabeytia López, Tomás; Sánchez Verdejo, Trinidad; Morillo González, Esmeralda; Maqueda Porras, Celia

    2004-01-01

    The influence of two organic amendments consisting of an urban waste compost (SUW) and a commercial amendment from olive mill wastes (OW) was assessed on the sorption properties and leaching of the ionizable herbicide imazaquin on four soils with different physicochemical characteristics. A loamy sand soil (CR), a loam soil (P44), a silt loam soil (AL), and a clay soil (TM), with low-medium organic matter contents, were chosen. Sorption-desorption experiments were performed on ...

  6. Hydraulic conductivity in sugar cane cultivated in soils previous vin aza application

    International Nuclear Information System (INIS)

    This work analyzes the hydraulic conductivity in soil clay loams developed in Libertad formation in Bella Union where grows sugar cane with vinaza. In the agricultural activities are used different chemical additives such as organic and inorganic fertilizers, herbicides and pesticides, which interact with the biotic (roots, soil microbiology) and abiotic (clay, soil solution, etc.) elements

  7. Behaviour of radiocesium in a turf weakly podzolic loam soil: critical evaluation of the sequential extraction results

    International Nuclear Information System (INIS)

    A sequential extraction procedure was applied to study the behavior of radiocesium in a turf weakly podzolic soil. The soil was sampled within the 30-km zone of the Chernobyl NPP (near Buryakivka village). No significant difference between exchangeable fractions for 1990-1995 was observed. However, there was some decreasing in non extractable residues. The redistribution of radiocesium's fraction in the soil during this procedure was studied; decreasing of first fractions was showed. Therefore, it is confirmed that the value of mobile forms of radiocesium obtained by the extraction procedure is underestimated. These results confirm the necessity of improving the methods of cesium's forms definition for soil

  8. Using Agricultural Residue Biochar to Improve Soil Quality of Desert Soils

    OpenAIRE

    Yunhe Zhang; Omololu John Idowu; Catherine E. Brewer

    2016-01-01

    A laboratory study was conducted to test the effects of biochars made from different feedstocks on soil quality indicators of arid soils. Biochars were produced from four locally-available agricultural residues: pecan shells, pecan orchard prunings, cotton gin trash, and yard waste, using a lab-scale pyrolyzer operated at 450 °C under a nitrogen environment and slow pyrolysis conditions. Two local arid soils used for crop production, a sandy loam and a clay loam, were amended with these bioch...

  9. N leaching to groundwater from dairy production involving grazing over the winter on a clay-loam soil.

    Science.gov (United States)

    Necpalova, M; Fenton, O; Casey, I; Humphreys, J

    2012-08-15

    This study investigated concentrations of various N species in shallow groundwater (piezometers was installed to determine groundwater flow direction and N spatial and temporal variation. Estimated vertical travel times through the unsaturated zone (piezometer, DOC concentration). A high explanatory power of NO(3)(-)-N/Cl(-) ratio and the distance of the sampling point from the closest receptor indicated the influence of point sources and groundwater-surface water interactions. PMID:22728303

  10. Investigations into aspects of nitrogen and carbon dynamics in grassland used for dairy production on a clay loam soil

    OpenAIRE

    Necpálová, Magdaléna

    2012-01-01

    Increasing concentrations of nitrogen (N) in the waterbodies along with increasing concentrations of nitrous oxide (N2O) and carbon dioxide in the atmosphere have become an international environmental concern. Permanent grasslands are important sources of feed for intensively managed dairy and beef farming systems in North West Europe and represent around 90% of agricultural land in Ireland. However, there is a potential for substantial N losses following grazing during the win...

  11. Study and Estimation of the Ratio of 137CS and 40K Specific Activities in Sandy and Loam Soils

    Directory of Open Access Journals (Sweden)

    Renata Mikalauskienė

    2011-12-01

    Full Text Available The present article describes changes in specific activities and fluctuations in the ratio of natural 40K and artificial 137Cs radionuclides in soil samples taken from different places of Lithuanian territory. The samples of soil have been selected from the districts polluted after the accident in Chernobyl nuclear plant performing nuclear testing operations. The study has established the main physical and chemical properties of soil samples and their impact on the concentration of 40K activities. 137Cs/40K specific activities in soil have been observed under the dry weight of the sample that varied from 0.0034 to 0.0240. The results of the study could be used for establishing and estimating 137Cs and 40K transfer in the system “soil-plant”.Article in Lithuanian

  12. Adsorption and desorption study of 14C-Chloropyrifos in two Malaysian agricultural soils

    International Nuclear Information System (INIS)

    The adsorption equilibrium time and effects of pH and concentration of 14C-labeled chloropyrifos 0,0-diethyl 0-(3, 5, 6 tricloro-2-pyridyl)-phosphorothiote in soil were investigated. Two types of Malaysian soil under oil palm were used in this study; namely clay loam and clay soil obtained from the Sungai Sedu and Kuala Lumpur International Airport (KLIA) Estates, respectively. Equilibrium studies of chloropyrifos between the agricultural soil and the pesticide solution were conducted. Adsorption equilibrium time was achieved within 6 and 24 hours for clay loam and clay soil, respectively. It was found that chloropyrifos adsorbed by the soil samples was characterized by an initial rapid adsorption after which adsorption remained approximately constant. The percentage of 14C-labeled chloropyrifos adsorption on soil was found to be higher in clay loam than in clay soils. Results of the study demonstrated that pH affected the adsorption of chloropyrifos on both clay loam and clay soils. The adsorption of chloropyrifos on both types of soil was higher at low pH with the adsorption reduced as the pH increased. Results also suggest that chloropyrifos sorption by soil is concentration dependent. (Author)

  13. Effects of Tillage Methods on Soil Fragmentation in Loamy-Clay Soils

    Directory of Open Access Journals (Sweden)

    Yousef Abbaspour-Gilandeh

    2009-01-01

    Full Text Available Problem statement: Soil fragmentation is a primary aim in tillage in order to create a favorable soil environment for crop growth. Soil fragmentation is defined as the process of breakdown and crumbling of soil aggregates. Currently, there is no published research data on optimum tillage operations for seedbed preparation in loamy-clay soils of western Caspian Sea region of Iran. Approach: Tests were conducted on a loamy-clay soil near the city of Ardabil, Iran, to investigate the effects of different tillage operations on soil crumbling. Four tillage treatments: Moldboard plow (M (conventional method, Moldboard plow and Disk-Harrow (MH, Decompactor and Moldboard plow (DM and De-Compactor and Disk-Harrow (DH were used in this study with four replications. The tillage depth for all treatments was about 30 cm. Following tillage operations, intensive soil samples were taken from the top 25 cm of soil at 5 cm depth increments and were analyzed for aggregate size and distribution using 9 standard sieves (0.25-19 mm mesh. Analysis of variance was carried out regarding soil crumbling percentage and mean diameter of soil aggregates in each treatment. The experiment was arranged in a split-plot design with five levels of soil sampling depths and two main factors (tillage method and tillage depth which were arranged in Latin Square design. Results: Results showed that the tillage treatments had a significant effect on soil crumbling. Also, soil crumbling varied with soil depth and the optimum particle sizes were developed at the 5-20 cm soil depth. There was a non-linear correlation between soil crumbling percentage and tillage depth. Conclusion/Recommendations: Tillage methods and soil sampling depth had interaction effect on soil crumbling percentage. The MH treatment had the greatest amount of soil crumbling and the best seed-bed condition.

  14. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, E.; Tuller, M.; Møldrup, Per;

    2015-01-01

    (average RMSE = 5.0%, ME = 2.4%) prediction of clay contents. However, the model for soils with small OC contents showed only minor improvement when compared with recently published models. Three main sources of prediction errors, namely large OC and silt contents, and a prevalence of 1:1 clay minerals......Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... for estimating clay content from hygroscopic water at different relative humidity (RH) levels while considering hysteresis and organic matter content. Continuous adsorption/desorption vapour sorption isotherm loops were measured for 150 differently textured soils with a state-of-the-art vapour...

  15. Improved estimation of soil clay content by the fusion of remote hyperspectral and proximal geophysical sensing

    Science.gov (United States)

    Ciampalini, Andrea; André, Frédéric; Garfagnoli, Francesca; Grandjean, Gilles; Lambot, Sébastien; Chiarantini, Leandro; Moretti, Sandro

    2015-05-01

    Planning sustainable soil exploitation and land resource evaluation require up-to-date and accurate maps of soil properties. In that respect, geophysical techniques present particular interests given their non-invasiveness and their fast data acquisition capacity, which permit to characterize large areas with fine spatial and/or temporal resolutions. We investigated the relevancy of combining data from airborne hyperspectral (Hs), electromagnetic induction (EMI) and far-field ground-penetrating radar (GPR) for mapping soil properties, in particular soil clay content, at the field scale. Data from the three techniques were acquired at a test site in Mugello (Italy) characterized by relatively strong spatial variations of soil texture. Soil samples were collected for determining ground truth clay content. For the frequencies used in this study (200-650 MHz), the GPR surface reflection is mainly determined by soil dielectric permittivity, itself primarily influenced by soil moisture. In contrast, EMI is mostly sensitive to soil electrical conductivity, which integrates several soil properties including in particular soil moisture and clay content. Taking advantage of the complementary information provided by the two instruments, the GPR and EMI data were combined and correlated to local ground-truth clay content data to provide high-resolution clay content maps over the entire field area. Besides, a relationship was also observed between Hs data and clay content measurements, which permitted to produce a Hs-derived clay content map. EMI-GPR and Hs maps showed close spatial patterns and a relatively high correlation was observed between both clay content estimates, as well as between clay content estimates and ground-truth clay content measurements. Moreover, data fusion allowed constraining the EMI-GPR and Hs information and reduced the uncertainty of mapped clay content estimates. These results demonstrated great promise for integrated, digital soil mapping

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

    Science.gov (United States)

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

    2015-09-01

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

  17. Infiltration and Bypass Flow of Cracking Puddled Soils

    Directory of Open Access Journals (Sweden)

    M.J. Islam

    2004-01-01

    Full Text Available A study of infiltration and bypass flow was conducted in a wet soil bin with three different soils treatments (sandy loam, clay loam and clay soil to determine the swelling behaviour of cracking puddled soils by watering and its impact on bypass flow. Infiltration rate for the soils was recorded after puddling the soils. Then the puddled soils were allowed to dry for a period of up to 15 days. After that the plots were rewetted in order to observe the swelling and bypass behaviour of cracked soils. From this study it is observed that the infiltration rates of puddled soils were very low (0.03-0.05 mm h-1 mainly due to the puddling effect. The study indicates that cracks on puddled soils at 15th day�s of drying are effectively irreversible. The maximum bypass flow was recorded for the clay loam soil. During the first day, the flow rate was extremely high at 313 mm h-1. But this higher rate gradually reduced from the second day and onwards. The bypass flow rate for the clay loam and clay soil was almost same. The study reveals that it is not possible to swell up shrinkage cracks on puddled soils by watering alone. Re-working of the soil is necessary to seal the cracks.

  18. Jatropha curcas L. root structure and growth in diverse soils.

    Science.gov (United States)

    Valdés-Rodríguez, Ofelia Andrea; Sánchez-Sánchez, Odilón; Pérez-Vázquez, Arturo; Caplan, Joshua S; Danjon, Frédéric

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots). The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14 ± 5% (mean ± standard deviation). Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil. PMID:23844412

  19. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    Directory of Open Access Journals (Sweden)

    Ofelia Andrea Valdés-Rodríguez

    2013-01-01

    Full Text Available Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four lateral roots. The sandy soil reduced the growth of both shoot and root systems significantly more than sandy-loam or clay-loam soils; there was particularly high plasticity in root and shoot thickness, as well as shoot length. However, the architecture of the primary root system did not vary with soil type; the departure of the primary root system from an index of perfect symmetry was 14±5% (mean ± standard deviation. Although J. curcas developed more extensively in the sandy-loam and clay-loam soils than in sandy soil, it maintained a consistent root to shoot ratio and root system architecture across all types of soil. This strong genetic determination would make the species useful for soil stabilization purposes, even while being cultivated primarily for seed oil.

  20. Jatropha curcas L. Root Structure and Growth in Diverse Soils

    OpenAIRE

    Ofelia Andrea Valdés-Rodríguez; Odilón Sánchez-Sánchez; Arturo Pérez-Vázquez; Caplan, Joshua S.; Frédéric Danjon

    2013-01-01

    Unlike most biofuel species, Jatropha curcas has promise for use in marginal lands, but it may serve an additional role by stabilizing soils. We evaluated the growth and structural responsiveness of young J. curcas plants to diverse soil conditions. Soils included a sand, a sandy-loam, and a clay-loam from eastern Mexico. Growth and structural parameters were analyzed for shoots and roots, although the focus was the plasticity of the primary root system architecture (the taproot and four late...

  1. Effects of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils

    Institute of Scientific and Technical Information of China (English)

    WU Shao-fu; WU Liang-huan; SHI Qi-wei; WANG Zhong-qiang; CHEN Xian-you; LI Yong-shan

    2007-01-01

    In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3--N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3--N leaching significantly, whereas ammonium (NH4+-N) leaching increased slightly. In case of total N (NO3--N+NH4+-N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea+DMPP), 108.10 mg (ASN), 60.70 mg (ASN+DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea+DMPP), 37.86 mg (ASN), 31. 09 mg (ASN+DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4+-N and low levels of NO3--N in soil, and nitrification was slower. DMPP supplementation also resulted in potassium leached less, but the difference was not significant except the treatment ASN and ASN+DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

  2. Theoretical Analysis of the Influence of the Thermal Diffusivity of Clay Soil on the Thermal Energy Distribution in Clay Soil of Abakaliki, Nigeria

    OpenAIRE

    Ugwu, E. I.

    2010-01-01

    The influence of the thermal diffusivity of clay soil on thermal energy distribution in clay soil was studied using one and two dimensioned heat equation, which was solved, by using separation of variables method. In the analysis, heat was assumed to be propagated along rectangular moldedclaywithlength(L)with the width being considered negligible in the case of one dimension with different temperature ranging from 350 to 1290ºC within zero to one minute chosen where some parameters such as th...

  3. Clay slurry and engineered soils as containment technologies for remediation of contaminated sites

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.R. [Reclamation Technology, Inc., Athens, GA (United States); Dudka, S.; Miller, W.P. [Univ. of Georgia, Athens, GA (United States); Johnson, D.O. [Argonne National Lab., IL (United States)

    1997-12-31

    Clay Slurry and Engineered Soils are containment technologies for remediation of waste disposal sites where leaching, groundwater plumes and surface runoff of contaminants are serious ecological hazards to adjacent environments. This technology is a patent-pending process which involves the use of conditioned clay materials mixed with sand and water to form a readily pourable suspension, a clay slurry, which is either placed into a trench barrier system or allowed to de-water to create Engineered Soils. The Engineered Soil forms a layer impervious to water and air, therefore by inhibiting both water and oxygen from penetrating through the soil the material. This material can be installed in layers and as a vertical barrier to create a surface barrier containment system. The clay percentage in the clay slurry and Engineered Soils varies depending on site characteristics and desired performance standards. For example Engineered Soils with 1-2% of clay (dry wt.) had a hydraulic conductivity (K) of 10{sup -8} to 10{sup -1} cm/sec. Tests of tailing materials from a kyanite and pyrite mine showed that the clay slurry was effective not only in reducing the permeability of the treated tailings, but also in decreasing their acidity due to the inherent alkalinity of the clay. The untreated tailings had pH values in the range of 2.4 - 3.1; whereas, the effluent from clay and tailings mixtures had pH values in a slightly alkaline range (7.7-7.9). Pug-mills and high volume slurry pumps can be readily adapted for use in constructing and placing caps and creating Engineered Soils. Moreover, material on site or from a local sand supply can be used to create clay slurries and engineered soils. Clay materials used in cap construction are likewise readily available commercially. As a result, the clay slurry system is very cost effective compared to other capping systems, including the commonly used High Density Polyethylene (HDPE) liner systems.

  4. Effects of organic matter and clay content in soil on pesticide adsorption processes

    OpenAIRE

    Rada Đurović; Jelena Gajić-Umiljendić; Tijana Đorđević

    2009-01-01

    The effect of organic matter and clay content on the adsorption of atrazine, acetochlor, clomazone, pendimethalin and oxyfluorfen in soil samples was studied. In order to determine whether and to what degree different soil properties affect the process of determination of selected pesticides, three soils with different clay and organic matter contents were used. An optimized liquid-solid extraction procedure followed by SPME measurement was applied to analyze the selected pesticides in soil s...

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

    International Nuclear Information System (INIS)

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

  6. Impact of lfuxapyroxad on the microbial community structure and functional diversity in the silty-loam soil

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-hu; XU Jun; LIU Yong-zhuo; DONG Feng-shou; LIU Xin-gang; ZHANG Wen-wen; ZHENG Yong-quan

    2015-01-01

    The aim of this work was to assess the effect of applying three different doses of lfuxapyroxad on microbial activity, com-munity structure and functional diversity as measured by respiration, microbial biomass C, phospholipid fatty acid (PLFA) and community-level physiological proifles (CLPPs). Our results demonstrated that substrate-induced respiration (on day 15) and microbial biomass C (on days 7 and 15) were inhibited by lfuxapyroxad, but stimulation was observed thereafter. In contrast, lfuxapyroxad addition increased the basal respiration and metabolic quotients (qCO2) and respiratory quotients (QR). Analysis of the PLFA proifles revealed that the total and bacterial biomass (both Gram-positive bacteria (GP) and Gram-negative bacteria (GN)) were decreased within the initial 15 days, whereas those as wel as the GN/GP ratio were increased at days 30 and 60. Fluxapyroxad input decreased the fungi biomass but increased the bacteria/fungi ratio at al incubation time. Moreover, high lfuxapyroxad input (75 mg lfuxapyroxad kg–1 soil dry weight) increased the microbial stress level. A principal component analysis (PCA) of the PLFAs revealed that lfuxapyroxad treatment signiifcantly shifted the microbial community structure, but al of the observed effects were transient. Biolog results showed that average wel color development (AWCD) and functional diversity index (H´) were increased only on day 60. In addition, the dissipation of lfuxa-pyroxad was slow in soil, and the degradation half-lives varied from 158 to 385 days depending on the concentration tested.

  7. The Effects of Land Configuration and Wood-Shavings Mulch on the Properties of a Sandy Loam Soil in Northeast Nigeria. 2. Changes in Physical Properties

    Directory of Open Access Journals (Sweden)

    Chiroma, AM.

    2006-01-01

    Full Text Available Mulching and ridge tillage are proven technologies for improving soil productivity in semi-arid regions. Yet data quantifying the combined influences of these practices are limited. Our objectives were to determine the changes in selected physical properties of a sandy loam after 4-years of annual tillage and wood-shavings mulching. The tillage and wood-shavings treatments consisted of: Flat bed (FB, Open ridge (OR, Tiedridge (TR, FBM, ORM and TRM were same as FB, OR and TR, respectively except that wood-shavings at a rate of 10 t/ha were surface applied ≈ 2 weeks after sowing each year to serve as both a mulch and an organic amendment. At the end of the trial in 2002, bulk density, penetration resistance, total porosity and soil water content from each of 0-0.075, 0.075-0.15 and 0.15-0.30 m depths were determined. Composite samples from the surface (0.075 and 0.075-0.15 m layers from 3 replicates of each treatment were also collected for the determination of wet aggregate stability and from 0-0.15 m and 0.15-0.30 m layers for determination of saturated hydraulic conductivity (Ksat. After 4 years of annual tillage and addition of woodshavings, soil bulk density and penetration resistance were consistently lower and total porosity higher in the FBM, ORM and TRM treatments than in the FB, OR and TR treatments. Penetration resistance in all treatments was strongly related to soil water content. A 'hoe pan' was established below 0.15 m depth beneath the furrows of the ridged treatments. This could be attributed to human traffic during field operations and ponding of water, which occurred in the furrows following heavy rains. Wet aggregate stability estimated as the proportion of aggregates of size > 0.25 mm (macro-aggregates in the 0-0.15 m layer were significantly (P< 0.05 higher under FBM, ORM and TRM than under FB, OR or TR treatments. Ksat was not influenced by either tillage or wood-shavings treatments but were higher for the mulched plots

  8. Prediction of Soil Moisture Content and Soil Salt Concentration from Hyperspectral Laboratory and Field Data

    OpenAIRE

    Chi Xu; Wenzhi Zeng; Jiesheng Huang; Jingwei Wu; Willem J. D. van Leeuwen

    2016-01-01

    This research examines the simultaneous retrieval of surface soil moisture and salt concentrations using hyperspectral reflectance data in an arid environment. We conducted laboratory and outdoor field experiments in which we examined three key soil variables: soil moisture, salt and texture (silty loam, clay and silty clay). The soil moisture content models for multiple textures (M_SMC models) were based on selected hyperspectral reflectance data located around 1460, 1900 and 2010 nm and res...

  9. Impact of soil texture on soil moisture measurement accuracy by TDR in Sistan plain of Iran

    Science.gov (United States)

    sarani, noushin; Afrasiab, Peyman

    2014-05-01

    In the recent past, many researchers have developed various techniques for determining moisture content of soil. Among the various methods of estimating soil moisture, Time Domain Reflectometry (TDR) method is a relatively new method. TDR has been widely used in water system investigation in Agriculture, Geosciences, etc. The purpose of this study is determination of moisture measurement accuracy by TDR in various soil textures in Sistan plain. For this purpose, six textures and for each of them three Iteration were used. The studied textures were clay, loam, sandy loam, sandy clay loam, clay loam and sandy. The experiments were carried out at the laboratory of water engineering department of Zabol University in Iran. The provided textures were laid in the PVC cylinder with 50 cm height and 30 cm diameter. After 24 h of saturation, the soil water content of the samples was measured by oven-dry gravimetric and TDR methods. In each day the moisture measurement of each texture was carried out by these two methods until a moisture range was determined. For comparison between measured moisture values by TDR and gravimetric method, two statistical parameters include coefficient of determination (R2) and root mean square error (RMSE) were applied here. The results showed that by using SPSS, statistically significant at probably level of 1% indicated no difference between the measured value of moisture by TDR device and gravimetric method. For heavy textures consist of sandy clay loam, clay loam, and clay with increasing clay content when the moisture was low, TDR measured the moisture values less than the gravimetric method. Furthermore for light textures consist of sandy loam and sand, the TDR device measured the moisture values more than the gravimetric method. Also for clay loam and sandy clay at high moisture values, data measured by TDR was close to the gravimetric method. For all studied textures with increasing of clay content, the fitted lines slope and RMSE

  10. Radiological aspects of choice of a system of cultivation of sod-podzolic sandy loam soils with different degree of humidity on lands of Mogilev region contaminated with 137Cs

    International Nuclear Information System (INIS)

    In the conditions of the Republic of Belarus there were presented data about the influence of technological factors on entry of 137Cs into plant products (grain and green mass). In course of the study there were analyzed the following variants of soil cultivation: moldboard plowing; subsurface chisel soil tillage; subsurface surface soil tillage; minimal tillage. There were presented data on specific activity of 137Cs in plant product samples of oat (Avena sativa) grain; field pea (Pisum arvense L.) and oat mixture grain and green mass; wheat (Triticum aestivum) grain. There were determined the main principles of influence of cultivation systems of sod-podzolic sandy loam soil with different degree of humidity on transition of 137Cs into plants depending on the degree of soil and crop humidity. On the automorphic soil there was revealed a tendency of increased transition of 137Cs into grain and green mass after application of subsurface surface soil tillage system

  11. Effect of Clay Minerals on the Chemical Characteristics of Soil Humus

    Institute of Scientific and Technical Information of China (English)

    YEWEI; WENQIXIAO

    1996-01-01

    Chemical characteristics of humic substances in soils with different mineralogical characteristics and under different utilization paterns in Zhangpu,Fujian Province,together with two pairs of cultivated soils in North China Plain were studied by chemical analysis,visible and IR spectroscopy and 13C NMR spectrometry.For soils in Zhanpu the HA/FA ratio and both the aromaticity and the degree of humification of HA were higher in soils with montmorillonite as the predominant clay mineral than in those with kaolinite as the predominant clay mineral,provided these soils were under the same utilization pattern.While for each pair of soils with similar mineralogical characteristics the HA/FA ratio was higher and the C/H ratio and the contnet of carboxyl group of HA were lower in paddy soil than in upland soil.Among the upland soils(or paddy soils)studied the Ha/FA ratio of soil in Zhangpu with kaolinite as the predominant clay mineral was the lowest,and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest .the lowest.and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest It was concluded that the presence of montmorillonite favored the fromation and maturation of humic acid.

  12. Interactions between Soil Texture and Placement of Dairy Slurry Application

    DEFF Research Database (Denmark)

    Glæsner, Nadia; Kjærgaard, Charlotte; Rubæk, Gitte Holton;

    2011-01-01

    soils. We compared leaching of slurry-applied bromide through intact soil columns (20 cm diam., 20 cm high) of differing textures following surface application or injection of slurry. The volumetric fraction of soil pores >30 μm ranged from 43% in a loamy sand to 28% in a sandy loam and 15% in a loam......-textured soil. Smaller active flow volumes and higher proportions of preferential flow were observed with increasing soil clay content. Injection of slurry in the loam soil significantly enhanced diffusion of applied bromide into the large fraction of small pores compared with surface application. The resulting...... physical protection against leaching of bromide was reflected by 60.2% of the bromide tracer was recovered in the effluent after injection, compared with 80.6% recovery after surface application. No effect of slurry injection was observed in the loamy sand and sandy loam soils. Our findings point to soil...

  13. Polyacrylamide effects on aggregate and structure stability of soils with different clay mineralogy

    Science.gov (United States)

    Adding anionic polyacrylamide (PAM) to soils stabilizes existing aggregates and improves bonding between and aggregation of soil particles. However, the dependence of PAM efficacy as an aggregate stabilizing agent with soils having different clay mineralogy has not been studied. Sixteen soil samples...

  14. Soil aggregate stability as affected by clay mineralogy and polyacrylamide addition

    Science.gov (United States)

    The addition of polyacrylamide (PAM) to soil leads to stabilization of existing aggregates and improved bonding between, and aggregation of adjacent soil particles However, the dependence of PAM efficacy as an aggregate stabilizing agent on soil-clay mineralogy has not been studied. Sixteen soil sam...

  15. Soil Compaction and Oil Palm (Elaeis guineensis Yield in a Clay Textured Soil

    Directory of Open Access Journals (Sweden)

    Zuraidah Yahya

    2010-01-01

    Full Text Available Problem statement: The impacts of soil compaction on crop yields have been studied extensively by soil scientists due to declining soil productivity associated with mechanisation. However, a relationship between machine-induced soil compaction and oil palm (Elaeis guineensis yield is unclear. Therefore, the objectives of this study were to determine the effects of mechanization on soil physical properties and the influence on oil palm yield. Approach: The palms were planted in Bernam series soil which is clay textured. Compaction treatments were imposed for 6 consecutive years. Comparisons were made between the effects of soil compaction caused by different trailer weights and monthly transportation frequency. Results: The results showed a beneficial effect of soil compaction on the oil palm yield. It significantly increased the yield with increased mean soil bulk density. The transportation frequency played a greater role than the trailer weight. After six years of soil compaction, there was a positive relationship between mean soil bulk density, porosity and oil palm yield. Conclusion: Thus compaction may not often be a problem.

  16. Effects of a Novel Poly (AA-co-AAm/AlZnFe2O4/potassium Humate Superabsorbent Hydrogel Nanocomposite on Water Retention of Sandy Loam Soil and Wheat Seedling Growth

    Directory of Open Access Journals (Sweden)

    Farooq Anwar

    2012-10-01

    Full Text Available A novel poly(acrylic acid-co-acrylamideAlZnFe2O4/potassium humate superabsorbent hydrogel nanocomposite (PHNC was synthesized and its physical properties characterized using SEM, Energy Dispersive X-ray (EDX and FTIR spectroscopic techniques. Air dried sandy loam soil was amended with 0.1 to 0.4 w/w% of PHNC to evaluate its soil moisture retention attributes. Effect of PHNC amendment on pH, electrical conductivity (EC, porosity, bulk density and hydraulic conductivity of sandy loam soil was also studied. The soil amendment with 0.1 to 0.4 w/w% of PHNC remarkably enhanced the moisture retention at field capacity as compared to the un-amended soils. Seed germination and seedling growth of wheat (Triticum aestivum L. was considerably increased and a delay by 6–9 days in wilting of seedlings was observed in the soil amended with PHNC, resulting in improved wheat plant establishment and growth.

  17. Estimation of the density of the clay-organic complex in soil

    Science.gov (United States)

    Czyż, Ewa A.; Dexter, Anthony R.

    2016-01-01

    Soil bulk density was investigated as a function of soil contents of clay and organic matter in arable agricultural soils at a range of locations. The contents of clay and organic matter were used in an algorithmic procedure to calculate the amounts of clay-organic complex in the soils. Values of soil bulk density as a function of soil organic matter content were used to estimate the amount of pore space occupied by unit amount of complex. These estimations show that the effective density of the clay-organic matter complex is very low with a mean value of 0.17 ± 0.04 g ml-1 in arable soils. This value is much smaller than the soil bulk density and smaller than any of the other components of the soil considered separately (with the exception of the gas content). This low value suggests that the clay-soil complex has an extremely porous and open structure. When the complex is considered as a separate phase in soil, it can account for the observed reduction of bulk density with increasing content of organic matter.

  18. Clays Can Decrease Gaseous Nutrient Losses from Soil-Applied Livestock Manures.

    Science.gov (United States)

    Pratt, Chris; Redding, Matthew; Hill, Jaye; Brown, Grant; Westermann, Maren

    2016-03-01

    Clays could underpin a viable agricultural greenhouse gas (GHG) abatement technology given their affinity for nitrogen and carbon compounds. We provide the first investigation into the efficacy of clays to decrease agricultural nitrogen GHG emissions (i.e., NO and NH). Via laboratory experiments using an automated closed-vessel analysis system, we tested the capacity of two clays (vermiculite and bentonite) to decrease NO and NH emissions and organic carbon losses from livestock manures (beef, pig, poultry, and egg layer) incorporated into an agricultural soil. Clay addition levels varied, with a maximum of 1:1 to manure (dry weight). Cumulative gas emissions were modeled using the biological logistic function, with 15 of 16 treatments successfully fitted ( carbon retained in treatments containing clay compared with treatments containing no clay. This preliminary assessment of the efficacy of clays to mitigate agricultural GHG emissions indicates strong promise. PMID:27065411

  19. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    OpenAIRE

    Lei Gao; Guohui Hu; Nan Xu; Junyi Fu; Chao Xiang; Chen Yang

    2015-01-01

    In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0...

  20. Clay mineral formation and transformation in rocks and soils

    Science.gov (United States)

    Eberl, D.D.

    1983-01-01

    Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.

  1. Phosphorus leaching from clay soils can be counteracted by structure liming

    OpenAIRE

    Ulen, Barbro; Etana, Ararso

    2014-01-01

    Two field experiments with drained plots on clay soils (60 and 25 % clay) demonstrated a significant reduction in leaching of total phosphorus after application of structure lime. Aggregate stability, was significantly improved. Phosphorus leaching in particulate form was significantly reduced following structure liming at the site with a very high clay content. Sites representing low (50 mg kg-1) and high (140 mg kg-1) levels of phosphorus extractable with acid ammonium lactate in topsoil di...

  2. Searching the critical soil organic carbon threshold for satisfactory tilth conditions – test of the Dexter clay:carbon hypothesis

    OpenAIRE

    Schjønning, P.; de Jonge, L. W.; P. Moldrup; B. T. Christensen; Olesen, J.E.

    2010-01-01

    The concern for deteriorating soil structure at low soil organic matter (SOM) contents calls for better knowledge of SOM interaction with soil minerals as well as guidelines for soil conservation. We measured clay dispersibility in a field with a textural gradient. Our results support the concept of differentiating soil content of clay in a complexed and non-complexed part although our data did not point out an exact clay/OC ratio threshold. Our results also indicated that labile fractions of...

  3. Measurements of Texture of Soils Formed from Glaciolimnic Sediments by Areometric Method, Pipette Method and Laser Diffraction Method

    Directory of Open Access Journals (Sweden)

    Orzechowski Mirosław

    2014-10-01

    Full Text Available The aim of the research was to compare the results of texture analyses of glaciolimnic sediments deposited in the basins of ice-dammed lakes origin in north eastern Poland. The study was carried out using aerometric method, pipette method and laser diffraction method. The studied soils were classified as Haplic and Mollic Vertisol, Vertic Cambisol, and Gleyic Chernozem. The soils were formed from clayey (clay, heavy clay, loamy (loam, clay loam, sand clay loam and silty (silt loam, clay loam deposits. The studied soils did not contain fractions > 2.0 mm. The amounts of clay fraction (< 0.002 mm measured by areometric and pipette methods were similar and strongly correlated. In comparison to laser diffraction method, these amounts were 3-4-fold higher. The sub-fraction of fine silt (0.02-0.002 mm predominated in soil formations analyzed by laser diffraction method. In comparison to areometric or pipette method, the amounts of fine silt were 2-4 fold higher. Basing on the calculated sedimentological indices, it was stated that the examined soils were well sorted and the mean grain diameter (GSS was very low and did not exceed 0.005 mm in areometric and pipette methods, and 0.011 mm in laser diffraction method for clay sediments.

  4. Electrical properties of water in clay and silty soils

    Science.gov (United States)

    Saarenketo, Timo

    1998-10-01

    In order to better understand ground penetrating radar (GPR) results obtained in road surveys and site investigations, the dielectric properties and electrical conductivity of four silt and clay soils were measured at different densities and moisture contents ranging from oven dry material to the plastic state. The real parts K' and imaginary parts K″ of the relative dielectric permittivity values of the soils were measured with an HP Surface Network Analyzer over a frequency range from 30 MHz to 3.0 GHz. A dielectric and electrical conductivity meter produced by Adek was also used. The results suggest that water in soils can be classified according to its electrical properties as: (1) an adsorption water layer, also known as the hygroscopic water layer; (2) a viscous or capillary water layer; and (3) free water. The measurements also showed that the adsorption water layer can be divided into inner and outer layers in accordance with the electrical double layer theory. The imaginary part of the dielectric value of the material is formed mainly in the outer layer and partly in the viscous (capillary) water layer, which also has two layers with differing electrical properties. The measurements also clearly showed that if the Cation Exchange Capacity (CEC) of a material is low, the water molecules are orderly arranged around the soil particles and the dielectric values of the bound water layers remain almost independent of frequency. If the CEC increases, the molecular structure of the bound water layers is disturbed and the water molecules more easily follow the changing AC field so that the dielectric value is higher. These materials are also highly dielectrically dispersive, especially at GPR frequencies below 400 MHz. Increasing CEC correlates well with increasing imaginary part of the adsorption water layer. Measured ohmic electrical conductivities were low at low moisture content and increased as the outer viscous water layer developed with higher moisture

  5. Comparing Kriging and Regression Approaches for Mapping Soil Clay Content in a diverse Danish Landscape

    DEFF Research Database (Denmark)

    Adhikari, Kabindra; Bou Kheir, Rania; Greve, Mette Balslev;

    2013-01-01

    Information on the spatial variability of soil texture including soil clay content in a landscape is very important for agricultural and environmental use. Different prediction techniques are available to assess and map spatial variability of soil properties, but selecting the most suitable...

  6. Evaluation of Water Vapor Sorption Hysteresis in Soils: The Role of Organic Matter and Clay

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per;

    2015-01-01

    Hysteresis of the soil water characteristic (SWC) has been extensively studied for matric potentials between zero and −1.5 MPa. However, little information is available on how to quantify, evaluate, and identify the causes of hysteresis at potentials below −10 MPa where vapor sorption plays an...... important role. It is clear that modeling physical and biological soil processes is more accurate when SWC hysteresis is considered, particularly at low potentials where small differences in water content are associated with large changes in potential energy. The objectives of the presented study were to......: (i) evaluate and compare recently developed methods (MBET-n, Dh and SPN) for quantifying hysteresis in soils and pure clays, and (ii) investigate the role of organic matter (OM) and clay content and type on hysteresis. Five pure clays and two sets of soils with gradients in organic matter and clay...

  7. Effect of Polypropylene Fibers, Lime and Ceramic Additives on the Compressibility of Silty-Clay Soil

    OpenAIRE

    Hiba D. Saleem; Asad H. Humaish

    2016-01-01

    Soil stabilization is widely used by geotechnical engineers in the world to increase soil strength, soil compressibility and reduce the permeability. The main aim of this paper is to investigate the effect of adding different materials to the silty clayey soil (i.e. polypropylene fibers, lime and ceramic) and to figure out how the compressibility behave under mixture soil and these stabilized material at different percent (investigation their effect on the value of settlement). Silty clay ...

  8. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous mineralsaccompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which aredomi...

  9. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous minerals accompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which are...

  10. Mineral composition of the clay fraction in soils with a cambic horizon in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Žigová, Anna; Šťastný, Martin; Krejčová, J.

    Szeged : University of Szeged, 2010 - (Zaharia, L.). Roč. 6, - (2010), s. 648-648 ISSN 0324-6523. [Mid-European Clay Conference (MECC 2010) /5./. 25.08.2010-29.08.2010, Budapest] R&D Projects: GA ČR GA526/08/0434 Institutional research plan: CEZ:AV0Z30130516 Keywords : soil s * cambic horizon * parent material * clay minerals Subject RIV: DF - Soil Science

  11. Relation between various soil phosphorus extraction methods and sorption parameters in calcareous soils with different texture.

    Science.gov (United States)

    Jalali, Mohsen; Jalali, Mahdi

    2016-10-01

    The aim of this study was to investigate the influence of soil texture on phosphorus (P) extractability and sorption from a wide range of calcareous soils across Hamedan, western Iran. Fifty seven soil samples were selected and partitioned into five types on the basis of soil texture (clay, sandy, sandy clay loam, sandy loam and mixed loam) and the P extracted with calcium chloride (PCaCl2), citrate (Pcitrate), HCl (PHCl), Olsen (POls), and Mehlich-3 (PM3) solutions. On the average, the P extracted was in the order PHCl>PM3>Pcitrate>POls>PCaCl2. The P extracted by Pcitrate, PHCl, POls, and PM3 methods were significantly higher in sandy, sandy clay loam and sandy loam textures than clay and mixed loam textures, while soil phosphorus buffer capacity (PBC) was significantly higher in clay and mixed loam soil textures. The correlation analysis revealed a significant positive relationship between silt content Freundlich sorption coefficient (KF), maximum P sorption (Qmax), linear distribution coefficient (Kd), and PBC. All extractions were highly correlated with each other and among soil components with silt content. The principal component analysis (PCA) performed on data identified five principal components describing 74.5% of total variation. The results point to soil texture as an important factor and that silt was the crucial soil property associated with P sorption and its extractability in these calcareous soils. DPSM3-2 (PM3PM3+Qmax×100) and DPScitrate (PcitratePcitrate+Qmax×100) proved to be good indicators of soil's potential P release in these calcareous soils. Among the DPS, 21% of soils reported DPSM3-2, values higher than the environmental threshold, indicating build-up of P and P release. Most of the studied sandy clay loam soils had exceeded the environmentally unacceptable P concentration. Various management practices should be taken into account to reduce P losses from these soils. Further inorganic and organic P fertilizer inputs should be reduced

  12. Potential use of lateritic and marine clay soils as landfill liners to retain heavy metals.

    Science.gov (United States)

    Chalermyanont, Tanit; Arrykul, Surapon; Charoenthaisong, Nanthanit

    2009-01-01

    The potential of a lateritic soil and a marine clay, typical of those found in hot and humid climatic regions, was assessed for use as a landfill liner material. A series of tests were conducted - physical and chemical, batch adsorption, column, hydraulic conductivity, etc., - to evaluate the heavy metal sorption capacity, chemical compatibility of hydraulic conductivity, and transport parameters of the soils. Experimental results showed that the marine clay had better adsorption capacity than that of the lateritic soil and that its hydraulic conductivity was an order of magnitude lower. In addition, the hydraulic conductivities of both soils when permeated with low concentration heavy metal solutions were below 1x10(-7)cm/s. When permeated with Cr, Pb, Cd, Zn, and Ni solutions, the retardation factors of the lateritic soil and the marine clay ranged from 10 to 98 and 37 to 165, respectively, while the diffusion coefficients ranged from 1.0x10(-5) to 7.5x10(-6) and 3.0 to 9.14x10(-7)cm2/s, respectively. For both soils, Cr and Pb were retained relatively well, while Cd, Zn, and Ni were more mobile. The marine clay had higher retardation factors and lower diffusion coefficients, and its hydraulic conductivity was more compatible with Cr solution, than that of the lateritic soil. In general, the properties of the marine clay indicate that it has significant advantages over the lateritic soil as landfill liner material. PMID:18550353

  13. Estimation of hydraulic conductivity on clay content in soil determined from resistivity data

    Energy Technology Data Exchange (ETDEWEB)

    Shevnin, Vladimir; Delgado-Rodriguez, Omar; Mousatov, Aleksandr [Mexican Petroleum Institute, Mexico, D.F. (Mexico); Ryjov, Albert [Moscow State Geological Prospecting Academy, Geophysical Faculty, Moscow (Russian Federation)

    2006-07-15

    The influence of clay content in sandy and clayey soils on hydraulic conductivity (filtration coefficient) is considered. A review of published experimental data on the relationship of hydraulic conductivity with soil lithology and grain size, as dependent on clay content is presented. Theoretical calculations include clay content. Experimental and calculated data agree, and several approximation formulas for filtration coefficient vs clay content are presented. Clay content in soil is estimated from electric resistivity data obtained from 2D VES interpretation. A two-step method is proposed, the first step including clay content calculating from soil resistivity and groundwater salinity, and the second step including filtration coefficient estimating from clay content. Two applications are presented. [Spanish] El contenido de arcilla en suelos areno-arcillosos influye sobre la permeabilidad hidraulica (coeficiente de filtracion). Se presenta una revision de datos experimentales publicados que relacionan el coeficiente de filtracion con el tipo litologico del suelo y el tamano de las particulas. A partir de calculos teoricos, se modifican las conocidas formulas que relacionan el coeficiente de filtracion con el contenido de arcilla. Se estima el contenido de arcilla a partir de los datos interpretados por el metodo SEV, y se propone un procedimiento para la estimacion del coeficiente de filtracion: (a) calculo del contenido de arcilla a partir de la resistividad del suelo y de la salinidad del agua subterranea, (b) estimacion del coeficiente de filtracion a partir del contenido de arcilla. Se presentan algunos ejemplos de la aplicacion de esta metodologia.

  14. Measurement of recharge rates in soils through detection of tritium in Chinese thermonuclear tests

    International Nuclear Information System (INIS)

    Variation in environmental tritium and moisture content with depth was measured at three sites in sandy-loam and sandy-clay-loam soils, sampled near Hyderabad in May 1974. The tritium input function for precipitation around Hyderabad for the years 1969 to 1973 was determined through measurements on available rain samples and through extrapolation of strontium-90 data for HASL network station at Rawalpindi. Three peaks noticed in the tritium input function and probably caused by Chinese thermonuclear tests in 1970, 1971 and 1972, could be matched with those sequentially identified in the soil profiles. This identification has helped in dating the soil moisture and in calculation of average annual recharge to groundwater. The recharge was found to be 15.4 cm and 14.6 cm for sandy-loam and 11.1 cm for sandy-clay-loam soils. (auth.)

  15. Effects of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction

    OpenAIRE

    AHMADI, Iman; GHAUR, Hossein

    2015-01-01

    Soil compaction causes deleterious effects on physical and mechanical proprieties of agricultural soils. In order to investigate the effect of soil moisture content and tractor wheeling intensity on traffic-induced soil compaction, this study was carried out on a field with clay loam soil. Soil dry bulk density and hydraulic conductivity as well as emergence percentage of corn seedlings and dry mass of the sampled mature plants were considered the dependent variables of the experiment. Ind...

  16. Evaluation of pedotransfer functions for estimating the soil water retention points

    Science.gov (United States)

    Bahmani, Omid; Palangi, Sahar

    2016-06-01

    Direct measurement of soil moisture has been often expensive and time-consuming. The aim of this study was determining the best method to estimate the soil moisture using the pedotransfer functions in the soil par2 model. Soil samples selected from the database UNSODA in three textures include sandy loam, silty loam and clay. In clay soil, the Campbell model indicated better results at field capacity (FC) and wilting point (WP) with RMSE = (0.06, 0.09) and d = (0.65, 0.55) respectively. In silty loam soil, the Epic model had accurate estimation with MBE = 0.00 at FC and Campbell model had the acceptable result of WP with RMSE = 0.03 and d = 0.77. In sandy loam, Hutson and Campbell models had a better result to estimation the FC and WP than others. Also Hutson model had an acceptable result to estimation the TAW (Total Available Water) with RMSE = (0.03, 0.04, 0.04) and MBE = (0.02, 0.01, 0.01) for clay, sandy loam and silty loam, respectively. These models demonstrate the moisture points had the internal linkage with the soil textures. Results indicated that the PTFs models simulate the agreement results with the experimental observations.

  17. Integrating auxiliary data and geophysical techniques for the estimation of soil clay content using CHAID algorithm

    Science.gov (United States)

    Abbaszadeh Afshar, Farideh; Ayoubi, Shamsollah; Besalatpour, Ali Asghar; Khademi, Hossein; Castrignano, Annamaria

    2016-03-01

    This study was conducted to estimate soil clay content in two depths using geophysical techniques (Ground Penetration Radar-GPR and Electromagnetic Induction-EMI) and ancillary variables (remote sensing and topographic data) in an arid region of the southeastern Iran. GPR measurements were performed throughout ten transects of 100 m length with the line spacing of 10 m, and the EMI measurements were done every 10 m on the same transect in six sites. Ten soil cores were sampled randomly in each site and soil samples were taken from the depth of 0-20 and 20-40 cm, and then the clay fraction of each of sixty soil samples was measured in the laboratory. Clay content was predicted using three different sets of properties including geophysical data, ancillary data, and a combination of both as inputs to multiple linear regressions (MLR) and decision tree-based algorithm of Chi-Squared Automatic Interaction Detection (CHAID) models. The results of the CHAID and MLR models with all combined data showed that geophysical data were the most important variables for the prediction of clay content in two depths in the study area. The proposed MLR model, using the combined data, could explain only 0.44 and 0.31% of the total variability of clay content in 0-20 and 20-40 cm depths, respectively. Also, the coefficient of determination (R2) values for the clay content prediction, using the constructed CHAID model with the combined data, was 0.82 and 0.76 in 0-20 and 20-40 cm depths, respectively. CHAID models, therefore, showed a greater potential in predicting soil clay content from geophysical and ancillary data, while traditional regression methods (i.e. the MLR models) did not perform as well. Overall, the results may encourage researchers in using georeferenced GPR and EMI data as ancillary variables and CHAID algorithm to improve the estimation of soil clay content.

  18. Effect of Soil Clay Content on RNA Isolation and on Detection and Quantification of Bacterial Gene Transcripts in Soil by Quantitative Reverse Transcription-PCR ▿†

    OpenAIRE

    Novinscak, A.; Filion, M.

    2011-01-01

    In this study, we evaluated the effect of soil clay content on RNA isolation and on quantitative reverse transcription-PCR (qRT-PCR) quantification of microbial gene transcripts. The amount of clay significantly altered RNA isolation yields and qRT-PCR analyses. Recommendations are made for quantifying microbial gene transcripts in soil samples varying in clay content.

  19. Water storage change estimation from in situ shrinkage measurements of clay soils

    OpenAIRE

    Brake, B.; M. J. van der Ploeg; Rooij, G. H.

    2012-01-01

    The objective of this study is to assess the applicability of clay soil elevation change measurements to estimate soil water storage changes, using a simplified approach. We measured moisture contents in aggregates by EC-5 sensors, and in multiple aggregate and inter-aggregate spaces (bulk soil) by CS616 sensors. In a long dry period, the assumption of constant isotropic shrinkage proved invalid and a soil moisture dependant geo...

  20. Metal Extraction From Soil Samples By chelation in a Microwave System

    OpenAIRE

    Chatreewongsin, Urai

    2000-01-01

    This work involves the combination of chelation and microwave extraction as a technique for extracting adsorbed metals in soil. It has been termed in this work, Chelate Assisted Microwave Extraction (CAME). Unlike other extraction methods, CAME is able to differentiate between anthropological and geological trace metals. The method has been applied to major sample matrices included three types of soils (Bertie Sandy Loam, Davidson Silty Clay, and Davidson Clayey Loam) as well as se...

  1. THE SIDE-EFFECT OF ORGANIC INSECTICIDE SPINOSAD ON BIOCHEMICAL AND MICROBIOLOGICAL PROPERTIES OF CLAY SOIL

    Directory of Open Access Journals (Sweden)

    Arkadiusz Telesiński

    2015-09-01

    Full Text Available The aim of the study was to determine the effect of spinosad on soil biochemical and microbiological properties. The experiment was carried out on sandy loam with Corg content 10.91 g·kg-l. Spinosad, as Spintor 240 SC was added into soil in dosages: a recommended field dosage, and fivefold, tenfold, and twenty-fivefold higher dosages. The amount of spinosad introduced into soil was between 12.55 and 313.75 g·kg-l. Moreover, soil samples without spinosad supplement were prepared as a reference. Respective Spintor 240 SC doses were converted into 1 kg soil, taking into account 10 cm depth. After application of insecticide water emulsions, soil moisture was brought to 60% maximum holding water capacity. The soil was thoroughly mixed and stored in tightly-closed polyethylene bags at 20 °C for a period 4 weeks. During the experiment dissipation of spinosad, soil enzymes (dehydrogenase, alkaline phosphatase, acid phosphatase, urease and number of bacteria, fungi, actinomycetes were assayed. Obtained results showed, that dissipation of spinosad in soil was relatively fast – the DT50 of this insecticide was ranged between 1.11 and 2.21 days. Spinosad residues had different effects on soil microbiological and biochemical properties. However, over time the impact of this insecticide definitely decreased. This indicated that the use of spinosad in organic farming, particularly in the field dosage, does not pose a long-term threat to the soil environment.

  2. Measurement of exchangeable aluminium in soils and clay minerals by isotopic exchange

    International Nuclear Information System (INIS)

    Isotopically exchangeable Al was determined in soils and clay minerals by equilibration with 28Al. Best results were obtained with a weak extractant and an equilibration time of eight min. The calculated amount of isotopically exchangeable Al was independent of the amount of carrier-Al added with the 28Al. In some soils isotopically exchangeable Al did not appear to be related to the amount of Al which could be extracted by various electrolyte solutions. This technique provides an improved means of studying the exchange reactions of Al in acid soils and clay minerals

  3. Chemical dispersants and pre-treatments to determine clay in soils with different mineralogy

    Directory of Open Access Journals (Sweden)

    Cristiane Rodrigues

    2011-10-01

    Full Text Available Knowledge of the soil physical properties, including the clay content, is of utmost importance for agriculture. The behavior of apparently similar soils can differ in intrinsic characteristics determined by different formation processes and nature of the parent material. The purpose of this study was to assess the efficacy of separate or combined pre-treatments, dispersion methods and chemical dispersant agents to determine clay in some soil classes, selected according to their mineralogy. Two Brazilian Oxisols, two Alfisols and one Mollisol with contrasting mineralogy were selected. Different treatments were applied: chemical substances as dispersants (lithium hydroxide, sodium hydroxide, and hexametaphosphate; pre-treatment with dithionite, ammonium oxalate, and hydrogen peroxide to eliminate organic matter; and coarse sand as abrasive and ultrasound, to test their mechanical action. The conclusion was drawn that different treatments must be applied to determine clay, in view of the soil mineralogy. Lithium hydroxide was not efficient to disperse low-CEC electropositive soils and very efficient in dispersing high-CEC electronegative soils. The use of coarse sand as an abrasive increased the clay content of all soils and in all treatments in which dispersion occurred, with or without the use of chemical dispersants. The efficiency of coarse sand is not the same for all soil classes.

  4. Efficient resource management in dairy farming on peat and heavy clay soils

    NARCIS (Netherlands)

    Visser, de P.H.B.; Keulen, van H.; Lantinga, E.A.; Udo, H.M.J.

    2001-01-01

    Peat and heavy clay soils in the Netherlands are mainly used for permanent grassland to support dairy farming. As a result of intensification in dairy farming during the last decades, environmental quality is threatened by high emissions of N and P. Increased drainage of the wet soils has induced hi

  5. CO2 emission and structural characteristics of two calcareous soils amended with municipal solid waste and plant residue

    Directory of Open Access Journals (Sweden)

    N. Yazdanpanah

    2015-11-01

    Full Text Available This investigation examines the effect of different amendments on selected soil physical and biological properties over a twenty four month period in two cropland fields. Urban municipal solid waste (MSW compost and alfalfa residue (AR were used as different organic amendments at the rates of 0 (control, 10 and 30 Mg ha−1 to a clay loam soil and a loamy sand soil in a semiarid region. Result showed that the soil improvement was controlled by the application rate and decomposability of amendments and soil type. The addition of organic amendments to the soils improved aggregate stability and consequently enhanced total porosity, especially macro pores fraction. The increased soil organic carbon (SOC and total porosity values as compared to the control treatment were greater in the loamy sand soil than in the clay loam soil. Moreover, compared to the microbial respiration of control plots, the application of MSW resulted in higher values of microbial respiration in the clay loam soil than in the loamy sand soil, whereas the reverse order was found for AR. Linear and power functions were provided for the relationships between microbial respiration and SOC in the loamy sand and clay loam soils, respectively. Also, CO2 emission was stimulated significantly as power functions of the total porosity and the ratio of macro to micro pores. However, the soil microbial respiration and carbon storage improved aggregate stability and pore size distribution, as a response, soil porosity especially macro pores fraction controlled CO2 flux.

  6. CO2 emission and structural characteristics of two calcareous soils amended with municipal solid waste and plant residue

    Science.gov (United States)

    Yazdanpanah, N.

    2016-01-01

    This investigation examines the effect of different amendments on selected soil physical and biological properties over a 24-month period in two cropland fields. Urban municipal solid waste (MSW) compost and alfalfa residue (AR) were used as different organic amendments at the rates of 0 (control), 10 and 30 Mg ha-1 to a clay loam soil and a loamy sand soil in a semiarid region. Results showed that the soil improvement was controlled by the application rate and decomposability of amendments and soil type. The addition of organic amendments to the soils improved aggregate stability and consequently enhanced total porosity, especially macropore fraction. The increased soil organic carbon (SOC) and total porosity values as compared to the control treatment were greater in the loamy sand soil than in the clay loam soil. Moreover, compared to the microbial respiration of control plots, the application of MSW resulted in higher values of microbial respiration in the clay loam soil than in the loamy sand soil, whereas the reverse was found for AR. Linear and power functions were provided for the relationships between microbial respiration and SOC in the loamy sand and clay loam soils, respectively. Also, CO2 emission was stimulated significantly as power functions of the total porosity and the ratio of macroporosity to microporosity. However, the soil microbial respiration and carbon storage improved aggregate stability and pore size distribution, and as a response, soil porosity, especially the macropore fraction, controlled CO2 flux.

  7. Aging Effect of Cs-137 Obtained from Cs-137 in the Kanto Loam Layer from the Fukushima Nuclear Power Plant Accident and in the Nishiyama Loam Layer from the Nagasaki A-bomb Explosion

    OpenAIRE

    Ohta, Tomoko; Mahara, Yasunori; Kubota, Takumi; Igarashi, Toshifumi

    2013-01-01

    We measured Cs-134 and Cs-137 in the surface soil of the Kanto loam in the eastern Tokyo metropolitan area and the Nishiyama loam in Nagasaki, Japan. The observed Cs-137 deposition in the Kanto loam from the Fukushima nuclear power plant (NPP) accident ranged from 4.0 to 77 kBq m(-2), which corresponds to 0.3 - 5 times of that in the Nishiyama loam. The Cs-137 retardation factor in the Kanto loam obtained seven months after the Fukusima NPP accident and in the Nishiyama loam after 36 and 38 y...

  8. Fate of polychlorinated biphenyls (PCBs) in anaerobic soils

    International Nuclear Information System (INIS)

    Degradation of 14C labelled 2,5,2; 2,5,2',5' PCBs was studied in Hagerstown silty clay loam with and without sludge amendments under anaerobic conditions for 42 days. Soil respiration was enhanced by PCBs in soil. PCBs reduced the soil respiration in soil with sludge. Volatilization of PCBs was decreased by sludge in soil. Most of the radioactivity was found in hexane extracts of soils. No further degradation products were observed. (author)

  9. Effects of acid atmospheric deposition on the chemical composition of loess, clay and peat soils under forest in the Netherlands

    NARCIS (Netherlands)

    Klap, J.M.; Vries, de W.; Leeters, E.E.J.M.

    1999-01-01

    In addition to a survey of the soils under 150 forest stands on non-calcareous sandy soils, the chemical composition of the soils under 40 stands on non-calcareous loess soil, 30 stands on non-calcareous clay soils and 30 stands on oligotrophous peat soils have been examined, to assess the current s

  10. Effects of clay minerals on radiocesium sorption behavior onto paddy field soils

    International Nuclear Information System (INIS)

    From the viewpoint of radiological dose assessment, 137Cs is one of the most important radionuclides due to its long half life (30 y). In this work, sorption behavior of 137Cs in Japanese paddy field soils was investigated, taking into account effects of chemical properties. Soil-soil solution distribution coefficients (KdS) which are defined as the relation between an adsorbed radionuclide concentration and that present in the solution were measured for 30 daddy field soil samples collected throughout Japan. These measurements were carried out using the batch sorption test. Then, sequential extraction methods were carried out to determine the ratio of 137Cs fixed on soil. In addition, soil properties, such as pH, cation exchange capacity (CEC) and total carbon, total nitrogen and clay contents were measured as well. X-ray diffraction analysis was carried out to identify the clay minerals in soil samples. In particular, content of illite which can sorb Cs strongly was determined as a relative amount for all soil samples. Kd values ranged from 269-16 637 L/kg (geometric mean=2 286 L/kg). A correlation was observed between the Kd values and clay content with a Spearman rank correlation coefficient (Rc) of 0.55 (p 137Cs fixed in soil had good correlation with relative illite content (Rc=0.68, p137Cs fixed on soil. (author)

  11. Effects of Organic Matter and Clay Content in Soil on Pesticide Adsorption Processes

    Directory of Open Access Journals (Sweden)

    Rada Đurović

    2009-01-01

    Full Text Available The effect of organic matter and clay content on the adsorption of atrazine, acetochlor, clomazone, pendimethalin and oxyfluorfen in soil samples was studied. In order to determine whether and to what degree different soil properties affect the process of determinationof selected pesticides, three soils with different clay and organic matter contents were used. An optimized liquid-solid extraction procedure followed by SPME measurement was applied to analyse the selected pesticides in soil samples. Detection and quantificationwere done by gas chromatography-mass spectrometry (GC/MS. Relative standard deviation (RSD values for multiple analyses of soil samples fortified at 30 μg/kg of each pesticide were below 19%. Limits of detection (LODs for all compounds studied were less than 2 μg/kg. The results indicate that soils with different physico-chemical properties have different effects on the adsorption of most pesticides, especially at higher concentration levels.

  12. Differential response of soil texture for leaching of salts receiving different pore volumes of water in saline-sodic soil column

    International Nuclear Information System (INIS)

    This study examined the leaching requirement of three saline-sodic soils in polyvinyl chloride (PVC) columns of 50 cm long and 11 cm internal diameter. Air-dried soils were packed in PVC lysimeters receiving different pore volume (PV) of water (EC 0.89 dS m/sup -1/, SAR 1.55, RSC 1.02 mmolc L/sup -1). Leaching with 2.5 PV of water removed 94 % of soluble salts and decreased EC/sub e/from 33.9 to 5.9 dS m/sup -1/ in 0-25 cm layer of sandy clay loam soil. For lowering EC/sub e/ to < 4 dS m/sup -1/ in loamy sand up to 0-25 cm soil layer, 2.0 PV water removed 67 % soluble salts. In silty clay loam soil, 2.5 PV water lowered EC/sub e/ to < 4 dS m/sup -1/only up to 0-10 cm depth with 83 % removal of salts. Relationships between EC/EC 0 and D w/Ds established were for the soils as EC/EC/sub 0/ = 0.329 (D w/D/sub S/)/sup -2.12/ with r= 0.87 for loamy sand; EC/EC/sub 0/ = 0.16sub -0.60/ with r=0.89 for silty clay loam and EC/EC/sub 0/sup = 0.06/ (Dw/D/sub s/)/sup 0.78/ with r=0.98 for sandy clay loam soil. These relationships leads to conclude that reduction in salinity of loamy sand, silty clay loam and sandy clay loam soil was 67, 83 and 94 % when leached with 1.88, 2.72 and 2.67 cm of water, respectively. (author)

  13. "Clay grounds” in Denmark: from soil to canvas

    DEFF Research Database (Denmark)

    Buti, David; Vila, Anna; Haack Christensen, Anne; Filtenborg, Troels Folke; Dalby, Kim Nicole; Wadum, Jørgen

    large decorative scheme showed that at least two grounds from those paintings consist mainly of clay mixed with iron and magnesium-containing compounds. Furthermore, both SEM-EDX and µRaman measurements clearly highlighted the presence of a large amount of quartz particles. It is well known that clay is...... a sheet silicate mineral and may contain variable amounts of water trapped in its structure and can occur with other phases including quartz and carbonates. Studies carried out by Kühn and Groen and summarized by the latter show that in the Netherlands this kind of preparation layer was first...

  14. Effect of potassium on fixation of ammonium by clay minerals in different soil layers

    Directory of Open Access Journals (Sweden)

    Agelda Ajazi

    2013-12-01

    Full Text Available In intensive agriculture systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environment management. Fixation of NH4+ and K+ by soil clays affect N and K availability to plants. Latest studies indicates that non-exchangeable NH4+, may affect crop productivity and soil N dynamics more than previously thought. An incubation study with K2SO4 and NH4NO3 was conducted to evaluate NH4+ and K+ fixation in two southern Albanian soils. Soils contained significant amount of native-fixed NH4+ and showed relatively high NH4+ fixing capacity. Native fixed ammonium content varied for horizons Ap and BCg, from 97 to 133 mg/kg and accounted for between 5 to 19, 8 % of the total nitrogen, respectively . Ammonium fixation was increased with N rates and was reduced with increased K rates. When K was added to the soil prior to the NH4, the amount of ammonium fixed was reduced. By contrast, when K+ and NH4+ were added to the soils simultaneously (equivalent amount; 2mEq/100g, the ammonium fixation was increased somewhat in the BCg horizon , whereas no such preference for ammonium fixation was found in the Ap horizon. In case when NH4+ and K+ were added to the soil samples in form of solutions, containing equal amounts of NH4+ (corresponding to 2 mEq NH4+/100 g soil but varying amounts of K+, the capacity of the soil to fix ammonium was reduced in proportion to the amount of K+ added. The soil samples incubated anaerobically, were with high differences in clay minerals content. The dominate clay minerals for profile (I-Ap horizon are smectite > vermiculite > Ilite, while vermiculite plus ilite (as the most important clay fixed minerals, comprised 21% of clay fraction and 13 % of the soil. In the profile (II-BCg horizon, the dominant clay minerals ranged; vermiculite > Ilite > smectite, while (vermiculite + ilite, comprised 52% of the clay fraction and 23, 4 % of the soil. Studies on Ap and BCg horizons comparing the amount of

  15. Nematodes in clay colliery spoil heaps and experimentally introduced strips of meadow soil

    Czech Academy of Sciences Publication Activity Database

    Háněl, Ladislav

    České Budějovice : Institute of Soil Biology AS CR, 2003. s. 25. [Central European Workshop on Soil Zoology /7./. 14.04.2003-16.04.2003, České Budějovice] R&D Projects: GA ČR GA526/01/1055 Institutional research plan: CEZ:AV0Z6066911 Keywords : nematodes * clay colliery spoil heaps * strips of meadow soil Subject RIV: EH - Ecology, Behaviour

  16. Effect of nitrogen and water availability of three soil types on yield, radiation use efficiency and evapotranspiration in field-grown quinoa

    DEFF Research Database (Denmark)

    Razzaghi, Fatemeh; Plauborg, Finn; Jacobsen, Sven-Erik;

    2012-01-01

    irrigation. This lead to higher interception of photosynthetic active radiation and higher seed yield on sandy clay loam (3.3 Mg ha-1) and sandy loam (3.0 Mg ha-1) than on sand (2.3 Mg ha-1). The soil with higher clay content had also the highest transpiration, crop evapotranspiration and yield due to the......Quinoa (Chenopodium quinoa Willd.) is believed to be tolerant to abiotic stress including salinity, drought and poor soil quality. To investigate the effect of soil type and soil-drying during the seed-filling phase on N-uptake, yield and water use, a Danish-bred cultivar (cv. Titicaca) was grown...... in field lysimeters with sand, sandy loam and sandy clay loam soil. Despite application of the same amount of nitrogen (120 kg N ha-1) to all plots, there were large differences in crop nitrogen-uptake for sandy clay loam (134 kg ha-1), sandy loam (102 kg ha-1) and sand (77 kg ha-1) under full...

  17. The utility of surface temperature measurements for the remote sensing of surface soil water status

    Science.gov (United States)

    Idso, S. B.; Jackson, R. D.; Reginato, R. J.; Schmugge, T. J.

    1975-01-01

    Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day-night periods. They were also found to be linear functions of the daily maximum value of the surface soil-air-temperature differential. Tests on three additional soils ranging from sandy loam to clay indicated that the relations determined for Avondale loam could not be accurately applied to these other soil types. When the moisture characteristic curves of each soil were used to transform water contents into pressure potentials, however, it was found that soil water pressure potential could be determined without prior knowledge of soil type, and thus its value as a potential soil water status survey tool was significantly enhanced.

  18. Hydraulic conductivity study of compacted clay soils used as landfill liners for an acidic waste

    International Nuclear Information System (INIS)

    Highlights: ► Examined the hydraulic conductivity evolution as function of dry density of Tunisian clay soil. ► Follow the hydraulic conductivity evolution at long-term of three clay materials using the waste solution (pH=2.7). ► Determined how compaction affects the hydraulic conductivity of clay soils. ► Analyzed the concentration of F and P and examined the retention of each soil. - Abstract: Three natural clayey soils from Tunisia were studied to assess their suitability for use as a liner for an acid waste disposal site. An investigation of the effect of the mineral composition and mechanical compaction on the hydraulic conductivity and fluoride and phosphate removal of three different soils is presented. The hydraulic conductivity of these three natural soils are 8.5 × 10−10, 2.08 × 10−9 and 6.8 × 10−10 m/s for soil-1, soil-2 and soil-3, respectively. Soil specimens were compacted under various compaction strains in order to obtain three wet densities (1850, 1950 and 2050 kg/m3). In this condition, the hydraulic conductivity (k) was reduced with increasing density of sample for all soils. The test results of hydraulic conductivity at long-term (>200 days) using acidic waste solution (pH = 2.7, charged with fluoride and phosphate ions) shows a decrease in k with time only for natural soil-1 and soil-2. However, the specimens of soil-2 compressed to the two highest densities (1950 and 2050 kg/m3) are cracked after 60 and 20 days, respectively, of hydraulic conductivity testing. This damage is the result of a continued increase in the internal stress due to the swelling and to the effect of aggressive wastewater. The analysis of anions shows that the retention of fluoride is higher compared to phosphate and soil-1 has the highest sorption capacity.

  19. Carbon-Nitrogen Relationships during the Humification of Cellulose in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1981-01-01

    amount of labeled N incorporated into organic forms increased in the clay-rich soils with increasing size of amendments. Of the total labeled C remaining in the soils after the 1st mo. of incubation 50-70% was acid hydrolyzable, compared to 80-100% of the total remaining labeled organic N. This...... 1st mo. of incubation at temperatures of 10, 20 and 30.degree. C, respectively, 38-65% of the labeled C added in cellulose had disappeared from the soils as CO2, and 60-nearly 100% of the labeled N added as NH4+ were incorporated into organic forms. The retention of total labeled C was largest in...... the soil with thg highest content of clay where after 4 yr it was 25% of that added, compared to 12 in the soil with the lowest content of clay. The incorporation of labeled N in organic forms and its retention in these forms was not directly related to the content of clay in the soils, presumably...

  20. Soil Clay Minerals in Namibia and their Significance for the Terrestrial and Marine Past Global Change Research

    OpenAIRE

    HEINE, Klaus; Völkel, Jörg

    2010-01-01

    We delineated seven soil clay mineral provinces in Namibia. Many individual clay mineral assemblages occur in fluvial, pan, cave and other environments. Previous researchers have used clay mineral compositions as evidence for palaeoenvironmental reconstructions, often without analyzing the formation, the transport and the deposition of these clay minerals. In Namibia, rates of erosion and denudation by water and wind have been very small since early Quaternary times. During the Quaternary, th...

  1. A semi-analytical solution for frost heave prediction of clay soil

    Institute of Scientific and Technical Information of China (English)

    Hui Bing; Ying Zhang; GuoYu Li

    2014-01-01

    Frost heave is one of the main freezing problems for construction in permafrost regions. The Konrad-Morgenstern seg-regation potential (SP) model is being used in practice for frost heave using numerical techniques. However, the heat re-lease from in-situ and migrated water in the freezing zone could result in some numerical instability, so the simulation of frost fringe is not ideal. In this study, a semi-analytical solution is developed for frost heave prediction of clay soil. The prediction results to the two tests with different freezing mode with clay soil agree well with the tested behavior, which indicates the feasibility of the solution.

  2. Clay Mineralogical Composition of Tea Garden Soils in Shandong Province, China

    OpenAIRE

    Han, Jing-Long; Yang, Qi-Xia; Ming ZHAO; Liu, Ying-Xia; Egashira, Kazuhiko

    2008-01-01

    For assistance of the appropriate plant-nutrient management practice to keep the sustainable tea production in Shandong Province, particle-size and clay mineral analyses were carried out to the surface layer of soils collected in tea gardens of Laoshan region of Qingdao City and Dahainanchun region of Jimo City, Shandong Province, People's Republic of China. Variation of the particle-size distribution with sites was small in each region. The clay content ranged from 17.6 to 22.7% for soils ...

  3. Clay Mineralogy Investigation In The Soils Of Arid Almanaqil Ridge Gezira State Sudan Using Xrd Diffractograms

    Directory of Open Access Journals (Sweden)

    Elhag A.M.H

    2015-07-01

    Full Text Available Abstract Clay mineralogy was studied in the soils of Arid Almanaqil Ridge. The soils are classified according to the American System Keys to Soil Taxonomy 2010 in the fallowing families Fine loamy mixed isohyperthermic TypicHaplustepts unit1 sample A1 and A2 Fine mont superactive Isohyperthermic VerticHaplocambids unit2 sample A3 and Fine mont superactive isohyperthermic TypicHaploustert unit3 sample A4. Representative soil samples were collected from these units. These samples were samples A1 and A2 for unit1 sample A3 for unit 2 and sample A4 for uint3 respectively. Those samples were compared with samples from outside the study area from north of the study area sample A5 and A6 and from the alluvium of the Blue Nile sample A7 according to their lithology topographic position soil types and soil mapping units. Clay mineralogy of the samples was studied using X-ray diffractograms XRD techniques. The XRD diffractograms indicated the presence of smectite chlorite illite and kaolinite as the major clay minerals in the soil of the study area and outside of the study area. The major clay minerals in these soils Chlorite illite and kaolinite could have originated from parent material. Smectite showed an increasing trend in samples A7 outside of study area and sample A4 unit 3. The CEC of clay minerals in unit 1 and 2 were less than 50 Cmolkg which indicated that minerals with low CEC were dominant this result conformed with the XRD results that showed dominance of Chlorite illite and Kaolinite. Higher CEC values more than 50 Cmolkg of the clay were encountered in soils samples from unit3 A4 and those from outside study area Sample A7 XRD results showed that the samples were dominated by smectite. Moreover the CEC values of clay minerals were consistent with results of XRD. The X-ray mineralogy indicated that the Vertisols and Aridisols of the study area had the same origin as that of the Gezira soils.

  4. Is the geological concept of clay minerals appropriate for soil science? A literature-based and philosophical analysis

    Science.gov (United States)

    Churchman, G. Jock

    Data in the literature for soils that are dominated by each of the main types of clay minerals were examined and compared with those for reference clay minerals of the same types to determine the extent to which the nature and properties of clay-size minerals in soils could be explained by those of clay minerals with the same name from non-soil, ‘geological’ environments. Published information on soils from Australia, New Zealand and Iran was sourced for this study. The clay fractions of each of the soils are dominated by either one of the common phyllosilicates: kaolinite, halloysite, illite/mica, vermiculite, smectite, and palygorskite, or by the nanocrystalline mineral, allophane. Data for samples of kaolinite that had been extracted from soils from several countries (Australia, Thailand, Indonesia and Brazil) and purified before characterization have also been examined. In soils, each dominant clay mineral is generally associated with other materials, including iron oxides, other phyllosilicates and/or nanocrystalline minerals and organic matter. As the most studied example of an extracted phyllosilicate, kaolinite shows a wide range of properties in different soils, but a narrower range of properties within a particular locality. However, almost all of the soil kaolinites studied have larger specific surface areas and higher cation exchange capacities than reference kaolinites. The literature also reveals that, among phyllosilicates in soils, illites have a wide range of potassium contents, expandable minerals (vermiculites and smectites) may be interlayered by hydroxy-Al species particularly, and smectitic layers often occur interstratified with other layers, including those of illite, kaolinite and halloysite. The variability of soil phyllosilicates and their common association with other, often poorly crystallized but highly reactive minerals and compounds can be explained by their formation in the highly heterogeneous and dynamic soil environment

  5. Clay-associated organic matter in kaolinitic and smectitic soils

    NARCIS (Netherlands)

    Wattel-Koekkoek, E.J.W.

    2002-01-01

    The primary source of soil organic matter is plant debris of all kinds, such as dead roots, leaves and branches that enter into the soil and are then biologically decomposed at variable rates. Organic matter has many different important functions on a local and global scale. Soil organic matter is a

  6. Effects of acid atmospheric deposition on the chemical composition of loess, clay and peat soils under forest in the Netherlands

    OpenAIRE

    Klap, J.M.; Vries, de, H.J.C.; Leeters, E.E.J.M.

    1999-01-01

    In addition to a survey of the soils under 150 forest stands on non-calcareous sandy soils, the chemical composition of the soils under 40 stands on non-calcareous loess soil, 30 stands on non-calcareous clay soils and 30 stands on oligotrophous peat soils have been examined, to assess the current status with repect to acidification and eutrophication, and the provide data for further studies. Only the clay soils are not yet seriously affected by the atmospheric inputs. The loess soils are ge...

  7. Soil Texture and Cultivar Effects on Rice (Oryza sativa, L. Grain Yield, Yield Components and Water Productivity in Three Water Regimes.

    Directory of Open Access Journals (Sweden)

    Fugen Dou

    Full Text Available The objective of this study was to determine the effects of water regime/soil condition (continuous flooding, saturated, and aerobic, cultivar ('Cocodrie' and 'Rondo', and soil texture (clay and sandy loam on rice grain yield, yield components and water productivity using a greenhouse trial. Rice grain yield was significantly affected by soil texture and the interaction between water regime and cultivar. Significantly higher yield was obtained in continuous flooding than in aerobic and saturated soil conditions but the latter treatments were comparable to each other. For Rondo, its grain yield has decreased with soil water regimes in the order of continuous flooding, saturated and aerobic treatments. The rice grain yield in clay soil was 46% higher than in sandy loam soil averaged across cultivar and water regime. Compared to aerobic condition, saturated and continuous flooding treatments had greater panicle numbers. In addition, panicle number in clay soil was 25% higher than in sandy loam soil. The spikelet number of Cocodrie was 29% greater than that of Rondo, indicating that rice cultivar had greater effect on spikelet number than soil type and water management. Water productivity was significantly affected by the interaction of water regime and cultivar. Compared to sandy loam soil, clay soil was 25% higher in water productivity. Our results indicated that cultivar selection and soil texture are important factors in deciding what water management option to practice.

  8. Adsorption-Desorption of Hexaconazole in Soils with Respect to Soil Properties, Temperature, and pH

    Directory of Open Access Journals (Sweden)

    Maznah Zainol

    2016-07-01

    Full Text Available The effect of temperature and pH on adsorption-desorption of fungicide hexaconazole was studied in two Malaysian soil types; namely clay loam and sandy loam. The adsorption-desorption experiment was conducted using the batch equilibration technique and the residues of hexaconazole were analysed using the GC-ECD. The results showed that the adsorption-desorption isotherms of hexaconazole can be described with Freundlich equation. The Freundlich sorption coefficient (Kd values were positively correlated to the clay and organic matter content in the soils. Hexaconazole attained the equilibrium phase within 24 h in both soil types studied. The adsorption coefficient (Kd values obtained for clay loam soil and sandy loam soil were 2.54 mL/g and 2.27 mL/g, respectively, indicating that hexaconazole was weakly sorbed onto the soils due to the low organic content of the soils. Regarding thermodynamic parameters, the Gibb’s free energy change (ΔG analysis showed that hexaconazole adsorption onto soil was spontaneous and exothermic, plus it exhibited positive hysteresis. A strong correlation was observed between the adsorption of hexaconazole and pH of the soil solution. However, temperature was found to have no effect on the adsorption of hexaconazole onto the soils; for the range tested.

  9. THE EFFECT OF REINFORCEMENT ON THE GBFS AND LIME TREATED MARINE CLAY FOR FOUNDATION SOIL BEDS

    Directory of Open Access Journals (Sweden)

    D. Koteswara Rao,

    2011-03-01

    Full Text Available India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinada Sea Port Ltd, Kakinada, A.P, India. The effect of lime on the strength characteristics of marine clay are studied in this investigation along with the reinforcement effect using geotextile as reinforcement and separator for the foundation soil bed.

  10. The non-steroidal anti-inflammatory drug diclofenac is readily biodegradable in agricultural soils

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rajab, Abdul Jabbar; Sabourin, Lyne [Agriculture and Agri-Food Canada, London, ON, Canada N5V 4T3 (Canada); Lapen, David R. [Agriculture and Agri-Food Canada, Ottawa ON, Canada K1A 0C6 (Canada); Topp, Edward, E-mail: ed.topp@agr.gc.ca [Agriculture and Agri-Food Canada, London, ON, Canada N5V 4T3 (Canada)

    2010-12-01

    Diclofenac, 2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetic acid, is an important non-steroidal anti-inflammatory drug widely used for human and animals to reduce inflammation and pain. Diclofenac could potentially reach agricultural lands through the application of municipal biosolids or wastewater, and in the absence of any environmental fate data, we evaluated its persistence in agricultural soils incubated in the laboratory. {sup 14}C-Diclofenac was rapidly mineralized without a lag when added to soils varying widely in texture (sandy loam, loam, clay loam). Over a range of temperature and moisture conditions extractable {sup 14}C-diclofenac residues decreased with half lives < 5 days. No extractable transformation products were detectable by HPLC. Diclofenac mineralization in the loam soil was abolished by heat sterilization. Addition of biosolids to sterile or non-sterile soil did not accelerate the dissipation of diclofenac. These findings indicate that diclofenac is readily biodegradable in agricultural soils.

  11. The non-steroidal anti-inflammatory drug diclofenac is readily biodegradable in agricultural soils

    International Nuclear Information System (INIS)

    Diclofenac, 2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetic acid, is an important non-steroidal anti-inflammatory drug widely used for human and animals to reduce inflammation and pain. Diclofenac could potentially reach agricultural lands through the application of municipal biosolids or wastewater, and in the absence of any environmental fate data, we evaluated its persistence in agricultural soils incubated in the laboratory. 14C-Diclofenac was rapidly mineralized without a lag when added to soils varying widely in texture (sandy loam, loam, clay loam). Over a range of temperature and moisture conditions extractable 14C-diclofenac residues decreased with half lives < 5 days. No extractable transformation products were detectable by HPLC. Diclofenac mineralization in the loam soil was abolished by heat sterilization. Addition of biosolids to sterile or non-sterile soil did not accelerate the dissipation of diclofenac. These findings indicate that diclofenac is readily biodegradable in agricultural soils.

  12. Soil carbon stock and soil characteristics at Tasik Chini Forest Reserve, Pahang, Malaysia

    Science.gov (United States)

    Nur Aqlili Riana, R.; Sahibin A., R.

    2015-09-01

    This study was carried out to determine soil carbon stock and soil characteristic at Tasik Chini Forest Reserve (TCFR), Pahang. A total of 10 (20 m x 25 m) permanent sampling plot was selected randomly within the area of TCFR. Soil samples were taken from all subplots using dutch auger based on soil depth of 0-20cm, 20-40cm, 40-60cm. Soil parameters determined were size distribution, soil water content, bulk density, organic matter, organic carbon content, pH and electrical conductivity. All parameters were determined following their respective standard methods. Results obtained showed that the soil in TCFR was dominated by clay texture (40%), followed by sandy clay loam (30%), loam (20%). Silty clay, clay loam and sandy loam constitutes about 10% of the soil texture. Range of mean percentage of organic matter and bulk density are from 2.42±0.06% to 11.64±0.39% and 1.01 to 1.04 (gcm-ł), respectively. Soil pH are relatively very acidic and mean of electrical conductivity is low. Soil carbon content ranged from 0.83±0.03 to 1.87±0.41%. All soil parameter showed a decreasing trend with depth except electrical conductivity. ANOVA test of mean percentage of organic matter, soil water content, soil pH and electrical conductivity showed a significant difference between plot (p0.05). There are no significant difference in mean percentage of soil water content, organic matter and bulk density between three different depth (p>0.05). There were a significant difference on percentage of soil carbon organic between plots and depth. The mean of soil organic carbon stock in soil to a depth of 60 cm calculated was 35.50 t/ha.

  13. Modified clay sorbents for wastewater treatment and immobilization of heavy metals in soils

    Science.gov (United States)

    Burlakovs, Juris; Klavins, Maris; Vincevica-Gaile, Zane; Stapkevica, Mara

    2014-05-01

    Soil and groundwater pollution with heavy metals is the result of both, anthropogenic and natural processes in the environment. Anthropogenic influence in great extent appears from industry, mining, treatment of metal ores and waste incineration. Contamination of soil and water can be induced by diffuse sources such as applications of agrochemicals and fertilizers in agriculture, air pollution from industry and transport, and by point sources, e.g., wastewater streams, runoff from dump sites and factories. Treatment processes used for metal removal from polluted soil and water include methodologies based on chemical precipitation, ion exchange, carbon adsorption, membrane filtration, adsorption and co-precipitation. Optimal removal of heavy metal ions from aqueous medium can be achieved by adsorption process which is considered as one of the most effective methods due to its cost-effectiveness and high efficiency. Immobilization of metals in contaminated soil also can be done with different adsorbents as the in situ technology. Use of natural and modified clay can be developed as one of the solutions in immobilization of lead, zinc, copper and other elements in polluted sites. Within the present study clay samples of different geological genesis were modified with sodium and calcium chlorides, iron oxyhydroxides and ammonium dihydrogen phosphate in variable proportions of Ca/P equimolar ratio to test and compare immobilization efficiency of metals by sorption and batch leaching tests. Sorption capacity for raw clay samples was considered as relatively lower referring to the modified species of the same clay type. In addition, clay samples were tested for powder X-ray difractometry, cation exchange, surface area properties, elemental composition, as well as scanning electron microscopy pictures of clay sample surface structures were obtained. Modified clay sorbents were tested for sorption of lead as monocontaminant and for complex contamination of heavy metals. The

  14. Sand and clay mineralogy of sal forest soils of the Doon Siwalik Himalayas

    Indian Academy of Sciences (India)

    Mukesh; R K Manhas; A K Tripathi; A K Raina; M K Gupta; S K Kamboj

    2011-02-01

    The peteromineralogical characterization of the soil was carried out for the 12 soil profiles exposed in the Shorea robusta dominated forests of the Siwalik forest division, Dehradun. The quartz was observed as the dominating light mineral fraction (64–80%) in all the profiles studied. Biotite, hornblende, zircon, tourmaline, rutile and opaques comprising of iron minerals constituted the heavy mineral fraction (20%). The mineralogy of both the sand and clay fractions revealed a mixed mineralogy. The clay minerals in the order of their dominance were vermiculite, illite, kaolinite and mixed layer minerals. The presence of vermiculite and illite in appreciable quantities indicates that these were synthesized from the K-rich soil solution, as orthoclase and micas were present in significant quantities in the sand minerals. The mineral suites identified in the study shows that the geological, climatological and topographical factors of the region collectively played a dominant role in their formation and transformation. After critical appraisal of the results, it may be deduced that the mineralogical composition, physicochemical properties and total elemental analysis of the soils do not show any deficiency of the bases and other plant nutrients in general. The inherent fertility of the soil is good as indicated by the sand and clay mineralogy of the soil and the biotite and feldspar together with the mica is an important source of nutrients for the vegetation in the soils of the Doon valley.

  15. The Influence of Clay on the Rate of Decay of Amino Acid Metabolites Synthesized in Soils during Decomposition of Cellulose

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1975-01-01

    amounts of labelled amino acid C in the soils were proportional to their content of silt + clay. After 30 days of incubation labelled amino acid C remaining in the soil with the lowest content of silt + clay constituted 6 per cent of the carbon added in cellulose, as compared with 18 per cent in the soil...... increase in the CO2 evolution caused by the treatments in the different soils was, however, not related to the amount of silt + clay, and a high content of this material did not protect organic material against the effect of the treatments. is concluded that the silt + clay fraction ensures stabilization......14C-labelled cellulose was added to seven different soils containing silt + clay (particles <0.02 mm) in amounts which varied from 8 to 75 per cent. The cellulose was allowed to decompose, and the amounts of labelled C transformed into metabolites hydrolyzable into amino acids were determined. The...

  16. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    DEFF Research Database (Denmark)

    Karup, Dan; Møldrup, Per; Paradelo Pérez, Marcos;

    2016-01-01

    -and-eighty-seven undisturbed soil columns 20 cm in height and 20 cm in diameter were sampled from six conventionally managed agricultural fields in Denmark. The soils exhibited a wide range in texture, with clay contents and organic carbon (OC) contents ranging from 0.03 to 0.41 kg kg-1 and 0.01 to 0.08 kg kg-1, respectively...... (particles ≤ 50 μm). The results showed that the mineral fines content was strongly correlated to functional soil structure and the derived tracer breakthrough curve (BTC), whereas the OC content appeared less important for the shape of the BTC. Organic carbon was believed to support the stability of the......Solute transport through the soil matrix is heterogeneous and greatly affected by soil texture, soil structure, and macropore networks. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. Hundred...

  17. Effect of clay minerals on the stabilization of black cotton and lateritic soils

    International Nuclear Information System (INIS)

    The problem associated with black cotton and lateritic soils because of the swelling-shrinkage property of their constituent clay minerals were investigated. Samples of black cotton lateritic soils were collected from different parts of Kenya. The samples were analysed for their mineral compositions and later treated with hydrated lime in order to eliminate the swelling shrinkage behaviour. The samples were subsequently tested for their engineering properties in a soil mechanics laboratory using shear box and Casagrande apparatus. It was found that the chemical treatment of the soils with hydrated lime removes their plastic property and improves their shear strength. (author)

  18. Effect of potassium on fixation of ammonium by clay minerals in different soil layers

    OpenAIRE

    , Agelda Ajazi; Liri Miho; Aida Bani; , Ardian Maçi

    2013-01-01

    In intensive agriculture systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environment management. Fixation of NH4+ and K+ by soil clays affect N and K availability to plants. Latest studies indicates that non-exchangeable NH4+, may affect crop productivity and soil N dynamics more than previously thought. An incubation study with K2SO4 and NH4NO3 was conducted to evaluate NH4+ and K+ fixation in two southern Albanian soils. Soils contained significa...

  19. Effect of water content and soil texture on consolidation in unsaturated soils

    Science.gov (United States)

    Lo, Wei-Cheng; Lee, Jhe-Wei

    2015-08-01

    Soil consolidation, involving time-dependent coupling between deformation of a porous medium and interstitial fluid flows within it, is of relevance to many subsurface engineering problems. A comprehensive model of poroelasticity for consolidation in unsaturated soils has been recently developed by Lo et al. (2014), but it still remains elusive how variations in soil texture and water content affect consolidation behavior, and the underlying parameters deriving this behavior. In the current study, a boundary-value problem is first setup corresponding to two symmetric semi-permeable drainage conditions, and then solved analytically for describing the excess pore air and water pressures along with the total settlement in response to time-invariant external loading using the Laplace transform. These solutions are numerically calculated for unsaturated soils with eleven texture classes as a function of three initial water saturations as representative examples. Our results reveal that the excess pore water pressure and time-dependent total settlement are indeed significantly sensitive to both soil texture and initial water saturation. We demonstrate that the coefficient of consolidation for water and its loading efficiency are two important physical parameters controlling consolidation behavior. With respect to the same soil texture, the coefficient of consolidation for water increases with an increase in initial water saturation, taking a value approximately four to five orders of magnitude greater in saturated soils than that in unsaturated ones. For a given initial water saturation, the rate of dissipation of excess pore water pressure is smallest in clay, followed by silty clay, silty clay loam, sandy clay, clay loam, silt loam, loam, sandy clay loam, sandy loam, loamy sand, and sand. A comparative study shows that in the early stage of consolidation, unsaturated soils bear smaller excess pore water pressure, but its dissipation is completed faster in saturated

  20. 垆土铁棍山药与沙土铁棍山药的性状比较%Characters comparison of the loam soil iron yam and sand iron yam

    Institute of Scientific and Technical Information of China (English)

    张庆岭

    2012-01-01

      Iron yam in Huai yam road real estate area divided into loam soil iron yam and sand iron yam, the article analyze the difference of two kinds of iron yam from plant growth environment, appearance and ingredients, for further research and development.%  怀山药道地产区的铁棍山药分为垆土铁棍山药与沙土铁棍山药两种,本文从植物生长环境以及外观性状以及成分含量入手,分析此两种铁棍山药的区别,为进一步研究和开发提供依据。

  1. Modeling selenite adsorption envelopes on oxides, clay minerals, and soils using the triple layer model

    Science.gov (United States)

    Selenite adsorption behavior was investigated on amorphous aluminum and iron oxides, clay minerals: kaolinite, montmorillonite, and illite, and 45 surface and subsurface soil samples from the Southwestern and Midwestern regions of the USA as a function of solution pH. Selenite adsorption decreased ...

  2. Modeling selenate adsorption behavior on oxides, clay minerals, and soils using the triple layer model

    Science.gov (United States)

    Selenate adsorption behavior was investigated on amorphous aluminum oxide, amorphous iron oxide, goethite, clay minerals: kaolinites, montmorillonites, illite, and 18 soil samples from Hawaii, and the Southwestern and the Midwestern regions of the US as a function of solution pH. Selenate adsorpti...

  3. Effects of clay amendment on adsorption and desorption of copper in water repellent soils

    NARCIS (Netherlands)

    Xiong, X.; Stagnitti, F.; Allinson, G.; Turoczy, N.; Li, P.; LeBlanc, M.; Cann, M.A.; Doerr, S.H.; Steenhuis, M.M.; Parlange, J.Y.; Rooij, de G.; Ritsema, C.J.; Dekker, L.W.

    2005-01-01

    Copper is an important micronutrient and trace amounts are essential for crop growth. However, high concentrations of copper will produce toxic effects. Australia is increasingly developing production of crops in water repellent soils. Clay amendment, a common amelioration techniques used in Austral

  4. Peculiarities of strength and deformability properties of clay soils in districts of Western Siberia

    Science.gov (United States)

    Efimenko, Sergey; Efimenko, Vladimir; Sukhorukov, Alexey

    2016-01-01

    The article demonstrates the methodology of the substantiation of the calculated values of moisture, strength, and deformability characteristics of clay subgrade soils for the design of pavements by strength conditions in II, III, and IV road-climatic zones in West Siberia. The main purpose of the work is to ensure the quality of the design of roads in newly developed regions of Russia. To achieve this goal the following problems have been solved: the dislocation of boundary lines of road-climatic zones has been specified, zoning of the investigated territory for the design of roads has been detailed; regularities of changes in strength and deformability characteristics of clay subgrade soils of their moisture have been established; the territorial normalization of the calculated values of moisture, strength, and deformability of clay subgrade soils in relation to the allocated road districts has been carried out. Specification of boundary lines of road-climatic zones has been implemented on the basis of the taxonomic system "zone-subzone-road district". The calculated values of moisture, strength, and deformability characteristics of clay soils, established and differentiated according to road-climatic zones, will ensure the required level of the reliability of transport infrastructure facilities during the life cycle of roads.

  5. COMPARISON OF GLYPHOSATE PERSISTENCE IN CLAY SOIL ON NO-TILLED AND AUTUMN PLOUGHED PLOTS

    OpenAIRE

    Petruneva, Ekaterina

    2015-01-01

    The present work was based on the analysis of glyphosate concentrations in six soil layers after continuous multiple applications of herbicide products and various sampling times during the study period of 2010−2012, and aimed to contribute to a better recognition of the glyphosate persistence in clay soil. Two tillage methods (conventional tillage and no-till) were carried out in two replicates on the experimental field located in Jokioinen, South-Western Finland. This experiment was impo...

  6. Multisensor on-the-go mapping of readily dispersible clay, particle size and soil organic matter

    Science.gov (United States)

    Debaene, Guillaume; Niedźwiecki, Jacek; Papierowska, Ewa

    2016-04-01

    Particle size fractions affect strongly the physical and chemical properties of soil. Readily dispersible clay (RDC) is the part of the clay fraction in soils that is easily or potentially dispersible in water when small amounts of mechanical energy are applied to soil. The amount of RDC in the soil is of significant importance for agriculture and environment because clay dispersion is a cause of poor soil stability in water which in turn contributes to soil erodibility, mud flows, and cementation. To obtain a detailed map of soil texture, many samples are needed. Moreover, RDC determination is time consuming. The use of a mobile visible and near-infrared (VIS-NIR) platform is proposed here to map those soil properties and obtain the first detailed map of RDC at field level. Soil properties prediction was based on calibration model developed with 10 representative samples selected by a fuzzy logic algorithm. Calibration samples were analysed for soil texture (clay, silt and sand), RDC and soil organic carbon (SOC) using conventional wet chemistry analysis. Moreover, the Veris mobile sensor platform is also collecting electrical conductivity (EC) data (deep and shallow), and soil temperature. These auxiliary data were combined with VIS-NIR measurement (data fusion) to improve prediction results. EC maps were also produced to help understanding RDC data. The resulting maps were visually compared with an orthophotography of the field taken at the beginning of the plant growing season. Models were developed with partial least square regression (PLSR) and support vector machine regression (SVMR). There were no significant differences between calibration using PLSR or SVMR. Nevertheless, the best models were obtained with PLSR and standard normal variate (SNV) pretreatment and the fusion with deep EC data (e.g. for RDC and clay content: RMSECV = 0,35% and R2 = 0,71; RMSECV = 0,32% and R2 = 0,73 respectively). The best models were used to predict soil properties from the

  7. Soil moisture increment as a controlling variable of the Birch effect . Interactions with the pre-wetting soil moisture and litter addition

    OpenAIRE

    Lado Monserrat, Luis; Lull Noguera, Cristina; Bautista Carrascosa, María Inmaculada; Lidón Cerezuela, Antonio Luis; Herrera Fernandez, Rafael

    2014-01-01

    The Birch effect is a pulse in soil C and N mineralization caused by the wetting of dry soils, but the role of the soil moisture increment (Delta SWC) is still poorly understood. We quantified the relationship between Delta SWC and the Birch effect, and its interactions with pre-wetting soil moisture (preSWC) and substrate supply. Two soils (clay loam and sandy loam) under a Pinus halepensis forest were subjected to rewetting in laboratory treatments combining different Delta SWC and preSWC v...

  8. Theoretical Analysis of the Influence of the Thermal Diffusivity of Clay Soil on the Thermal Energy Distribution in Clay Soil of Abakaliki, Nigeria

    Directory of Open Access Journals (Sweden)

    E.I Ugwu

    2010-05-01

    Full Text Available The influence of the thermal diffusivity of clay soil on thermal energy distribution in clay soil was studied using one and two dimensioned heat equation, which was solved, by using separation of variables method. In the analysis, heat was assumed to be propagated along rectangular moldedclaywithlength(Lwith the width being considered negligible in the case of one dimension with different temperature ranging from 350 to 1290ºC within zero to one minute chosen where some parameters such as thermal diffusivity In the second case, a steady state heat flow was considered in two dimensions w ith the assumption that temperature distribution is constant. Different temperature ranging from 350 to 1290ºC within zero to one minute were chosen with some parameters such as thermal diffusivity, specific heat and m ass per unit length of the clay are specified. The variation of the thermal conductivity and diffusivity with temperature was analyzed while that of the energy flux, u(x,t variation with time for different chosen length were plotted Two dimensional thermal energy distribution viewed at different points was also considered using different values of therm al diffusivity respectively.

  9. Distinguishing black carbon from biogenic humic substances in soil clay fractions

    Science.gov (United States)

    Laird, D.A.; Chappell, M.A.; Martens, D.A.; Wershaw, R. L.; Thompson, M.

    2008-01-01

    Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2-2.0????m e.s.d.), medium (0.02-0.2????m e.s.d.), and fine (> 0.02????m e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2-5????m as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that BC particles were originally charcoal formed during prairie fires. As the BC particles aged in soil their surfaces were oxidized to form carboxylic groups and anomeric and aliphatic C accumulated in the BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter was physically separated with the medium and fine clay subfractions and was dominated by aliphatic, anomeric, and carboxylic C. The results indicate that the biogenic humic materials in our soils have little aromatic C, which is inconsistent with the traditional heteropolymer model of humic substances.

  10. Effect of clay minerals and nanoparticles on chromium fractionation in soil contaminated with leather factory waste.

    Science.gov (United States)

    Taghipour, Marzieh; Jalali, Mohsen

    2015-10-30

    This study was conducted to investigate the effect of time, clay minerals and nanoparticles (NPs) on chromium (Cr) fractionation in a soil contaminated with leather factory waste (LFW). Soil was mixed with LFW, then, the contaminated soils were treated with clay minerals (bentonite and zeolite) and nanoparticles (MgO, TiO2 and ZnO) at 5% and 1%, respectively. The samples were incubated for 15-180 days at 25 °C and constant moisture. After incubation, Cr in control and treated soils was fractionated by the sequential extraction procedure. The distribution of various Cr fractions in control soil indicated that the greatest amounts of Cr were found in the residual fraction (RES) followed by the carbonate (CAR), organic matter (OM) and exchangeable (EXC) fractions. The addition of LFW in soils increased Cr concentration in all fractions. The higher proportion of EXC fraction in the soil treated with LFW indicates its higher potential of leaching and runoff transport. In all treated soils, the RES fraction was increased, while EXC and OM fractions were decreased during incubation. The results indicated that NPs are effective adsorbent for the removal of Cr ions from LFW treated soil, and they could be useful in reducing their environment risk. PMID:25956643

  11. Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Morales

    2014-04-01

    Full Text Available Segmented mesocosms (n = 3 packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 pfu/mL STE, respectively. In all soils, removal rates were >99.99% at 25 cm. The transport simulation compared (1 optimization; and (2 trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide.

  12. ESTIMATING SOIL PARTICLE-SIZE DISTRIBUTION FOR SICILIAN SOILS

    Directory of Open Access Journals (Sweden)

    Vincenzo Bagarello

    2009-09-01

    Full Text Available The soil particle-size distribution (PSD is commonly used for soil classification and for estimating soil behavior. An accurate mathematical representation of the PSD is required to estimate soil hydraulic properties and to compare texture measurements from different classification systems. The objective of this study was to evaluate the ability of the Haverkamp and Parlange (HP and Fredlund et al. (F PSD models to fit 243 measured PSDs from a wide range of 38 005_Bagarello(547_33 18-11-2009 11:55 Pagina 38 soil textures in Sicily and to test the effect of the number of measured particle diameters on the fitting of the theoretical PSD. For each soil textural class, the best fitting performance, established using three statistical indices (MXE, ME, RMSE, was obtained for the F model with three fitting parameters. In particular, this model performed better in the fine-textured soils than the coarse-textured ones but a good performance (i.e., RMSE < 0.03 was detected for the majority of the investigated soil textural classes, i.e. clay, silty-clay, silty-clay-loam, silt-loam, clay-loam, loamy-sand, and loam classes. Decreasing the number of measured data pairs from 14 to eight determined a worse fitting of the theoretical distribution to the measured one. It was concluded that the F model with three fitting parameters has a wide applicability for Sicilian soils and that the comparison of different PSD investigations can be affected by the number of measured data pairs.

  13. Competitive sorption between glyphosphate and inorganic phosphate on clay minerals and low organic matter soils

    International Nuclear Information System (INIS)

    Inorganic phosphate may influence the adsorption of glyphosate to soil surface sites. It has been postulated that glyphosphate sorption is dominated by the phosphoric acid moiety, therefore, inorganic phosphate could compete with glyphosate for surface sorption sites. Sorption of glyphosate is examined in low organic carbon systems where clay minerals dominate the available adsorption sites using 32P-labeled phosphate and 14C-labeled glyphosate to track sorption. Glyphosate sorption was found to be strongly dependent on phosphate additions. Isotherms were generally of the L type, which is consistent with a limited number of surface sites. Most sorption on whole soils could be accounted for by sorption observed on model clays of the same mineral type as found in the soils. (author)

  14. Irrigation with saline-sodic water: effects on two clay soils

    OpenAIRE

    Giovanna Cucci; Giovanni Lacolla

    2013-01-01

    The results of a 4-year experiment aimed at evaluating the effect of irrigation with saline-sodic water on the soil are reported. The research was carried out at the Campus of the Agricultural Faculty of Bari University (Italy) on 2 clay soils (Bologna – T1 and Locorotondo – T2). The soils were cropped to borlotto bean (Phaseolus vulgaris L.), capsicum (Capsicum annuum L.), sunflower (Helianthus annuus L.), wheat (Triticum durum Desf) grown in succession; the crops were irrigated with 9 salin...

  15. Lead pollution of soil and groundwater in clay-pigeon shooting ranges

    International Nuclear Information System (INIS)

    Within the framework of the exemplary investigation of soil and groundwater pollution with lead on clay-pigeon shooting ranges, three facilities were sampled. The analyses for depth distribution in the main area of the ammunition deposition showed that the dissolved lead amounts are as a rule smaller than the limiting value of the Sewage Sludge Regulation (100 mg/kg). In two groundwater samples, no lead could be found. Considerable amounts of small lead balls are found on the soil surface, but only a very small part appears to be washed out and adsorbed by the soil matrix. (orig.)

  16. Swelling clays and salt-affected soils : demixing of Na / Ca clays as the rationale for discouraging the use of sodium adsorption ratio (SAR)

    OpenAIRE

    Guilhem Bourrie

    2014-01-01

    Sodium adsorption ratio SAR defined as SAR = (Na) / V w(Ca+Mg)/2 here concentrations of cations in solution are expressed in meq/L has long been considered as correlated to exchangeable sodium percentage (ESP) on clay minerals or soil exchange complex, and as the key concept to explain swelling of clay minerals and the difficulties of reclaiming salt-affected soils. Though its basis is empirical, it was alleged to be theoretically justified on the basis of ion exchange, derived from the Gapo...

  17. How do changes in bulk soil organic carbon content affect carbon concentrations in individual soil particle fractions?

    Science.gov (United States)

    Yang, X M; Drury, C F; Reynolds, W D; Yang, J Y

    2016-01-01

    We test the common assumption that organic carbon (OC) storage occurs on sand-sized soil particles only after the OC storage capacity on silt- and clay-sized particles is saturated. Soil samples from a Brookston clay loam in Southwestern Ontario were analysed for the OC concentrations in bulk soil, and on the clay (<2 μm), silt (2-53 μm) and sand (53-2000 μm) particle size fractions. The OC concentrations in bulk soil ranged from 4.7 to 70.8 g C kg(-1) soil. The OC concentrations on all three particle size fractions were significantly related to the OC concentration of bulk soil. However, OC concentration increased slowly toward an apparent maximum on silt and clay, but this maximum was far greater than the maximum predicted by established C sequestration models. In addition, significant increases in OC associated with sand occurred when the bulk soil OC concentration exceeded 30 g C kg(-1), but this increase occurred when the OC concentration on silt + clay was still far below the predicted storage capacity for silt and clay fractions. Since the OC concentrations in all fractions of Brookston clay loam soil continued to increase with increasing C (bulk soil OC content) input, we concluded that the concept of OC storage capacity requires further investigation. PMID:27251365

  18. Removal of MTBE from a clay soil using electrokinetic technique.

    Science.gov (United States)

    Estabragh, A R; Bordbar, A T; Ghaziani, F; Javadi, A A

    2016-01-01

    Remediation of a soil contaminated with methyl tertiary butyl ether (MTBE) was studied by using the electrokinetic technique. A series of experimental tests were carried out on contaminated soil in an electro-osmotic apparatus at different applied gradients of voltage and time. The tests were conducted with distilled water and ethylenediaminetetra acetic acid (EDTA) solution as electrolyte. During each test the values of pH at anode and cathode reservoirs and also the discharge from cathode were measured. At the end of each test a number of soil samples were extracted from the middle of the soil at different distances from the anode and the removal of contaminant was measured by a gas chromatography apparatus. The results indicate that with EDTA as electrolyte the highest efficiency for removal of MTBE is achieved with 2.0 V/cm gradient and in the duration of 14 days. In addition, EDTA causes the values of pH to increase and decrease in the cathode and anode reservoirs, respectively. It also decreases the effluent and electro-osmotic permeability in comparison with distilled water. Experimental data were analysed by ANOVA and t-test methods. These statistical analyses showed significant difference (at 5% level) between the reference and other tests. PMID:26787321

  19. Competitive adsorption of 90Sr on soil sediments, pure clay phases and feldspar minerals

    International Nuclear Information System (INIS)

    Study of the adsorption of 90Sr by a soil sediment, mineralogically pure clay phases and feldspar minerals as a function of ionic composition of Ca, Mg and Na has been conducted. It is shown that a theoretical slope value of -1 for a pure ion-exchange mechanism of strontium adsorption onto Ca-saturated clay is predicted. Experimentally determined slopes represent an average of adsorption on several different mineral surfaces having different relative affinities for strontium, calcium and magnesium. Strontium was found to be adsorbed to ion-exchange sites and calcium and magnesium cations were observed to be effective competitors for these sites. Pure clay minerals yielded adsorption coefficients from equations with slopes of -10. (author)

  20. Influence of Residue and Nitrogen Fertilizer Additions on Carbon Mineralization in Soils with Different Texture and Cropping Histories

    OpenAIRE

    Xianni Chen; Xudong Wang; Matt Liebman; Michel Cavigelli; Michelle Wander

    2014-01-01

    To improve our ability to predict SOC mineralization response to residue and N additions in soils with different inherent and dynamic organic matter properties, a 330-day incubation was conducted using samples from two long-term experiments (clay loam Mollisols in Iowa [IAsoil] and silt loam Ultisols in Maryland [MDsoil]) comparing conventional grain systems (Conv) amended with inorganic fertilizers with 3 yr (Med) and longer (Long), more diverse cropping systems amended with manure. A double...

  1. Additional Information on Methodology: Extraction of Water from Soil and Plant Samples for 18O/16O and D/H Isotope Ratio Measurements

    International Nuclear Information System (INIS)

    The outline of the study carried out for obtaining and validating the SOP results is provided. Two different soil types: Ebendorf silty clay loam and Reisenberg sandy loam were used. They were adjusted to two different soil moistures: close to field capacity (FC) and near permanent wilting point (PWP). This is equivalent to 0.1 bar for Ebendorf soil and 0.3 bar for Reisenberg soil for the FC study, and equivalent to 12.5 bar for the Ebendorf soil and 1 bar for the Reisenberg soil

  2. Enhancement of physical and hydrological properties of a sandy loam soil via application of different biochar particle sizes during incubation period

    Directory of Open Access Journals (Sweden)

    Leila Esmaeelnejad

    2016-06-01

    Full Text Available In spite of many studies that have been carried out, there is a knowledge-gap as to how different sizes of biochars alter soil properties. Therefore, the main objective of this study was to investigate the effects of different sizes of biochars on soil properties. The biochars were produced at two pyrolysis temperatures (350 and 550°C from two feedstocks (rice husk and apple wood chips. Produced biochars were prepared at two diameters (1-2 mm and <1 mm and mixed with soil at a rate of 2% (w/w. Multiple effects of type, temperature and size of biochars were significant, so as the mixture of soil and finer woodchip biochars produced at 550°C had significant effects on all soil properties. Soil aggregation and stabilization of macro-aggregates, values of mean weight diameter and water stable aggregates were improved due to increased soil organic matter as binding agents and microbial biomass. In addition, plant available water capacity, air capacity, S-index, meso-pores and water retention content were significantly increased compared to control. But, saturated hydraulic conductivity (Ks was reduced due to blockage of pores by biochar particles, reduction of pore throat size and available space for flow and also, high field capacity of biochars. So, application of biochar to soil, especially the finest particles of high-tempered woody biochars, can improve physical and hydrological properties of coarse-textured soils and reduce their water drainage by modification of Ks.

  3. Using Agricultural Residue Biochar to Improve Soil Quality of Desert Soils

    Directory of Open Access Journals (Sweden)

    Yunhe Zhang

    2016-03-01

    Full Text Available A laboratory study was conducted to test the effects of biochars made from different feedstocks on soil quality indicators of arid soils. Biochars were produced from four locally-available agricultural residues: pecan shells, pecan orchard prunings, cotton gin trash, and yard waste, using a lab-scale pyrolyzer operated at 450 °C under a nitrogen environment and slow pyrolysis conditions. Two local arid soils used for crop production, a sandy loam and a clay loam, were amended with these biochars at a rate of 45 Mg·ha−1 and incubated for three weeks in a growth chamber. The soils were analyzed for multiple soil quality indicators including soil organic matter content, pH, electrical conductivity (EC, and available nutrients. Results showed that amendment with cotton gin trash biochar has the greatest impact on both soils, significantly increasing SOM and plant nutrient (P, K, Ca, Mn contents, as well as increasing the electrical conductivity, which creates concerns about soil salinity. Other biochar treatments significantly elevated soil salinity in clay loam soil, except for pecan shell biochar amended soil, which was not statistically different in EC from the control treatment. Generally, the effects of the biochar amendments were minimal for many soil measurements and varied with soil texture. Effects of biochars on soil salinity and pH/nutrient availability will be important considerations for research on biochar application to arid soils.

  4. Time and frequency GPR waveforms analysis for clay content evaluation in soils

    Science.gov (United States)

    Tosti, F.; Patriarca, C.

    2012-04-01

    The mechanical behaviour of soils is partly affected by their clay content, which exerts some considerable effects in many applications in the fields of civil engineering, geology and environmental engineering. This study focuses on pavement engineering, but the approach can be extended to other purposes. The presence of clay in the bearing structural layers of pavements frequently causes damages and defects, such as transversal and longitudinal cracks, deformations and rutting. Consequently, the road safety and operability decrease, while the expected number of accidents increases. In this work Ground Penetrating Radar (GPR) laboratory inspections are carried out in order to predict the presence of clay in pavement structural layers. Data are post-processed in the frequency domain, according to the Rayleigh scattering method based on the Fresnel theory. This new technique can be supported by other survey methods, improving the quality of the results. Analysis are carried out using two different GPR systems. A Radar is used with ground-coupled antennae in a bistatic configuration and common offset; the transmitter and receiver are linked by optic fiber electronic modules and operate at 500 MHz central frequency. The received signal is sampled in the time domain at time steps of 7.8125 x 10-2 ns. A Vector Network Analyzer (VNA) acquires ultra-wide band data in a bandwidth from 500 MHz to 3000 MHz. The signal is sampled in the frequency domain with approximately 1.56 MHz frequency steps. A double-ridged broadband horn antenna is connected via a high-quality coaxial cable to the VNA pulse generator and illuminates the analyzed target in a monostatic off-ground configuration. The experimental setting required the use of road material, typically employed for sub-grade and sub-base layers. Three kind of soils, classified as A1, A2, A3 by AASHTO are used and adequately compacted in electrically and hydraulically isolated boxes. Bentonite clay is gradually added from 2% to

  5. Sorption of radioiodine on organic rich soil, clay minerals and alumina

    International Nuclear Information System (INIS)

    Batch method was used to investigate the sorption behavior of radioiodine on organic rich soil, alumina, chlorite-illite clay mixture and bentonite. 131 I was used as tracer. The grain sizes of the samples used were all below 38μm. A rather slow kinetics was observed for the adsorption of radioiodine on organic rich soil. The distribution ratio increased with increasing solution/solid (V/m) ratio, and the contact time. The pH of the synthetic groundwater did not change the distribution ratio appreciably. The soil biomass however, showed a striking effect on the adsorption of radioiodine. Among the clay minerals, the highest distribution ratio value was found for chlorite-illite clay mixture. All the values were however well below those of the organic rich soil. The sorption data were fitted to Freundlich and Dubinin-Radushkevich type isotherms. Mean energies of adsorption, as well as the affinity ratios of the sorption sites to iodine and chlorine were calculated. (author) 13 refs.; 6 figs.; 6 tabs

  6. Comparative adsorption of sup 90 Sr on soil sediments, pure clay phases and feldspar minerals

    International Nuclear Information System (INIS)

    Laboratory batch experiments were conducted to determine the adsorption of 90 Sr by a soil sediment, mineralogically pure clay phases (vermiculites, smectites and illites) and feldspar minerals (adesine, albite, microcline and oligoclase) as a function of ionic composition. The clay minerals were present at different proportion in the soil sediment. The important adsorbing phases and the adsorption mechanism(s) can be determined from the studies. Twenty two stock solutions were prepared with concentrations of the major cations Ca, Mg and Na and were varied from 0.0 to 0.00312 M, 0.0 to 0.00165 M, and 0.0 to 0.00312 M, respectively. The experiments yielded adsorption coefficient values K sub d that could be described by equations. Theoretical slope value -1 for pure ion-exchange mechanism of strontium adsorption onto Ca-saturated clay was described. The slopes obtained in the experiments represented an average of adsorption on several different mineral surfaces having different relative affinities for strontium, calcium and magnesium. Experiment results showed that strontium was adsorbed to ion-exchange sites and that calcium and magnesium cations were effective competitors for these sites. Pure clay minerals yielded adsorption coefficients that could be described by equations slopes -1.0 similar to the theoretical value. The feldspar minerals yielded slope ranges from -072 to -1.13, and the sediments slope value of -0.81. These suggest that ion-exchange was the dominant adsorption mechanism for strontium

  7. Influence of Amang (Tin Tailing) on Geotechnical Properties of Clay Soil

    International Nuclear Information System (INIS)

    Amang or tin tailing is commonly found in the vicinity of disused mining area and responsible in downgrading the water quality, landscape and mechanical behaviour of soils. It was generated from extraction process of separating valuable metal from particular ore. This paper presents the geotechnical characteristics of amang-contaminated clay soil. The geotechnical properties of uncontaminated soils were studied in order to compare to that of amang contaminated soils. The base soil used in this study represents completely weathered horizon of meta sedimentary rock. Meanwhile, tin tailing sample was taken from the disused mine at Sungai Lembing, Pahang. The geotechnical characterisations of base soil and contaminated soils were determined based on consistency index, compaction behaviour, hydraulic conductivity and undrained shear strength (UU tests). Contaminated soil samples were prepared by adding 5, 10 and 20 % of tailing, based on dry weigh of the studied base soil. The results from the particle size distribution analysis showed that residual soil from meta sedimentary rock comprised 42.6 % clay, 32.2 % silt and 25.2 % sand whilst tailing was dominated by 98 % of sand fraction. XRD analysis indicated the presence of quartz, kaolinite and muscovite minerals in the studied soil. The specific gravity of soil used is 2.67 and the pH is 3.88. Tailing found to have higher specific gravity of 3.37. The consistency index of contaminated soils showed that liquid limit, wL and plastic limit, wP decreased with the increase in the percentage of tailing added to the soil samples. The value of maximum dry density, ρ dry max increased while optimum moisture content decreased due to the increase in tailing content in soil sample. The permeability of contaminated soil also increased with the increase in tailing contents ranged from 19.8 cm/ hr to 23.8 cm/ hr. The undrained shear strength, Cu, of contaminated soil decreased from 646 kPa (5 % of tailing) to 312 kPa (20 % of

  8. Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

    Directory of Open Access Journals (Sweden)

    Yu Su Young

    2015-06-01

    Full Text Available In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear parameters of soil models was investigated by Dynamic Embedment Factor (DEF concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

  9. Nonlinear soil parameter effects on dynamic embedment of offshore pipeline on soft clay

    Science.gov (United States)

    Yu, Su Young; Choi, Han Suk; Lee, Seung Keon; Park, Kyu-Sik; Kim, Do Kyun

    2015-06-01

    In this paper, the effects of nonlinear soft clay on dynamic embedment of offshore pipeline were investigated. Seabed embedment by pipe-soil interactions has impacts on the structural boundary conditions for various subsea structures such as pipeline, riser, pile, and many other systems. A number of studies have been performed to estimate real soil behavior, but their estimation of seabed embedment has not been fully identified and there are still many uncertainties. In this regards, comparison of embedment between field survey and existing empirical models has been performed to identify uncertainties and investigate the effect of nonlinear soil parameter on dynamic embedment. From the comparison, it is found that the dynamic embedment with installation effects based on nonlinear soil model have an influence on seabed embedment. Therefore, the pipe embedment under dynamic condition by nonlinear parameters of soil models was investigated by Dynamic Embedment Factor (DEF) concept, which is defined as the ratio of the dynamic and static embedment of pipeline, in order to overcome the gap between field embedment and currently used empirical and numerical formula. Although DEF through various researches is suggested, its range is too wide and it does not consider dynamic laying effect. It is difficult to find critical parameters that are affecting to the embedment result. Therefore, the study on dynamic embedment factor by soft clay parameters of nonlinear soil model was conducted and the sensitivity analyses about parameters of nonlinear soil model were performed as well. The tendency on dynamic embedment factor was found by conducting numerical analyses using OrcaFlex software. It is found that DEF was influenced by shear strength gradient than other factors. The obtained results will be useful to understand the pipe embedment on soft clay seabed for applying offshore pipeline designs such as on-bottom stability and free span analyses.

  10. Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

    OpenAIRE

    Ivan Morales; Janet A. Atoyan; José A. Amador; Thomas Boving

    2014-01-01

    Segmented mesocosms (n = 3) packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE)-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE) and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 105 cfu/mL STE and 105–106 p...

  11. Salt—Water Dynamics in Soils:V.Salt Balance in Soil Profiles

    Institute of Scientific and Technical Information of China (English)

    YOUWEN-RUI; MENGFAN-HUA

    1995-01-01

    Salt balance in simulated soil coulumns was calculated on the basis of a large amount of long term observation data.The results showed that under the climate conditions of semi-arid region of the Huang-Huai-Hai Plain,the soils in the columns were under salt accumulation conditions when the groundwater depth was controlled at less than 2.0m,and under desalinization conditions when at larger than 2.5m.In the soil columns with clay soil and silty loam soil intercalated with a clay layer,the amount of salt accumulated was far less than that in the soil column with silty loam soil throughout the whole profile.Under no irriagtion conditions crop planting may increase groundwater evaporation and hence salt accumulation in soil,making the soil columns under desalinization be under salt accumulation conditions.

  12. Traditional Underground Grain Storage in Clay Soils in Sudan Improved by Recent Innovations

    Directory of Open Access Journals (Sweden)

    Abdalla, AT.

    2002-01-01

    Full Text Available In the central clay plain of the Sudan, traditional subsistence farmers and small farmers that also produce for local markets want to keep the region near food self-sufficiency. They combine annual production of sorghum with underground pit storage of part of the harvest. With increasing climate variability this food security is coming more and more under pressure. Farmers recently experimented with pit innovations that would allow storage for more than one season. These innovations were quantified and further improvements were suggested. It was found that in the most abundantly occurring cracking clay soils, wide shallow pits, using thick chaff linings, with wider above ground soil caps, are most suitable for longer term storage.

  13. Enrichment of trace elements in the clay size fraction of mining soils.

    Science.gov (United States)

    Gomes, Patrícia; Valente, Teresa; Braga, M Amália Sequeira; Grande, J A; de la Torre, M L

    2016-04-01

    Reactive waste dumps with sulfide minerals promote acid mine drainage (AMD), which results in water and soil contamination by metals and metalloids. In these systems, contamination is regulated by many factors, such as mineralogical composition of soil and the presence of sorption sites on specific mineral phases. So, the present study dedicates itself to understanding the distribution of trace elements in different size fractions (clay size fraction. Hence, the higher degree of contamination by toxic elements, especially arsenic in Penedono as well as the role of clay minerals, jarosite, and goethite in retaining trace elements has management implications. Such information must be carefully thought in the rehabilitation projects to be planned for both waste dumps. PMID:25712883

  14. THE EFFECT OF SALINITY-SODICITY AND GLYPHOSATE FORMULATIONS – AVANS PREMIUM 360 SL ON PHOSPHOMONOESTERASE ACTIVITIES IN SANDY LOAM

    Directory of Open Access Journals (Sweden)

    Maciej Płatkowski

    2016-01-01

    Full Text Available The aim of study was to determine the influence of NaCl and glyphosate-based herbicide Avans Premium 360 SL on acid and alkaline phosphomonoesterase activities in sandy loam. The experiment was carried out in laboratory conditions on sandy loam with Corg content 10.90 g/kg. Soil was divided into half kilogram samples and adjusted to 60% of maximum water holding capacity. In the experiment dependent variables were: I – dosages of Avans Premium 360 SL (0, a recommended field dosage – FD, a tenfold higher dosage – 10 FD and hundredfold higher dosage – 100 FD, II – amount of NaCl (0, 3% and 6%, III – day of experiment (1, 7, 14, 28 and 56. On days of experiment the activity of alkaline and acid phosphomonoesterase activity was assayed spectrophotometrically. The obtained result showed that the application of Avans Premium 360 SL decreased in acid and alkaline phosphomonoesterase activity in clay soil. Significant interaction effect between the dosage of Avans Premium 360 SL, NaCl amount and day of experiment was reported in the experiment. The inhibitory effect of Avans Premium 360 SL was the highest in soil with NaCl at the amount of 6%.

  15. Effect of air injection under subsurface drip irrigation on yield and water use efficiency of corn in a sandy clay loam soil

    OpenAIRE

    Mohamed Abuarab; Ehab Mostafa; Mohamed Ibrahim

    2013-01-01

    Subsurface drip irrigation (SDI) can substantially reduce the amount of irrigation water needed for corn production. However, corn yields need to be improved to offset the initial cost of drip installation. Air-injection is at least potentially applicable to the (SDI) system. However, the vertical stream of emitted air moving above the emitter outlet directly toward the surface creates a chimney effect, which should be avoided, and to ensure that there are adequate oxygen for root respiration...

  16. Bulk and clay mineral composition indicate origin of terra rossa soils in Western Herzegovina

    OpenAIRE

    Durn, Goran; Ćorić, Radica; Tadej, Neven; Barudžija, Uroš; Rubinić, Vedran; Husnjak, Stjepan

    2014-01-01

    The B horizons of terra rossa soils developed on three different carbonate lithologies having variable insoluble residue contents were studied in Western Herzegovina. Comparison of  their composition and properties illustrates to what extent mineral (especially clay mineral assemblage) and particle size composition of those horizons and the insoluble residue of the underlying carbonate rocks can be used as indicators of the polygenetic nature of terra rossa in this region. Terra rossa B horiz...

  17. The role of clay minerals on the hardsetting properties of soils in the Carnarvon horticultural district of Western Australia

    International Nuclear Information System (INIS)

    Full text: We investigated the role of clay minerals on the hardsetting properties of soils used for intensive irrigated horticulture in the Carnarvon horticultural district of Western Australia. Hardsetting soils break down when wetted due to a combination of slaking and dispersion processes, resulting in a structureless mass of soil when dry. Soil samples were studied from several horizons from six profiles with hardsetting problems. On bulk samples, we measured the cation exchange capacity (CEC) and following treatment with sodium (Na), measured the tensile strength of (Na saturated) remoulded cores. On clay separates we measured the clay mineralogy using X-ray . diffraction (XRD) analysis and CEC by X-ray fluorescence (XRF) analysis after barium (Ba) saturation. Samples were also investigated using transmission electron microscopy (TEM). The tensile strength of the Na saturated remoulded cores was highly correlated (p ≤ 0.001) to both clay % and CEC of the soil. Lugo (1975) working with dried briquettes of soil materials produced similar results, and demonstrated that the increase in tensile strength adversely affected the stand of plants. When the tensile strength of the remoulded cores was compared to the CEC of the clay fractions, the soil clays with higher CEC had greater tensile strength than soils lower in CEC (p=0.09). Initial qualitative XRD results using the SIROQUANT method indicated that the soil clays mainly consisted of kaolinite with some illite, but very little smectite content. However the measured CEC's (by Ba saturation) were higher than expected and could not be explained on the basis of the illite and kaolinite contents. It was therefore inferred that interstratified smectite was also present. Using the proprietary software 'Traces', and a Pseudo-Voigt peak-shape algorithm, each XRD pattern was fitted with calculated peaks for the clay minerals present. Comparison with calculated patterns for interstratified illite/smectite (I/S) using

  18. Evaluation of clay content in soils for pavement engineering applications using GPR

    Science.gov (United States)

    Tosti, Fabio; Patriarca, Claudio; Benedetto, Andrea; Slob, Evert C.; Lambot, Sébastien

    2013-04-01

    Clay content significantly influences the mechanical behavior of soils, thereby playing an important role in many fields of applications such as civil engineering, geology and agriculture. In the area of pavement engineering, clay content in structural bearing courses of pavement frequently causes damages and defects, such as transversal and longitudinal cracks, or other faults. The main consequence is a lowering of both the road safety and operability, with the number of expected accidents increasing. In this study, ground-penetrating radar (GPR) laboratory tests were carried out to predict the clay amount in pavement structural layers under different clay and moisture conditions. GPR data processing is performed using two different methods. The first method is based on the Fresnel theory and focuses on the Rayleigh scattering of the radar waves. The approach is based on a different scattering of the various components of the frequency spectrum, mostly depending on both the soil texture and variation in soil moisture content. For the application of this method, we used a pulse radar with ground-coupled, 500 MHz centre-frequency antennas in a common offset, bistatic configuration. The transmitter and receiver were linked by optic fiber electronic modules. The second method is based on full-waveform inversion of the ultra wideband radar data. In particular, a specific radar-antenna electromagnetic model is used to filter out antenna effects and antenna-medium interactions from the raw radar data and retrieve the response of the soil only, expressed in terms of a layered medium Green's function. To estimate the medium geometrical and electrical values, an optimization inverse problem is formulated. For the application of that second method, we used a vector network analyzer (VNA) as continuous-wave stepped-frequency radar system to acquire data in the 500-3000 MHz frequency range. A doubled-ridged broadband horn antenna operating in far-field conditions was used as

  19. Novel clay carriers for the controlled release of organic agrochemicals

    International Nuclear Information System (INIS)

    Controlled-release (CR) formulations of alachlor and atrazine herbicides were prepared using sodium alginate and pectine as natural, biodegradable matrices and clay minerals as inert fillers. The release of the two herbicides from different type of CR formulations was studied in static water. The release of alachlor from alginate based formulations and a commercial formulation in sandy loam soil and its movement in a soil column was also studied. The rate of release was affected by the type of clay and the size of the formulation beads. The addition of Fisher bentonite to the alginate reduced the rate of release of herbicides. The release was slower from the larger beads and from those prepared using high viscosity alginate. The release of alachlor in the soil and its movement through the soil column was faster from the commercial formulation than the CR formulation. (author). 6 refs, 10 figs, 2 tabs

  20. IMPACT OF POLLUTION ON THE CLAY MINERALOGICAL COMPOSITION OF SOME SOILS FROM ZLATNA AREA (ROMANIA

    Directory of Open Access Journals (Sweden)

    C. Craciun

    2008-10-01

    Full Text Available Zlatna area is a high polluted zone with heavy metals due to industrial activity (extraction and processing of non-ferrous area. In spite of the fact that industrial activity was stoped for 2-3 years, the effect of pollution are still obvious. The aim of this paper is to make evident some aspects concerning the impact of pollution on the mineralogical composition of the clay fraction (below 2μ from some soils belonging to dystric cambisol and luvisol type. From the chemical point of view, the effect of pollution is the acidifiation and depletion of bases, reflected by the decrease of values of indices which express soil reaction (pH and soil exchange properties, especially in the surface horizon. From mineralogical point of view, the acidifiation determines a strong alteration of primary minerals (micas and feldspars and just of secondary minerals (illite, evolution beeing towards hydroxy interlayered minerals (intergrade and kaolinite. As result of this alteration the content of kaolinite increases, achiving a double content in the surface horizon of some polluted soils. Sometimes kaolinite becomes the dominant mineral in the clay fraction of some strong polluted soil.

  1. Arbuscular mycorrhizal fungus enhances P acquisition of wheat (Triticum aestivum L.) in a sandy loam soil with long-term inorganic fertilization regime.

    Science.gov (United States)

    Hu, Junli; Lin, Xiangui; Wang, Junhua; Cui, Xiangchao; Dai, Jue; Chu, Haiyan; Zhang, Jiabao

    2010-10-01

    The P efficiency, crop yield, and response of wheat to arbuscular mycorrhizal fungus (AMF) Glomus caledonium were tested in an experimental field with long-term (19 years) fertilizer management. The experiment included five fertilizer treatments: organic amendment (OA), half organic amendment plus half mineral fertilizer (1/2 OM), mineral fertilizer NPK, mineral fertilizer NK, and the control (without fertilization). AMF inoculation responsiveness (MIR) of wheat plants at acquiring P were estimated by comparing plants grown in unsterilized soil inoculated with G. caledonium and in untreated soil containing indigenous AMF. Without AMF inoculation, higher crop yields but lower colonization rates were observed in the NPK and two OA-inputted treatments, and NPK had significantly (P amendments by improving P-acquisition efficiency in arable soils. PMID:20683717

  2. The origin and early genesis of clay bands in youthful sandy soils along lake Michigan, U.S.A.

    Science.gov (United States)

    Berg, R.C.

    1984-01-01

    A beach ridge and dune complex with good radiocarbon control sampling the last 3500 radiocarbon years B.P. provides new insights on the early genesis of clay bands in sandy soils. Soil profiles were sampled by age groups, described in the field, and then subjected to laboratory analyses for particle-size distribution, pH, organic carbon, carbonate minerals, and extractable iron and manganese. This study suggests that small increases in pH, brought about by small increases in carbonate content within the soil profile, are responsible for flocculating small amounts of illuviated clay. This process, along with a transition to a greater hydraulic conductivity with soil depth due to coarser textures in any given profile, partly explains the existence and possible reason for the initiation of illuvial zones and eventually for clay-band horizons. A pronounced increase in the thickness of incipient clay-band horizons in soils older than 2300 years appears due to finer textures in the parent materials than are present in younger soils. Because of slightly reduced porosity and lower permeability, carbonates and a high pH are retained in both illuvial and eluvial horizons of some of these older soils. In addition, only in those profiles older than 2300 years do clay and iron oxide concentrations coincide and is there some suggestion of greater amounts of extractable manganese in horizons of minimum iron and clay. A pronounced segregation of clay-iron bands is not apparent at the study area but should occur in future years as additional amounts of iron and clay are deposited. ?? 1984.

  3. Effect of Polypropylene Fibers, Lime and Ceramic Additives on the Compressibility of Silty-Clay Soil

    Directory of Open Access Journals (Sweden)

    Hiba D. Saleem

    2016-07-01

    Full Text Available Soil stabilization is widely used by geotechnical engineers in the world to increase soil strength, soil compressibility and reduce the permeability. The main aim of this paper is to investigate the effect of adding different materials to the silty clayey soil (i.e. polypropylene fibers, lime and ceramic and to figure out how the compressibility behave under mixture soil and these stabilized material at different percent (investigation their effect on the value of settlement. Silty clay soil it is used in this research in the geotechnical laboratories of the University of Wasit and the samples of soil are subjected to two main stress level using one-dimensional compression apparatus (i.e. 40KP and 80 KPa for both untreated and treated (stabilized soil with additives. A total of 48 hours of loading time is used and conventional reading rate for one-dimensional compression test is followed. Two main percentages (i.e. 1.5% and 3.5% from the total weight of soil specimens and they had been mixed with soil for 30 min using electrical mixer to attain a uniform soil-material mixture prior to consolidation cell preparation and loading procedure. The results of the experimental tests show that the compressibility of the treated soil specimens were decrease when the soil stabilized with these material and minimum compressibility was obtained when the polypropylene fibers at 1.5 % percentages is used at the higher stress level and 3.5% of lime-stabilized at low stress level.

  4. 222Rn and CO2 soil-gas geochemical characterization of thermally altered clays at Orciatico (Tuscany, Central Italy)

    International Nuclear Information System (INIS)

    Research highlights: → Soil-gas technique is applied to study gas permeability of Orciatico clay units. → Clay permeability depends on thermal and mechanical alteration degree. → Soil-gas distributions are due to shallow fracturing of clays. → Rn and CO2 soil-gas anomalies highlight secondary permeability in clay sequence. → Soil-gas results are supported by detailed geoelectrical surveys. - Abstract: The physical properties of clay allow argillaceous formations to be considered geological barriers to radionuclide migration in high-level radioactive-waste isolation systems. As laboratory simulations are short term and numerical models always involve assumptions and simplifications of the natural system, natural analogues are extremely attractive surrogates for the study of long-term isolation. The clays of the Orciatico area (Tuscany, Central Italy), which were thermally altered via the intrusion of an alkali-trachyte laccolith, represent an interesting natural model of a heat source which acted on argillaceous materials. The study of this natural analogue was performed through detailed geoelectrical and soil-gas surveys to define both the geometry of the intrusive body and the gas permeability of a clay unit characterized by different degrees of thermal alteration. The results of this study show that gas permeability is increased in the clay sequences subjected to greater heat input from the emplacement of the Orciatico intrusion, despite the lack of apparent mineral and geotechnical variations. These results, which take into consideration long time periods in a natural, large-scale geological system, may have important implications for the long-term safety of underground storage of nuclear waste in clay formations.

  5. Availability and bio-accessibility of metals in the clay fraction of urban soils of Sevilla

    International Nuclear Information System (INIS)

    The availability of Cd, Cr, Cu, Ni, Mn, Pb and Zn present in the finest size particles of urban soils is studied by comparing the concentrations in the clay fraction with those extracted from the whole soil by either single-extraction or sequential extraction method. Many metals are preferentially present in the finest particles as compared to coarser fractions. This is true for most metals studied, except Mn and, perhaps, Cd. Those metals present in the clay fraction are often in easily bio-accessible forms, especially Cu, Pb and Zn. The results suggest that bio-accessible forms of these three metals are distributed among the three sequential fractions, and even the fraction considered as 'residual' is also bio-accessible to a significant extent. The statistical analysis shows some distinctions among metals that are compared to the 'urban', 'natural', or intermediate behaviour of the various metals as proposed earlier in the literature. - The recreational use of most urban soils causes that the availability of metals in the finest soil particles must be studied and eventually controlled

  6. Determination of essential and toxic elements in clay soil commonly consumed by pregnant women in Tanzania

    International Nuclear Information System (INIS)

    A habit of eating clay soil especially among pregnant women is a common practice in Tanzania. This practice known as geophagy might introduce toxic elements in the consumer's body to endanger the health of the mother and her child. Therefore it is very important to have information on the elemental composition of the eaten soil so as to assess the safety nature of the habit. In this study 100 samples of clay soil, which were reported to be originating from five regions in Tanzania and are consumed by pregnant women were analyzed to determine their levels of essential and toxic elements. The analysis was carried out using energy dispersive X-ray fluorescent technique (EDXRF) of Tanzania Atomic Energy Commission, Arusha. Essential elements Fe, Zn, Cu, Se and Mn and toxic elements As, Pb, Co, Ni, U and Th were detected in concentrations above WHO permissible limits in some of the samples. The results from this study show that the habit of eating soil is exposing the pregnant mothers and their children to metal toxicity which is detrimental to their health. Hence, further actions should be taken to discourage the habit of eating soil at all levels. - Highlights: • We assessed exposure of heavy metals to pregnant mothers who consume geophagic soil. • We analyzed 100 samples of soil originated in Tanzania. • The technique used was energy dispersive X-ray fluorescent. • Essential and toxic elements were detected in concentrations above WHO limits. • Hence, geophagy is exposing pregnant mothers and their children to metal toxicity

  7. Dissolution kinetics of soil clays in sulfuric acid solutions: Ionic strength and temperature effects

    International Nuclear Information System (INIS)

    Highlights: • Acid sulfate dissolution of clay-rich sediments from inland acid sulfate site in flow-through reactor experiments at pH 1–4. • Enhanced Al and K release at the higher ionic strength of solutions compared to the lower ionic strength. • Acid neutralization capacity (ANC) of 1.11 kg H2SO4/tonne clay-rich sediment/day was provided at pH 1, 25 °C. • ANC provided at 45 °C by the same amount of clay-rich sediment was more than three times higher than the ANC at 25 °C. - Abstract: Significant amounts of sulfuric acid (H2SO4) rich saline water can be produced by the oxidation of sulfide minerals contained in inland acid sulfate soils (IASS). In the absence of carbonate minerals, the dissolution of phyllosilicate minerals is one of very few processes that can provide long-term acid neutralisation. It is therefore important to understand the acid dissolution behavior of naturally occurring clay minerals from IASS under saline–acidic solutions. The objective of this study was to investigate the dissolution of a natural clay-rich sample under saline–acidic conditions (pH 1–4; ionic strengths = 0.01 and 0.25 M; 25 °C) and over a range of temperatures (25–45 °C; pH 1 and pH 4). The clay-rich sample referred to as Bottle Bend clay (BB clay) used was from an IASS (Bottle Bend lagoon) in south-western New South Wales (Australia) and contained smectite (40%), illite (27%), kaolinite (26%) and quartz (6%). Acid dissolution of the BB clay was initially rapid, as indicated by the fast release of cations (Si, Al, K, Fe, Mg). Relatively higher Al (pH 4) and K (pH 2–4) release was obtained from BB clay dissolution in higher ionic strength solutions compared to the lower ionic strength solutions. The steady state dissolution rate (as determined from Si, Al and Fe release rates; RSi, RAl, RFe) increased with decreasing solution pH and increasing temperature. For example, the highest log RSi value was obtained at pH 1 and 45 °C (−9.07 mol g−1 s−1

  8. Soil-Structural Stability as Affected by Clay Mineralogy, Soil Texture and Polyacrylamide Application

    Science.gov (United States)

    Soil-structural stability (expressed in terms of aggregate stability and pore size distribution) depends on (i) soil inherent properties, (ii) extrinsic condition prevailing in the soil that may vary temporally and spatially, and (iii) addition of soil amendments. Different soil management practices...

  9. Compressive behaviour of the soil in buffer zones under different management practices in Finland

    OpenAIRE

    Räty, Mari; Horn, Rainer; Rasa, Kimmo; Yli-Halla, Markku; Pietola, Liisa

    2010-01-01

    Soil structure that favours infiltration is essential for successful functioning of vegetated buffer zones. We measured bulk density, air permeability and precompression stress in a clay soil (Vertic Cambisol) and a sandy loam (Haplic Regosol) in Finland, to identify management-related changes in the physical and mechanical properties in the surface soil of buffer zones. In addition, the impact of texture on these properties was studied at depths down to 180?200 cm. Soil cores (240 cm3) were ...

  10. Effects of Humic Acid and Solution pH on Dispersion of Na—and Ca—Soil Clays

    Institute of Scientific and Technical Information of China (English)

    LANYEQING; HUQIONGYING; 等

    1996-01-01

    Dispersed soil clays have a negative impact on soil structure and contribute to soil erosion and contaminant movement.In this study,two typical soils from the south of China were chosen for investigating roles of pH and humic acid(HA) on dispersion of soil clays.Critical flocculation concentration (CFC) of the soil clay suspension was determined by using light transmission at a wavelength of 600 nm.The results indicated that effects of pH and HA on dispersion of the soil clays were closely related to the type of the major minerals makin up the soil and to the valence of the exchangeable cations as well.At four rates of pH(4,6,8and 10),the CFC for the Na-yellow-brown soil treated with H2O2 was increased from 0.32 to 0.56,6.0 to 14.0,10.0 to 24.6 and 26.0 to 52.0mmol L-1 NaCl,respectively when Na-HA was added at the rate of from 0 to 40mgL-1,With the same Na-HA addition and three pH(6,8and 10)treatments,the CFC for the Na-red soil was incresed from 0.5 to 20.0,1.0 to 40.0 and 6.0 to 141.0mmol L-1 NaCl,respectively.Obviously,pH and HA has greater effects on clay dispersion of the red soil(dominated by 1:1 minerals and oxides) than on that of the yellow-brown soil(dominated by 2:1minerals).However,at three rates of pH(6,8and 10) and with the addition of Ca-HA from 0 to 40mg L-1,the CFC of the Ca-yellow-brown soil and Ca-red soil treated with H2O2 was increased from 0.55 to 0.81,0.75 to 1.28,0.55 to 1.45and 0.038 to 0.266.0.25 to 0.62,0.7to 1.6mmol CaCl2 L-1,respectively.So,Na-soil claye are more sensitive to pH and HA than Ca-soil clays.

  11. Study of Various Techniques for Improving Weak and Compressible Clay Soil under a High Earth Embankment

    Directory of Open Access Journals (Sweden)

    Zein A.K. M.

    2014-04-01

    Full Text Available This paper investigates the suitability of three soil improvement techniques for the construction of a high earth embankment on thick weak and highly compressible clay soil. The eastern approach embankment of Alhalfaya Bridge on the River Nile linking Khartoum North and Omdurman cities was chosen as a case study and a comprehensive site investigation program was carried out to determine the properties the subsurface soils. The study results showed that unless the subsurface soils have been improved they may fail or undergo excessively large settlements due to the embankment construction. Three ground improvement techniques based on the principles of the “staged construction method, SCM”, “vertical sand drain, VSD” and “sand compaction piles, SCP” of embankment foundation soil treatment are discussed and evaluated. Embankment design options based on applications of the above methods have been proposed for foundation treatment to adequately support embankment loads. A method performance evaluation based on the improvement of soil properties achieved; the time required for construction and compared estimated costs criteria was made to assess the effectiveness and expected overall performance. Adoption of any of the soil improvement techniques considered depends mainly on the most critical and decisive factor governing the embankment design. Based on the overall performance for the embankment case studied, the sand drains is considered as the most appropriate improvement method followed by the sand compaction piles technique whereas the staged construction method showed the poorest overall performance.

  12. Influence of soil texture on hydraulic properties and water relations of a dominant warm-desert phreatophyte.

    Science.gov (United States)

    Hultine, K R; Koepke, D F; Pockman, W T; Fravolini, A; Sperry, J S; Williams, D G

    2006-03-01

    We investigated hydraulic constraints on water uptake by velvet mesquite (Prosopis velutina Woot.) at a site with sandy-loam soil and at a site with loamy-clay soil in southeastern Arizona, USA. We predicted that trees on sandy-loam soil have less negative xylem and soil water potentials during drought and a lower resistance to xylem cavitation, and reach E(crit) (the maximum steady-state transpiration rate without hydraulic failure) at higher soil water potentials than trees on loamy-clay soil. However, minimum predawn leaf xylem water potentials measured during the height of summer drought were significantly lower at the sandy-loam site (-3.5 +/- 0.1 MPa; all errors are 95% confidence limits) than at the loamy-clay site (-2.9 +/- 0.1 MPa). Minimum midday xylem water potentials also were lower at the sandy-loam site (-4.5 +/- 0.1 MPa) than at the loamy-clay site (-4.0 +/- 0.1 MPa). Despite the differences in leaf water potentials, there were no significant differences in either root or stem xylem embolism, mean cavitation pressure or Psi(95) (xylem water potential causing 95% cavitation) between trees at the two sites. A soil-plant hydraulic model parameterized with the field data predicted that E(crit) approaches zero at a substantially higher bulk soil water potential (Psi(s)) on sandy-loam soil than on loamy-clay soil, because of limiting rhizosphere conductance. The model predicted that transpiration at the sandy-loam site is limited by E(crit) and is tightly coupled to Psi(s) over much of the growing season, suggesting that seasonal transpiration fluxes at the sandy-loam site are strongly linked to intra-annual precipitation pulses. Conversely, the model predicted that trees on loamy-clay soil operate below E(crit) throughout the growing season, suggesting that fluxes on fine-textured soils are closely coupled to inter-annual changes in precipitation. Information on the combined importance of xylem and rhizosphere constraints to leaf water supply across soil

  13. Effect of Kiwi Shell and Incubation Time on Mobility of Lead and Cadmium in Contaminated Clay Soil

    OpenAIRE

    Bahareh Lorestani; Chia Arjangi; Hajar Merrikhpour

    2014-01-01

    In this study, the effectiveness of kiwi shell was investigated to reduce the mobility of Lead and Cadmium in clay soil in different intervals. For this purpose a clay soil sample was contaminated with Lead and Cadmium in distinct dishes with 10 and 600 ppm concentrations respectively and mixed with 5% kiwi shell. Samples were placed in incubator, and then sampling of soil in incubator was performed in intervals 3 hours, 1, 3, 7, 14, 21 and 28 days. Heavy metals concentrations were determined...

  14. Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model

    Directory of Open Access Journals (Sweden)

    T. J. Besien

    1997-01-01

    Full Text Available In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications could potentially reduce pesticide leaching to surface waters by up to 60%.

  15. Water flow and nutrient transport in a layered silt loam.

    OpenAIRE

    Vos

    1997-01-01

    Theory, numerical models, and field and laboratory measurements are used to describe and predict water flow and nutrient transport in a layered silt loam soil. One- and two-dimensional models based on the Darcy equation for water flow and the convection-dispersion equation for solute transport are evaluated. Pressure heads simulated with the one-dimensional water balance model SWATRE are too large. The two-dimensional SWMS_2D model simulates water flow well for the winter leaching periods. Th...

  16. Water and solute transport in agricultural soils predicted by volumetric clay and silt contents

    Science.gov (United States)

    Karup, Dan; Moldrup, Per; Paradelo, Marcos; Katuwal, Sheela; Norgaard, Trine; Greve, Mogens H.; de Jonge, Lis W.

    2016-09-01

    Solute transport through the soil matrix is non-uniform and greatly affected by soil texture, soil structure, and macropore networks. Attempts have been made in previous studies to use infiltration experiments to identify the degree of preferential flow, but these attempts have often been based on small datasets or data collected from literature with differing initial and boundary conditions. This study examined the relationship between tracer breakthrough characteristics, soil hydraulic properties, and basic soil properties. From six agricultural fields in Denmark, 193 intact surface soil columns 20 cm in height and 20 cm in diameter were collected. The soils exhibited a wide range in texture, with clay and organic carbon (OC) contents ranging from 0.03 to 0.41 and 0.01 to 0.08 kg kg- 1, respectively. All experiments were carried out under the same initial and boundary conditions using tritium as a conservative tracer. The breakthrough characteristics ranged from being near normally distributed to gradually skewed to the right along with an increase in the content of the mineral fines (particles ≤ 50 μm). The results showed that the mineral fines content was strongly correlated to functional soil structure and the derived tracer breakthrough curves (BTCs), whereas the OC content appeared less important for the shape of the BTC. Organic carbon was believed to support the stability of the soil structure rather than the actual formation of macropores causing preferential flow. The arrival times of 5% and up to 50% of the tracer mass were found to be strongly correlated with volumetric fines content. Predicted tracer concentration breakthrough points as a function of time up to 50% of applied tracer mass could be well fitted to an analytical solution to the classical advection-dispersion equation. Both cumulative tracer mass and concentration as a function of time were well predicted from the simple inputs of bulk density, clay and silt contents, and applied tracer

  17. Biochar Effects on Soil Aggregate Properties Under No-Till Maize

    DEFF Research Database (Denmark)

    Khademalrasoul, Ataalah; Naveed, Muhammad; Heckrath, Goswin Johann;

    2014-01-01

    –10 kg m−2), in combination with swine manure (2.1 and 4.2 kg m−2), to a no-till maize (Zea mays L.) cropping system on a sandy loam soil in Denmark. Topsoil (0–20 cm) aggregates were analyzed for clay dispersibility, aggregate stability, tensile strength (TS), and specific rupture energy (SRE) using end...

  18. Soil Loss by Wind Erosion for Three Different Textured Soils Treated with Polyacrylamide and Crude Oil, Iraq

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The study is conducted to estimate the resistance of three soils (EL-Hartha clay loam, Barjisiya sandy loam and the soil near the sand dunes in Sheikh sa'ad area sandy soil) to wind erosion, it is also aimed at getting full acquaintance of the relationship between the soil loss and the physical and chemical features of soil. In addition to the experiment of some soil stabilizers, polyacrylamide (PAM) concentration of 0.2 % and crude oil in concentration of 1 % in order to reduce or prevent wind erosion. The study shows that the amendment increased the dry soil aggregate >1 mm, mean weight diameter and soil moisture. It is clear that polyacrylamide had greater effect than that of crude oil, besides the great effectiveness of these amendments in decreasing bulk density and relations of soil loss.

  19. IMPACT OF POLLUTION ON THE CLAY MINERALOGICAL COMPOSITION OF SOME SOILS FROM ZLATNA AREA (ROMANIA)

    OpenAIRE

    C.Craciun; Alexandrina Manea; Laura Paulette; Marius Eftene; Victoria Mocanu

    2008-01-01

    Zlatna area is a high polluted zone with heavy metals due to industrial activity (extraction and processing of non-ferrous area). In spite of the fact that industrial activity was stoped for 2-3 years, the effect of pollution are still obvious. The aim of this paper is to make evident some aspects concerning the impact of pollution on the mineralogical composition of the clay fraction (below 2μ) from some soils belonging to dystric cambisol and luvisol type. From the chemical point of view, ...

  20. Irrigation with saline-sodic water: effects on two clay soils

    Directory of Open Access Journals (Sweden)

    Giovanna Cucci

    2013-05-01

    Full Text Available The results of a 4-year experiment aimed at evaluating the effect of irrigation with saline-sodic water on the soil are reported. The research was carried out at the Campus of the Agricultural Faculty of Bari University (Italy on 2 clay soils (Bologna – T1 and Locorotondo – T2. The soils were cropped to borlotto bean (Phaseolus vulgaris L., capsicum (Capsicum annuum L., sunflower (Helianthus annuus L., wheat (Triticum durum Desf grown in succession; the crops were irrigated with 9 saline-sodic types of water and subjected to two different leaching fractions (10% and 20% of the watering volume. The 9 solutions were obtained dissolving in de-ionised water weighted amounts of sodium chloride (NaCl and calcium chloride (CaCl2, deriving from the combination of 3 saline concentrations and 3 sodicity levels. The crops were irrigated whenever the water lost by evapotranspiration from the soil contained in the pots was equal to 30% of the soil maximum available water. The results showed that, though the soils were leached during the watering period, they showed a high salt accumulation. Consequently, the saturated soil extract electrical conductivity increased from initial values of 0.65 and 0.68 dS m-1 to 11.24 and 13.61 dS m-1 at the end of the experiment, for the soils T1 and T2, respectively. The saline concentration increase in irrigation water caused in both soils a progressive increase in exchangeable sodium, and a decrease in exchangeable calcium and non-significant variations in exchangeable potassium (K and magnesium (Mg.

  1. Risk assessment of gas oil and kerosene contamination on some properties of silty clay soil.

    Science.gov (United States)

    Fallah, M; Shabanpor, M; Zakerinia, M; Ebrahimi, S

    2015-07-01

    Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40%) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15% in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, Θ s, from nearly 49% in the control sample to just under 53% in the polluted ones. Contaminants not only decreased the residual water content, Θ r, but also reduced the SWRC gradient, n, and amount of α parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey. PMID:26085279

  2. Interactions of Cations with Electrodialyzed Clay Fraction of Soils as Inferred from Wien Effect in Soil Suspensions

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrical conductivities (ECs) of suspensions containing 25 and 30 g kg-1 solids prepared from theelectrodialyzed clay fraction (< 2 μm in diameter) of latosol, yellow-brown soil, and black soil, dispersed invarious nitrate solutions having concentrations of 1 × 10-4/z mol L-1, where z is the valence, and in distilledwater, were measured at field strengths ranging from 14 kV cm-1 to 210 kV cm-1. On the basis of analysesof the charge density and exchangeable ion composition on the surfaces of soil particles in the suspensions,and of the characters of the EC-field strength curves of the various suspensions, it was inferred that theincrement of EC (△EC) and/or relative electrical conductivity (REC) can indicate the bonding strengthbetween cations and soil particles. The bonding strengths of various cations with the soils diminished in theorder: K+ > Zn2+ > Mg2+ = Ca2+ > Na+ for latosol, Ca2+ > Zn2+ > Mg2+ = K+ > Na+ for yellow-brownsoil, and Zn2+ >Ca2+ > Mg2+ > K+ > Na+ for black soil.

  3. CO2 emission and structural characteristics of two calcareous soils amended with municipal solid waste and plant residue

    OpenAIRE

    Yazdanpanah, N.

    2016-01-01

    This investigation examines the effect of different amendments on selected soil physical and biological properties over a 24-month period in two cropland fields. Urban municipal solid waste (MSW) compost and alfalfa residue (AR) were used as different organic amendments at the rates of 0 (control), 10 and 30 Mg ha−1 to a clay loam soil and a loamy sand soil in a semiarid region. Results showed that the soil improvement was controlled by the application rate and decomposabili...

  4. Adsorption-desorption characteristics of Ni, Zn and Pb in soils of a landfill environment in Metro Manila, Philippines

    International Nuclear Information System (INIS)

    This study investigated the sorption-desorption characteristics of Ni, Zn, and Pb on two soil types in the environment of a municipal waste disposal facility. Batch experiments were carried out in ambient temperature and in unadjusted and close to soil field pH conditions. The kinetics of of adsorption fitted a pseudo second-order model. Rate constants were calculated and an empirical model for predicting adsorption of metal ions at a given time was derived from these constants. The equilibrium sorption capacities for the heavy metals in the clay and sandy loam soils were estimated using the Linear, Freundlich, and Langmuir isotherm models. The sorption process of Ni, Pb, and Zn in both soils generally fitted well with the Freundlich isotherm model at moderate to high initial concentration range of the metals. The Langmuir isotherm was applicable to the adsorption of Ni and Zn only. The adsorption capacity of the clay soil for the metals followed the order Zn > Pb > Ni. In the sandy loam soil, the adsorption capacity for the metals under the same conditions followed the order Pb > Zn > Ni. The adsorption capacities for the metals were in order of 1mg/g in both the landfill clay soil and the Lukutan River sandy loam soil, with slightly higher values for the clay soil. Desorption was minimal, less than 1% in the clay soil and about 2% in the sandy loam soil. Sorption reversibility tests showed that the retention of the metals in both soils follows the order Ni> Pb> Zn. (author)

  5. Microorganism-induced weathering of clay minerals in a hydromorphic soil

    Science.gov (United States)

    Hong, Hanlie; Fang, Qian; Cheng, Liuling; Wang, Chaowen; Churchman, Gordon Jock

    2016-07-01

    In order to improve the understanding of factors influencing weathering in hydromorphic soils, the clay mineral and chemical compositions, iron (hydr)oxides, organic compounds, and Sr and Nd isotopic compositions, of hydromorphic soils on the banks of the Liangzi Lake, Hubei province, south China, were investigated. The B horizon in the lower profile exhibits a distinct net-like pattern, with abundant short white veins within the red-brown matrix. Their various 87Sr/86Sr and 143Nd/144Nd isotopic compositions showed only small variations of 0.7270-0.7235 and 0.51200-0.51204, respectively, consistent with the composition of Yangtze River sediments, indicating that the soils were all derived from alluvium from the catchment. The white veins contained notably more SiO2, Al2O3, TiO2, and mobile elements relative to the red-brown matrix, while they both showed similar values for the chemical index of alteration of 86.7 and 87.1, respectively, and displayed similar degrees of weathering. The clay minerals in A, AE, and E horizons of the soil profile were illite, kaolinite, and mixed-layer illite-smectite. These same three clay minerals comprised the white net-like veins in the soil B horizon, whereas only illite and kaolinite were observed in the red-brown matrix. Iron (hydr)oxides in A, AE, and E horizons of the soil profile were hematite and goethite, whereas in the red-brown matrix of the B horizon they were hematite, goethite, and ferrihydrite. Different organic compounds were observed for the white vein and the red-brown matrix in the soil B horizon: an 18:2 fatty acid biomarker for fungi in the net-like vein, but not in the red-brown matrix. Compared with the red-brown matrix, the white net-like vein also clearly contained more mono-unsaturated fatty acids, which are sometimes associated with bacteria that have the capacity to reduce Fe(III). Thus, migration of iron and the formation of the net-like veins involved the participation of biota during the hydromorphic

  6. Clay and Soil Photolysis of the Pesticides Mesotrione and Metsulfuron Methyl

    Directory of Open Access Journals (Sweden)

    Marie Siampiringue

    2014-01-01

    Full Text Available Photolysis may represent an important degradation process of pollutants at the surface of soil. In the present work, we report a detailed study on the degradation of two pesticides: mesotrione and metsulfuron methyl using a sunlight simulator. In a first step, we studied the photochemical behaviour at the surface of clays from the kinetic as well as from the analytical point of view. In both cases, the quantum yields were found to be higher when compared to those obtained in aqueous solutions. The effect of iron(III, water, and humic substances contents was studied. In the former cases, an increase of the degradation rate was observed while an inhibition was observed with the latter owing to a filter effect phenomenon. In a second step, we studied the photodegradation at the surface of natural soil and identified the generated byproducts. They appear to mainly arise from photohydrolysis process.

  7. The influence of clay mineralogy on the mobility of radiocaesium in upland soils of NW Italy

    International Nuclear Information System (INIS)

    137Cs extraction experiments were performed on 14 contaminated soils from NW Italy with different characteristics and mineralogical composition. Solutions of HCl (pH=0.5) and buffered EDTA/ammonium acetate (Lakanen solution) were used to assess bioavailability. The results show that less than 2% of 137Cs is available for leaching and/or root uptake. Even within a complex natural system it was possible to identify the amount of swelling clays (vermiculite+smectite) as the main control on Cs mobility under acidic conditions. The ammonium ion appears to be effective in desorbing Cs and its role is briefly discussed in terms of crystal chemistry. The relevance of mineralogy in assessing soil vulnerability is underlined

  8. Water storage change estimation from in situ shrinkage measurements of clay soils

    Directory of Open Access Journals (Sweden)

    B. te Brake

    2013-05-01

    Full Text Available The objective of this study is to assess the applicability of clay soil elevation change measurements to estimate soil water storage changes, using a simplified approach. We measured moisture contents in aggregates by EC-5 sensors, and in multiple aggregate and inter-aggregate spaces (bulk soil by CS616 sensors. In a long dry period, the assumption of constant isotropic shrinkage proved invalid and a soil moisture dependant geometry factor was applied. The relative overestimation made by assuming constant isotropic shrinkage in the linear (basic shrinkage phase was 26.4% (17.5 mm for the actively shrinking layer between 0 and 60 cm. Aggregate-scale water storage and volume change revealed a linear relation for layers ≥ 30 cm depth. The range of basic shrinkage in the bulk soil was limited by delayed drying of deep soil layers, and maximum water loss in the structural shrinkage phase was 40% of total water loss in the 0–60 cm layer, and over 60% in deeper layers. In the dry period, fitted slopes of the ΔV–ΔW relationship ranged from 0.41 to 0.56 (EC-5 and 0.42 to 0.55 (CS616. Under a dynamic drying and wetting regime, slopes ranged from 0.21 to 0.38 (EC-5 and 0.22 to 0.36 (CS616. Alternating shrinkage and incomplete swelling resulted in limited volume change relative to water storage change. The slope of the ΔV–ΔW relationship depended on the drying regime, measurement scale and combined effect of different soil layers. Therefore, solely relying on surface level elevation changes to infer soil water storage changes will lead to large underestimations. Recent and future developments might provide a basis for application of shrinkage relations to field situations, but in situ observations will be required to do so.

  9. Carbon-Nitrogen Relationships during the Humification of Cellulose in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1981-01-01

    amount of labeled N incorporated into organic forms increased in the clay-rich soils with increasing size of amendments. Of the total labeled C remaining in the soils after the 1st mo. of incubation 50-70% was acid hydrolyzable, compared to 80-100% of the total remaining labeled organic N. This...... immobilization reactions. Some of the labeled organic N when mineralized was re-incorporated into organic compounds containing increasing proportions of native soil-C, whereas labeled C when mineralized as CO2 disappeared from the soils. The amount of labeled amino acid-C, formed during decomposition of the...... 1st mo. of incubation at temperatures of 10, 20 and 30.degree. C, respectively, 38-65% of the labeled C added in cellulose had disappeared from the soils as CO2, and 60-nearly 100% of the labeled N added as NH4+ were incorporated into organic forms. The retention of total labeled C was largest in...

  10. Study on factitious levels of 131 iodine contamination on its uptake and soil to crop transfer in groundnut (Arachis Hypogaea L.)

    International Nuclear Information System (INIS)

    An investigation was carried out to determine iodine-131 uptake and transfer factor (TF) in groundnut, pot-grown on three soils of varying texture, viz., a clay loam, a sandy clay loam and a sandy soil. The soils were factitiously contaminated with 131I at the rate 20, 40, 60, and 80 kBq kg-1 of soil. The effect of level of 131I was significant in the case of 131I uptake and TF. The 131I uptake increased significantly with the increasing levels of 131I and recorded a peak at the contamination level of 80 kBq kg-1 of soil. This was so in other plant parts as stem, leaf and shell and in whole plant as well. The uptake by kernel was significantly influenced by the soil texture. The values were lowest in the sandy soil and highest in sandy clay loam and sandy loam soils. The TF values in all plant parts decreased significantly with the 131I contamination levels. The TF values were significantly higher in roots than in the above-ground parts, amongst which the lowest TF was in the edible part kernel. (author)

  11. Effects of changes in land use on soil physical properties and soil organic carbon content in a wheat-corn-sunflower crop sequence, in a loam soil of Argentina.

    Science.gov (United States)

    Aparicio, V.; Costa, J. L.

    2012-04-01

    The Argentinean Humid Pampas extend over about 60 million hectares, 90% of which are agricultural lands. The Southeast of the Buenos Aires Province is part of the Humid Pampas, it covers over 1,206,162 hectares, the mean annual temperature is 13.3 °C and the climate is sub-humid. At the present only 6% of the lands are used for pasture. The main activities are agriculture and cattle production. The main crops are wheat, sunflower, corn and soybean. The tillage systems used in the area are: moldboard plow (MP), chisel plow (CP) and no-till (NT). Excessive soil cultivation under MP generates decreases in the levels of soil organic carbon (SOC). The magnitude of such decrease depends on the intensity of the tillage system, the tillage timeliness and the amount and quality of the residues. Adopting NT may reduce the effects of intensive agriculture, through the maintenance and accumulation of SOC. However, there are evidences that, under NT, the bulk density (ρb) in the superficial layers of the soil increases. The soil compaction causes degradation of the soil structure, reduces the soil water availability and reduces the soil hydraulic conductivity. With this scenario and the tendency to increase the surface under NT in the Southeast Humid Pampas, we evaluated the evolution of some soil physical properties and the SOC in a 10-year experiment with a wheat-corn-sunflower rotation. The experiment was carried out in four localities at farmerś fields under three different tillage systems: MP, CP and NT in a randomized complete block design, considering each locality as a block. Each plot had 50 m in width by 100 m length and the treatments were: NT, MP and CP. The results of this experiment have allowed us to verify that: i) the wheat-corn-sunflower crop sequence showed a tendency to reduce the values of bulk density (ρb) but NT increased ρb in the superficial soil layers; ii) the more intensive the tillage system, the higher the change in the mean weight diameter

  12. Comparing predictive abilities of three visible-near infrared spectrophotometers for soil organic carbon and clay determination

    DEFF Research Database (Denmark)

    Knadel, Maria; Stenberg, Bo; Deng, Fan;

    2013-01-01

    -NIRS sensors for soil characterization. There is a need for more work on the effects of scanning strategies, and use of different soil instrumentation. We compared three vis-NIR sensors with varying resolution, signal-to-noise ratios and spectral range. Their performance was evaluated based on soil organic...... carbon (SOC) and clay calibrations for 194 Danish top soils. Scanning procedures for the three spectrophotometers where done according to uniform laboratory protocols. SOC and clay calibrations were performed using PLS regression. One third of the data was used as an independent test set. A range of......Due to advances in optical technology a wide range of spectrometers is available. Recent interests in soil global libraries and sensor fusion presents a challenge with respect to combining data from different instrumentation. Only little research, however, has been done on the comparison of vis...

  13. Iodine-131 uptake and transfer from soil to rice following factitious contaminations

    International Nuclear Information System (INIS)

    An investigation was carried out to determine iodine-131 uptake and transfer factor (TF) in pot-grown rice ('IR 20') with three soils of different texture, viz., a sandy clay loam, a sandy loam, and a sandy soil. The soils were factitiously contaminated with four levels of 131I: 20, 40, 60, and 80 kBq kg-1 of soil. Soil texture greatly influenced biomass yield, 131I uptake and TF in rice. The effect of level of 131I was significant only in the case of grain. In the case of straw, neither the 131I content nor uptake were influenced by the variables. The 131I uptake by grain appeared to increase with the level of 131I contamination. The highest uptake was at the highest level of 131I contamination and in the sandy loam soil. The TF values in all plant parts decreased significantly with the 131I contamination levels and were lowest, quite interestingly, in the sandy clay loam soil for root and in the sandy soil for grain. The TFs followed the order: root > straw > grain. (author)

  14. Determining photon energy absorption parameters for different soil samples.

    Science.gov (United States)

    Kucuk, Nil; Tumsavas, Zeynal; Cakir, Merve

    2013-05-01

    The mass attenuation coefficients (μs) for five different soil samples were measured at 661.6, 1173.2 and 1332.5 keV photon energies. The soil samples were separately irradiated with (137)Cs and (60)Co (370 kBq) radioactive point gamma sources. The measurements were made by performing transmission experiments with a 2″ × 2″ NaI(Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of (137)Cs. The effective atomic numbers (Zeff) and the effective electron densities (Neff) were determined experimentally and theoretically using the obtained μs values for the soil samples. Furthermore, the Zeff and Neff values of the soil samples were computed for the total photon interaction cross-sections using theoretical data over a wide energy region ranging from 1 keV to 15 MeV. The experimental values of the soils were found to be in good agreement with the theoretical values. Sandy loam and sandy clay loam soils demonstrated poor photon energy absorption characteristics. However, clay loam and clay soils had good photon energy absorption characteristics. PMID:23179375

  15. Effects of conservation tillage on water infiltration in two soils in south-eastern Australia

    OpenAIRE

    Bissett, M.J.; G.J. O'Leary

    1996-01-01

    Metadata only record This paper reports on a study in Southeast Australia comparing water infiltration on two soil types (gray cracking clay and sandy loam) under two tillage systems - conservation tillage (zero and sub-soil, residues retained) and conventional tillage (frequently tined tillage, no surface residues). The objective of the study is to determine if conservation tillage increases the water infiltration rate on two different soils, with the hope of better explaining the mechani...

  16. Availability of N amino sugar fraction and response to nitrogen fertilization ({sup 15}N) on soils containing increasing concentrations of organic matter; Disponibilidade da fracao N amino-acucar e resposta a fertilizacao nitrogenada ({sup 15}N) em solos com teores crescentes de materia organica

    Energy Technology Data Exchange (ETDEWEB)

    Galvao, Sandra R. da S.; Salcedo, Ignacio H.; Menezes, Romulo S.C. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear]. E-mail: reginassg@uol.com.br; salcedo@ufpe.br; rmenezes@ufpe.br; Tiessen, Holm [Goettingen Universitaet (Germany)]. E-mail: tiessen@sask.usask.ca

    2005-07-01

    It has been proposed that the soil N amino sugar fraction (N amino), obtained by chemical extraction, represents a reservoir of labile N for the plants. To test the availability of this fraction and how it affects the response to N fertilization ({sup 15}N), we conducted a pot experiment with twenty soil samples containing increasing concentrations of total N, ten of which were sandy clay loam and ten sandy loam. PVC pots containing 500 cm{sup 3} of soil were divided in two groups: one group received 40 mg N kg{sup -1} as NH{sub 4}NO{sub 3} enriched with 2,5 atoms- % of {sup 15}N while the other group did not receive nitrogen. All the soil samples were supplied with 25 mg P kg{sup -1} and cultivated with buffel grass (Cenchrus ciliaris) during 60 days. Total soil N and N amino contents were greater in fine textured samples, in average, than in sandy loams. Dry matter production and N uptake were positively related with N amino concentrations and were greater (p < 0,1) in sandy clay loams than in sandy loams, independently of N fertilization. Ndds% was greater also in fine textured samples than in sandy loams, while Nddf%, in average, did not vary with texture. The use efficiency of fertilizer-N oscillated between 78 and 98%, but the percent yield response decreased from 404% to 47% with the increase in N amino concentrations. (author)

  17. CO2 emission and structural characteristics of two calcareous soils amended with municipal solid waste and plant residue

    OpenAIRE

    Yazdanpanah, N.

    2015-01-01

    This investigation examines the effect of different amendments on selected soil physical and biological properties over a twenty four month period in two cropland fields. Urban municipal solid waste (MSW) compost and alfalfa residue (AR) were used as different organic amendments at the rates of 0 (control), 10 and 30 Mg ha−1 to a clay loam soil and a loamy sand soil in a semiarid region. Result showed that the soil improvement was controlled by the app...

  18. Measuring the specific caesium sorption capacity of soils, sediments and clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    De Koning, A. [aEnergy Research Centre of the Netherlands (ECN), Westerduinweg 3, P.O. Box 1, 1755 ZG, Petten (Netherlands); Konoplev, A.V. [Institute of Experimental Meteorology, 82 Lenin Avenue, Obninsk, Kaluga Region, 249020 (Russian Federation); Comans, R.N.J. [Wageningen University, Department of Soil Quality, P.O. Box 8005, 6700 EC Wageningen (Netherlands)

    2007-01-15

    Two methods to quantify the specific Cs sorption capacity of soils and sediments, which is generally believed to be associated with the Frayed Edge Sites (FES) of illitic clay minerals, are described in detail and are critically reviewed. The first method is a direct measurement of the FES capacity, while the second quantifies the combined parameter K{sub D}{sup C}s x [K{sup +}] (=K{sub C}(K-->Cs) x [FES]) i.e. the product of the FES capacity and the affinity of these sites for Cs. Both methods use the bulky AgTU-complex to mask non-specific sorption sites for Cs and are applied to a number of different soils and pure minerals. Measurement of the FES capacity of pure illite is straightforward. It is shown that the measured capacity is independent of the saturating ion, but does depend on particle size. This method could not be successfully applied to a peat bog soil with 90% organic matter, because the necessary correction for non-specific Cs sorption by the large pool of organic exchange sites overpasses the capacity of the small FES fraction. Measurement of the combined parameter K{sub D}{sup C}s x [K{sup +}] is shown to be more appropriate in such cases. Application of the FES capacity method to the hydrous aluminosilicate mineral allophane, an important soil constituent of Andisols, shows that the AgTU-complex is unable to block all non-specific sorption sites for Cs on this mineral. The K{sub D}{sup C}s x [K{sup +}] measurements show evidence of a very small number of specific Cs sorption sites on allophane, much smaller than inferred from the FES capacity measurement. The FES capacity of the clay mineral vermiculite is difficult to quantify because the high Cs concentrations that are needed to measure the FES capacity probably cause a collapse of the vermiculite interlayers, thereby creating more high-affinity sites for Cs. The K{sub D}{sup C}s x [K{sup +}] method, in which only trace concentrations of Cs are used, is shown to be more appropriate for soils

  19. Clay mineralogical evidence of a bioclimatically-affected soil, Rouge River basin, South-Central Ontario, Canada

    Science.gov (United States)

    Mahaney, W. C.

    2015-01-01

    Holocene soils in drainage basins of South-Central Ontario, Canada, are generally Fluvisols (Entisols) in floodplains transitioning to Brunisols (Inceptisols), Luvisols (Alfisols) and Podzols (Spodosols) in older terraces and in the glaciated tableland. A single landslide sourced from the highest fluvial terrace in the Rouge basin, with a rubble drop of ~ 12 m emplaced a lobe-shaped mass of reworked stream gravel, glaciolacustrine sediment and till, emplaced approximately 6 m above mean water level at a height roughly equivalent to previously dated mid-Holocene terraces and soils. Clay mineralogy of the soil formed in this transported regolith produced the usual semi-detrital/pedogenic distribution of 1:1 (Si:Al = 1:1), 2:1 and 2:1:1 clay minerals as well as primary minerals consisting of plagioclase feldspar, quartz, mica and calcite. Unexpectedly, the presence of moderate amounts of Ca-smectite in the Bk and Ck horizons, relative to a clay-mineral depleted parent material (Cuk), argues for a soil hydrological change affecting the wetting depth in the deposit. The presence of the uncommon 'maidenhair fern' (Adiantum pedantum) in the mass wasted deposit, a plant capable of high evapotranspiration, is interpreted as producing a bioclimatic disruption limiting soil water penetration to near root depth (wetting depth), thus producing a clay mineral anomaly.

  20. Clay fractions from a soil chronosequence after glacier retreat reveal the initial evolution of organo-mineral associations

    Science.gov (United States)

    Dümig, Alexander; Häusler, Werner; Steffens, Markus; Kögel-Knabner, Ingrid

    2012-05-01

    Interactions between organic and mineral constituents prolong the residence time of organic matter in soils. However, the structural organization and mechanisms of organic coverage on mineral surfaces as well as their development with time are still unclear. We used clay fractions from a soil chronosequence (15, 75 and 120 years) in the foreland of the retreating Damma glacier (Switzerland) and from mature soils outside the proglacial area (>700 and mature soils. These findings from solid-state 13C NMR spectroscopy are in line with the increasing amounts of microbial-derived carbohydrates with soil age. The large accumulation of proteins, which was comparable to those of carbohydrates, and the very low C/N ratios of H2O2-resistant OM indicated strong and preferential associations between proteinaceous compounds and mineral surfaces. In the acid soils, poorly crystalline Fe oxides were the main providers of mineral surface area and important for the stabilization of OM during aging of the clay fractions. This was indicated by (I) the strong correlations between oxalate soluble Fe and both, SSA of H2O2-treated clay fractions and OC content, and (II) the low formation of expandable clays due to small extents of mineral weathering. Our chronosequence approach provided new insights into the evolution of organo-mineral interactions in acid soils. The formation of organo-mineral associations started with the sorption of proteinaceous compounds and microbial-derived carbohydrates on mineral surfaces which were mainly provided by ferrihydrite. The sequential accumulation of different organic compounds and the large OC loadings point to multiple accretion of OM in distinct zones or layers during the initial evolution of clay fractions.

  1. Study on Soil Mobility of Two Neonicotinoid Insecticides

    Directory of Open Access Journals (Sweden)

    Mária Mörtl

    2016-01-01

    Full Text Available Movement of two neonicotinoid insecticide active ingredients, clothianidin (CLO and thiamethoxam (TMX, was investigated in different soil types (sand, clay, or loam and in pumice. Elution profiles were determined to explore differences in binding capacity. Soil characterized by high organic matter content retained the ingredients, whereas high clay content resulted in long release of compounds. Decrease in concentration was strongly influenced by soil types: both CLO and TMX were retained in loam and clay soils and showed ready elution through sandy soil and pumice. Elution capability of the active ingredients in sandy soil correlated with their water solubility, indicating approximately 30% higher rapidity for TMX than for CLO. Soil organic carbon-water partitioning coefficients (Koc determined were in good agreement with literature values with somewhat lower value for CLO in sandy soil and substantially higher values for TMX in clay soil. High mobility of these neonicotinoid active ingredients in given soil types urges stronger precautionary approach taken during their application.

  2. Source Zone Remediation by ZVI-Clay Soil-Mixing: Reduction of Tetrachloroethene Mass and Mass Discharge at a Danish DNAPL Site

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Lange, Ida Vedel; Binning, Philip John; Bjerg, Poul Løgstrup; Riis, Charlotte; Christensen, Anders G.; Terkelsen, Mads; Kjeldsen, Peter

    ZVI-Clay soil-mixing is a relatively new in situ remediation technology for remediation of chlorinated dense non-aqueous phase liquids (DNAPLs). The technology combines abiotic degradation (via zero-valent iron, ZVI, addition) and immobilization (via soil mixing and clay addition), whereby both c...

  3. Reducing the Influence of Soil Moisture on the Estimation of Clay from Hyperspectral Data: A Case Study Using Simulated PRISMA Data

    OpenAIRE

    Fabio Castaldi; Angelo Palombo; Simone Pascucci; Stefano Pignatti; Federico Santini; Raffaele Casa

    2015-01-01

    Soil moisture hampers the estimation of soil variables such as clay content from remote and proximal sensing data, reducing the strength of the relevant spectral absorption features. In the present study, two different strategies have been evaluated for their ability to minimize the influence of soil moisture on clay estimation by using soil spectra acquired in a laboratory and by simulating satellite hyperspectral data. Simulated satellite data were obtained according to the spectral charact...

  4. Spatiotemporal analyses of soil moisture from point to footprint scale in two different hydroclimatic regions

    Science.gov (United States)

    Joshi, Champa; Mohanty, Binayak P.; Jacobs, Jennifer M.; Ines, Amor V. M.

    2011-01-01

    This paper presents time stability analyses of soil moisture at different spatial measurement support scales (point scale and airborne remote sensing (RS) footprint scale 800 m × 800 m) in two different hydroclimatic regions. The data used in the analyses consist of in situ and passive microwave remotely sensed soil moisture data from the Southern Great Plains Hydrology Experiments 1997 and 1999 (SGP97 and SGP99) conducted in the Little Washita (LW) watershed, Oklahoma, and the Soil Moisture Experiments 2002 and 2005 (SMEX02 and SMEX05) in the Walnut Creek (WC) watershed, Iowa. Results show that in both the regions soil properties (i.e., percent silt, percent sand, and soil texture) and topography (elevation and slope) are significant physical controls jointly affecting the spatiotemporal evolution and time stability of soil moisture at both point and footprint scales. In Iowa, using point-scale soil moisture measurements, the WC11 field was found to be more time stable (TS) than the WC12 field. The common TS points using data across the 3 year period (2002-2005) were mostly located at moderate to high elevations in both the fields. Furthermore, the soil texture at these locations consists of either loam or clay loam soil. Drainage features and cropping practices also affected the field-scale soil moisture variability in the WC fields. In Oklahoma, the field having a flat topography (LW21) showed the worst TS features compared to the fields having gently rolling topography (LW03 and LW13). The LW13 field (silt loam) exhibited better time stability than the LW03 field (sandy loam) and the LW21 field (silt loam). At the RS footprint scale, in Iowa, the analysis of variance (ANOVA) tests show that the percent clay and percent sand are better able to discern the TS features of the footprints compared to the soil texture. The best soil indicator of soil moisture time stability is the loam soil texture. Furthermore, the hilltops (slope ˜0%-0.45%) exhibited the best TS

  5. Oxygen Isotope Fractionation Effects in Soil Water via Cations Adsorbed to High-CEC Clays

    Science.gov (United States)

    Oerter, E.; Finstad, K.; Schaefer, J.; Goldsmith, G. R.; Dawson, T. E.; Amundson, R.

    2012-12-01

    In isotope-based approaches to hydrology, soil and sediment are implicitly considered to be an inert matrix in which water resides or moves. Yet, this assumption is inconsistent with the fact that soils contain a wide range of solutes, and highly variable concentrations of chemically reactive clay particles, all of which may react with bulk water and create pools of energetically differing water with varying isotope compositions. The empirical basis of this hypothesis is the work of Sofer and Gat (1972, EPSL, 15(3)), who showed that the formation of hydration spheres around cations in aqueous solutions fractionate oxygen isotopes of water in ways that appear to be dependent on the cation's ionic potential and concentration. Because soil solutions commonly have high solid to fluid ratios, the potential for solids to create substantial pools of low free energy water, with corresponding isotope fractionation of the free and low energy waters, may be a common process. The potential for this to create measurable isotopic effects would be most evident in soils with high Cation Exchange Capacity (CEC). In order to test this hypothesis, montmorillonite (CEC ≈ 100 meq/100g), kaolinite (CEC≈10) and quartz (CEC≈0) mineral powders were saturated with 3M MgCl2 and KCl solutions (separately), rinsed with methanol and dried to saturate all available CEC sites with either Mg or K cations. Triplicate sets of monominerallic-deionized water mixtures were created at 5, 25, 50, 75 and 95% gravimetric water content. Each set of samples was then subjected to one of three water extraction techniques designed to access specific "pools" of soil water: (1) direct equilibration with CO2 to sample the soil's "free water", i.e. water not adsorbed to cations via hydration spheres; (2) centrifugation to simulate permanent wilting point conditions, thereby yielding most micro-pore, macro-pore, and free water; and (3) cryogenic vacuum distillation to recover all the soil water (free, pore and

  6. Determination of dependence between physical clay content in sod-podzolic soils and specific activity of 40K natural isotope

    International Nuclear Information System (INIS)

    In the conditions of the Republic of Belarus there was analyzed the dependence between physical clay content in sod-podzolic soil and specific activity of 40K natural isotope. There was described a new method of determination of soil belonging to a particular soil type in the conditions of identification of the natural isotope K40. Experiments were realized on sod-podzolic automorphous and half-hydromorphic soils of natural and cultural agrocoenosis polluted with 137Cs and 90Sr after the Chernobyl disaster. The pollution density of 137Cs was from 313 to 2480 kBq/m2 and 90Sr – from 2 to 63 kBq/m2. Research results showed that soil texture content influenced on radionuclide fixation. Radionuclide entering into plants from sod-podzolic loamy soils was in 1,5-2,0 times and more lower in comparison with radionuclide entering from sod-podzolic sandy soils. The highest base exchange capacity of 137Cs, 90Sr and 40K was typical for the fraction of physical clay with the minimal particle size of 0,01mm. There was marked a close correlation connection between natural isotope 40K and a content of physical clay

  7. New best estimates for radionuclide solid-liquid distribution coefficients in soils, Part 1: radiostrontium and radiocaesium

    International Nuclear Information System (INIS)

    Best estimates for the solid-liquid distribution coefficients (Kd) of radiostrontium and radiocaesium for various soil types, were derived from geometric means (GM) calculated from grouping soils by texture and organic matter content, and also using soil cofactors governing soil-radionuclide interaction. The Kd (Sr) GM for Sand, Loam, Clay and Organic groups were similar, although the value for the Sand group was significantly lower. The Sr cofactor approach, based on the ratios of cation exchange capacity (CEC) to Ca and Mg concentrations in the soil solution, leads to Kd (Sr) GM with a lower variability, from which best estimates could be proposed. The Kd (Cs) GM for Sand and Organic groups differed, although similar values were obtained for Loam and Clay groups. Grouping the Kd (Cs) according to the Radiocaesium Interception Potential (RIP) and the RIP divided by the K concentration in the soil solution also allows to suggest Kd (Cs) best estimates with a lower variability.

  8. Effect of land-use changes and site variables on surface soil organic carbon pool at Mediterranean Region

    Science.gov (United States)

    Abu-hashim, Mohamed; Elsayed, Mohamed; Belal, Abd-ElAziz

    2016-02-01

    Soil organic carbon pool (SOCP) is affected by several factors particularly soil type, climate, topography, crop management, and anthropogenic factors. The study was carried out to clarify relationships between SOCP under different soil types and land-use changes in the Mediterranean region. Data of 26 pedons were investigated in Tanta catchment, middle Nile Delta, Egypt (30°45 N, 30°55 E), that the collected soil samples covered different soil types and land-uses. There were significant differences of SOCP among soils: loam and clay loams were rather similar. Clay soils were the most extensive and have mean SOCP of 4.08 ± 1.41 kg C m-2. The highest SOCP of 7.07 kg C m-2 was in clay loam soil associated with bare soil, while the lowest of 2.57 kg C m-2 in sandy clay loam soil associated with bare soil. Losing cropland showed highest increase from 1990 to 2015 with increasing urban encroachment by 15.3%. The overall average results of SOCP in cropland area showed 53.85 Mg C ha-1 under different soils. Losing the arable lands to urbanization resulted in a decrease of 285.421 Gg C of SOCP. With the decrease in SOCP sequestrated within the soil surface, carbon dioxide would be emitted to the atmosphere. The emitted CO2 resulted from losing the cropland equal to 1047.5 Gg CO2. Land-use changes have marked impact on surface SOCP and C sequestration.

  9. Soil nitrous oxide emissions after deposition of dairy cow excreta in eastern Canada.

    Science.gov (United States)

    Rochette, Philippe; Chantigny, Martin H; Ziadi, Noura; Angers, Denis A; Bélanger, Gilles; Charbonneau, Édith; Pellerin, Doris; Liang, Chang; Bertrand, Normand

    2014-05-01

    Urine and dung deposited by grazing dairy cows are a major source of nitrous oxide (NO), a potent greenhouse gas that contributes to stratospheric ozone depletion. In this study, we quantified the emissions of NO after deposition of dairy cow excreta onto two grassland sites with contrasting soil types in eastern Canada. Our objectives were to determine the impact of excreta type, urine-N rate, time of the year, and soil type on annual NO emissions. Emissions were monitored on sandy loam and clay soils after spring, summer, and fall urine (5 and 10 g N patch) and dung (1.75 kg fresh weight dung) applications to perennial grasses in two successive years. The mean NO emission factor (EF) for urine was 1.09% of applied N in the clay soil and 0.31% in the sandy loam soil, estimates much smaller than the default Intergovernmental Panel on Climate Change (IPCC) default value for total excreta N (2%). Despite variations in urine composition and in climatic conditions, these soil-specific EFs were similar for the two urine-N application rates. The time of the year when urine was applied had no impact on emissions from the sandy loam soil, but greater EFs were observed after summer (1.59%) than spring (1.14%) and fall (0.55%) applications in the clay soil. Dung deposition impact on NO emission was smaller than that of urine, with a mean EF of 0.15% in the sandy loam soil and 0.08% in the clay soil. Our results suggest (i) that the IPCC default EF overestimates NO emissions from grazing cattle excreta in eastern Canada by a factor of 4.3 and (ii) that a region-specific inventory methodology should account for soil type and should use specific EFs for urine and dung. PMID:25602812

  10. Impact of Long-Term Alfalfa Cropping on Soil Potassium Content and Clay Minerals in a Semi-Arid Loess Soil in China

    Institute of Scientific and Technical Information of China (English)

    LI De-Cheng; B. VELDE; LI Feng-Min; ZHANG Gan-Lin; ZHAO Ming-Song; HUANG Lai-Ming

    2011-01-01

    Alfalfa cropping has been considered an efficient method of increasing soil fertility.Usually nitrogen increase in root nodules is considered to be the major beneficial effect.A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil,initially containing illite and chlorite,in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping,soil potassium (K) content and soil clay minerals.The results indicated that soil K significantly accumulated after cropping,with a peak value at about 15 years,and decreased afterwards.The accumulated K was associated with the K increase in the well-crystallized illite,which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability.The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa soil.Plant biomass productivity peaked at near 9 years of culture,whereas soil K and clay minerals continued to increase until cropping for 15 years.This suggested that K increased in the topsoil came from the deep root zone.Thus alfalfa continued to store K in clays even after peak production occurred.Nitrogen did not follow these trends,showing a general decline compared with the native prairie soils that had not been cropped.Therefore,the traditional alfalfa cropping can increase K content in the topsoil.

  11. Radiotracer studies on the degradation of lindane in three Malaysian soils

    International Nuclear Information System (INIS)

    The degradation of 14C-labelled lindane in three Malaysian soils i.e. Benta fine sandy loam, Selangor clay and Serdang fine sandy clay loam, under flooded and non-flooded (upland) conditions was studied. The rate of disappearance of lindane for the three soils under upland and sterilized flooded conditions after 90 days of incubation at 30+-0.50C were less than 41% w/w when compared to non-sterilized flooded condition (greater than 94% w/w). The most rapid degradation in non-sterilized flooded condition occurred in Benta soil, followed by Serdang and Selangor soils, in which half-life in each soil was 10.5, 23.5 and 34.5 days respectively. (author)

  12. Estimating of Soil Texture Using Landsat Imagery: a Case Study in Thatta Tehsil, Sindh

    Science.gov (United States)

    Khalil, Zahid

    2016-07-01

    Soil texture is considered as an important environment factor for agricultural growth. It is the most essential part for soil classification in large scale. Today the precise soil information in large scale is of great demand from various stakeholders including soil scientists, environmental managers, land use planners and traditional agricultural users. With the increasing demand of soil properties in fine scale spatial resolution made the traditional laboratory methods inadequate. In addition the costs of soil analysis with precision agriculture systems are more expensive than traditional methods. In this regard, the application of geo-spatial techniques can be used as an alternative for examining soil analysis. This study aims to examine the ability of Geo-spatial techniques in identifying the spatial patterns of soil attributes in fine scale. Around 28 samples of soil were collected from the different areas of Thatta Tehsil, Sindh, Pakistan for analyzing soil texture. An Ordinary Least Square (OLS) regression analysis was used to relate the reflectance values of Landsat8 OLI imagery with the soil variables. The analysis showed there was a significant relationship (p<0.05) of band 2 and 5 with silt% (R2 = 0.52), and band 4 and 6 with clay% (R2 =0.40). The equation derived from OLS analysis was then used for the whole study area for deriving soil attributes. The USDA textural classification triangle was implementing for the derivation of soil texture map in GIS environment. The outcome revealed that the 'sandy loam' was in great quantity followed by loam, sandy clay loam and clay loam. The outcome shows that the Geo-spatial techniques could be used efficiently for mapping soil texture of a larger area in fine scale. This technology helped in decreasing cost, time and increase detailed information by reducing field work to a considerable level.

  13. INFLUENCE OF THE SATURATION PERCENTAGE OF THE CLAY-BEARING SOIL ON ITS STRESS-STRAIN STATE

    OpenAIRE

    Ter-Martirosyan Zaven Grigorevich; Nguyen Huy Hiep Huy Hiep

    2012-01-01

    The authors propose new analytical and numerical solutions to develop an advanced method of assessment of the stress-strain state of unsaturated clay soils exposed to external loading. The research findings demonstrate that the stress-strain state of the soil exposed to distributed loading in the half-space b = 2a is complex and homogeneous. It depends on the percentage of saturation and on the excessive pore pressure based on the saturation percentage. At the interim stage, when ...

  14. Distribution, fate and formation of non-extractable residues of a nonylphenol isomer in soil with special emphasis on soil derived organo-clay complexes.

    Science.gov (United States)

    Riefer, Patrick; Klausmeyer, Timm; Schäffer, Andreas; Schwarzbauer, Jan; Schmidt, Burkhard

    2011-01-01

    Anthropogenic contaminants like nonylphenols (NP) are added to soil, for instance if sewage-sludge is used as fertilizer in agriculture. A commercial mixture of NP consists of more than 20 isomers. For our study, we used one of the predominate isomers of NP mixtures, 4-(3,5-dimethylhept-3-yl)phenol, as a representative compound. The aim was to investigate the fate and distribution of the isomer within soil and soil derived organo-clay complexes. Therefore, (14)C- and (13)C-labeled NP was added to soil samples and incubated up to 180 days. Mineralization was measured and soil samples were fractionated into sand, silt and clay; the clay fraction was further separated in humic acids, fulvic acids and humin. The organo-clay complexes pre-incubated for 90 or 180 days were re-incubated with fresh soil for 180 days, to study the potential of re-mobilization of incorporated residues. The predominate incorporation sites of the nonylphenol isomer in soil were the organo-clay complexes. After 180 days of incubation, 22 % of the applied (14)C was mineralized. The bioavailable, water extractable portion was low (9 % of applied (14)C) and remained constant during the entire incubation period, which could be explained by an incorporation/release equilibrium. Separation of organo-clay complexes, after extraction with solvents to release weakly incorporated, bioaccessible portions, showed that non-extractable residues (NER) were preferentially located in the humic acid fraction, which was regarded as an effect of the chemical composition of this fraction. Generally, 27 % of applied (14)C was incorporated into organo-clay complexes as NER, whereas 9 % of applied (14)C was bioaccessible after 180 days of incubation. The re-mobilization experiments showed on the one hand, a decrease of the bioavailability of the nonylphenol residues due to stronger incorporation, when the pre-incubation period was increased from 90 to 180 days. On the other hand, a shift of these residues from the

  15. Effectiveness of the GAEC cross-compliance standard Ploughing in good soil moisture conditions in soil structure protection

    Directory of Open Access Journals (Sweden)

    Maria Teresa Dell'Abate

    2011-08-01

    Full Text Available Researches have been carried out within the framework on the EFFICOND Project, focused at evaluating the effectiveness of the standards of Good Agricultural and Environmental Conditions (GAECs established for Cross Compliance implementation under EC Regulation 1782/2003. In particular the standard 3.1b deals with soil structure protection through appropriate machinery use, with particular reference to ploughing in good soil moisture conditions. The study deals with the evaluation of soil structure after tillage in tilth and no-tilth conditions at soil moisture contents other than the optimum water content for tillage. The Mean Weight Diameter (MWD of water stable aggregates was used as an indicator of tillage effectiveness. The study was carried out in the period 2008-2009 at six experimental farms belonging to Research Centres and Units of the Italian Agricultural Research Council (CRA with different pedo-climatic and cropping conditions. Farm management and data collection in the different sites were carried out by the local CRA researchers and technicians. The comparison of MWD values in tilth and no tilth theses showed statistically significant differences in most cases, depending on topsoil texture. On clay, clay loam, silty clay, and silty clay loam topsoils a general and significant increase of MWD values under no tilth conditions were observed. No significant differences were observed in silt loam and sandy loam textures, probably due to the weak soil structure of the topsoils. Moreover, ploughing in good soil moisture condition determined higher crop production and less weed development than ploughing in high soil moisture conditions.

  16. Effect of Alumina Colloid on the Sorption of Cs+ onto Sand and Clay Soils under Different Conditions

    International Nuclear Information System (INIS)

    Distribution coefficient of cesium on soil (yellow sand and clay) with and without alumina as a colloidal material was measured by batch technique. The adsorption of Cs+ ions from aqueous sodium chloride solution onto yellow sand and clay in absences and presence of Al2O3, was investigated under different physicochemical conditions including contact time between liquid and solid phases, ph, ionic strength, initial metal ion concentration and temperature. Pseudo first order and pseudo second-order kinetic models were used to analyze the sorption rate data and the results showed that the pseudo second-order model is best correlation the kinetics data in all studied sorption processes. Both Freundlich and Langmuir isotherm models were applicable to describe the adsorption of Cs+ ions by yellow sand with and without alumina but in case of clay with and without alumina Langmuir model not applicable. The maximum sorption capacities of clay in absences and presence of Al2O3 were found to be greater than that of yellow sand with and without Al2O3. The maximum sorption capacities for two sorbents were increased in presence of colloid alumina thane in absences. The sorption capacity is reduced at high temperature was related to the partial enhancement of desorption from yellow sand and clay surfaces. The adsorption of Cs+ ions by yellow sand and clay with and without alumina was exothermic reaction.

  17. The effect of two soil applied fungicides - PCNB and thiram on the mineralization of 14C - labelled rice straw in soils

    International Nuclear Information System (INIS)

    The effect of PCNB and thiram was studied on the mineralization of 14C - labelled rice straw in clay and sandy loam soils for 40 days. PCNB at normal and 10-times the field application rates had no effect on the rate of 14CO2 evolution from 14C - labelled rice straw in both the soils. The rate of 14CO2 evolution in soils was unchanged by thiram at normal field application rate, but the same at 10-times field application rate retarded initially and stimulated later the rate of 14CO2 evolution. PCNB and thiram had no deleterious effect on the total mineralization of 14C - labelled rice straw in both clay and sandy loam soils at the end of 40-days incubation. (author)

  18. Estimating hydraulic conductivities of the soil aggregates and their clay-organic coatings using numerical inversion of capillary rise data

    Science.gov (United States)

    Fér, Miroslav; Kodešová, Radka

    2012-10-01

    SummarySoil aggregates are in some soils and their horizons covered by organomineral coatings, which may significantly influence water and solute transfer into the aggregates. Knowledge of a coating occurrence, their structure and hydraulic properties is required for a more precise description of water flow and contaminant transport in soils. The aim of this study was to describe hydraulic properties of clay and organic matter coatings in the iluvial (Bt2) horizon of Haplic Luvisol. Sets of 30 unsorted aggregates, 24 aggregates with mostly clay coatings and 24 aggregates with clay-organic coatings, respectively, were studied to evaluate an impact of various coating composition. The coatings were removed from a half of the aggregates of each set. First, the wetting soil-water retention curve was measured on all soil aggregates. Then the capillary rise from the saturation pan into the multiple aggregates (set of 14 or 15 aggregates) without and with coatings was measured. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program were applied to estimate the saturated hydraulic conductivities of the aggregates, Ks,aggr, and their coatings, Ks,coat. Results were compared with saturated hydraulic conductivities evaluated analytically using the sorptivity method, which was proposed previously. Data of the soil-water retention curves, measured on aggregates with and without coatings, did not allow distinguishing between retention curve parameters of the soil aggregates and their coatings. Therefore the same parameters were evaluated for both. Capillary rise into the soil aggregates without coatings was always faster than into the aggregates with coatings. As result the optimized saturated hydraulic conductivities, Ks,coat, of the clay and the organic matter coatings (the average values for unsorted, mostly clay and clay-organic coatings were 3.69 × 10-7, 2.76 × 10-7 and 1.81 × 10-7 cm min-1, respectively) were one to two order of

  19. Mineralization of 14C-ring Labelled 2,4-D in Egyptian Soils Under Aerobic and Anaerobic Conditions

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Obiectives To study the mineralization of 2,4-D in clay and clay loam Egyptian soils under subtropical conditions over a period of 90 d. Methods Using 14C-ring labelled pesticide, laboratory studies under aerobic and anaerobic conditions were conducted. 14C-activity in solutions was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion.The nature of methanolic 14C-residues was determined by thin layer and high performance liquid chromatographic analysis. Results Under aerobic conditions 10%-14% of applied dose was mineralized during 90 d irrespective of soil type. The soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding capacity of about 26%-29% was observed in clay soil under aerobic conditions after 90 d. A good balance sheet was obtained and the percentage recovery was generally between 91% and 100%. Conclusion The mineralization of 2,4-D in clay soil was higher than that in clay loam soil under anaerobic conditions.Under aerobic conditions, the soil type had no influence on mineralizaion capacity of 2,4-D during 90 d. The soil binding increased with time whereby the extractable 14C-residues simultaneously decreased.Chromatographic analysis of the methanol extractable 14C-residues of soils revealed the presence of 2,4-D as a main product together with 2,4-dichlorophenol.

  20. Swelling clays and salt-affected soils : demixing of Na / Ca clays as the rationale for discouraging the use of sodium adsorption ratio (SAR

    Directory of Open Access Journals (Sweden)

    Guilhem Bourrie

    2014-12-01

    Full Text Available Sodium adsorption ratio SAR defined as SAR = (Na / V w(Ca+Mg/2 here concentrations of cations in solution are expressed in meq/L has long been considered as correlated to exchangeable sodium percentage (ESP on clay minerals or soil exchange complex, and as the key concept to explain swelling of clay minerals and the difficulties of reclaiming salt-affected soils. Though its basis is empirical, it was alleged to be theoretically justified on the basis of ion exchange, derived from the Gapon convention. However, it has long been challenged on the basis of both field observations and experimental evidence : it fails to account for the fact that calcium and magnesium do not play the same role, while potassium is absent from the formula ; calcium concentration must be “corrected “when calcite is present etc. There exist specific ion effects. Experimental measurements of the decrease of permeability when solutions are diluted led Quirk and Schofield (1955 to define the concept of critical threshold, and to show that potassium and magnesium play an intermediate role between sodium and calcium. This threshold is simply determined by the concentration of calcium, irrespective of the value of SAR or ESP. Indeed, demixing of Ca-Na clay minerals during ion exchange, a phenomenon well known since Glaeser and Mering (1954, implies that there exists an interaction between adjacent sites. This undermines the theoretical basis of SAR : the derivation of SAR from ion exchange equilibria implies to use an equilibrium constant. This parameter is no more constant if demixing occurs. The results obtained are positive : demixing leads to expulsion of sodium from inner exchange surfaces and its replacement by calcium, according to the “three crystals pore”proposed by Quirk (2003b. Sodium can then be more easily leached, as permeability is maintained by clusters of Ca-sites. Calcium concentration in solution appears thus as the simpler parameter to guide

  1. An Improved Description of the Seismic Response of Sites with High Plasticity Soils, Organic Clays, and Deep Soft Soil Deposits

    Science.gov (United States)

    Carlton, Brian

    Near surface soils can greatly influence the amplitude, duration, and frequency content of ground motions. The amount of their influence depends on many factors, such as the geometry and engineering properties of the soils and underlying bedrock, as well as the earthquake source mechanism and travel path. Building codes such as the 2012 International Building Code (IBC) define six site categories for seismic design of structures, which are based on the sites defined by the National Earthquake Hazards Reduction Program (NEHRP). Site categories A, B, C, D, and E are defined by the time averaged shear wave velocity over the top 30 meters of the soil deposit. Site category F is defined as sites that include liquefiable or sensitive soils, as well as sites with more than 3 meters (10 ft) of peat or highly organic clays, more than 7.5 meters (25 ft) of soil with PI > 75, and more than 37 meters (120 ft) of soft to medium stiff clays. The IBC specifies simplified procedures to calculate design spectra for NEHRP sites A through E, and requires a site specific investigation for NEHRP F sites. However, established procedures for performing the required site specific investigations for NEHRP F sites are limited. The objective of this research is to develop a simplified procedure to estimate design spectra for non-liquefiable NEHRP F sites, specifically sites with organic soils, highly plastic soils, and deep soft soil deposits. The results from this research will directly affect US practice by developing much needed guidelines in this area. There is little empirical data on the seismic response of non-liquefiable NEHRP F sites. As a result, this study focused on generating data from site response analyses. To capture the variability of ground motions, this study selected five base case scenarios according to tectonic environments and representative cases encountered in common US practice. Suites of ground motions for each scenario were created by collecting ground motions

  2. Clay content drives carbon stocks in soils under a plantation of Eucalyptus saligna Labill. in southern Brazil

    Directory of Open Access Journals (Sweden)

    Tanise Luisa Sausen

    2014-06-01

    Full Text Available Soil carbon accumulation is largely dependent on net primary productivity. To our knowledge, there have been no studies investigating the dynamics of carbon accumulation in weathered subtropical soils, especially in managed eucalyptus plantations. We quantified the seasonal input of leaf litter, the leaf decomposition rate and soil carbon stocks in an commercial plantation of Eucalyptus saligna Labill. in southern Brazil. Our goal was to evaluate, through multiple linear regression, the influence that certain chemical characteristics of litter, as well as chemical and physical characteristics of soil, have on carbon accumulation in soil organic matter fractions. Variables related to the chemical composition of litter were not associated with the soil carbon stock in the particulate and mineral fractions. However, certain soil characteristics were significantly associated with the carbon stock in both fractions. The concentrations of nutrients associated with plant growth and productivity, such as phosphorus, sulfur, copper and zinc, were associated with variations in the labile carbon pool (particulate fraction. Clay content was strongly associated with the carbon stock in the mineral fraction. The carbon accumulation and stabilization in weathered subtropical Ultisol seems to be mainly associated with the intrinsic characteristics of the soil, particularly clay content, rather than with the quantity, chemical composition or decomposition rate of the litter.

  3. Carbon sequestration in clay and silt fractions of Brazilian soils under conventional and no-tillage systems

    Directory of Open Access Journals (Sweden)

    Cecília Estima Sacramento dos Reis

    2014-08-01

    Full Text Available The capacity of soils to sequestrate carbon (C is mainly related to the formation of organo-mineral complexes. In this study, we investigated the influence of soil management systems on the C retention capacity of soil with an emphasis on the silt and clay fractions of two subtropical soils with different mineralogy and climate. Samples from a Humic Hapludox and a Rhodic Hapludox, clayey soils cultivated for approximately 30 years under no-tillage (NT and conventional tillage (CT were collected from six layers distributed within 100-cm soil depth from each site and from an adjacent native forest. After the removal of particulate organic matter (POM, the suspension (<53 µm was sonicated, the silt and clay fractions were separated in accordance with Stokes' law and the carbon content of whole soil and physical fractions was determined. In the Humic Hapludox, the clay and silt fractions under NT showed a higher maximum C retention (72 and 52 g kg-1, respectively in comparison to those under CT (54 and 38 g kg-1, respectively. Moreover, the C concentration increase in both fractions under NT occurred mainly in the topsoil (up to 5 cm. The C retention in physical fractions of Rhodic Hapludox varied from 25 to 32 g kg-1, and no difference was observed whether under an NT or a CT management system. The predominance of goethite and gibbsite in the Humic Hapludox, as well as its exposure to a colder climate, may have contributed to its greater C retention capacity. In addition to the organo-mineral interaction, a mechanism of organic matter self-assemblage, enhanced by longer periods of soil non-disturbance, seems to have contributed to the carbon stabilization in both soils.

  4. Enhanced degradation of 14C-HCB in two tropical clay soils using multiple anaerobic–aerobic cycles

    International Nuclear Information System (INIS)

    The aim of the study was to induce and enhance the degradation of hexachlorobenzene (HCB), a highly-chlorinated persistent organic pollutant, in two ecologically different tropical soils: a paddy soil (PS) and a non-paddy soil (FS). The degradation of HCB was enhanced using two anaerobic–aerobic cycles in model laboratory experiments. There was greater degradation of HCB in the PS (half-life of 224 days) relative to the FS (half-life of 286 days). It was further shown that soils amended with compost had higher metabolite concentrations relative to the non-amended soils. In the first cycle, there was little degradation of HCB in both soils. However, in the second cycle, there was enhanced mineralization in the PS under aerobic conditions, with the compost-treated samples showing higher mineralization. There was also extensive volatilization in both soils. The metabolite pattern revealed that the increased mineralization and volatilization was due to the formation of lower chlorinated benzenes. - Highlights: ► Two anaerobic–aerobic cycles enhanced the dissipation of HCB in two tropical soils – a paddy and non-paddy soil. ► The paddy soil was more effective in degrading HCB. ► The non-paddy soil adapted and degraded HCB in the second anaerobic–aerobic cycle. ► An additional carbon source enhanced degradation and mineralisation of HCB in both soils. - Two anaerobic–aerobic cycles enhance the degradation of HCB in two ecologically different tropical clay soils.

  5. Production of CO2 in crude oil bioremediation in clay soil

    Directory of Open Access Journals (Sweden)

    Sandro José Baptista

    2005-06-01

    Full Text Available The aim of the present work was to evaluate the biodegradation of petroleum hydrocarbons in clay soil a 45-days experiment. The experiment was conducted using an aerobic fixed bed reactor, containing 300g of contaminated soil at room temperature with an air rate of 6 L/h. The growth medium was supplemented with 2.5% (w/w (NH42SO4 and 0.035% (w/w KH2PO4. Biodegradation of the crude oil in the contaminated clay soil was monitored by measuring CO2 production and removal of organic matter (OM, oil and grease (OandG, and total petroleum hydrocarbons (TPH, measured before and after the 45-days experiment, together with total heterotrophic and hydrocarbon-degrading bacterial count. The best removals of OM (50%, OandG (37% and TPH (45% were obtained in the bioreactors in which the highest CO2 production was achieved.O objetivo do trabalho foi avaliar a biodegradação de petróleo em solo argiloso durante 45 dias de ensaios. Os ensaios de biodegradação foram conduzidos em biorreatores aeróbios de leito fixo, com 300 g de solo contaminado, à temperatura ambiente e com uma vazão de ar de 6 L/h. As deficiências nutricionais foram corrigidas com 2,5% (p/p (NH42SO4 e com 0,035% (p/p KH2PO4. O monitoramento foi realizado em função da produção de CO2, da remoção de matéria orgânica (OM, de óleos e graxas (OandG e de hidrocarbonetos totais de petróleo (TPH, além bactérias heterotróficas totais (BHT e hidrocarbonoclásticas (BHc, no início e após 45 dias. Nos biorreatores onde houve maior crescimento de bactérias hidrocarbonoclásticas e maior produção de CO2, obteve-se os melhores percentuais de remoções de MO (50%, OandG (37% e TPH (45%.

  6. Impact of soil type, moisture, and depth on swede midge (Diptera: Cecidomyiidae) pupation and emergence.

    Science.gov (United States)

    Chen, Mao; Shelton, Anthony M

    2007-12-01

    Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), a common insect pest in Europe and a new invasive pest in North America, causes severe damage to cruciferous crops. Currently, many counties in Canada and the United States in which C. nasturtii has not been previously reported are at risk of being infested by C. nasturtii. Effectiveness of chemical control is limited, especially under high population pressure in fields, because the cryptic habits of C. nasturtii protect them from insecticidal sprays. Alternative management strategies against C. nasturtii that are needed to protect crucifers and soil management for the pupal stage were studied as one option. Six different types of soils (loam fine sand, fine sand, clay loam, muck, Chenango shale loam, and silt loam soil) were collected from commercial cabbage fields in New York and studied in the laboratory for their impact on C. nasturtii pupation and emergence. The results indicated that extremely wet or dry soils significantly hindered C. nasturtii emergence, regardless of soil type, suggesting that soil type alone may not be a major factor regulating C. nasturtii abundance. Optimal moisture content for C. nasturtii emergence varied for different soils. Most C. nasturtii pupated within the top 1 cm of soil. Furthermore, we found that >5 cm of soil cover effectively reduced the emergence number and delayed the time of emergence. Based on these results, we suggest that soil manipulation (moisture content and cultivation practices) should be considered as an important component in an overall integrated pest management program for C. nasturtii. PMID:18284762

  7. Estimation model of Cs-137 activity in soil samples derives from percentage of organic carbon and silt-clay

    International Nuclear Information System (INIS)

    Estimation of Cs-137 activity in soil samples was conducted at Nganjuk area through its soil organic carbon and silt-clay percentage. Twenty-six soil samples taken from Nganjuk area have been used to establish the relationship of Cs-137 activity and its soil samples quality parameters by using SPSS (Statistical Product and Service Solutions) software. Chemical parameters of samples have higher variation compared to the physical. Estimated of Cs-137 activity in soil samples can be established by two parameters, those are percent of total organic carbon and percent of silt-clay contents. However, these two parameters could only explained 69.3 % of Cs-137 activity, the remaining 30.7 % potentially could be due to 10 % of error measurement, run-on redistribution of soil, farming as well as tillage system. By using the soil quality parameters, the Cs-137 activity under the limit detection could be estimated, hence, its usefulness to estimate the erosion rate through applying the Cs-model. (author)

  8. The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils

    International Nuclear Information System (INIS)

    Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface. - The relative importance of organic matter and clay in butachlor adsorption in soil will depend on the ratio of clay content to total organic carbon content

  9. Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda T K K; Arthur, Emmanuel; Møldrup, Per;

    2013-01-01

    ka measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity–disconnectivity analysis to characterize the soil–gas phase. The main objective of this study is to investigate the effect of soil–moisture condition, clay content, and other...... moisture conditions showed a strong linear relation (R2 = 0.74) to clay content. The Xa, further showed promising relations to specific surface area, Rosin–Rammler particle size distribution indices, α and β (representing characteristic particle size and degree of sorting, respectively), and the Campbell...... water retention parameter, b. Considering clay as a main driver of soil–gas phase characteristics, we developed expressions linking clay content and ka,1000 at ɛ1000 and discussed the effect of clay content on general ka–ɛ behavior....

  10. Influence of foliar application of algae extract and amino acids mixture on fenugreek plants in sandy and clay soils

    OpenAIRE

    SHAHIRA A. TARRAF; Talaat, Iman M.; ABO EL-KHAIR B. EL-SAYED; LAILA K. BALBAA

    2015-01-01

    Abstract. Tarraf SA, Talaat IM, El-Sayed AEB, Balbaa LK. 2015. Influence of foliar application of algae extract and amino acids mixture on fenugreek plants in sandy and clay soils. Nusantara Bioscience 7: 33-37. Two pot experiments were conducted to study the effect of foliar application of algae extract and amino acids mixture on the growth and chemical constituents of fenugreek plants (Trigonella foenum-graecum L.). Plants were sprayed with different concentrations of algae extract (0.0, 2....

  11. Tropical dryland agroforestry on clay soils: : Analysis of systems based on Acacia senegal in the Blue Nile region, Sudan

    OpenAIRE

    Raddad, Elamin Yousif Abdalla

    2006-01-01

    Acacia senegal, the gum arabic producing tree, is the most important component in traditional dryland agroforestry systems in the Blue Nile region, Sudan. The aim of the present study was to provide new knowledge on the potential use of A. senegal in dryland agroforestry systems on clay soils, as well as information on tree/crop interaction, and on silvicultural and management tools, with consideration on system productivity, nutrient cycling and sustainability. Moreover, the aim was also to ...

  12. THE EFFECT OF REINFORCEMENT ON THE GBFS AND LIME TREATED MARINE CLAY FOR FOUNDATION SOIL BEDS

    OpenAIRE

    D. Koteswara Rao,; G.V.R. Prasada Raju,; N. L. Manikanta Kumar

    2011-01-01

    India being peninsular country has large area coming under coastal region and also it has been the habitat for considerable percentage of population. The marine clays are generally found in the coastal region of West Bengal, Orissa, Andhra Pradesh, Tamilnadu, Kerala, Karnataka, Maharashtra and some parts of Gujarat. Marine or soft clays exists in these region are weak and deformative in nature. The present study deals with the strength characteristics of the marine clay collected from Kakinad...

  13. Influence of Cracking on the distribution of Suction profile of a clay soil:comparative Approach by modeling of thermo-fluid coupling

    International Nuclear Information System (INIS)

    Soil shrinks as it desiccates, and the magnitude of shrinkage can be large for clay soils, rich in fine particles. Soil drying leads to cracks formation, causing a phenomenon of high significance in environmental geotechnics. To illustrate the effect of cracking, a numerical model of soil atmosphere interaction has been developed taking into account the thermo fluid coupling of an unsaturated clay soil. The model is used to simulate the evolution if suction during the drying process. The study simulates firstly the model of an intact soil. Then, the study is extended to investigate the case of a cracked soil. The main results showed a significant influence of the presence of crack on the suction profile.In cracked soil, further loss of moisture occurs as direct evaporation from crack followed by an increase of the suction in the soil. High suction is initially concentrated on the head of the crack then extended to both vertical and horizontal sideway directions. (author)

  14. Clay composition and swelling potential estimation of soils using depth of absorption bands in the SWIR (1100-2500 nm) spectral domain

    Science.gov (United States)

    Dufréchou, Grégory; Granjean, Gilles; Bourguignon, Anne

    2014-05-01

    Swelling soils contain clay minerals that change volume with water content and cause extensive and expensive damage on infrastructures. Presence of clay minerals is traditionally a good estimator of soils swelling and shrinking behavior. Montmorillonite (i.e. smectite group), illite, kaolinite are the most common minerals in soils and are usually associated to high, moderate, and low swelling potential when they are present in significant amount. Characterization of swelling potential and identification of clay minerals of soils using conventional analysis are slow, expensive, and does not permit integrated measurements. SWIR (1100-2500 nm) spectral domain are characterized by significant spectral absorption bands related to clay content that can be used to recognize main clay minerals. Hyperspectral laboratory using an ASD Fieldspec Pro spectrometer provides thus a rapid and less expensive field surface sensing that permits to measure soil spectral properties. This study presents a new laboratory reflectance spectroscopy method that used depth of clay diagnostic absorption bands (1400 nm, 1900 nm, and 2200 nm) to compare natural soils to synthetic montmorillonite-illite-kaolinite mixtures. We observe in mixtures that illite, montmorillonite, and kaolinite content respectively strongly influence the depth of absorption bands at 1400 nm (D1400), 1900 nm (D1900), and 2200 nm (D2200). To attenuate or removed effects of abundance and grain size, depth of absorption bands ratios were thus used to performed (i) 3D (using D1900/D2200, D1400/D1900, and D2200/D1400 as axis), and (ii) 2D (using D1400/D1900 and D1900/D2200 as axis) diagrams of synthetic mixtures. In this case we supposed that the overall reduction or growth of depth absorption bands should be similarly affected by the abundance and grain size of materials in soil. In 3D and 2D diagrams, the mixtures define a triangular shape formed by two clay minerals as external envelop and the three clay minerals mixtures

  15. Residual effect of organic matter on cadmium uptake by plants and its distribution in soils

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B.R.; Almas, A. [Agricultural University of Norway (Norway). Dept. of Soil and Water Science; Narwal, R.P. [Haryana Agricultural Univ., Hissar (India). Dept. of Soil Science

    1997-12-31

    A greenhouse experiment with different levels (from 0 to 320 g/kg of the air-dried soil on mass basis) of organic matter (sphagnum peat) has been carried out and its residual effect on the distribution and extractability of Cd in soils (sand, sandy loam and clay loam) and Cd uptake by rye grass is studied during two years. Results show that the Cd concentration in rye grass decreased by increasing the rate of organic matter addition in the first year, while in the second and third year it was not consistently affected in any of the three soils. The concentration of Cd in rye grass is in the decreasing order: sand, sandy loam, clay loam. pH and organic matter addition rate have been related. The amount of Cd extracted by DTPA increased with increasing levels of organic matter in all soils; the exchangeable fraction of Cd is the highest fraction of the total Cd; the evolution of exchangeable, carbonate bound, oxide bound, residual and organic bound with organic matter application and time is analyzed

  16. Spatial Trends in the Texture, Moisture Content, and pH of a Virginia Coastal Plain Soil

    OpenAIRE

    Zacharais, S.; Heatwole, C.D.; Campbell, J. B.

    1997-01-01

    Soil texture, moisture content, and pH data from an agricultural field area of 48 _ 32 m in a Suffolk sandy loam soil in the Virginia Coastal Plain was examined for spatial trends. Trend surface analysis of sand, silt, and clay content data (n = 35) found that 68%, 74%, and 31% of the total variability in sand, silt, and clay content, respectively, was explained by second-order trend surfaces. Soil moisture content and pH also exhibited spatial trends, which resulted in statistically signific...

  17. Effect of Soil Texture on Starch Accumulation and Activities of Key Enzymes of Starch Synthesis in the Kernel of ZM 9023

    Institute of Scientific and Technical Information of China (English)

    WANG Wen-jing; ZHAN Hai-hong

    2008-01-01

    Three kinds of soil texture (clay-loam, mid-loam, and sand-loam soil) were used to study the effects of soil texture on starch accumulating rate and the changes in activities of the key enzymes of starch synthesis in the kernel during grain filling in high gluten content wheat ZM 9023, under conditions of pond culture. The content of starch and its components were measured according to the method of double-wave length described by Bao (1996). ADP-glucose pyrophosphorylase (AGPP) activity was tested according to the method described by Doehlert et al. (1988). Soluble starch synthase (SSS) and starch branching enzyme (SBE) activities were tested according to the method described by Nakamura et al. (1989). The amylose, amylopectin, and total starch accumulating rate in the kernel of ZM 9023 were found to be a single-peak curve in three different soil textures during grain filling, and peaked 20, 15, and 15 d after anthesis, respectively. The activities of the enzymes, AGPP, SSS, and SBE, in the kernel of ZM 9023 had a single-peaked curve, which peaked 20, 15, and 15 d after anthesis, respectively. The activities of the above three enzymes of ZM 9023 were higher in the sand-loam soil. The accumulating peak of amylose formed later compared to that of amylopectin. The sand-loam soil could help high gluten content cultivars to synthesize starch.

  18. Colloid and Phosphorus Leaching From Undisturbed Soil Cores Sampled Along a Natural Clay Gradient

    DEFF Research Database (Denmark)

    Vendelboe, Anders Lindblad; Møldrup, Per; Heckrath, Goswin Johann;

    2011-01-01

    followed by lower and stable colloid and phosphorus concentrations. The mass of particles leached at first flush was independent of clay content and was attributed to the instant release of particles associated with the macropore walls and released upon contact with flowing water. Below a clay content of È......0.15 kg kgj1, the later leaching (after the first flush) of particles was independent of the clay content. Above this threshold, there was a positive relationship between the mass of leached particles after the first flush and the clay content. Particle release after the first flush was linearly...... correlated to the accumulated outflow and was described as a diffusion controlled process, using ¾(accumulated outflow). The mass of leached particles was positively correlated to the clay content as well as to water-dispersible colloids. Particulate phosphorus (P) was linearly correlated to concentration of...

  19. Combined effects of short term rainfall patterns and soil texture on soil nitrogen cycling — A modeling analysis

    Science.gov (United States)

    Gu, Chuanhui; Riley, William J.

    2010-03-01

    Precipitation variability and magnitude are expected to change in many parts of the world over the 21st century. We examined the potential effects of intra-annual rainfall patterns on soil nitrogen (N) transport and transformation in the unsaturated soil zone using a deterministic dynamic modeling approach. The model (TOUGHREACT-N), which has been tested and applied in several experimental and observational systems, mechanistically accounts for microbial activity, soil moisture dynamics that respond to precipitation variability, and gaseous and aqueous tracer transport in the soil. Here, we further tested and calibrated the model against data from a precipitation variability experiment in a tropical system in Costa Rica. The model was then used to simulate responses of soil moisture, microbial dynamics, N leaching, and N trace-gas emissions to changes in rainfall patterns; the effect of soil texture was also examined. The temporal variability of nitrate leaching and NO, NH 3, and N 2O effluxes were significantly influenced by rainfall dynamics. Soil texture combined with rainfall dynamics altered soil moisture dynamics, and consequently regulated soil N responses to precipitation changes. The clay loam soil more effectively buffered water stress during relatively long intervals between precipitation events, particularly after a large rainfall event. Subsequent soil N aqueous and gaseous losses showed either increases or decreases in response to increasing precipitation variability due to complex soil moisture dynamics. For a high rainfall scenario, high precipitation variability resulted in as high as 2.4-, 2.4-, 1.2-, and 13-fold increases in NH 3, NO, N 2O and NO 3- fluxes, respectively, in clay loam soil. In sandy loam soil, however, NO and N 2O fluxes decreased by 15% and 28%, respectively, in response to high precipitation variability. Our results demonstrate that soil N cycling responses to increasing precipitation variability depends on precipitation amount

  20. Multitracer and filter-separated half-cell method for measuring solute diffusion in undisturbed soil

    DEFF Research Database (Denmark)

    Lægdsmand, Mette; Møldrup, Per; Schjønning, Per

    2010-01-01

    Solute diffusion controls important processes in soils: plant uptake of nutrients, sorption-desorption processes, degradation of organic matter, and leaching of radionuclides through clay barriers. We developed a new method for measuring the solute diffusivity (solute diffusion coefficient in the...... soil relative to water) in intact soil samples (the Multiple Tracer, Filter Separated half-cell method using a Dynamic Model for parameter estimation [MT-FS-DM]). The MT-FS-DM method consists of half-cell diffusion of two pairs of counterdiffusing anionic tracers and a parameter estimation scheme that...... the MT-FS-DM method provided reliable results. We compared diffusivities measured on a sandy loam soil using the MT-FS-DM method with diffusivities from six sandy loam test soils from the literature. The new method can be used to estimate solute diffusivity in intact structured soil and provides a...

  1. The development of a multi-surface soil speciation model for Cd (II) and Pb (II): Comparison of two approaches for metal adsorption to clay fractions

    International Nuclear Information System (INIS)

    Highlights: • A two-site surface complexation model was used to predict metal binding onto clays. • Five different surfaces are included in the multi-surface speciation model. • The improved model well predicted metal adsorption under various I and pH. • Adsorption on clays should be considered especially at low I and high pH condition. - Abstract: The mobility of toxic metals in soils or sediments is of great concern to scientists and environmentalists since it directly affects the bioavailability of metals and their movement to surface and ground waters. In this study, a multi-surface soil speciation model for Cd (II) and Pb (II) was developed to predict the partition of metals on various soil solid components (e.g. soil organic matter (SOM), oxide mineral, and clay mineral). In previous study, the sorption of metal cations on SOM and oxide minerals has been evaluated by thermodynamically based surface complexation model. However, metal binding to soil clay fractions was normally treated in a simplistic manner: only cation exchange reactions were considered and exchange coefficient was assumed unity. In this study, the binding of metals onto clays was described by a two-site surface sorption model (a basal surface site and an edge site). The model was checked by predicting the adsorption behavior of Cd (II) and Pb (II) onto three selected Chinese soils as a function of pH and ionic strengths. Results showed that the proposed model more accurately predicted the metal adsorption on soils under studied condition, especially in low ionic strength condition, suggesting that adsorption of metals to soil clay fractions need to be considered more carefully when modeling the partition of trace elements in soils. The developed soil speciation model will be useful when evaluating the movement and bioavailability of toxic metals in soil environment

  2. Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

    KAUST Repository

    Serrano, O.

    2016-01-18

    The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e. silt and clay), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud (i.e. silt and clay, particle sizes <63 μm) contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relative high soil Corg contents with relatively low mud contents (i.e. mud-Corg saturation) together with significant allochthonous inputs of terrestrial organic matter could overall disrupt the correlation expected between soil Corg and mud contents. This study shows that mud (i.e. silt and clay content) is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass

  3. Clay mineralogy and geochemistry of the soils derived from metamorphic and mafic igneous parent rocks in Lahijan area

    International Nuclear Information System (INIS)

    The mineralogical and geochemical composition of the soils of three representative pedons formed on basaltic andesite, andesitic basalt and phyllite were investigated. Results by x-ray diffraction showed that progressive weathering of rocks have been marked by gradual accumulation of Al, Fe, Ti, Mg, H3O+ and depletion of Na, K, Ca and Si in the soil; although, predominant clay, loss and gain trend of elements was different on the various rocks. Based on x-ray diffraction analysis, minerals in basaltic andesite and andesitic basalt were similar but, the intensity of mica to smectite or vermiculite transformation for latter was relatively higher than the former. This process revealed the degradation mineral because of two reasons: (i) - smectite and vermiculite increased whereas mica decreased in surface horizons. (i i)-Irregular mixed layer of mica-smectite or vermiculite was present in deeper part (170 cm) of the soils from andesitic basalt but shallower depth (75 em) of the soils from basaltic andesite. Clay minerals in phyllite were mica and chlorite that stratified with vermiculite. However, the absence of smectite in phyllite might be attributed to more acidic condition or position of the Fe ion in the mineral lattice of chlorite (higher Fe in the interlayer hydroxide sheet)

  4. Effect of Mulching Rates on Evaporation, Water and Salt Distribution in two soils with different texture from Upper Soil Layer, in Derab region, Kingdom of Saudi Arabia

    International Nuclear Information System (INIS)

    Dry desert climate zone require search for the best ways to, conserve water. This study was conducted to minimize evaporation using mulching with different rates in two soils loamy sand (S1), and sandy clay loam (S2). Sawdust mulch rates used were (zero, 2, and 4 cm) depth. Tape water was added to soil columns on the basis of required water to saturate soil. After the leach ate (free water drainage) ceased, evaporation experiment was started until stable weight of the control (no mulch) was achieved (83 days). The cumulative evaporation (E) was determined by daily weighing soil columns. The soil waters and salts distribution on soil profiles was determined by daily weighing soil columns. The soil water and soil distribution on soil profiles were determined each (10cm) increments before and after evaporation experiments. Results indicated that the two soils had different hydro physical properties, such that sandy clay loam soil (S2) was higher in water retention. The study revealed that sawdust mulching reduced evaporation significantly on both soils. Mulching with (2cm.) depth was enough for evaporation reduction to a rate lower than that of water flow toward soil surface. Results indicated that there is a linear relationship between (E) and square root of (t) (E=bt1/2) for all mulching rates of both soils. It has been found that the soil water profile distribution was significantly higher with mulched soil columns compared with the control for both soils. However, there were no significant differences between saw dust mulching with (2 or 4 cm depth). These results were reflected on the soil water storage, where mulched soil columns were higher than that of the control. In general results of evaporation, soil water distribution and water storage proved that sawdust mulching with (2cm) depth was enough to limit evaporation and conserve water for both soils. This effect was more pronounced in loamy sand soil. Generally, the result of the (EC) and salt distribution

  5. Some Fertility Characteristics and Fertilizer Requirements of a Newly Reclaimed Upland Red Soil Derived from Quaternary Red Clay

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of field experiments from 1990 to 1994 in Yingtan, Jiangxi Province, were conducted on an upland red soil derived from Quaternary red clay which had been reclaimed three years before the experiments, in order to study the fertility characteristics and fertilizer requirements of the newly reclaimed soil. The field experiments included that on nutrient characteristics and fertilizer effect, that on K-supplying potential and K-Mg relationship, that on fertilization rates of K and N, etc. The newly reclaimed upland soil was low in both N and P, and its responses to nitrogen and phosphate application were very significant. The K-supplying potential was also low, so the soil was highly responsive to K fertilizer. The effect of Ca and Mg fertilizers was not so great for the reason that certain amounts of Ca and Mg were incorporated into the soil through application of calcium magnesium phosphate during land leveling before the experiments. Among the four micronutrients, B, Mo, Zn and Cu, B had the greatest effect on the soil. The fertilizer requirements of the soil were in an order of P and N > K > lime and B > Mg > Mo, Zn and Cu. Eight crops tested had different fertilizer-requiring characteristics. Rapeseed was very sensitive to P and B fertilizers. Barely was especially sensitive to P and lime and it also responded to B, Mo, Zn and Cu. And sweet potato was especially sensitive to K.

  6. Survival of Escherichia coli and Salmonella Typhimurium in slurry applied to clay soil on a Danish swine farm

    DEFF Research Database (Denmark)

    Boes, J.; Alban, L.; Bagger, J.;

    2005-01-01

    A pilot study was carried out on a Danish swine farm infected with multi-resistant Salmonella Typhimurium DT104 (MRDT104). We aimed to (1) investigate to which degree the decline of Escherichia coli and Salmonella in swine slurry applied to farmland depended on the application method; (2) estimate...... the survival times of E. coli and Salmonella in the soil surface following deposition of naturally contaminated pig slurry; and (3) simulate survival of Salmonella in different infection levels using E. coli data as input estimates. Slurry was deposited by four different methods: (1) hose applicator...... soil amended with contaminated pig slurry was an effective means to reduce environmental exposure to E. coli and Salmonella on this clay-soil farm....

  7. Methodical comparison of neutron depth probes and long-term soil moisture measurements on loess, sandy loess, and boulder clay

    International Nuclear Information System (INIS)

    Three measuring instruments were tested: 0.05 mCi Cf-252, 100 mCi Am-241/Be, 500 mCi Am-241/Be. The advantages - measurement in undisturbed soil profiles, large depths of measurement, reproducibility of measurements in the same place over several years - and the disadvantages - radiation protection, resolution, variations of measured volume in dependence of moisture, background influences etc. - have been critically checked by experiment. In addition, annual soil moisture curves have been measured over two years by parallel use of the free probes on a loess, sandy loess, and boulder clay site. The results were compared and discussed with a view to the soil water dynamics of these sites. (orig./HP)

  8. Effects of different fertilizers on the abundance and community structure of ammonia oxidizers in a yellow clay soil.

    Science.gov (United States)

    Yao, Huaiying; Huang, Sha; Qiu, Qiongfen; Li, Yaying; Wu, Lianghuan; Mi, Wenhai; Dai, Feng

    2016-08-01

    Yellow clay paddy soil (Oxisols) is a typical soil with low productivity in southern China. Nitrification inhibitors and slow release fertilizers have been used to improve nitrogen fertilizer utilization and reduce environmental impaction of the paddy soil. However, their effects on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in paddy soil have rarely been investigated. In the present work, we compared the influences of several slow release fertilizers and nitrification inhibitors on the community structure and activities of the ammonia oxidizers in yellow clay soil. The abundances and community compositions of AOA and AOB were determined with qPCR, terminal restriction fragment length polymorphism (T-RFLP), and clone library approaches. Our results indicated that the potential nitrification rate (PNR) of the soil was significantly related to the abundances of both AOA and AOB. Nitrogen fertilizer application stimulated the growth of AOA and AOB, and the combinations of nitrapyrin with urea (NPU) and urea-formaldehyde (UF) inhibited the growth of AOA and AOB, respectively. Compared with other treatments, the applications of NPU and UF also led to significant shifts in the community compositions of AOA and AOB, respectively. NPU showed an inhibitory effect on AOA T-RF 166 bp that belonged to Nitrosotalea. UF had a negative effect on AOB T-RF 62 bp that was assigned to Nitrosospira. These results suggested that NPU inhibited PNR and increased nitrogen use efficiency (NUE) by inhibiting the growth of AOA and altering AOA community. UF showed no effect on NUE but decreased AOB abundance and shifted AOB community. PMID:27063014

  9. Mineralization-immobilization and plant uptake of nitrogen as influenced by the spatial distribution of cattle slurry in soils of different texture

    DEFF Research Database (Denmark)

    Sørensen, P.; Jensen, E.S.

    1995-01-01

    +-N were insignificant. Consequently, the availability of slurry N to plants was mainly influenced by the mineralization-immobilization processes. The apparent utilization of slurry NH4+-N mixed into soil was 7%, 14% and 24% lower than the utilization of (NH4)(2)SO4-N in a sand soil, a sandy loam soil...... and a loam soil, respectively. Thus, the net immobilization of N due to slurry application increased with increasing soil clay content, whereas the recovery in plants of N-15-labelled NH4+-N from slurry was similar on the three soils. A parallel incubation experiment showed that the immobilization of...... slurry N occurred within the first week after slurry application. The incorporation of slurry N by simulated injection increased the plant uptake of both total and labelled N compared to mixing the slurry into the soil. The apparent utilization of injected slurry NH4+-N was 7% higher, 8% lower and 4...

  10. Properties of a clay soil from 1.5 to 3.5 years after biochar application and the impact on rice yield

    NARCIS (Netherlands)

    Carvalho, M.T.M.; Madari, B.E.; Bastiaans, L.; Oort, van P.A.J.; Leal, W.G.O.; Heinemann, A.B.; Silva, da M.A.S.; Maia, A.H.N.; Parsons, D.; Meinke, H.

    2016-01-01

    We assessed the impact of a single application of wood biochar on soil chemical and physical properties and aerobic rice grain yield on an irrigated kaolinitic clay Ferralsol in a tropical Savannah. We used linear mixed models to analyse the response of soil and plant variables to application rat

  11. 不同根部微灌水器对云南红壤和黄沙土水分分布的影响%Impacts of different root miroirrigation emitters on water distribution of red loam and yellow sand soils in Yunnan

    Institute of Scientific and Technical Information of China (English)

    余杨; 杨振杰; 张建生; 国攀; 薛翔; 张新星; 胡红超; 油瑞菊

    2015-01-01

    It is important to explore the effect of different root micro emitters on soil water distribution, which improves the efficiency of root micro irrigation system. The influence of micro emitter type on soil water distribution was studied in this paper. Two different irrigation systems (surface drip irrigation and root micro irrigation), two different irrigation emitter types (flow adjustable irrigation emitter and drip irrigation belt embedded with inner patch) and three different irrigation times (5, 15 and 30 minutes) were applied on the Yunnan red loam and the yellow sand soils. Soil moisture was determined. The results showed that there was a very significant interaction between the emitter type and the soil type, the emitter type and the irrigation time (P 0.05). The flow adjustable irrigation emitter has 8 horizontal drainage holes. The horizontal width of the irrigation water in the 2 soils was both wide (about 25 cm). The drip irrigation belt embedded with inner patch has a downward single hole. The horizontal width of the irrigation water in the 2 soils was both narrow (about 16 cm). Therefore, for the wide root extension of crops, the application of the flow adjustable irrigation emitter should be more suitable, on the contrary, the drip irrigation belt embedded with inner patch are used instead. In the Yunnan red loam, the areas with higher water content for the root micro-irrigation using belt embedded with inner patch were more close to those of crop roots, the areas with higher water content for the surface drip irrigation basically concentrated on the upper part of the soil of the flower pot. Therefore, compared to the surface drip irrigation, water loss due to evaporation in root irrigation greatly reduced. In the Yunnan red loam, the matric potential to the movement of irrigation water played the main role and water was easy to sink; In yellow sand soil, the gravitational potential to the movement of irrigation water played a main role which could

  12. Research Note:Determination of soil hydraulic properties using pedotransfer functions in a semi-arid basin, Turkey

    Directory of Open Access Journals (Sweden)

    M. Tombul

    2004-01-01

    Full Text Available Spatial and temporal variations in soil hydraulic properties such as soil moisture q(h and hydraulic conductivity K(q or K(h, may affect the performance of hydrological models. Moreover, the cost of determining soil hydraulic properties by field or laboratory methods makes alternative indirect methods desirable. In this paper, various pedotransfer functions (PTFs are used to estimate soil hydraulic properties for a small semi-arid basin (Kurukavak in the north-west of Turkey. The field measurements were a good fit with the retention curve derived using Rosetta SSC-BD for a loamy soil. To predict parameters to describe soil hydraulic characteristics, continuous PTFs such as Rosetta SSC-BD (Model H3 and SSC-BD-q33q1500 (Model H5 have been applied. Using soil hydraulic properties that vary in time and space, the characteristic curves for three soil types, loam, sandy clay loam and sandy loam have been developed. Spatial and temporal variations in soil moisture have been demonstrated on a plot and catchment scale for loamy soil. It is concluded that accurate site-specific measurements of the soil hydraulic characteristics are the only and probably the most promising method to progress in the future. Keywords: soil hydraulic properties, soil characteristic curves, PTFs

  13. Self diffusion coefficient of phosphorus in different soils of Egypt as affected by soil moisture and phosphate fertilizer

    International Nuclear Information System (INIS)

    The effect of soil water content and phosphate fertilization vz. phosphate diffusion on plant growth and p-uptake was studied by use of tracer technique. Two experiments were conducted using three different Egyptian soils, i.e. clay from Bahtim, loamy from Burg El-Arab and sandy loam from Abou-Zaabal. The first was a laboratory experiment and aimed to determine the self diffusion coefficient of 32P, sup(D)P, in these different soils, as affected by soil moisture content and phosphate fertilization. The second was a pot experiment conducted to further investigate the uptake and dry matter yield of corn plants under the same conditions mentioned in the first experiment. The data revealed that as the P applied was raised from 0 to 100 Kgp/Fed, the values of sup(D)P were increased with different magnitude according to the soil texture and its moisture content. The highest values for the sup(D)P were of the clay soil of Bahtim, while the lowest were of the sandy loam soil of Abou-Zaabal. The data showed the positive trends towards increasing the sup(D)P values with increasing soil moisture contents. The study of pot experiment showed that plant uptake of P is closely related to the diffusion coefficient of P in soils. The practical implication of the present study indicates that more phosphorus needs to be applied to crops during periods of moisture stress than during periods of adequate soil moisture level to provide optimum phosphorus nutrition to plants. The clay soils should show less tendency toward P deficiency during dry conditions than would sandy soils having less clay. Similarly, irrigation should help to overcome P-deficiencies, particularly on light-textured soils. (author)

  14. Salt—Water Dynamics in Soils:I.Salt—Water Dynamics in Unsaturated Soils Under Stable Evaporation Condition

    Institute of Scientific and Technical Information of China (English)

    YOUWEN-RUI; MENGFAN-HUA; 等

    1992-01-01

    A long term simulation test on salt-water dynamics in unsaturated soils with different groundwater depths and soil texture profiles under stable evaporation condition was conducted.Salinity sensors and tensiometers were used to monitor salt and water variation in soils.The experiment revealed that in the process of fresh groundwater moving upwards by capillary rise in the column,the salts in subsoil were brought upwards and accumulated in the surface soil,and consequently the salinization of surface soil took place.The rate of salt accumulation is determined mainly by the volume of capillary water flow and the conditions of salts contained in the soil profile.Water flux in soils decreased obviously when groundwater depths fell below 1.5m.When there was an interbedded clay layer 30cm in thickness in the silty loam soil profile or a clay layer 100cm in thickness at the top layer,the water flux was 3-5 times less than in the soil profile of homogeneous silty loam soil.Therefore,the rate of salt accumulation was decreased and the effect of variation of groundwater depth on the water flux in soils was weakened comparatively.If there was precipitation or irrigation supplying water to the soil,the groundwater could rarely take a direct part in the process of salt accumulation in surface soil,especially,in soil profiles with an interbedded stratum or a clayey surface soil layer.

  15. Mapping of Total Carbon and Clay Contents in Glacial Till Soil Using On-the-Go Near-Infrared Reflectance Spectroscopy and Partial Least Squares Regression

    Institute of Scientific and Technical Information of China (English)

    SHEN Zhang-Quan; SHAN Ying-Jie; PENG Li; JIANG Yu-Gen

    2013-01-01

    Characterizing spatial variability of soil attributes,using traditional soil sampling and laboratory analysis,is cost prohibitive.The potential benefit of managing soils on a site-specific basis is well established.High variations in glacial till soil render detailed soil mapping difficult with limited number of soil samples.To overcome this problem,this paper demonstrates the feasibility of soil carbon and clay mapping using the newly developed on-the-go near-infrared reflectance spectroscopy (NIRS).Compared with the geostatistics method,the partial least squares regression (PLSR),with NIRS measurements,could yield a more detailed map for both soil carbon and clay.Further,by using independent validation dataset,the accuracy of predicting could be improved significantly for soil clay content and only slightly for soil carbon content.Owing to the complexity of field conditions,more work on data processing and calibration modeling might be necessary for using on-the-go NIRS measurements.

  16. Prediction of Nitrogen Responses of Corn by Soil Nitrogen Mineralization Indicators

    Directory of Open Access Journals (Sweden)

    R.R. Simard

    2001-01-01

    Full Text Available Soil nitrogen mineralization potential (Nmin has to be spatially quantified to enable farmers to vary N fertilizer rates, optimize crop yields, and minimize N transfer from soils to the environment. The study objectives were to assess the spatial variability in soil Nmin potential based on clay and organic matter (OM contents and the impact of grouping soils using these criteria on corn grain (Zea mays L. yield, N uptake response curves to N fertilizer, and soil residual N. Four indicators were used: OM content and three equations involving OM and clay content. The study was conducted on a 15-ha field near Montreal, Quebec, Canada. In the spring 2000, soil samples (n = 150 were collected on a 30- x 30-m grid and six rates of N fertilizer (0 to 250 kg N ha-1 were applied. Kriged maps of particle size showed areas of clay, clay loam, and fine sandy loam soils. The Nmin indicators were spatially structured but soil nitrate (NO3– was not. The N fertilizer rate to reach maximum grain yield (Nmax, as estimated by a quadratic model, varied among textural classes and Nmin indicators, and ranged from 159 to 250 kg N ha-1. The proportion of variability (R2 and the standard error of the estimate (SE varied among textural groups and Nmin indicators. The R2 ranged from 0.53 to 0.91 and the SE from 0.13 to 1.62. Corn grain N uptake was significantly affected by N fertilizer and the pattern of response differed with soil texture. For the 50 kg N ha-1 rate, the apparent Nmin potential (ANM was significantly larger in the clay loam (122 kg ha-1 than in the fine sandy loam (80 kg ha-1 or clay (64 kg ha-1 soils. The fall soil residual N was not affected by N fertlizer inputs. Textural classes can be used to predict Nmax. The Nmin indicators may also assist the variable rate N fertilizer inputs for corn production.

  17. Prediction of nitrogen responses of corn by soil nitrogen mineralization indicators.

    Science.gov (United States)

    Simard, R R; Ziadi, N; Nolin, M C; Cambouris, A N

    2001-11-01

    Soil nitrogen mineralization potential (N min) has to be spatially quantified to enable farmers to vary N fertilizer rates, optimize crop yields, and minimize N transfer from soils to the environment. The study objectives were to assess the spatial variability in soil N min potential based on clay and organic matter (OM) contents and the impact of grouping soils using these criteria on corn grain (Zea mays L.) yield, N uptake response curves to N fertilizer, and soil residual N. Four indicators were used: OM content and three equations involving OM and clay content. The study was conducted on a 15-ha field near Montreal, Quebec, Canada. In the spring 2000, soil samples (n = 150) were collected on a 30- x 30-m grid and six rates of N fertilizer (0 to 250 kg N ha(-1)) were applied. Kriged maps of particle size showed areas of clay, clay loam, and fine sandy loam soils. The N min indicators were spatially structured but soil nitrate (NO3-) was not. The N fertilizer rate to reach maximum grain yield (N max), as estimated by a quadratic model, varied among textural classes and Nmin indicators, and ranged from 159 to 250 kg N ha(-1). The proportion of variability (R2) and the standard error of the estimate (SE) varied among textural groups and N min indicators. The R2 ranged from 0.53 to 0.91 and the SE from 0.13 to 1.62. Corn grain N uptake was significantly affected by N fertilizer and the pattern of response differed with soil texture. For the 50 kg N ha(-1) rate, the apparent N min potential (ANM) was significantly larger in the clay loam (122 kg ha(-1)) than in the fine sandy loam (80 kg ha(-1)) or clay (64 kg ha(-1)) soils. The fall soil residual N was not affected by N fertlizer inputs. Textural classes can be used to predict N max. The N min indicators may also assist the variable rate N fertilizer inputs for corn production. PMID:12805786

  18. Innovative Uses of Organo-philic Clays for Remediation of Soils, Sediments and Groundwater

    International Nuclear Information System (INIS)

    PCBs and similar low-solubility organic compounds continue to offer significant challenges in terrestrial and sediment remediation applications. While selective media such as granular activated carbon (GAC) have proven to be successful at absorbing soluble organics, these media may have reduced performance due to blinding in the presence of high molecular weight organic matter. An alternative technology addresses this problem with a clay-based adsorption media, which effectively and efficiently stabilizes low-solubility organic matter. OrganoclayTM reactive media utilizes granular sodium bentonite, which has been chemically modified to attract organic matter without absorbing water. The unique platelet structure of bentonite clays provides tremendous surface area and the capacity of the media to absorb over 60 percent of its own weight in organic matter. Because of these properties, organo-clays allow for several cost-effective in-situ remediation techniques, such as: - Flow-through filtration for removal of organic matter from aqueous solutions. Organo-clay can be utilized as a fixed-bed media in a column operation. This specialty media offers a high efficient alternative to Granular Activated Carbon (GAC) when applied as a flow through media to remove oil, PCB and other low soluble organic contaminates from water. - Placement in a Reactive Core MatTM. Organo-clay may be encapsulated into carrier textiles which are adhered together to create a thin reactive layer with high strength and even distribution of the reactive media. This type of delivery mechanism can be successfully applied in a sub aqueous or terrestrial environment for sediment capping applications - Permeable reactive barriers. Organo-clay can deliver high sorption capacity, high efficiency, and excellent hydraulic conductivity as a passive reactive media in these applications. (authors)

  19. Size and Persistence of the Microbial Biomass Formed during the Humification of Glucose Hemicellulose Cellulose, and Straw in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1983-01-01

    straw. The half-life of labelled C in biomass during the second year of incubation ranged from 2 to 3 years.Native C in biomass ranged from 0.5 to 1.4% of the total C in native soil organic matter, the highest values occurring in the clay-rich soils. The half-life of native soil C, estimated from CO2...

  20. Pupal development of Ceratitis capitata (Diptera: Tephritidae) and Diachasmimorpha longicaudata (Hymenoptera: Braconidae) at different moisture values in four soil types.

    Science.gov (United States)

    Bento, F de M M; Marques, R N; Costa, M L Z; Walder, J M M; Silva, A P; Parra, J R P

    2010-08-01

    This study aimed to evaluate adult emergence and duration of the pupal stage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and emergence of the fruit fly parasitoid, Diachasmimorpha longicaudata (Ashmead), under different moisture conditions in four soil types, using soil water matric potential. Pupal stage duration in C. capitata was influenced differently for males and females. In females, only soil type affected pupal stage duration, which was longer in a clay soil. In males, pupal stage duration was individually influenced by moisture and soil type, with a reduction in pupal stage duration in a heavy clay soil and in a sandy clay, with longer duration in the clay soil. As matric potential decreased, duration of the pupal stage of C. capitata males increased, regardless of soil type. C. capitata emergence was affected by moisture, regardless of soil type, and was higher in drier soils. The emergence of D. longicaudata adults was individually influenced by soil type and moisture factors, and the number of emerged D. longicaudata adults was three times higher in sandy loam and lower in a heavy clay soil. Always, the number of emerged adults was higher at higher moisture conditions. C. capitata and D. longicaudata pupal development was affected by moisture and soil type, which may facilitate pest sampling and allow release areas for the parasitoid to be defined under field conditions. PMID:22127183

  1. CONSTRUCTION OF A NEW HIGHWAY EMBANKMENT ON THE SOFT CLAY SOIL TREATMENT BY STONE COLUMNS IN MALAYSIA

    Directory of Open Access Journals (Sweden)

    QASIM A. ALJANABI

    2013-08-01

    Full Text Available To continue of the second phase of the East Coast Expressway between Kuantan and Kula Terengganu in Malaysia system innovative solution are required. In this new phase there are embankment region has been subjected to extensive soft clay soil. These comprise typically of clayey silts of very high water content and undrained shear strengths in the range of 8 to 11 kPa to depths of up to 8m. To support an embankment height of up to 12 m, were filled and thereafter Vibro Replacement treatment was carried out to treat the very soft soil. Extensive instrumentation using rod settlement gauges, inclinometers and piezometers were installed to monitor the performance of the Vibro Replacement treatment. This paper reports on aspects of design, installation and the measured results from the instrumentation scheme.

  2. Use of Clay Deposits in Water Management of Calcareous Sandy Soils Under-surface and Sub-surface Drip Irrigation

    International Nuclear Information System (INIS)

    The objective of this study was to investigate the effect of irrigation (levels and methods) and type of clay deposits on lettuce yield, water use efficiency WUE and the distributions of soil moisture and salts in the root zone of sandy calcareous soils. A field experiment was conducted at the college experimental station in 2002-2003. It consists of three clay deposits, three rates (0, 1.0 and 2.0%), and four total irrigation applied water levels, 360 mm (T1), 520 mm (T2), 635 mm (T3) and 822 mm (T4), using surface and subsurface drip irrigation. Results indicated that yield was significantly increased with the increase of irrigation level, whereas WUE significantly decreased with increase of irrigation level. The average yield increased by 9.30% in a high irrigation level compared to a moderate irrigation level, and decreased by 14.2% at the more stressed irrigation level. WUE decreased by 49.0% at a moderate irrigation level and yield was significantly affected by amendment rates. The difference between surface and subsurface drip on yields and WUE were also significant. Results indicated that the moisture content of the subsurface treated layer increased dramatically, while salts were accumulated at the surface and away from the emitters in subsurface drip irrigation. The advantages of surface drip irrigation were related to the relative decrease in salt accumulation in the root zone area where the plant roots were active and the water content was relatively high. (author)

  3. Characteristics of Soil and Organic Carbon Loss Induced by Water Erosion on the Loess Plateau in China.

    Science.gov (United States)

    Li, Zhongwu; Nie, Xiaodong; Chang, Xiaofeng; Liu, Lin; Sun, Liying

    2016-01-01

    Soil erosion has been a common environmental problem in the Loess Plateau in China. This study aims to better understand the losses of soil organic carbon (SOC) induced by water erosion. Laboratory-simulated rainfall experiments were conducted to investigate the characteristics of SOC loss induced by water erosion. The applied treatments included two rainfall intensities (90 and 120 mm h-1), four slope gradients (10°, 15°, 20°, and 25°), and two typical soil types- silty clay loam and silty loam. Results showed that the sediment OC enrichment ratios (ERoc) in all the events were relative stable with values ranged from 0.85 to1.21 and 0.64 to 1.52 and mean values of 0.98 and 1.01 for silty clay loam and silty loam, respectively. Similar to the ERoc, the proportions of different sized particles in sediment showed tiny variations during erosion processes. No significant correlation was observed between ERoc values and the proportions of sediment particles. Slope, rainfall intensity and soil type almost had no impact on ERoc. These results indicate that the transportation of SOC during erosion processes was nonselective. While the mean SOC loss rates for the events of silty clay loam and silty loam were 0.30 and 0.08 g m-2 min-1, respectively. Greater differences in SOC loss rates were found in events among different soil types. Meanwhile, significant correlations between SOC loss and soil loss for all the events were observed. These results indicated that the amount of SOC loss was influenced primarily by soil loss and the SOC content of the original soil. Erosion pattern and original SOC content are two main factors by which different soils can influence SOC loss. It seems that soil type has a greater impact on SOC loss than rainfall characteristics on the Loess Plateau of China. However, more kinds of soils should be further studied due to the special formation processes in the Loess Plateau. PMID:27124482

  4. Pore Structure Characteristics after 2 Years of Biochar Application to a Sandy Loam Field

    DEFF Research Database (Denmark)

    Sun, Zhencai; Arthur, Emmanuel; de Jonge, Lis Wollesen;

    2015-01-01

    , where the maximum increment was 12% at 100 Mg ha-1 biochar treatment. A pore size distribution index, B, derived from water retention, indicated a wider soil pore size distribution in biochar-amended soil than in the reference soil, especially for the 100-Mg ha-1 application. At given matric potentials......Soil pore structure comprises the size and shape of soil pores and has a major impact on water retention and gas movement. The porous nature of biochar suggests that its application to soil can potentially alter soil pore structure characteristics, and the purpose of this study was to evaluate the...... effects of birch wood biochar (20, 40, and 100 Mg ha-1) applied to a sandy loam on soil total porosity and pore structure indices. Bulk and intact soil samples were collected for physicochemical analyses and water retention and gas diffusivity measurements between pF 1.0 and pF 3.0. Biochar application...

  5. Environmental Factors Influencing Numbers of Rhizobium leguminosarum biovar trifolii and Its Bacteriophages in Two Field Soils.

    Science.gov (United States)

    Lawson, K A; Barnet, Y M; McGilchrist, C A

    1987-05-01

    Fluctuations in numbers of Rhizobium leguminosarum biovar trifolii and its bacteriophages in two fields with different soil types were followed during a 17-month period in 1981 and 1982. Mean levels of both phage and rhizobia varied significantly (P soil and phage from 0 to 1.7 x 10 PFU/g of soil. Multivariate regression analysis showed rhizobial levels to be significantly and positively related to vegetation height and solar radiation, but not to mean temperature, precipitation, soil matric potential, or soil type. Rhizobiophage concentrations were significantly and positively related to soil matric potential and vegetation height. They were reduced in the silty clay loam soil, although the presence of 34% clay did not prevent phage multiplication and the occurrence of high phage levels. PMID:16347339

  6. Liquefaction Susceptibility of Soils With Clay Particles from Earthquake-induced Landslides

    Institute of Scientific and Technical Information of China (English)

    CHEN Chuan-sheng; JIANG Xin; ZHANG Xu

    2007-01-01

    The main reason for earthquake-induced landslides is liquefaction of soil, a process considered to occur mostly in sandy soils. Liquefaction can occur in clayey soils has also been reported and proven in the recent literature, but liquefaction in clayey soils still remains unclear and there are many questions that need to be addressed. In order to address these questions, an depth study on the liquefaction potential of clayey soils was conducted on the basis of field investigation and a series of laboratory tests on the samples collected from the sliding surface of the landslides. The liquefaction potential of the soils was studied by means of undrained cyclic ring-shear tests. Research results show that the liquefaction potential of sandy soils is higher than that of clayey soils given the same void ratio;the soil resistance to liquefaction rises with an increase in plasticity for clayey soils; relation between plasticity index and the liquefaction potential of soil can be used in practical application to estimate the liquefaction potential of soil.

  7. Evaluation of biostimulation in clay soil contaminated by petroleum; Avaliacao da bioestimulacao em solos argilosos contaminados com petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Sandro J.; Cammarota, Magali C.; Freire, Denize D.C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Bioquimica. Lab. de Tecnologia Ambiental]. E-mail: baptista@eq.ufrj.br; denize@eq.ufrj.br

    2003-07-01

    Biostimulation has been used as a technic in order to increase the microbial activity adding inorganic nutrients and/or terminal electron acceptor in the contaminated place. The main goal of this work was evaluate how each inorganic nutrient could help the biodegradation at a given petroleum contaminated clay soil. At first, the work was designed to investigate the optimal relation between C:N:P that could influence the best organic matter removal (OMR) in aerobic bioreactors with 50 ml during 30 days. It was noticed that when one worked with 35 mg KH{sub 2}PO{sub 4}/100 g soil, without adding nitrogen source, the OMR was 35%. Furthermore, it was noticed that the highest concentration of nitrogen and phosphorus was a limiting factor for microbial degradation and this resulted in the lowest OMR. At second, it was designed in aerobic bioreactor with 500 ml for 45 days and worked with the optimal concentrations of added phosphorus from the last stage. Although the assays have focused that nitrogen was not necessary to add to the soil, it was worked with 2,5 g (NH{sub 4}){sub 2}SO{sub 4}/100 g soil. The OMR was 46%, Oil and Grease removal was around 38% and TPH removal was around 45%. (author)

  8. Effects of subsoil compaction on hydraulic properties and preferential flow in a Swedish clay soil

    DEFF Research Database (Denmark)

    Mossadeghi-Björklund, M; Arvidsson, J.; Keller, Thomas;

    2016-01-01

    preferential transport derived from non-reactive tracer breakthrough curves and measurements of saturated hydraulic conductivity (Ks) and air permeability at the field moisture content (Ka). Although the traffic treatment did not cause any compaction effects at one of the two sites, it did result in significant......Soil compaction by vehicular traffic modifies the pore structure and soil hydraulic properties. These changes potentially influence the occurrence of preferential flow, which so far has been little studied. Our aim was to study the effect of compaction on soil hydraulic and transport properties in...... subsoil. A randomized block design trial at two sites on a well-structured clay soil in central Sweden was established. Plots with two levels of compaction were created at both sites, in the following referred to as trafficked and control. The trafficked treatment was created by 4 passes track-by-track with...

  9. Effect of soil texture on phytoremediation of arsenic-contaminated soils

    Science.gov (United States)

    Pallud, C. E.; Matzen, S. L.; Olson, A.

    2015-12-01

    Soil arsenic (As) contamination is a global problem, resulting in part from anthropogenic activities, including the use of arsenical pesticides and treated wood, mining, and irrigated agriculture. Phytoextraction using the hyperaccumulating fern Pteris vittata is a promising new technology to remediate soils with shallow arsenic contamination with minimal site disturbance. However, many challenges still lie ahead for a global application of phytoremediation. For example, remediation times using P. vittata are on the order of decades. In addition, most research on As phytoextraction with P. vittata has examined As removal from sandy soils, where As is more available, with little research focusing on As removal from clayey soils, where As is less available. The objective of this study is to determine the effects of soil texture and soil fertilization on As extraction by P. vittata, to optimize remediation efficiency and decrease remediation time under complex field conditions. A field study was established 2.5 years ago in an abandoned railroad grade contaminated with As (average 85.5 mg kg-1) with texture varying from sandy loam to silty clay loam. Organic N, inorganic N, organic P, inorganic P, and compost were applied to separate sub-plots; control ferns were grown in untreated soil. In a parallel greenhouse experiment, ferns were grown in sandy loam soil extracted from the field (180 mg As kg-1), with similar treatments as those used at the field site, plus a high phosphate treatment and treatments with arbuscular mycorrhizal fungi. In the field study, fern mortality was 24% higher in clayey soil than in sandy soil due to waterlogging, while As was primarily associated with sandy soil. Results from the sandy loam soil indicate that soil treatments did not significantly increase As phytoextraction, which was lower in phosphate-treated ferns than in control ferns, both in the field and greenhouse study. Under greenhouse conditions, ferns treated with organic N were

  10. Synthesis and Characterization of the Hybrid Clay- Based Material Montmorillonite-Melanoidin: A Potential Soil Model

    Energy Technology Data Exchange (ETDEWEB)

    V Vilas; B Matthiasch; J Huth; J Kratz; S Rubert de la Rosa; P Michel; T Schäfer

    2011-12-31

    The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay-based material (HCM), montmorillonite (STx-1)-melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx-1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. The melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle.

  11. Effect of ISPAD Anaerobic Digestion on Ammonia Volatilization from Soil Applied Swine Manure

    Directory of Open Access Journals (Sweden)

    Susan King

    2012-01-01

    Full Text Available Swine manure subjected to in-storage psychrophilic anaerobic digestion (ISPAD undergoes proteins degradation but limited NH3 volatilization, producing an effluent rich in plant-available nitrogen. Accordingly, ISPAD effluent can offer a higher fertilizer value during land application, as compared to manure of similar age stored in an open tank. However, this additional nitrogen can also be lost by volatilization during land application. The objective of this study was therefore to measure NH3 volatilization from both ISPAD and open tank swine manures when applied to 5 different soils, namely, washed sand, a Ste Rosalie clay, an Upland sandy loam, a St Bernard loam, and an Ormstown loam. This research was conducted using laboratory wind tunnels simulating land application. The five experimental soils offered similar pH values but different water holding capacity, cation exchange capacity, cation saturation, and organic matter. After 47 h of wind tunnel monitoring, the % of total available nitrogen (TAN or NH4 + and NH3 volatilized varied with both manure and soil type. For all soil types, the ISPAD manure consistently lost less NH3 as compared to the open tank manure, averaging 53% less. Lower volatile solids content improving manure infiltration into the soil and a more complex ionic solution explain the effect of the ISPAD manure advantages. This was reinforced by the St Bernard sandy loam losing the same nitrogen mass for both manures, because of its higher pH and buffer pH coupled with an intermediate CEC resulting in more soil solution NH3. Within each manure type, % TAN volatilized was highest for washed sand and lowest for the clay soil. As a result, ISPAD manure can offer up to 21% more plant-available nitrogen fertilizer especially when the manure is not incorporated into the soil following its application.

  12. Sorption of water vapour by the Na+-exchanged clay-sized fractions of some tropical soil samples

    International Nuclear Information System (INIS)

    Water vapour sorption isotherms at 299K for the Na+-exchanged clay-sized (≤ 2μm e.s.d.) fraction of two sets of samples taken at three different depths from a tropical soil profile have been studied. One set of samples was treated (with H2O2) for the removal of much of the organic matter (OM); the other set (of the same samples) was not so treated. The isotherms obtained were all of type II and analyses by the BET method yielded values for the Specific Surface Areas (SSA) and for the average energy of adsorption of the first layer of adsorbate (Ea). OM content and SSA for the untreated samples were found to decrease with depth. Whereas removal of organic matter made negligible difference to the SSA of the top/surface soil, the same treatment produced a significant increase in the SSA of the samples taken from the middle and from the lower depths in the profile; the resulting increase was more pronounced for the subsoil. It has been deduced from these results that OM in the surface soil was less involved with the inorganic soil colloids than that in the subsoil. The increase in surface area which resulted from the removal of OM from the subsoil was most probably due to disaggregation. Values of Ea obtained show that for all the samples the adsorption of water vapour became more energetic after the oxidative removal of organic matter; the resulting ΔEa also increased with depth. This suggests that in the dry state, the ''cleaned'' surface of the inorganic soil colloids was more energetic than the ''organic-matter-coater surface''. These data provide strong support for the deduction that OM in the subsoil was in a more ''combined'' state than that in the surface soil. (author). 21 refs, 4 figs, 2 tabs

  13. Tensile behaviour of unsaturated compacted clay soils — A direct assessment method.

    OpenAIRE

    Stirling, R.A.; Hughes, P N; Davie, C. T.; Glendinning, S.

    2015-01-01

    This paper presents a new method for testing the behaviour of soils placed under tensile load and demonstrates its suitability for testing a number of soil types under various conditions including saturation, compaction and stabilisation. Validation of the results obtained for the soils at relatively low saturation has been conducted using the established Brazilian (indirect) test for measuring the tensile strength of brittle materials. A fair comparison has been found and the results highlig...

  14. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    OpenAIRE

    S. C. Vettorazzo; F. C. S. Amaral; J. C. Chitolina

    2001-01-01

    This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1), on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased ...

  15. Movement of 14C-carbofuran in a silt clay soil. A laboratory study

    International Nuclear Information System (INIS)

    Carbofuran is used in the Syrian Arab Republic to control the sitona weevil, Sitona crinitus Herbst (S. macularius Marsch), on legume crops. It is sprayed on soil to kill the immature stages, which attack the leaves close to the soil surface and the nitrogen fixing nodes on the roots in the soil. A laboratory study was conducted to examine the movement of this pesticide into the soil. A known amount of 14C-carbofuran (specific activity of 2 μCi/mg) was applied to the top of the soil columns inside hard polyvinyl chloride (PVC) cylinders inserted into PVC tanks filled with soil of the same origin. The columns were sampled at varying intervals for up to 120 days. Each column was divided vertically from top to bottom into five zones. Each zone was 5 cm high. The radioactive residues were Soxhlet extracted for 6 hours. Extracts were concentrated and the aliquots counted for radioactivity using a liquid scintillation counter (LSC). In addition, samples of Soxhlet extracted soil were combusted in a biological oxidizer and the radioactivity was counted using LSC. The results show that recovery was good. Twenty-four hours after treatment the total radioactivity recovered was 71% of the total amount of insecticide applied. The major radioactive residues were confined to the top 5 cm of the soil column 24 hours after application. The amount of radioactive residues present in the lower layers increased gradually with time. However, this was accompanied by a relatively rapid and gradual loss in the total radioactivity recovered from the whole soil column. At the end of the experiment, most of the recovered radioactive residues (29%) were bound to the soil surface, whereas only 2% of the applied dose was extractable from the whole soil column. (author). 11 refs, 1 fig., 1 tab

  16. Least Limiting Water Range of soils in the Colonia Agrícola de Turen, Venezuela

    Science.gov (United States)

    Perez, Maiby Yolanda; Florentino de Andreu, Adriana

    2013-04-01

    Soil physical degradation is a major problem affecting the soil quality for crops production in Venezuelan agricultural areas. The least limiting water range (LLWR) is considered a soil physical quality index defined as the range in soil water content within which the limitations to plant response associated with water potential, poor aeration and high mechanical resistance are minimal. The study was carried out to characterize the LLWR and to determine the LLWR response to structural changes on soils of the Colonia Agricola de Turen, Venezuela. The soils were cropped with maize under different tillage systems (no tillage, conventional and conventional - fallow) and non-cropped under native forest. Hundred and seventy undisturbed samples were taken from specific sites under each of the above soil conditions to determine the water retention curve, the soil resistance curve and bulk density. Disturbed samples were also taken from each site to determine particle size and organic matter content. Pedotransfer functions relating the water retention curve and soil resistance curve with particle size distribution, organic matter content and bulk density were developed and use to calculate the LLWR for each site. According to the results, soil physical degradation under conventional tillage and high clay content had the highest negative impact on the LLWR. For this case (silty clay loam soil), the LLWR became narrower due to the lower water content associated with poor aeration and the higher water content associated with high mechanical resistance. In contrast, for non degraded soils with high sand content (sandy loam) the LLWR showed the highest values associated with the water content at field capacity and the water content at permanent wilting point, both the upper and lower critical limits of LLWR. For silty loam and loam soils the LLWR declined with increasing bulk density and clay content associated with water content at field capacity and water content at high

  17. Innovative uses of organo-philic clays for remediation of soils, sediments and groundwater

    International Nuclear Information System (INIS)

    PCBs and similar low-solubility organic compounds continue to offer significant challenges in terrestrial and sediment remediation applications. While selective media such as granular activated carbon (GAC) have proven to be successful at absorbing soluble organics, these media may have reduced performance due to blinding in the presence of high molecular weight organic matter. An alternative technology addresses this problem with a clay-based adsorption media, which effectively and efficiently stabilizes low-solubility organic matter. OrganoclayTM reactive media utilizes granular sodium bentonite, which has been chemically modified to attract organic matter without absorbing water. The unique platelet structure of bentonite clays provides tremendous surface area and the capacity of the media to absorb over 60 percent of its own weight in organic matter. Because of these properties, organo-clays allow for several cost-effective in-situ remediation techniques, such as: - Flow-through filtration for removal of organic matter from aqueous solutions: Organoclay can be utilized as a fixed-bed media in a column operation. This specialty media offers a high efficient alternative to Granular Activated Carbon (GAC) when applied as a flow through media to remove oil, PCB and other low soluble organic contaminates from water. - Placement in a Reactive Core MatTM: Organoclay may be encapsulated into carrier textiles which are adhered together to create a thin reactive layer with high strength and even distribution of the reactive media. This type of delivery mechanism can be successfully applied in a sub aqueous or terrestrial environment for sediment capping applications - Permeable reactive barriers: Organoclay can deliver high sorption capacity, high efficiency, and excellent hydraulic conductivity as a passive reactive media in these applications. (authors)

  18. Critical soil bulk density for soybean growth in Oxisols

    Science.gov (United States)

    Keisuke Sato, Michel; Veras de Lima, Herdjania; Oliveira, Pedro Daniel de; Rodrigues, Sueli

    2015-10-01

    The aim of this study was to evaluate the critical soil bulk density from the soil penetration resistance measurements for soybean root growth in Brazilian Amazon Oxisols. The experiment was carried out in a greenhouse using disturbed soil samples collected from the northwest of Para characterized by different texture. The treatments consisted of a range of soil bulk densities for each soil textural class. Three pots were used for soybean growth of and two for the soil penetration resistance curve. From the fitted model, the critical soil bulk density was determined considering the penetration resistance values of 2 and 3 MPa. After sixty days, plants were cut and root length, dry mass of root, and dry mass of shoots were determined. At higher bulk densities, the increase in soil water content decreased the penetration resistance, allowing unrestricted growth of soybean roots. Regardless of soil texture, the penetration resistance of 2 and 3 MPa had a slight effect on root growth in soil moisture at field capacity and a reduction of 50% in the soybean root growth was achieved at critical soil bulk density of 1.82, 1.75, 1.51, and 1.45 Mg m-3 for the sandy loam, sandy clay loam, clayey, and very clayey soil.

  19. The Influence of Stress Treatments on the Microbial Biomass and the Rate of Decomposition of Humified Matter in Soils Containing Different Amounts of Clay

    DEFF Research Database (Denmark)

    Sørensen, Lasse Holst

    1983-01-01

    content of clay. The effect of the other treatments was largely the same in all 4 soils. The effect of the treatments towards the native biomass and humic matter was largely parallel to that on the labeled biomass. The observations are consistent with the view that the biomass as determined by fumigation...

  20. The effect of kauri (Agathis australis) on grain size distribution and clay mineralogy of andesitic soils in the Waitakere Ranges, New Zealand

    NARCIS (Netherlands)

    Jongkind, A.G.; Buurman, P.

    2006-01-01

    Kauri (Agathis australis) is generally associated with intense podzolisation, but little research has been carried out to substantiate this. We studied soil profiles, grain size distribution patterns and clay mineralogy under kauri and broadleaf/tree fern vegetation in the Waitakere Ranges, North Is

  1. Source zone remediation by ZVI-clay soil-mixing: Reduction of tetrachloroethene mass and mass discharge at a Danish DNAPL site

    DEFF Research Database (Denmark)

    Fjordbøge, Annika Sidelmann; Lange, Ida Vedel; Binning, Philip John;

    2012-01-01

    test was to document in situ destruction of the contaminant mass and the down-gradient response in contaminant mass discharge. The field sampling consisted of baseline measurements and a 19-month monitoring program (7 sampling campaigns) subsequent to the implementation of ZVI-Clay soil mixing. The...

  2. Evolution of the soil humus status on the calcareous Neogene clay dumps of the Sokolov quarry complex in the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Abakumov, E.V.; Frouz, Jan

    2009-01-01

    Roč. 42, č. 7 (2009), s. 718-724. ISSN 1064-2293 Grant ostatní: Russian Foundation for Basic Research(XE) 08-04-01128 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil humus status * calcareous Neogene clay dumps * Sokolov quarry complex Subject RIV: EH - Ecology, Behaviour Impact factor: 0.222, year: 2009

  3. CLAY MINERALS AND THE ACCUMULATION OF SOIL ORGANIC MATTER IN NORTHWESTERN U.S. FORESTS

    Science.gov (United States)

    Globally soils are an important terrestrial reservoir of carbon, storing approximately 3 times the carbon held in vegetation and 2 times the amount contained in the atmosphere. With the potential for global climate change it is imperative that world soils continue to be a sink f...

  4. Removal of Pah from clay soil contaminated with diesel oil by bioremediation treatments

    International Nuclear Information System (INIS)

    Diesel oil is one of the most common soil organic pollutants, as a consequence of spilling of storage tank spills and accidental leaks. In Pernambuco State, Northeast part of Brazil, there are several evidences of soil contamination by petroleum derivates due to gas station leaking. (Author)

  5. Removal of Pah from clay soil contaminated with diesel oil by bioremediation treatments

    Energy Technology Data Exchange (ETDEWEB)

    Changas-spinelli, A. C. O.; Kato, M. T.; Lima, E. S.; Gavazza, S.

    2009-07-01

    Diesel oil is one of the most common soil organic pollutants, as a consequence of spilling of storage tank spills and accidental leaks. In Pernambuco State, Northeast part of Brazil, there are several evidences of soil contamination by petroleum derivates due to gas station leaking. (Author)

  6. Settling Velocity, Aggregate Stability, and Interrill Erodibility of Soils Varying in Clay Mineralogy

    Science.gov (United States)

    The relation of soil structural stability with soil erodibility depends on the mechanisms of aggregate disruption of different aggregate sizes and the measurement technique. In this study, we evaluated the relationship between settling velocity and stability of aggregates of different sizes, and int...

  7. influence of some types of Algerian soil on the development of rot-knot nematodes Meloidogyne incognita, M. javanica and M. arenaria (Tylenchida,Meloidogynidae)

    International Nuclear Information System (INIS)

    Crops under greenhouses offer the possibility of vegetables production of high added value by focusing on earliness. They help to spread the availability timing of vegetables and fruits in the market throughout the year. However, these crops are subject to numerous attacks entailing heavy losses of yield quantity and quality. The plant parasitic nematodes especially rot-knot nematodes of the genus Meloidogyne are considered dangerous enemies of these cultures. The evolution study of these nematodes in different soil types allows one to compare the migration and movement of these nematodes in sandy soils considered as light soils, in clay soils heavy and intermediate silty clay soils. These soils have also rates of organic matter and a percentage of magnesium and calcium that might provide better conditions to the survival and migration of second stage larvae inoculated at a rate of 650 juveniles per pot of 24 cm in diameter where plants of melon Cucumis melo var. (Charentais) known to be susceptible to Meloidogyne was cultivated. The results for the population development of Meloidogyne, after a growing period of 3 months show an increase in the number of eggs, juvenile stages, inflated, swollen females and males in the 3 types of soil and that independently of clay fraction although clay soil may asphyxiate Meloidogyne. The development of the three species of Meloidogyne studied in these soils, the parameters taken into consideration (index of galls, which were 1.58, 1.75 and 1.5 for the sandy clay and the middle ground soils, vigour index and the evolution of populations of Meloidogyne and roots and soil as well as parameters related to production reveal the adaptation of these root-knot nematodes to the clay and sandy loam soils. At the end of culture, the final populations are important in the soils studied; 2680 for soil S. (sandy), 2272 for soil A (clay) and 2327 for soil I (intermediate) with a multiplication rate almost similar ( 4.12, 3.49 and 3

  8. Nematodes in clay colliery spoil dumps and experimentally introduced strips of meadow soil

    Czech Academy of Sciences Publication Activity Database

    Háněl, Ladislav

    České Budějovice : Institute of Soil Biology ASCR, 2005, s. 19-23. ISBN 80-86525-04-X. [Contributions to soil Zoology in Central Europe I. Central European Workshop on Soil Zoology /7./. České Budějovice (CZ), 14.04.2003-16.04.2003] R&D Projects: GA ČR(CZ) GA526/01/1055 Institutional research plan: CEZ:AV0Z6066911 Keywords : nematoda * trophic groups * landscape reclamation Subject RIV: EH - Ecology, Behaviour

  9. New Technique Assessment of Plastic Limit of Soft Clay Particularly Peat Soils

    OpenAIRE

    Adon, Rashidah; Yasufuku, Noriyuki; Ishikura, Ryohei; Wijeyesekera, Devapriya

    2013-01-01

    Plastic Limit (PL) is considered as the moisture content at which soil becomes too dry to remain plastic. Both the British Standards Institute (BS 1377 (1990)) and American Society for Testing and Materials (ASTM D4318 (2001)) are consistent with their proposition of determining PL as the moisture content when the soil crumbles upon rolling it to thread of 3 mm diameter. However for challenging soils such as peat which is naturally organic substance derived from the remains of plants, the “ro...

  10. Root-Zone Redox Dynamics - In Search for the Cause of Damage to Treated-Wastewater Irrigated Orchards in Clay Soils

    Science.gov (United States)

    Yalin, David; Shenker, Moshe; Schwartz, Amnon; Assouline, Shmuel; Tarchitzky, Jorge

    2016-04-01

    Treated wastewater (TW) has become a common source of water for agriculture. However recent findings raise concern regarding its use: a marked decrease (up to 40%) in yield appeared in orchards irrigated with TW compared with fresh water (FW) irrigated orchards. These detrimental effects appeared predominantly in orchards cultivated in clay soils. The association of the damage with clay soils rather than sandy soils led us to hypothesize that the damage is linked to soil aeration problems. We suspected that in clay soils, high sodium adsorption ratio (SAR) and high levels of organic material, both typical of TW, may jointly lead to an extreme decrease in soil oxygen levels, so as to shift soil reduction-oxidation (redox) state down to levels that are known to damage plants. Two-year continuous measurement of redox potential, pH, water tension, and oxygen were conducted in the root-zone (20-35 cm depth) of avocado trees planted in clay soil and irrigated with either TW or FW. Soil solution composition was sampled periodically in-situ and mineral composition was sampled in tree leaves and woody organs biannually. In dry periods the pe+pH values indicated oxic conditions (pe+pH>14), and the fluctuations in redox values were small in both TW and FW plots. Decreases in soil water tension following irrigation or rain were followed by drops in soil oxygen and pe+pH values. TW irrigated plots had significantly lower minimum pe+pH values compared with FW-irrigated plots, the most significant differences occurred during the irrigation season rather than the rain season. A linear correlation appeared between irrigation volume and reduction severity in TW-irrigated plots, but not in the FW plots, indicating a direct link to the irrigation regime in TW-irrigated plots. The minimum pe+pH values measured in the TW plots are indicative of suboxic conditions (9soil solution and in

  11. Dynamic model for the transfer of CS-137 through the soil-grass-lamb foodchain

    DEFF Research Database (Denmark)

    Nielsen, S.P.

    1994-01-01

    A dynamic radioecological model for the transfer of radiocaesium through the soil-grass-lamb foodchain was constructed on the basis of field data collected in 1990–1993 from the Nordic countries: Denmark, Faroe Islands, Finland, Iceland, Norway and Sweden. The model assumes an initial soil...... contamination of one kilobecquerel of 137Cs per square metre and simulates the transfer to grass through root uptake in addition to direct contamination from resuspended activity. The model covers two different soil types: clay-loam and organic, with significantly different transfers of radiocaesium to grass...

  12. Dynamic model for the transfer of CS-137 through the soil-grass-lamb foodchain

    DEFF Research Database (Denmark)

    Nielsen, S.P.

    A dynamic radioecological model for the transfer of radiocaesium through the soil-grass-lamb foodchain was constructed on the basis of field data collected in 1990–1993 from the Nordic countries: Denmark, Faroe Islands, Finland, Iceland, Norway and Sweden. The model assumes an initial soil...... contamination of one kilobecquerel of 137Cs per square metre and simulates the transfer to grass through root uptake in addition to direct contamination from resuspended activity. The model covers two different soil types: clay-loam and organic, with significantly different transfers of radiocaesium to grass...

  13. Clay:organic-carbon and organic carbon as determinants of the soil physical properties: reassessment of the Complexed Organic Carbon concept

    Science.gov (United States)

    Matter, Adrien; Johannes, Alice; Boivin, Pascal

    2016-04-01

    Soil Organic Carbon (SOC) is well known to largely determine the soil physical properties and fertility. Total porosity, structural porosity, aeration, structural stability among others are reported to increase linearly with increasing SOC in most studies. Is there an optimal SOC content as target in soil management, or is there no limit in physical fertility improvement with SOC? Dexter et al. (2008) investigated the relation between clay:SOC ratio and the physical properties of soils from different databases. They observed that the R2 of the relation between SOC and the physical properties were maximized when considering the SOC fraction limited to a clay:SOC ratio of 10. They concluded that this fraction of the SOC was complexed, and that the additional SOC was not influencing the physical properties as strongly as the complexed one. In this study, we reassessed this approach, on a database of 180 undisturbed soil samples collected from cambiluvisols of the Swiss Plateau, on an area of 2400 km2, and from different soil uses. The physical properties were obtained with Shrinkage Analysis, which involved the parameters used in Dexter et al., 2008. We used the same method, but detected biases in the statistical approach, which was, therefore, adapted. We showed that the relation between the bulk density and SOC was changing with the score of visual evaluation of the structure (VESS) (Ball et al., 2007). Therefore, we also worked only on the "good" structures according to VESS. All shrinkage parameters were linearly correlated to SOC regardless of the clay:SOC ratio, with R2 ranging from 0.45 to 0.8. Contrarily to Dexter et al. (2008), we did not observed an optimum in the R2 of the relation when considering a SOC fraction based on the clay:SOC ratio. R2 was increasing until a Clay:SOC of about 7, where it reached, and kept, its maximum value. The land use factor was not significant. The major difference with the former study is that we worked on the same soil group

  14. Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

    Directory of Open Access Journals (Sweden)

    S. C. Vettorazzo

    2001-09-01

    Full Text Available This experiment was carried out under greenhouse conditions with soil pots during 210 days, to evaluate the effect of calcitic papermill lime-sludge application (at the rates 0, 773, 1.547, and 2.320 mg kg-1 or respective equivalents to control, 2, 4, and 6 t ha-1, on chemical composition of soil leachate and its effects on eucalypt growth and yield. Highest soil leachate pH, SO4, and Na concentrations occurred in the 4 and 6 t ha-1 treatments. Soil leachate nitrate concentrations decreased with increasing lime-sludge rate. Soil leachate phosphate remained low (below the detection limit in all treatments until 120 days, while the concentration increased in the lime-sludge treatments at 210 days (last sampling in about 600 mg L-1. Lime-sludge decreased leachate Mg concentration, but had no significant effect among rates. Soil leachate Ca, K, B, Cu, Fe, and Zn did not change significantly for any lime-sludge application rates. The maximum NO3, Ca, Mg, K, and Na concentrations in the soil leachate occurred at 60 days after lime-sludge application (leaching equivalent to 1 pore volume, but for pH and SO4, the maximum occurred at 210 days (leaching equivalent to 4 pore volumes. Lime-sludge application decreased the concentration of exchangeable Al in the soil. Plant diameter growth and dry matter yield were increased with increasing lime-sludge rate. Beneficial effects on mineral nutrition (P, K, Ca, B, and Zn of eucalypts were also obtained by the application of 4 and 6 t ha-1 of lime-sludge.

  15. A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation.

    Science.gov (United States)

    Suzuki, Tasuma; Moribe, Mai; Okabe, Yohhei; Niinae, Masakazu

    2013-06-15

    Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1 h ON, 1 h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency. PMID:23643955

  16. An Improved Description of the Seismic Response of Sites with High Plasticity Soils, Organic Clays, and Deep Soft Soil Deposits

    OpenAIRE

    Carlton, Brian

    2014-01-01

    Near surface soils can greatly influence the amplitude, duration, and frequency content of ground motions. The amount of their influence depends on many factors, such as the geometry and engineering properties of the soils and underlying bedrock, as well as the earthquake source mechanism and travel path. Building codes such as the 2012 International Building Code (IBC) define six site categories for seismic design of structures, which are based on the sites defined by the National Earthqua...

  17. Investigation of the transport of actinide-bearing soil colloids in the soil-aquatic environment

    International Nuclear Information System (INIS)

    Uranium-233 particle size dependent distribution ratios for the 10 to 60 range were determined for muscatine silt loam, Burbank loamy sand, Ritzville silt loam, Fuquay sand, and Idaho sandy clay. A mathematical method for the analysis of centrifuge data was developed to determine particle size dependent distribution ratio for the 10 to 60 nm range. Comparison of the distribution ratio data for the 0 to 60 nm particle size range strongly suggests that particles in the 1 to 10 nm (8000 to 50,000 MW) range play a dominate role. Since these particles are probably humic acid polymers, future research should be focused on humic acid complexing of radionuclides. A mathematical analysis is given to demonstrate the role of humic acid complexing in the transport of radionuclides in the soil-aquatic environment

  18. Mobility Studies of (14)C-Chlorpyrifos in Malaysian Oil Palm Soils.

    Science.gov (United States)

    Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol

    2016-01-01

    The mobility of (14)C-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (14)C-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (14)C-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos. PMID:26546229

  19. Introducing Fractal Dimension to Estimation of Soil Sensitivity to Preferential Flow

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Food dye Brilliant Blue was introduced as the tracer in a dye-tracing experiment to obtain dye profile patterns of sandy loam soil, aeolian sandy soil, percolating paddy soil and permeable paddy soil. The dyed soil profiles were then photographed and the photos were scanned into a computer. Edited with certain software, only the dyed areas were left on the profile photos, which indicted the preferential flow paths for water and solute transport. Fractal dimensions of the dye patterns were calculated according to Arnold's function. Soil particle size distribution was analyzed by pipette method. The regression analysis showed that there was significant relationship between soil clay content and fractal dimension D of the dye pattern of soil profile. Based on the experiment results, the possibility of introducing fractal dimension to estimation of soil sensitivity to preferential flow is discussed.

  20. Primary succession of soil rotifers in clays of brown coal post-mining dumps

    Czech Academy of Sciences Publication Activity Database

    Devetter, Miloslav; Frouz, J.

    2011-01-01

    Roč. 96, č. 2 (2011), s. 164-174. ISSN 1434-2944 R&D Projects: GA MŠk 2B08023 Institutional research plan: CEZ:AV0Z60660521 Keywords : soil rotifers * post mining dumps * primary succession Subject RIV: EH - Ecology, Behaviour Impact factor: 1.190, year: 2011

  1. Improvement of Soil Moisture Retrieval from Hyperspectral VNIR-SWIR Data Using Clay Content Information: From Laboratory to Field Experiments

    Directory of Open Access Journals (Sweden)

    Rosa Oltra-Carrió

    2015-03-01

    Full Text Available The aim of this work is to study the constraints and performance of SMC retrieval methodologies in the VNIR (Visible-Near InfraRed and SWIR (ShortWave InfraRed regions (from 0.4 to 2.5 µm when passing from controlled laboratory conditions to field conditions. Five different approaches of signal processing found in literature were considered. Four local criteria are spectral indices (WISOIL, NSMI, NINSOL and NINSON. These indices are the ratios between the spectral reflectances acquired at two specific wavelengths to characterize moisture content in soil. The last criterion is based in the convex hull concept and it is a global method, which is based on the analysis of the full spectral signature of the soil. The database was composed of 464 and 9 spectra, respectively, measured over bare soils in laboratory and in-situ. For each measurement, SMC and texture were well-known and the database was divided in two parts dedicated to calibration and validation steps. The calibration part was used to define the empirical relation between SMC and SMC retrieval approaches, with coefficients of determination (R2 between 0.72 and 0.92. A clay content (CC dependence was detected for the NINSOL and NINSON indices. Consequently, two new criteria were proposed taking into account the CC contribution (NINSOLCC and NINSONCC. The well-marked regression between SMC and global/local indices, and the interest of using the CC, were confirmed during the validation step using laboratory data (R² superior to 0.76 and Root mean square errors inferior to 8.3% m3∙m−3 in all cases and using in-situ data, where WISOIL, NINSOLCC and NINSONCC criteria stand out among the NSMI and CH.

  2. Carbon storage in a heavy clay soil landfill site after biosolid application

    International Nuclear Information System (INIS)

    Applying organic amendments including biosolids and composts to agricultural land could increase carbon (C) storage in soils and contribute significantly to the reduction of greenhouse gas emissions. Although a number of studies have examined the potential value of biosolids as a soil conditioner and nutrient source, there has been only limited work on the impact of biosolid application on C sequestration in soils. The objective of this study was to examine the potential value of biosolids in C sequestration in soils. Two types of experiments were conducted to examine the effect of biosolid application on C sequestration. In the first laboratory incubation experiment, the rate of decomposition of a range of biosolid samples was compared with other organic amendments including composts and biochars. In the second field experiment, the effect of biosolids on the growth of two bioenergy crops, Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) on a landfill site was examined in relation to biomass production and C sequestration. The rate of decomposition varied amongst the organic amendments, and followed: composts > biosolids > biochar. There was a hundred fold difference in the rate of decomposition between biochar and other organic amendments. The rate of decomposition of biosolids decreased with increasing iron (Fe) and aluminum (Al) contents of biosolids. Biosolid application increased the dry matter yield of both plant species (by 2–2.5 fold), thereby increasing the biomass C input to soils. The rate of net C sequestration resulting from biosolid application (Mg C ha−1 yr−1 Mg−1 biosolids) was higher for mustard (0.103) than sunflower (0.087). Biosolid application is likely to result in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage, which is attributed to increased microbial biomass, and Fe and Al oxide-induced immobilization of C. - Graphical

  3. Carbon storage in a heavy clay soil landfill site after biosolid application

    Energy Technology Data Exchange (ETDEWEB)

    Bolan, N.S., E-mail: Nanthi.Bolan@unisa.edu.au [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia); Kunhikrishnan, A. [Chemical Safety Division, Department of Agro-Food Safety, National Academy of Agricultural Science, Suwon-si, Gyeonggi-do 441-707 (Korea, Republic of); Naidu, R. [Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, SA 5095 (Australia); Cooperative Research Centre for Contaminants Assessment and Remediation of the Environment (CRC CARE), University of South Australia, SA 5095 (Australia)

    2013-11-01

    Applying organic amendments including biosolids and composts to agricultural land could increase carbon (C) storage in soils and contribute significantly to the reduction of greenhouse gas emissions. Although a number of studies have examined the potential value of biosolids as a soil conditioner and nutrient source, there has been only limited work on the impact of biosolid application on C sequestration in soils. The objective of this study was to examine the potential value of biosolids in C sequestration in soils. Two types of experiments were conducted to examine the effect of biosolid application on C sequestration. In the first laboratory incubation experiment, the rate of decomposition of a range of biosolid samples was compared with other organic amendments including composts and biochars. In the second field experiment, the effect of biosolids on the growth of two bioenergy crops, Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) on a landfill site was examined in relation to biomass production and C sequestration. The rate of decomposition varied amongst the organic amendments, and followed: composts > biosolids > biochar. There was a hundred fold difference in the rate of decomposition between biochar and other organic amendments. The rate of decomposition of biosolids decreased with increasing iron (Fe) and aluminum (Al) contents of biosolids. Biosolid application increased the dry matter yield of both plant species (by 2–2.5 fold), thereby increasing the biomass C input to soils. The rate of net C sequestration resulting from biosolid application (Mg C ha{sup −1} yr{sup −1} Mg{sup −1} biosolids) was higher for mustard (0.103) than sunflower (0.087). Biosolid application is likely to result in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage, which is attributed to increased microbial biomass, and Fe and Al oxide-induced immobilization of C

  4. Influence of climate and eolian dust on the major-element chemistry and clay mineralogy of soils in the northern Bighorn basin, U.S.A.

    Science.gov (United States)

    Reheis, M.C.

    1990-01-01

    Soil chronosequences in the northern Bighorn basin permit the study of chronologic changes in the major-element chemistry and clay mineralogy of soils formed in different climates. Two chronosequences along Rock Creek in south-central Montana formed on granitic alluvium in humid and semiarid climates over the past two million years. A chronosequence at the Kane fans in north-central Wyoming formed on calcareous alluvium in an arid climate over the past 600,000 years. Detailed analyses of elemental chemistry indicate that the soils in all three areas gradually incorporated eolian dust that contained less zirconium, considered to be chemically immobile during weathering, than did the alluvium. B and C horizons of soils in the wettest of the chronosequences developed mainly at logarithmic rates, suggesting that leaching, initially rapid but decelerating, dominated the dust additions. In contrast, soils in the most arid of the chronosequences developed at linear rates that reflect progressive dust additions that were little affected by leaching. Both weathering and erosion may cause changes with time to appear logarithmic in A horizons of soils under the moist and semiarid climatic regimes. Clay minerals form with time in the basal B and C horizons and reflect climatic differences in the three areas. Vermiculite, mixed-layer illite-smectite, and smectite form in the soils of the moist-climate chronosequence; smectite forms in the semiarid-climate chronosequence; and smectite and palygorskite form in the arid-climate chronosequence. ?? 1990.

  5. Aspects of the X-ray identification of swelling clay minerals in soils and sediments

    International Nuclear Information System (INIS)

    Despite the interest in and necessity for identifying swelling clay minerals of the smectite group because of their economic importance, routine investigation by conventional X-ray diffraction methods seldom includes any attempt to identify the sub-group or species of smectite. The more important techniques for achieving such identification are examined with special reference to the Greene-Kelly test and intercalation with alkylammonium chlorides. The Greene-Kelly test can only be used for dioctahedral species and stevensite and fails to distinguish between montmorillonite and beidellite in a manner consistent with the internationally recognised definitions for these species based on layer charge. A better differentiation of species is achieved by the alkylammonium chloride method, but the effort involved makes routine application unattractive unless an abbreviated version is applied, in which case, however, the presence of chlorite may produce an ambiguos result. There are, nevertheless, distinct advantages to the use of this method, both in obtaining an identification of smectite species which is most consistent with definition, and in being able to predict the usefulness of a particular smectite for certain types of industrial application

  6. Bioavailability in rats of metal adsorbed to soils

    International Nuclear Information System (INIS)

    The toxicity of metals to humans and animals has been well documented, however little data are available on the physiological bioavailability of metals from various soil types. These studies were designed to assess the bioavailability of sodium 75selenate (NaS), 63nickel chloride (NiCl) and 109cadmium chloride (CdCl) adsorbed to sand or clay loam in rats. Each test compound was administered in seven dose groups: Group 1 - intravenously, Group 2 and 3 - oral aqueous solution by gavage, Groups 4-7 - aqueous suspension adsorbed to each soil type by gavage. Blood was collected from the jugular vein at intervals up to 48 hours post dosing and analyzed for radio-activity. Both NiCl and CdCl were poorly adsorbed from the soils. Approximately 3% of the CdCl bound to sand and 1.5% of the NiCl bound to clay loam were absorbed into the bloodstream. Approximately 0.5% and 0.1% of the CdCl bound to sand and clay, respectively were absorbed. NaS was well absorbed following oral administration with approximately 85% of the compound bound to sand and 94% bound to clay being absorbed into the blood. Bioavailability of metals from soil appears to be primarily affected by the ionic state of the metal. Anions, such as selenium, are more mobile in an acid environment and may leach more readily from soil. Cations, such as Ni and Cd may bind to soil more tightly, thus soil type becomes a factor affecting bioavailability

  7. Influence of elevation factor on soil profile texture configuration: a case study of the alluvial plain of Fengqiu County%冲积平原区高程因子对土壤剖面质地构型的影响——以封丘县为例

    Institute of Scientific and Technical Information of China (English)

    檀满枝; 密术晓; 李开丽; 陈杰

    2011-01-01

    Profile texture configuration of the soil in alluvial plains is a crucial factor determining soil water and nutrient conserving and supplying capacity and water and salt movement in the soil.Among the six major soil-forming factors in this regional soil, topography stands out to be the most prominent one.Analysis of the influence of topography on soil profile texture configuration is of important theoretical and practical significance to guiding agricultural production.Using the fuzzy c-means algorithm model nine soil profiles different in texture configuration was defined.Based on the data of thicknesses of the characteristic texture layers of nine soil profiles including sandy, loamy and clayey, surface layers, (0 -(30±10)cm),sandy, loamy and clayey center layers ( ( 30 ± 10 ) cm - ( 60 ± 10) cm) and sandy, loamy and clayey bottom layers ( ( 60 ± 10 )cm-(90±10) cm), nine types of soil profile texture configuration were identified, i.e.loam-clay-loam, loam-loam-clay,loam-clay-clay, clay-clay-clay, sand-sand-clay, sand-sand-sand, sand-loam-loam, loam-loam-sand and loam-loam-loam,among which loam-loam-loam and sand-sand-sand were the dominant types.As a result of frequent flooding by the Yellow River in history, oomplex process of sediment deposition, and in addition fanning practices and soil amelioration measures,like irrigation, deep plowing and field leveling, soil profile texture configuration varied sharply in distribution at a small spatial scale.Comparison analysis of the influence of landform on soil texture profile configuration in the whole study area and the typical area relatively concentrated with various types of soil profile texture configuration, shows that a positive correlation always exists between membership value of the soil profile texture configuration of the sand-sand-sand type and elevation,suggesting that the law prevails that soils in lands relatively high in elevation tend to be sandy, while the influence of landform on soil profile

  8. Comparative evaluation of the effect of rock phosphate and monoammonium phosphate on plant P: Nutrition in Sod-podzolic and peat soils

    International Nuclear Information System (INIS)

    The direct application of finely ground rock phosphate (RP) imported from Russia has been suggested as an alternative to the almost twice more expensive water-soluble monoammonium phosphate (MAP) on acid (moderately limed) Sod-podzolic and peat soils. A pot experiment was conducted in 1997-1998 for a comparative evaluation of P availability from RP and MAP using the 32P isotope dilution technique. The lupine was grown on Sod-podzolic silty clay loam soil with pH 6.0 and a medium level of available P. Ryegrass plants were grown on peat soil with pH 4.9 and a low level of native soil P fertility. Application of RP and MAP at a rate of 40 mg P/kg soil supplied similar moderate mount of P to lupine plants. The Pdff values, i.e. the fractions of P in the plants derived from the applied RP and MAP, were 7.4 and 8.4%, respectively. The application of the same P fertilizers to the peat soil had different effects on P nutrition of ryegrass plants. The Pdff values were 14.9% for RP and 22.1% for MAP. It may be concluded that for most annual crops water-soluble P forms such as MAP should be preferred. Direct application of RP is recommended for plants with an adequate rhizosphere ability to utilize P, such as lupine on acid Sod-podzolic silty clay loam soils (pH137Cs on contaminated, moderately limed Sod-podzolic silty clay loam and peat soils. These soils are widely spread in the radioactive contaminated area of Belarus after the Chernobyl accident. Direct application of RP may be one of the effective countermeasures for the decrease of 137Cs transfer from the contaminated acid soils to crop production. (author)

  9. Transport, sorption and degradation of atrazine in two clay soils from Mexico : Andosol and Vertisol

    OpenAIRE

    Prado, B.; Duwig, Céline; Hidalgo, C; Muller, K.; de Mora, L.; Raymundo, E.; Etchevers, J.D.

    2014-01-01

    Although atrazine has been banned in the European Union, it is still one of the most widely used herbicides in the world. It is has been detected in surface and groundwater and has been shown to be associated with major human health problems. Atrazine fate in the environment, e.g. sorption, leaching and degradation depends, inter alia, on soil characteristics. Independent static and dynamic experiments were conducted to identify and uncouple the processes governing the fate of atrazine. Two a...

  10. Performance of a Bentleg Subsoiler with Shallow Tines in a Clay Soil

    OpenAIRE

    M. H. Raoufat; M. Kazemi Najaf Abadi

    2007-01-01

    The present research was intended to alleviate the problems and costs of deep tilling in sugarcane production in Mian-Ab sugarcane farms located in Khuzestan province, Iran. The main objective was to investigate the feasibility of subsoiling operations with bentleg subsoiler (BLS) equipped with shallow tines, a combination expected to increase the critical depth resulting in less power consumption and improved soil physical conditions. Six treatments arranged in a completely randomized block ...

  11. Natural clay based soil as an effective barrier against radionuclide migration in a uranium tailings structure

    International Nuclear Information System (INIS)

    Olympic Dam Operations mines and processes copper, uranium, silver and gold from a vast underground ore body located in the far north of South Australia. The tailings from the milling operation are pumped at the current rate of 2.3 million tonnes annually into an above ground Tailings Retention System (TRS) covering an area of 180 hectares. Initial studies conducted at a small scale pilot plant TRS in 1985 indicated that contaminants in the acid based tailings were reduced to background levels within a short distance after the tailings/soil interface. This study was commenced to confirm the effectiveness of the natural soils at the base of the current TRS in preventing downward migration of radionuclides. Core samples have been taken at a number of locations, and radionuclide concentrations plotted against depth. Results from the core samples taken to date have confirmed that downward radionuclide movement is effectively stopped within the first 40 centimeters after the tailings/soil interface. 5 refs., 1 tab., 7 figs

  12. Adsorption-desorption and leaching behavior of kresoxim-methyl in different soils of India: kinetics and thermodynamic studies.

    Science.gov (United States)

    Sabale, Rupali P; Shabeer T P, Ahammed; Dasgupta, Soma; Utture, Sagar C; Banerjee, Kaushik; Oulkar, Dasharath P; Adsule, Pandurang G; Deshmukh, Madhukar B

    2015-07-01

    The sorption and leaching behavior of kresoxim-methyl was explored in four different soils, viz., clay, sandy loam, loamy sand, and sandy loam (saline), representing vegetables and fruits growing regions of India. Adsorption of kresoxim-methyl in all the soils reached equilibrium within 48 h. The rate constants for adsorption and desorption at two different temperatures were obtained from the Lindstrom model, which simultaneously evaluated adsorption and desorption kinetics. The data for rate constants, activation energies, enthalpy of activation, entropy of activation, and free energy indicated physical adsorption of kresoxim-methyl on soil. The relative adsorptivity of the test soils could be attributed to different organic matter and clay contents of the soils. A good fit to the linear and Freundlich isotherms was observed for both adsorption as well as desorption. The groundwater ubiquity score (GUS) for different soils varied between 0 and 2.26. The GUS and leaching study indicated moderately low leaching potential of kresoxim-methyl. The adsorption on four soil types largely depended on the soil physicochemical properties such as organic carbon content, cation-exchange capacity, and texture of the soil. PMID:26082423

  13. Boron and Zinc Transport Through Intact Columns of Calcareous Soils

    Institute of Scientific and Technical Information of China (English)

    M. MAHMOOD-UL-HASSAN; M. S. AKHTAR; G. NABI

    2008-01-01

    Leaching of boron (B) and zinc (Zn) can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter ×28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures:Lyallpur soil series, clay loam (fine-silty, mixed, hyperthermic Ustalfic Haplargid), and Sultanpur soil series, sandy loam (coarse-silty, mixed, hyperthermic Ustollic Camborthid). The adsorption isotherms were developed by equilibrating soil with 0.01 mol L-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L-1 blue dye solution was also applied to each column to mark the flow paths.The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio (the concentration in solution at equilibrium/concentration applied) was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils.

  14. Use of a flashiness index to predict phosphorus losses from subsurface drains on a Swedish farm with clay soils

    Science.gov (United States)

    Ulén, Barbro; Stenberg, Maria; Wesström, Ingrid

    2016-02-01

    Risk assessment for elevated leaching losses of phosphorus (P) from agricultural land is commonly based on indices, since such losses are highly episodic and difficult to predict. Here a flashiness index (FI) representing changes in daily water flow from drainage systems was estimated from measured discharge (agrohydrological years 2004-2013) after reconstruction of subsurface drainage systems in 16 fields on a former swine farm. The fields were analysed for ammonium lactate-extractable soil P (P-AL), clay, carbon and other soil parameters in 2004. Transport of total P (TP), dissolved reactive P (DRP) and unreactive P (UP) was estimated from concentrations in composite water samples taken flow-proportionally up to 20 times per year. On average, 2.20 kg TP ha-1 yr-1 was leached, with 27% in DRP form, from the entire farm. FI was significantly negatively correlated (Pearson correlation coefficient p < 0.05) to mean yearly discharge from each field. Stepwise regression demonstrated that FI index was the most important single explanatory parameter for flow-proportional yearly mean concentration of unreactive P losses (UP) from each field, with a coefficient of determination (r2) of 0.67. The corresponding concentration of dissolved reactive P (DRP) was significantly positively correlated (p = 0.015) to soil P-AL and FI. A regression model for TP leaching losses based on FI, P-AL and yearly discharge (Q) from 11 of the fields over nine years (r2 = 0.67, p = 0.002) was validated against TP leaching from the remaining five fields (32% of farm area). Root mean square error (RMSE) was 0.43, which represented 20% of measured leaching (mean 2.14 kg TP ha-1 yr-1). For individual years, RMSE for different fields was 37-80% of measured TP leaching (0.8-3.7 kg TP ha-1 yr-1). The FI index could be used together with soil P test to predict P leaching from individual fields of a drained farm.

  15. Mass relocation through soil exhaustion: Transformation of habitation patterns in the southern Netherlands (1000 BC-500 AD)

    Science.gov (United States)

    Kluiving, Sjoerd; Bekkema, Marijke; Roymans, Nico; van Mourik, Jan

    2015-04-01

    Long-term archaeological data gathering in the southern Netherlands may deliver an unprecedented regional comparison that could be exemplary for the Pleistocene sand areas of the Northwest European Plain. On a micro-scale level, it has become clear that Bronze Age (2000-800 BC) and Iron Age (800-12 BC) farmers intensively used the landscape, resulting in a relatively dense distribution pattern of settlements all over the ridges and planes of the cover sand landscape. However, this agricultural use of the landscape related to the "celtic field" system led to a process of soil degradation by increased acidification during which Umbric Podzols gradually transformed into Carbic Podzols that could no longer be used as farmland. According to established "models," this process of "secondary podzolization" particularly affected those sections of the landscape that were dominated by dry sandy soils with a low loam content (loam = clay and silt, between c. 10% and 20%). In the Late Iron Age (250-12 BC), the changing soil conditions resulted in a dramatic shift in the habitation pattern that clearly manifests itself in the Roman period (12 BC-410 AD); on the local scale, the habitation moved from the degenerated soils to nearby areas with better soil conditions (higher loam content), which became more densely inhabited now than in the Bronze Age/Early Iron Age (2000-500 BC). The introduction of new land management (in the later Iron Age, and also by Romans) could also have been important for soil degradation. The areas where the Roman period settlements concentrated became also the areas where we can find the early medieval habitation (447-751 AD) and where the Plaggic Anthrosols started to develop in the late medieval period (1270-1500 AD). This poster is based on the analysis of soil properties. Measured loam values of soil samples (n=181) in Veldhoven, southern Netherlands, are in agreement with the described model that the plaggen cover is located on soils containing high

  16. In-situ studies on the performance of landfill caps (compacted soil liners, geomembranes, geosynthetic clay liners, capillary barriers)

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, S. [IGB - Ingenieurbuero fuer Grundbau, Hamburg (Germany)

    1997-12-31

    Since 1986 different types of landfill covers have been studied in-situ on the Georgswerder landfill in Hamburg, Germany. Water balance data are available for eight years. The performance of different carriers has been measured by collecting the leakage on areas ranging from 100 m{sup 2} to 500 m{sup 2}. Composite liners with geomembranes performed best, showing no leakage. An extended capillary barrier also performed well. The performance of compacted soil liners, however, decreased severely within five years due to desiccation, shrinkage and plant root penetration (liner leakage now ranging from 150 mm/a to 200 mm/a). About 50 % of the water that reaches the surface of the liner is leaking through it. The maximum leakage rates have increased from 2 x 10{sup -10} m{sup 3} m{sup -2} s{sup -1} to 4 x 10{sup -8} m{sup 3} m{sup -2} s{sup -1}. Two types of geosynthetic clay liners (GCL) have been tested for two years now with disappointing results. The GCL desiccated during the first dry summer of the study. High percolation rates through the GCL were measured during the following winter (45 mm resp. 63 mm in four months). Wetting of the GCL did not significantly reduce the percolation rates.

  17. In-situ studies on the performance of landfill caps (compacted soil liners, geomembranes, geosynthetic clay liners, capillary barriers)

    International Nuclear Information System (INIS)

    Since 1986 different types of landfill covers have been studied in-situ on the Georgswerder landfill in Hamburg, Germany. Water balance data are available for eight years. The performance of different carriers has been measured by collecting the leakage on areas ranging from 100 m2 to 500 m2. Composite liners with geomembranes performed best, showing no leakage. An extended capillary barrier also performed well. The performance of compacted soil liners, however, decreased severely within five years due to desiccation, shrinkage and plant root penetration (liner leakage now ranging from 150 mm/a to 200 mm/a). About 50 % of the water that reaches the surface of the liner is leaking through it. The maximum leakage rates have increased from 2 x 10-10 m3 m-2 s-1 to 4 x 10-8 m3 m-2 s-1. Two types of geosynthetic clay liners (GCL) have been tested for two years now with disappointing results. The GCL desiccated during the first dry summer of the study. High percolation rates through the GCL were measured during the following winter (45 mm resp. 63 mm in four months). Wetting of the GCL did not significantly reduce the percolation rates

  18. Tillage System and Cover Crop Effects on Soil Quality

    DEFF Research Database (Denmark)

    Abdollahi, Lotfollah; Munkholm, Lars Juhl

    2014-01-01

    , penetration resistance, and visual evaluation of soil structure (VESS). In the laboratory, aggregate strength, water-stable aggregates (WSA), and clay dispersibility were measured. The analyzed chemical and biological properties included soil organic C (SOC), total N, microbial biomass C, labile P and K, and......Optimal use of management systems including tillage and winter cover crops is recommended to improve soil quality and sustain agricultural production. The effects on soil properties of three tillage systems (as main plot) including direct drilling (D), harrowing to a depth of 8 to 10 cm (H), and...... moldboard plowing (MP) with and without a cover crop were evaluated in a long-term experiment on a sandy loam soil in Denmark. Chemical, physical, and biological soil properties were measured in the spring of 2012. The field measurements included mean weight diameter (MWD) after the drop-shatter test...

  19. Dielectric properties of soils as a function of moisture content

    Science.gov (United States)

    Cihlar, J.; Ulaby, F. T.

    1974-01-01

    Soil dielectric constant measurements are reviewed and the dependence of the dielectric constant on various soil parameters is determined. Moisture content is given special attention because of its practical significance in remote sensing and because it represents the single most influential parameter as far as soil dielectric properties are concerned. Relative complex dielectric constant curves are derived as a function of volumetric soil water content at three frequencies (1.3 GHz, 4.0 GHz, and 10.0 GHz) for each of three soil textures (sand, loam, and clay). These curves, presented in both tabular and graphical form, were chosen as representative of the reported experimental data. Calculations based on these curves showed that the power reflection coefficient and emissivity, unlike skin depth, vary only slightly as a function of frequency and soil texture.

  20. Sorption of cesium and strontium by arid region desert soil

    International Nuclear Information System (INIS)

    Adsorption and ion exchange in soil systems are the principal mechanisms that retard the migration of nuclear waste to the biosphere. Cesium and strontium are two elements with radioactive isotopes (Cs137 and Sr90) that are commonly disposed of as nuclear waste. The sorption and ion exchange properties of nonradioactive cesium and strontium were studied in this investigation. The soil used in this study was collected at an experimental infiltration site on Frenchman Flat, a closed drainage basin on the Nevada Test Site. This soil is mostly nonsaline-alkali sandy loam and loamy sand with a cation exchange capacity ranging from 13 to 30 me/100g. The clay fraction of the soil contains illite, montmorillonite, and clinoptilolite. Ion exchange studies have shown that this soil sorbs cesium preferentially relative to strontium, and that charge for charge, the exchange-phase cations released from exchange sites exceed the cesium and strontium sorbed by the soil. 38 references, 22 figures

  1. Sedimentos arcillosos en un suelo del valle inferior del río Colorado (Argentina Clay sediments in a soil of the lower Colorado river valley (Argentina

    Directory of Open Access Journals (Sweden)

    Norman Peinemann

    2008-12-01

    Full Text Available Se describe la presencia de capas sedimentarias ricas en minerales de arcilla en un subsuelo del valle inferior del río Colorado por su importancia para el régimen hídrico de suelos bajo riego. Difractogramas de rayos X efectuados sobre la fracción arcilla fina de estos sedimentos revelaron que está compuesta por smectitas con muy buena cristalización. La caracterización fisicoquímica del perfil de suelo mostró que el fuerte incremento de minerales de arcilla en el subsuelo estuvo vinculado con un aumento de pH y PSI y en consecuencia una marcada disminución en la conductividad hidráulica, motivo por el cual la eventual presencia de estas capas sedimentarias debe ser muy tenida en cuenta en la programación de las prácticas de riego para evitar el posible deterioro de los suelos.The presence of sedimentary clay layers in subsoils of the lower Colorado river valley are described due to their impact on the water balance of soils under irrigation. X-ray difractograms of the fine clay fraction of these sediments show that they are composed of smectites with a very good crystallization. The physicochemical characterization of the soil profile indicates that the abrupt increase of clay minerals was associated with high pH and ESP values as well as a sharp decrease in hydraulic conductivity. Therefore, the presence of sedimentary clay layers in soils has to be considered when planning irrigation practices to avoid soil degradation.

  2. Selenium bioavailability and uptake as affected by four different plants in a loamy clay soil with particular attention to mycorrhizae inoculated ryegrass

    International Nuclear Information System (INIS)

    The aim of this study was to investigate the influence of plant species, especially of their rhizosphere soil, and of inoculation with an arbuscular mycorrhizal (AM) fungus on the bioavailability of selenium and its transfer in soil-plant systems. A pot experiment was performed with a loamy clay soil and four plant species: maize, lettuce, radish and ryegrass, the last one being inoculated or not with an arbuscular mycorrhizal fungus (Glomus mosseae). Plant biomass and Se concentration in shoots and roots were estimated at harvest. Se bioavailability in rhizosphere and unplanted soil was evaluated using sequential extractions. Plant biomass and selenium uptake varied with plant species. The quantity of rhizosphere soil also differed between plants and was not proportional to plant biomass. The highest plant biomass, Se concentration in plants, and soil to plant transfer factor were obtained with radish. The lowest Se transfer factors were obtained with ryegrass. For the latter, mycorrhizal inoculation did not significantly affect plant growth, but reduced selenium transfer from soil to plant by 30%. In unplanted soil after 65 days aging, more than 90% of added Se was water-extractable. On the contrary, Se concentration in water extracts of rhizosphere soil represented less than 1% and 20% of added Se for ryegrass and maize, respectively. No correlation was found between the water-extractable fraction and Se concentration in plants. The speciation of selenium in the water extracts indicated that selenate was reduced, may be under organic forms, in the rhizosphere soil

  3. Selenium bioavailability and uptake as affected by four different plants in a loamy clay soil with particular attention to mycorrhizae inoculated ryegrass

    Energy Technology Data Exchange (ETDEWEB)

    Munier-Lamy, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: colette.munier@limos.uhp-nancy.fr; Deneux-Mustin, S. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Mustin, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: christian.mustin@limos.uhp-nancy.fr; Merlet, D. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: denis.merlet@limos.uhp-nancy.fr; Berthelin, J. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: jacques.berthelin@limos.uhp-nancy.fr; Leyval, C. [LIMOS, UMR 7137 CNRS-Nancy University, Faculty of Sciences, P.O. Box 239, F-54506 Vandoeuvre-les-Nancy Cedex (France)], E-mail: corinne.leyval@limos.uhp-nancy.fr

    2007-10-15

    The aim of this study was to investigate the influence of plant species, especially of their rhizosphere soil, and of inoculation with an arbuscular mycorrhizal (AM) fungus on the bioavailability of selenium and its transfer in soil-plant systems. A pot experiment was performed with a loamy clay soil and four plant species: maize, lettuce, radish and ryegrass, the last one being inoculated or not with an arbuscular mycorrhizal fungus (Glomus mosseae). Plant biomass and Se concentration in shoots and roots were estimated at harvest. Se bioavailability in rhizosphere and unplanted soil was evaluated using sequential extractions. Plant biomass and selenium uptake varied with plant species. The quantity of rhizosphere soil also differed between plants and was not proportional to plant biomass. The highest plant biomass, Se concentration in plants, and soil to plant transfer factor were obtained with radish. The lowest Se transfer factors were obtained with ryegrass. For the latter, mycorrhizal inoculation did not significantly affect plant growth, but reduced selenium transfer from soil to plant by 30%. In unplanted soil after 65 days aging, more than 90% of added Se was water-extractable. On the contrary, Se concentration in water extracts of rhizosphere soil represented less than 1% and 20% of added Se for ryegrass and maize, respectively. No correlation was found between the water-extractable fraction and Se concentration in plants. The speciation of selenium in the water extracts indicated that selenate was reduced, may be under organic forms, in the rhizosphere soil.

  4. Fate of {sup 14}C-triclocarban in biosolids-amended soils

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, Elizabeth Hodges, E-mail: lizah@ufl.edu [Soil and Water Science Department, University of Florida, 408 Newell Hall, Gainesville, Florida, 32611 (United States); Department of Health Sciences, University of Alaska Anchorage, DPL 404, 3211 Providence Drive, Anchorage, AK 99508-4614 (United States); O' Connor, George A., E-mail: gao@ufl.edu [Soil and Water Science Department, P.O. Box 110510, University of Florida, Gainesville, FL 32611-01519 (United States); McAvoy, Drew C., E-mail: mcavoy.dc@pg.com [Environmental Safety Department, P.O. Box 538707, The Procter and Gamble Company, Cincinnati, OH, 45253-8707 (United States)

    2010-06-01

    Triclocarban (TCC) is an antibacterial compound commonly detected in biosolids at parts-per-million concentrations. Approximately half of the biosolids produced in the United States are land-applied, resulting in a systematic release of TCC into the soil environment. The extent of biosolids-borne TCC environmental transport and potential human/ecological exposures will be greatly affected by its bioavailability and the rate of degradation in amended soils. To investigate these factors, radiolabeled TCC ({sup 14}C-TCC) was incorporated into anaerobically digested biosolids, amended to two soils, and incubated under aerobic conditions. The evolution of {sup 14}CO2 (biodegradation) and changes in chemical extractability (bioavailability) was measured over time. Water extractable TCC over the study period was low and significantly decreased over the first 3 weeks of the study (from 14% to 4% in a fine sand soil and from 3 to < 1% in a silty clay loam soil). Mineralization (i.e. ultimate degradation), as measured by evolution of {sup 14}CO{sub 2}, was < 4% over 7.5 months. Methanol extracts of the amended soils were analyzed by radiolabel thin-layer chromatography (RAD-TLC), but no intermediate degradation products were detected. Approximately 20% and 50% of the radioactivity in the amended fine sand and silty clay loam soils, respectively, was converted to bound residue as measured by solids combustion. These results indicate that biosolids-borne TCC becomes less bioavailable over time and biodegrades at a very slow rate.

  5. Effect of regenerated soil structure on unsaturated transport of Escherichia coli and bromide

    Science.gov (United States)

    Safadoust, A.; Mahboubi, A. A.; Mosaddeghi, M. R.; Gharabaghi, B.; Unc, A.; Voroney, P.; Heydari, A.

    2012-04-01

    SummaryThis study was conducted to assess the role of the regeneration of soil structure by physical weathering of soils in columns on the transport of Nalidixic acid-resistant Escherichia coli strain (E. coli NAR) and also Bromide (Br). Leaching experiments were carried out at steady-state flow conditions, under a suction head of 5 cm, through columns of repacked and weathered clay loam (CL) and sandy loam (SL) soils. A pulse-type boundary condition was used and breakthrough curves for bacteria and Br were obtained at three depths during a 24 h leaching experiment. Observed data were analyzed employing the mobile-immobile water (MIM) models for repacked or weathered soil columns using HYDRUS-1D code. Both models described well the effluent concentrations. Calibration of the models to match the observed breakthrough curves of Br and E. coli NAR resulted in a smaller value of dispersivity for the later. For bacteria, the fitted attachment and straining coefficients increased with the clay content of the soil. Earlier peaks in the breakthrough curves were observed for the weathered soil columns. This was attributed to increased pore connectivity associated with weathering. In contrast the balanced and symmetrical shape of the breakthrough curves from the repacked soil columns indicates that leaching occurred mainly through matrix flow.

  6. Molecular modelling studies of clay-exopolysaccharide complexes: Soil aggregation and water retention phenomena

    International Nuclear Information System (INIS)

    In soils, the bacterial exopolysaccharides (EPS) aggregate mineral particles, enhancing their cohesion and their ability to retain water. These phenomena have been studied at the atomic scale by molecular modelling; we have considered seven rhizospheric polysaccharides interacting with the basal surfaces of montmorillonite. Models accounted for the aggregation phenomena induced by EPS: some segments of the polysaccharide were adsorbed on the mineral surfaces while others formed loops and bridges linking two surfaces. Adsorption energies were favourable and depended mostly on the interacting area. Cohesion of aggregates was estimated by the adhesion work, predicted values differed from one EPS to the other, suggesting that the chemical structure influences interaction strength with the mineral surface. Mechanisms of water uptake and release have also been investigated: hydration energies revealed that EPS strongly retain water at low water concentrations.

  7. Testing Some Pedo-Transfer Functions (PTFs in Apulia Region. Evaluation on the Basis of Soil Particle Size Distribution and Organic Matter Content for Estimating Field Capacity and Wilting Point

    Directory of Open Access Journals (Sweden)

    Floriano Buccigrossi

    2010-10-01

    Full Text Available The knowledge of soil water retention vs. soil water matric potential is applied to study irrigation and drainage scheduling, soil water storage capacity (plant available water, solute movement, plant growth and water stress. To measure field capacity and wilting point is expensive, laborious and is time consuming, so, frequently, matemathic models, called pedo-transfer functions (PTFs are utilized to estimate field capacity and wilting point through physical-chemical soil characteristics. Six PTFs have been evaluated (Gupta and Larson, 1979; Rawls et al., 1982; De Jong et al., 1983; Rawls and Brakensiek, 1985; Saxton et al., 1986; Vereecken et al., 1989 by comparing measured soil moisture values with estimated ones at soil water matric potential of -33 and -1500 kPa. Soil samples were collected (361 from 185 pedons of Apulian Region (Southern Italy. Accuracy of the soil moisture predictions is quantified with Root Mean Square Deviation (RMSD between estimated and measured water retention values. In Apulia Region the tested PTFs give different results on soils grouped on the basis of textural composition and organic matter (O.M. content both at the Field Capacity (FC and Wilting Point (WP. At the FC, Gupta and Larson model has given the best performance in Clayey (C, Sandy clay loam (SaCL, Sandy loam (SaL and Silty (Si soil, in loamy and tendency silty soils with O.M. content less than 1.9% and in tendency sandy soils with O.M. content less than 1.5% and greater than 2%; the Rawls model in Silty clay (SiC and Silty loam (SiL soils, in tendency clayey soils with O.M. less than 2.3% and in loamy and tendency silty soils with O.M. greater than 1.9%; the Rawls and Brakensiek model in tendency sandy soils with O.M. content between 1.5 and 2%; the Saxton model in Silty clay loam (SiCL, Loamy sand (LSa soils and in tendency clayey soils with O.M. content greater than 2.3% and the Vereecken model in Sandy clay (SaC, Loamy (L, Clay loam (CL and Sandy (Sa

  8. Study on soil water characteristics of tobacco fields based on canonical correlation analysis

    Institute of Scientific and Technical Information of China (English)

    Xiao-hou SHAO; Yu WANG; Li-dong BI; You-bo YUAN; Xian-kun SU; Jian-guo MO

    2009-01-01

    In order to identify the principal factors influencing soil water characteristics (SWC) and evaluate SWC effectively, the multivariate-statistical canonical correlation analysis (CCA) method was used to study and analyze the correlation between SWC and soil physical and chemical properties. Twenty-two soil samples were taken from 11 main tobacco-growing areas in Guizhou Province in China and the soil water characteristic curves (SWCC) and basic physical and chemical properties of the soil samples were determined. The results show that: (1) The soil bulk density, soil total porosity and soil capillary porosity have significant effects on SWC of tobacco fiels. Bulk density and total porosity are positively correlated with soil water retention characteristics (SWRC), and soil capillary porosity is positively correlated with soil water supply characteristics (SWSC). (2) Soil samples from different soil layers at the same soil sampling point show similarity or consistency in SWC. Inadequate soil water supply capability and imbalance between SWRC and SWSC are problems of tobacco soil. (3) The SWC of loamy clay are generally superior to those of silty clay loam.

  9. Studies on bound residues of 14C-malathion in soil

    International Nuclear Information System (INIS)

    The extractability and formation of bound 14C-labelled residues in clay loam soil under laboratory conditions were investigated with malathion. 14C-malathion rapidly decomposed to 14CO2. Twelve days after treatment 56% of the applied dose was lost as 14CO2. Methanol gave the highest extraction efficiency; 6% of the applied radiocarbon was extractable while bound residues amounted to 38%. The soil containing 14C-labelled residues was fractionated into humic acid, fulvic acid and humin fractions. These fractions contained 7.83%, 16.81% and 19.36%, respectively of applied radiocarbon. (author)

  10. INFLUENCE OF ELEMENTAL SULFUR AND/OR INOCULATION WITH SULFUR OXIDIZING BACTERIA ON GROWTH, AND NUTRIENT CONTENT OF SORGHUM PLANTS GROWN ON DIFFERENT SOILS

    OpenAIRE

    Hala Kandil; M. H. El-Halfawi; Ibrahim, S. A.

    2011-01-01

    A pot experiment was conducted to study the effect of elemental sulfur(E.S) rates (300 and 600 ppm) and/or sulfur oxidizing bacteria (S.O.B. ATCC 8158) on growth and nutrients content of sorghum plants grown on different soils (sandy soils(I & II) and clay loam soil).The obtained results could be summarized in the followings:Sorghum plants:Significant increases over the control were observed in fresh and dry weights of sorghum plant as well as its content of SO4=, N, P, K, Fe, Mn, Zn and Cu b...

  11. Two years of gaseous emissions from contrasting soils amended with organic and synthetic nitrogen fertilizers.

    Science.gov (United States)

    Pelster, D. E.; Chantigny, M. H.; Rochette, P.; Angers, D. A.; Rieux, C.; Vanasse, A.

    2012-04-01

    Animal manures are often used as a source of nitrogen (N) for agriculture; however impacts of amendment type on N2O production may vary. In this study, N2O emissions from two soil types with contrasting texture and carbon (C) content (a silty clay mixed frigid dystric eutrudept and a sandy loam mixed frigid typic dystrudept) were measured for two years under a cool, humid climate. Treatments consisted of a no N control (CTL), calcium ammonium nitrate (CAN), poultry manure (PM), liquid cattle manure (LCM), or liquid swine manure (LSM). The N sources were surface applied and immediately incorporated at 90 kg N ha-1 before seeding of spring wheat (Triticum aestivum L.). Leaching losses of N were also measured using zero-tension lysimeters located at approximately 0.35 m depth. Cumulative growing season N2O-N emissions from the silty clay ranged from 2.2 to 8.3 kg ha-1 yr-1 and were slightly lower in CTL plots than in the fertilized plots (P = 0.067). The mean N2O emission factors ranged from 2.0 to 4.4% of added N with no difference among treatments. Emissions of N2O from the sandy loam soil ranged from 0.3 to 2.2 kg N2O-N ha-1 yr-1, with greatest emissions following PM application (P amended with PM was 1.7%, more than double that of the other treatments (0.3 to 0.9%), likely because of the high C content of the PM. On the silty clay the yield-based N2O emissions (g N2O-N kg-1 grain yield N) were similar between treatments; while on the sandy loam, they were greatest when amended with PM. Annual N leaching losses averaged 28.7 kg ha-1 for the silty clay and 19.6 kg ha-1 for the sandy loam and were similar for all amendment types suggesting that off-site N2O emissions will also be similar amongst treatments. Preliminary data indicate that overwinter N2O emissions from sandy loam plots were consistently greater when amended with pig slurry compared with unamended soils, and that these overwinter losses may exceed growing season losses. Our findings suggest that

  12. Potential for Recycling Nutrients from Biosolids Amended with Clay and Lime in Coarse-Textured Water Repellence, Acidic Soils of Western Australia

    Directory of Open Access Journals (Sweden)

    Sanjutha Shanmugam

    2015-01-01

    Full Text Available Application of biosolids in soils is an efficient method of recycling nutrients from biosolids and it is considered even safer when it is modified after mixing and diluting with other suitable soil organic amendments. A variety of soil organic amendments, such as green manures and composts, are used for modifying and co-composting with biosolids. However, these may not be considered as appropriate biosolids disposal and remedial measures for soils with unique problems such as low soil pH, water repellence nature, and poor water and nutrient retention capacities due to soil textural issues. Historically, soil amendments such as lime, clay, and recently biochar are being applied for such problematic soils at Western Australia and these researches focused mostly on improvement in soil physical and chemical properties. However, studies with potential for applying modified biosolids with these amendments are not complete yet. This review focused on identifying such gaps in these studies from over 170 peer-reviewed key research and review articles published over decades to latest in these areas.

  13. Long-term influence of tillage and fertilization on net carbon dioxide exchange rate on two soils with different textures.

    Science.gov (United States)

    Feiziene, Dalia; Feiza, Virginijus; Slepetiene, Alvyra; Liaudanskiene, Inga; Kadziene, Grazina; Deveikyte, Irena; Vaideliene, Asta

    2011-01-01

    The importance of agricultural practices to greenhouse gas mitigation is examined worldwide. However, there is no consensus on soil organic carbon (SOC) content and CO emissions as affected by soil management practices and their relationships with soil texture. No-till (NT) agriculture often results in soil C gain, though, not always. Soil net CO exchange rate (NCER) and environmental factors (SOC, soil temperature [T], and water content [W]), as affected by soil type (loam and sandy loam), tillage (conventional, reduced, and NT), and fertilization, were quantified in long-term field experiments in Lithuania. Soil tillage and fertilization affected total CO flux (heterotrophic and autotrophic) through effect on soil SOC sequestration, water, and temperature regime. After 11 yr of different tillage and fertilization management, SOC content was 23% more in loam than in sandy loam. Long-term NT contributed to 7 to 27% more SOC sequestration on loam and to 29 to 33% more on sandy loam compared with reduced tillage (RT) or conventional tillage (CT). Soil water content in loam was 7% more than in sandy loam. Soil gravimetric water content, averaged across measurement dates and fertilization treatments, was significantly less in NT than CT and RT in both soils. Soil organic carbon content and water storage capacity of the loam and sandy loam soils exerted different influences on NCER. The NCER from the sandy loam soil was 13% greater than that from the loam. In addition, NCER was 4 to 9% less with NT than with CT and RT systems on both loam and sandy loam soils. Application of mineral NPK fertilizers promoted significantly greater NCER from loam but suppressed NCER by 15% from sandy loam. PMID:22031561

  14. Microbial assimilation of 14C of ground and unground plant materials decomposing in a loamy sand and a clay soil

    DEFF Research Database (Denmark)

    Sørensen, P.; Ladd, J.N.; Amato, M.

    1996-01-01

    The influence of grinding plant materials on the microbial decomposition and the distribution of plant-derived carbon in soil was measured. Ground and unground, C-14-labelled subclover leaves (Trifolium subterraneum) were added to a loamy sand and clay soil and incubated for 42 d at 25 degrees C....... More C-14 and N were mineralized and less microbial biomass C-14 accumulated in soils amended with unground than with ground subclover leaves. Differences in the amounts of (CO2)-C-14 and biomass C-14 were established during the initial 7 days of decomposition. At this time, biomass C-14 in the two...... rate of evolution of (CO2)-C-14 was least from glucose. Thus, the glucose-derived residual C-14, which was mainly present in microbial biomass, was to a higher degree retained in soil than residual C-14 from the decomposing plant materials. It is suggested that grinding of plant materials favours, on...

  15. Water consumption and soil moisture distribution in melon crop with mulching and in a protected environment

    Directory of Open Access Journals (Sweden)

    Rodrigo Otávio Câmara Monteiro

    2013-06-01

    Full Text Available Mulching has become an important technique for land cover, but there are some technical procedures which should be adjusted for these new modified conditions to establish optimum total water depth. It is also important to observe the soil-water relations as soil water distribution and wetted volume dimensions. The objective of the present study was to estimate melon evapotranspiration under mulching in a protected environment and to verify the water spatial distribution around the melon root system in two soil classes. Mulching provided 27 mm water saving by reducing water evaporation. In terms of volume each plant received, on average, the amount of 175.2 L of water in 84 days of cultivation without mulching, while when was used mulching the water requirement was 160.2 L per plant. The use of mulching reduced the soil moisture variability throughout the crop cycle and allowed a greater distribution of soil water that was more intense in the clay soil. The clayey soil provided on average 43 mm more water depth retention in 0.50 m soil deep relative to the sandy loam soil, and reduced 5.6 mm the crop cycle soil moisture variation compared to sandy loam soil.

  16. Fate of fenvalerate (Pydrin Insecticide) in the soil environment

    International Nuclear Information System (INIS)

    The fate of fenvalerate (Pydrin insecticide) in the soil environment was examined. The half-lives of fenvalerate under laboratory aerobic or outdoor conditions in sandy loam and silty clay loam soils are approximately 75-80 days. In addition to degradation products resulting from the cleavage of the ester linkage, CONH2√ and 4-OH-fenvalerate were detected. Further degradation of the soil metabolites was evident by the generation of 14CO2 and unextractable residues. The degradation of fenvalerate in the soil environment was primarily by microbial action. Lettuce, beets, and wheat were planted at 30 days, 120 days, and 1 year after the soil was treated with [14C] fenvalerate at a rate equivalent to 2lb/acre. The crops were harvested at maturity and were found to contain low levels of [chlorophenyl-14C]-and [phenoxyphenyl-14C] fenvalerate equivalent residues (below or 1-3 times the limit of detection). Little downward movement of radioactivity was observed in the soil container. It is concluded that under test conditions fenvalerate nonpersistent in the soil environment. In addition, rotational crops planted at various time intervals after soil treatment contained low, if any, significant residue levels of fenvalerate or its metabolites

  17. Transport of contaminants from energy-process-waste leachates through subsurface soils and soil components: laboratory experiments

    International Nuclear Information System (INIS)

    The subsurface transport and attenuation of inorganic contaminants common to a variety of energy process waste leachates are being studied using laboratory column methods. Anionic species currently being emphasized are As, B, Mo, and Se. Transport of the cations Cd and Ni is also being studied. The solid adsorbents consist of three soil mineral components (silica sand, kaolinite, and goethite), and four subsurface soils (a dunal sand, an oxidic sandy clay loam, an acidic clay loam, and an alkaline clay loam). Breakthrough patterns of these species from packed soil columns are followed by monitoring eluent concentrations vs time under carefully controlled laboratory conditions. This report describes the experimental methods being used, the results of preliminary batch adsorption studies, and the results of column experiments completed through calendar year 1981. Using column influent concentrations of about 10 mg/l, adsorption (mmoles/100 g) has been determined from the eluent volume corresponding to 50% breakthrough. On silica sand, kaolinite, dunal sand, and goethite, respectively, these are 2.0 x 10-4, 0.020, 0.013, and 0.31 for cadmium, 4.4 x 10-4, 0.039, 0.020, and 0.98 for nickel. On kaolinite, dunal sand, and goethite, respectively, adsorption values (mmoles/100 g) are As (0.24, 0.019, and 20.5), B (0.041, 0.0019, and 1.77), Mo (0.048, 0.0010, and 5.93), and Se (0.029, 0.00048, and 1.30). Arsenic is the most highly adsorbed contaminant species and goethite has the largest adsorption capacity of the adsorbents

  18. EVALUATION OF SOXTEC EXTRACTION PROCEDURE FOR EXTRACTING ORGANIC COMPOUNDS FROM SOILS AND SEDIMENTS

    Science.gov (United States)

    The U.S. EPA conducted a study to evaluate the Soxtec extraction of 29 target compounds from spiked sandy clay loam and clay loam. he study also compared two solvent mixtures and methylene chloride-acetone and investigated the effect on method recovery of five factors (matrix typ...

  19. Clay minerals and sedimentary basin history

    OpenAIRE

    Merriman, Richard J.

    2005-01-01

    Clay minerals in the mud and soil that coat the Earth's surface are part of a clay cycle that breaks down and creates rock in the crust. Clays generated by surface weathering and shallow diagenetic processes are transformed into mature clay mineral assemblages in the mudrocks found in sedimentary basins. During metamorphism, the release of alkali elements and boron from clay minerals generates magmas that are subsequently weathered and recycled, representing the magma-to-mud pathway of the cl...

  20. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  1. Minimum quantity of urban refuse compost affecting physical and chemical soil properties

    Directory of Open Access Journals (Sweden)

    Andrea Rocchini

    2011-02-01

    Full Text Available The increasing production of urban waste requires urgent responses because of various environmental problems that arise when urban refuse is stored in landfills or incinerated. Recycling of domestic waste and composting of its organic fraction has been indicated as a possible disposal solution. A three-year experiment was conducted to quantify the minimum rate of urban refuse compost (URC addition able to improve some physical and chemical soil properties at the lowest cost and environmental impact. URC was added to a silty clay soil and to a sandy loam soil 0%, 3%, 6%, 9% rate (w/w. Samplings were made 12, 24 and 36 months after URC application. To study the only effect of compost on soil due to its interaction with the soil matrix, each soil-compost mixture was divided into three boxes and kept outdoors weed free. After 12 months, 3% URC resulted the minimum quantity able to ameliorate several soil properties. In silty clay soil this rate significantly ameliorated microaggregate stability and hydraulic conductivity, but negative effects were observed on electrical conductivity. After 24 months, 3% rate significantly increased soil organic matter content. In the sandy loam soil, after 12 months, 3% rate of URC determined a positive effect on organic matter and cone resistance in dry soil condition. Electrical conductivity increased at 3% URC addition. The minimum URC quantity affecting hydraulic conductivity and plastic limit was 6%, and 9% for the liquid limit. Under these experimental conditions, the lowest rate (3% of URC incorporation to soils appears to be the minimum quantity able to improve most of the soil properties influencing fertility. What the results show is that, to achieve sustainability of urban refuse compost application to agricultural soil, further research is needed to investigate soil property changes in the range between 0% and 3%.

  2. Minimum quantity of urban refuse compost affecting physical and chemical soil properties

    Directory of Open Access Journals (Sweden)

    Paolo Bazzoffi

    Full Text Available The increasing production of urban waste requires urgent responses because of various environmental problems that arise when urban refuse is stored in landfills or incinerated. Recycling of domestic waste and composting of its organic fraction has been indicated as a possible disposal solution. A three-year experiment was conducted to quantify the minimum rate of urban refuse compost (URC addition able to improve some physical and chemical soil properties at the lowest cost and environmental impact. URC was added to a silty clay soil and to a sandy loam soil 0%, 3%, 6%, 9% rate (w/w. Samplings were made 12, 24 and 36 months after URC application. To study the only effect of compost on soil due to its interaction with the soil matrix, each soil-compost mixture was divided into three boxes and kept outdoors weed free. After 12 months, 3% URC resulted the minimum quantity able to ameliorate several soil properties. In silty clay soil this rate significantly ameliorated microaggregate stability and hydraulic conductivity, but negative effects were observed on electrical conductivity. After 24 months, 3% rate significantly increased soil organic matter content. In the sandy loam soil, after 12 months, 3% rate of URC determined a positive effect on organic matter and cone resistance in dry soil condition. Electrical conductivity increased at 3% URC addition. The minimum URC quantity affecting hydraulic conductivity and plastic limit was 6%, and 9% for the liquid limit. Under these experimental conditions, the lowest rate (3% of URC incorporation to soils appears to be the minimum quantity able to improve most of the soil properties influencing fertility. What the results show is that, to achieve sustainability of urban refuse compost application to agricultural soil, further research is needed to investigate soil property changes in the range between 0% and 3%.

  3. The velocity of shear waves in unsaturated soil

    OpenAIRE

    Whalley, W. R.; Jenkins, M; Attenborough, K.

    2012-01-01

    The velocities of shear waves Vs in two soils, a loamy sand and a sandy clay loam, were measured at various matric potentials and confining pressures. We used a combination of Haines apparatus, pressure plate apparatus and a Bishop and Wesley tri-axial cell to obtain a range of saturation and consolidation states. We proposed a single effective stress variable based on a modification to Bishop’s equation which could be used in a published empirical model (Santamarina et al., 2001) to relate s...

  4. Radionuclides in milk of dairy heifers raised on forages harvested from phosphatic clay soils on reclaimed mined land

    International Nuclear Information System (INIS)

    Alfalfa (AR; Medicago sativa L.) and corn (CSR; Zea mays L.) were grown in phosphatic clay soils on phosphate-mined reclaimed land in central Florida. Corn (CSC) also was grown on unmined land and served as a control forage. Upon harvesting, plants were chopped and ensiled. Concentrations of 226Ra averaged 2.44, 0.26 and 0.15; 210Pb averaged 1.04, 0.63, and 0.52; and 210Po averaged 1.59, 0.59, and 1.26 Bq kg-1 DM for AR, CSR, and CSC, respectively. These forages were fed separately to Holstein dairy replacement heifers (Bos taurus) (n=15 per forage) from approximately 9 to 25 mo of age. Heifers gave birth to calves at approximately 24 mo of age. Samples of milk were collected on d 1, 15, and 30 of lactation and analyzed for radionuclides. Averaged across sampling days, heifers fed AR had greater milk concentrations of 226Ra compared with those fed CSR (0.27 vs. 0.22 Bq kg-1 DM; P -1 DM; P 210Po compared with heifers fed CSR (0.58 vs. 0.30 Bq kg-1 DM; P -1 DM). Lead-210 was greater in milk from heifers fed CSR compared with those fed AR or CSC (1.38 vs. 0.94 and 0.92 Bq kg-1 DM; P < 0.13), respectively. Plasma S and Cu concentrations suggested subclinical molybdenosis in heifers fed AR. However, all heifers grew at an acceptable rate, conceived normally, had normal gestation periods, gave high quality colostrum at calving, and produced similar amounts of milk. 17 refs., 9 tabs

  5. Field experiments of Controlled Drainage of agricultural clay soils show positive effects on water quantity (retention, runoff) and water quality (nitrate leaching).

    Science.gov (United States)

    schipper, peter; stuyt, lodewijk; straat, van der, andre; schans, van der, martin

    2014-05-01

    Despite best management practices, agriculture is still facing major challenges to reduce nutrients leaching to the aquatic environment. In deltas, most of total nutrient losses from artificially drained agricultural soils are discharged via drains. Controlled drainage is a promising measure to prevent drainage of valuable nutrients, improve water quality and agricultural yield and adapt to climate change (reduce peak runoff, manage water scarcity and drought). In The Netherlands, this technique has attracted much attention by water managers and farmers alike, yet field studies to determine the expected (positive) effects for Dutch conditions were scarce. Recently, a field experiment was set up on clay soils. Research questions were: how does controlled, subsurface drainage perform on clay soils? Will deeper tile drains function just as well? What are the effects on drain water quality (especially with respect to nitrogen and salt) and crop yield? An agricultural field on clay soils was used to test different tile drainage configurations. Four types of tile drainage systems were installed, all in duplicate: eight plots in total. Each plot has its own outlet to a control box, where equipment was installed to control drain discharge and to measure the flow, concentrations of macro-ions, pH, nitrogen, N-isotopes and heavy metals. In each plot, groundwater observation wells and suction cups are installed in the saturated and vadose zones, at different depths, and crop yield is determined. Four plots discharge into a hydrologic isolated ditch, enabling the determination of water- and nutrient balances. Automatic drain water samplers and innovative nitrate sensors were installed in four plots. These enable identification and unravelling so-called first flush effects (changes in concentrations after a storm event). Water-, chloride- and nitrogen balances have been set up, and the interaction between groundwater and surface water has been quantified. The hydrological

  6. Hydraulic Anisotropy Characterization Using Azimuthal Self Potential Gradient [ASPG]: Results from Pneumatic Fracturing of Tight Clay Soils

    Science.gov (United States)

    Slater, L.; Wishart, D.; Schnell, D.; Hermann, G.

    2008-12-01

    Recent studies have shown that bulk hydraulic anisotropy associated with fractures in fractured rock aquifers can be inferred from Azimuthal Self Potential Gradient (ASPG) measurements. This extremely simple technique involves measuring the self potential gradient as a function of azimuth with a pair of non polarizing electrodes connected to a voltmeter. The electrokinetic effect associated with the flow of fluids within fractures is the source of the ASPG signal. Fracture strike mapping at multiple sites has repeatedly demonstrated the effectiveness of the method at the field scale and indicated that the direction of flow can be determined from the polarity of relatively large ASPG signals. A laboratory study was conducted to determine whether ASPG could also be used to characterize the hydraulic anisotropy associated with the enhancement of permeability and porosity of tight unconsolidated soils (e.g. clays) as a result of pneumatic fracturing, a technique to improve the effectiveness of remediation efforts. Compressed kaolinite sediments were pneumatically fractured following industry procedures. The resulting fracture geometry was quantified from strike analysis of visible fractures combined with strike data from optical borehole televiewer (BHTV) imaging. ASPG measurements were then made during injection of a simulated remedial treatment (electrolyte/dye) under an applied gas pressure. Consistent with previous findings in fractured rock aquifers, ASPG lobes are well correlated with azimuths of high fracture strike density suggesting that the ASPG anisotropy is a proxy measure of hydraulic anisotropy created by the pneumatic fracturing. The magnitude of the ASPG signal scales linearly (linear correlation coefficients > 0.74) with the applied gas pressure gradient for any particular hydraulically-active fracture set and the positive lobe of the ASP anomaly denotes the flow direction within that fracture set. These findings demonstrate that applications of the

  7. Mineralogical analysis of clays in hardsetting soil horizons, by X-ray fluorescence and X-ray diffraction using Rietveld method

    International Nuclear Information System (INIS)

    Diffraction and spectroscopic techniques have been shown to be suitable for obtaining physical and mineralogical properties in polycrystalline soil samples, and also in their precursor compounds. For instance, the X-ray fluorescence (XRF) spectroscopy allows obtaining the elemental composition of an investigated sample, while the X-ray diffraction (XRD) technique permits obtaining qualitative and quantitative composition of the soil minerals through the Rietveld method (RM). In this study Yellow Latosol (Oxisol), Yellow Argisol (Ultisol) and Gray Argisol (Ultisol) soil samples, classified as “hardsetting soils”, extracted from areas located at Northeast and Southeast of Brazilian coast were investigated. The soils and their fractions were analyzed in an EDX-700 and an XRD-6000 (Cu Kα radiation). XRF results indicate high percentages of Si and Al, and small percentage of Fe and Ti in the investigated samples. The DRX data and RM indicate that there was a predominance of kaolinite and halloysite minerals (kaolin group minerals) in the clay fractions, which are presumably responsible for the formation of kaolinitic plasma in these soils. Also, the obtained results showed that the XRF, XRD techniques and RM were very helpful for investigating the mineralogical composition of a hardsetting soil. - Highlights: ► Elemental composition of soil samples through X-Ray fluorescence. ► Mineralogical quantification through X-ray diffraction and Rietveld method. ► Oxisol and Ultisol, Brazil ‘Barreiras’ formation. ► High amounts of Si and Al oxides and low amounts of Fe and Ti oxides. ► Predominance of kaolinite in the clay fraction

  8. Combined effects of short term rainfall patterns and soil texture on soil nitrogen cycling - a modeling analysis.

    Science.gov (United States)

    Gu, Chuanhui; Riley, William J

    2010-03-01

    Precipitation variability and magnitude are expected to change in many parts of the world over the 21st century. We examined the potential effects of intra-annual rainfall patterns on soil nitrogen (N) transport and transformation in the unsaturated soil zone using a deterministic dynamic modeling approach. The model based on TOUGHREACT [corrected], which has been tested and applied in several experimental and observational systems, mechanistically accounts for microbial activity, soil moisture dynamics that respond to precipitation variability, and gaseous and aqueous tracer transport in the soil. Here, we further tested and calibrated the model against data from a precipitation variability experiment in a tropical system in Costa Rica. The model was then used to simulate responses of soil moisture, microbial dynamics, N leaching, and N trace-gas emissions to changes in rainfall patterns; the effect of soil texture was also examined. The temporal variability of nitrate leaching and NO, NH(3), and N(2)O effluxes were significantly influenced by rainfall dynamics. Soil texture combined with rainfall dynamics altered soil moisture dynamics, and consequently regulated soil N responses to precipitation changes. The clay loam soil more effectively buffered water stress during relatively long intervals between precipitation events, particularly after a large rainfall event. Subsequent soil N aqueous and gaseous losses showed either increases or decreases in response to increasing precipitation variability due to complex soil moisture dynamics. For a high rainfall scenario, high precipitation variability resulted in as high as 2.4-, 2.4-, 1.2-, and 13-fold increases in NH(3), NO, N(2)O and NO(3)(-) fluxes, respectively, in clay loam soil. In sandy loam soil, however, NO and N(2)O fluxes decreased by 15% and 28%, respectively, in response to high precipitation variability. Our results demonstrate that soil N cycling responses to increasing precipitation variability depends

  9. Monitoring Some Heavy Metal Contaminants in soils of Some Sites at Qalubiya Governorate

    International Nuclear Information System (INIS)

    Heavy metals Fe, Mn, Zn, Cu, Cr and Pb were determined in selected soils of El-Gabal El-Asfar (GA): sewage irrigated lands, Mostorod (MD): soils around steel, battery and plumbing factories and Abou-Zabal (AZ):soils around fertilizer, sulfate of aluminum and potassium (alum,p) and ceramic factories. All experimental sites are located within Qalubiya Governorate. Soils were sandy loam in GA and AZ, clay loam in MD. Averages of total contents of above-mentioned metals (mg kg-1) were 5472, 163, 178, 6.5, 160 and 151, respectively; 17500, 228, 647, 58, 260 and 293 ;and 6333, 219, 358, 27, 155 and 266 for GA, AZ and MD soils, respectively. Variations were considerable within each site as well as between the three sites. Highest contamination was in MD soils followed by AZ then GA soils. Highest Fe, Zn, Cr and Cu within AZ soils were around the fertilizer factory followed by those around the (alum,p) factory then around the ceramic factory. For the highest Pb, it was found in soils around the (alum,p) factory. There are evidences of pollution, particularly in the MD and AZ sites where the soils around industrial factories of steel, battery, fertilizers, smelters and ceramics exist.

  10. INTEGRATED NITROGEN AND BORON FERTILIZATION IMPROVES THE PRODUCTIVITY AND OIL QUALITY OF SUNFLOWER GROWN IN A CALCAREOUS SOIL

    OpenAIRE

    SHEHZAD, Muhammad Asif; Maqsood, Muhammad

    2015-01-01

    Among biotic and abiotic factors, imbalanced plant nutrition is more indispensable for low sunflower productivity. To assess the interaction behavior of nitrogen with boron on sunflower growth, yield and its oil quality in alkaline-calcareous soils, a field experiment was conducted for two consecutive growing seasons of 2011 and 2012. Sunflower hybrid (Helianthus annuus ‘Hysun-33’) was grown on sandy clay loam soil that was amended with diverse boron rates of 0, 2, 4, and 6 kg ha-1 under vari...

  11. The determination of caesium and silver in soil and fungal fruiting bodies by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Methods have been developed for the determination of caesium and silver in soil and fungal samples by microwave-assisted aqua regia digestion, followed by electrothermal atomic absorption spectrometry. The procedure was found to be repeatable (for soil, RSD -1, respectively, and for fungi, RSD -1, respectively) and reasonably efficient. Silver was recovered quantitatively from reference soils, but only about 80-85% of the caesium present could be extracted. Poorer caesium recoveries (< 70%) were obtained if, as part of the sample preparation procedure, solutions were taken to dryness in glass beakers prior to analysis. The detection limits were 0.02 mg Ag and 0.09 mg Cs per gram of dry soil, which are adequate for the determination of the analytes at typical environmental levels. The methods were applied in the analysis of three types of soil, a peaty podzol, a clay loam and a sandy loam and no significant matrix interferences were observed except in the determination of caesium in the sandy loam. For caesium, non-linear response curves, thought to be due to ionisation interference, were encountered using one atomic absorption spectrometer, but were not observed with the other instrument

  12. Direct and Indirect Short-term Effects of Biochar on Physical Characteristics of an Arable Sandy Loam

    DEFF Research Database (Denmark)

    Sun, Zhencai; Moldrup, Per; Elsgaard, Lars;

    2013-01-01

    Biochar addition to agricultural soil is reported in several studies to reduce climate gas emissions, boost carbon storage, and improve soil fertility and crop productivity. These effects may be partly related to soil physical changes resulting from biochar amendment, but knowledge of how biochar...... experiment on an arable sandy loam that included four reference plots without biochar and four plots with 20 tons ha(-1) biochar incorporated into the upper 20 cm 7 months before sampling. Water retention was measured at matric potentials ranging from wet (pF 1.0) to extremely dry conditions (pF similar to 6...

  13. Influence of organic amendments on diuron leaching through an acidic and a calcareous vineyard soil using undisturbed lysimeters

    International Nuclear Information System (INIS)

    The influence of different organic amendments on diuron leaching was studied through undisturbed vineyard soil columns. Two composts (A and D), the second at two stages of maturity, and two soils (VR and Bj) were sampled. After 1 year, the amount of residues (diuron + metabolites) in the leachates of the VR soil (0.19-0.71%) was lower than in the Bj soil (4.27-8.23%), which could be explained by stronger diuron adsorption on VR. An increase in the amount of diuron leached through the amended soil columns, compared to the blank, was observed for the Bj soil only. This result may be explained by the formation of mobile complexes between diuron and water-extractable organic matter (WEOM) through the Bj soil, or by competition between diuron and WEOM for the adsorption sites in the soil. For both soils, the nature of the composts and their degree of maturity did not significantly influence diuron leaching. - The application of organic amendments increased diuron leaching through a sandy-loam soil, in contrast to a clay-loam soil

  14. Evaluation of Turf-Grass and Prairie-Vegetated Rain Gardens in a Clay and Sand Soil, Madison, Wisconsin, Water Years 2004-08

    Science.gov (United States)

    Selbig, William R.; Balster, Nicholas

    2010-01-01

    The U.S. Geological Survey, in cooperation with a consortium of 19 cities, towns, and villages in Dane County, Wis., undertook a study to compare the capability of rain gardens with different vegetative species and soil types to infiltrate stormwater runoff from the roof of an adjacent structure. Two rain gardens, one planted with turf grass and the other with native prairie species, were constructed side-by-side in 2003 at two locations with different dominant soil types, either sand or clay. Each rain garden was sized to a ratio of approximately 5:1 contributing area to receiving area and to a depth of 0.5 foot. Each rain garden, regardless of vegetation or soil type, was capable of storing and infiltrating most of the runoff over the 5-year study period. Both rain gardens in sand, as well as the prairie rain garden in clay, retained and infiltrated 100 percent of all precipitation and snowmelt events during water years 2004-07. The turf rain garden in clay occasionally had runoff exceed its confining boundaries, but was still able to retain 96 percent of all precipitation and snowmelt events during the same time period. Precipitation intensity and number of antecedent dry days were important variables that influenced when the storage capacity of underlying soils would become saturated, which resulted in pooled water in the rain gardens. Because the rooftop area that drained runoff to each rain garden was approximately five times larger than the area of the rain garden itself, evapotranspiration was a small percentage of the annual water budget. For example, during water year 2005, the maximum evapotranspiration of total influent volume ranged from 21 percent for the turf rain garden in clay to 25 percent for the turf rain garden in sand, and the minimum ranged from 12 percent for the prairie rain garden in clay to 19 percent for the prairie rain garden in sand. Little to no runoff left each rain garden as effluent and a small percentage of runoff returned to the

  15. Soil and Waste Matrix Affects Spatial Heterogeneity of Bacteria Filtration during Unsaturated Flow

    Directory of Open Access Journals (Sweden)

    Adrian Unc

    2015-02-01

    Full Text Available Discontinuous flows resulting from discrete natural rain events induce temporal and spatial variability in the transport of bacteria from organic waste through soils in which the degree of saturation varies. Transport and continuity of associated pathways are dependent on structure and stability of the soil under conditions of variable moisture and ionic strength of the soil solution. Lysimeters containing undisturbed monoliths of clay, clay loam or sandy loam soils were used to investigate transport and pathway continuity for bacteria and hydrophobic fluorescent microspheres. Biosolids, to which the microspheres were added, were surface applied and followed by serial irrigation events. Microspheres, Escherichia coli, Enterococcus spp., Salmonella spp. and Clostridium perfringens were enumerated in drainage collected from 64 distinct collection areas through funnels installed in a grid pattern at the lower boundary of the monoliths. Bacteria-dependent filtration coefficients along pathways of increasing water flux were independent of flow volume, suggesting: (1 tracer or colloid dependent retention; and (2 transport depended on the total volume of contiguous pores accessible for bacteria transport. Management decisions, in this case resulting from the form of organic waste, induced changes in tortuosity and continuity of pores and modified the effective capacity of soil to retain bacteria. Surface application of liquid municipal biosolids had a negative impact on transport pathway continuity, relative to the solid municipal biosolids, enhancing retention under less favourable electrostatic conditions consistent with an initial increase in straining within inactive pores and subsequent by limited re-suspension from reactivated pores.

  16. The key role of micromorphology in studies of the genesis of clay minerals and their associations in soils and its relevance to advances in the philosophy of soil science

    OpenAIRE

    CHURCHMAN, Gordon Jock

    2013-01-01

    Micromorphological observations from 3 different published works have been studied to aid understanding of aggregation and of colloids, both unique to soils. Saprolites in Hong Kong included ‘veins’ of different thicknesses and colours. Optical mineralogy identified them as infill from the neogenesis of clays in rock fractures. The common thicker infills resulted from weathering. Dark infill contained comminuted primary minerals whereas thin pale infill originated hydrothe...

  17. 鹰咀界天然次生林自然保护区林地土壤特性研究%The Characteristics of Soil in Natural Secondary Forest Conservation Area of Yingzui Mountain

    Institute of Scientific and Technical Information of China (English)

    吴建平; 袁正科; 梁文斌

    2001-01-01

    According to the studies on 22 samples of soil profile from the natural forest conservation area at Yingzui mountain,the characteristics of soil were described.Research results indicated that the type of soil profile structure was A-B-C-D,and the soil development was successive.The average contents of organic matter in the soil was 54.30g*kg-1,the ratio of C/N was 10.93 and the bulk density was 1.25g*cm-3.the soil texture was heavy loam or light clay.The soil fertility was higher compared with the soil from natural forest conservation of ZhangJiajie mountain,which developed from the same parent material of silicon rocks as Yingzui area.The forest soil of the area is typical in the subtropical natural forest.So it is valuable to be protected.

  18. Fuel consumption of tractor for different soil types in semi-arid regions; Consumo de combustivel de um trator agricola para diferentes tipos de solo em regioes semi-aridas

    Energy Technology Data Exchange (ETDEWEB)

    Montanha, Gustavo K. [Universidade Estadual Paulista (FAC/UNESP), Botucatu, SP (Brazil). Fac. de Ciencias Agronomicas. Dept. de Engenharia Rural], E-mail: gmontanha@fca.unesp.br; Guerra, Saulo P.S. [Universidade Estadual Paulista (UNESP), Botucatu, SP (Brazil). Dept. de Gestao e Tecnologia Agroindustrial; Andrade-Sanchez, Pedro; Heun, John [The University of Arizona, Maricopa, AZ (United States); Monteiro, Leonardo A. [The University of Arizona (MAC/UA), Maricopa, AZ (United States). Maricopa Agricultural Center

    2010-07-01

    The appropriate use of agricultural machinery enables greater operational efficiency and higher productivity for the farmer. Some factors such as soil type can influence the fuel consumption, one of the biggest costs. This study aimed to compare the fuel consumption of a tractor operating in two different conditions of soil in semi-arid regions. The area used for testing is located in the city of Maricopa, in Arizona, belonging to 'The University of Arizona'. The area 1 is classified as sandy clay loam soil (52% sand, 35% clay, 13% silt). The area 2 is classified as a sandy loam soil (71% sand, 12% clay and 17% silt). The tractor 4 x 2 TDA, with 88 kw (120 hp) engine power equipped with auto pilot system and an implement for tillage were used in the experiment. A data acquisition system was installed in the tractor to collect the data generated by the GPS and fuel consumption sensor. The results showed significant statistical difference in fuel consumption between soil textures. (author)

  19. Mineralization of carbon and nitrogen from fresh and anaerobically stored sheep manure in soils of different texture

    DEFF Research Database (Denmark)

    Sørensen, P.; Jensen, E.S.

    1995-01-01

    insignificant or slightly negative in the three soil-sand mixtures (100% soil+0% quartz sand; 50% soil+50% quartz sand; 25% soil+75% quartz sand). After 84 days, the cumulative CO2 evolution and the net mineralization of N from the fresh manure were highest in the soil-sand mixutre with the lowest clay content...... (4% clay); 28% fo the manure C and 18% of the manure N were net mineralized. There was no significant difference between the soil-sand mixtures containing 8% and 16% clay, in which 24% of the manure C and -1% to 4% of the manure N were net mineralized. The higher net mineralization of N in the soil......A sandy loam soil was mixed with three different amounts of quartz sand and incubated with ((NH4)-N-15)(2)SO4 (60 mu g N g(-1) soil) and fresh or anaerobically stored sheep manure (60 mu g g(-1) soil). The mineralization-immobilization of N and the mineralization of C were studied during 84 days of...

  20. Precipitation pulse use by an invasive woody legume: the role of soil texture and pulse size.

    Science.gov (United States)

    Fravolini, Alessandra; Hultine, Kevin R; Brugnoli, Enrico; Gazal, Rico; English, Nathan B; Williams, David G

    2005-08-01

    Plant metabolic activity in arid and semi-arid environments is largely tied to episodic precipitation events or "pulses". The ability of plants to take up and utilize rain pulses during the growing season in these water-limited ecosystems is determined in part by pulse timing, intensity and amount, and by hydrological properties of the soil that translate precipitation into plant-available soil moisture. We assessed the sensitivity of an invasive woody plant, velvet mesquite (Prosopis velutina Woot.), to large (35 mm) and small (10 mm) isotopically labeled irrigation pulses on two contrasting soil textures (sandy-loam vs. loamy-clay) in semi-desert grassland in southeastern Arizona, USA. Predawn leaf water potential (psi(pd)), the isotopic abundance of deuterium in stem water (deltaD), the abundance of 13C in soluble leaf sugar (delta13C), and percent volumetric soil water content (theta(v)) were measured prior to irrigation and repeatedly for 2 weeks following irrigation. Plant water potential and the percent of pulse water present in the stem xylem indicated that although mesquite trees on both coarse- and fine-textured soils quickly responded to the large irrigation pulse, the magnitude and duration of this response substantially differed between soil textures. After reaching a maximum 4 days after the irrigation, the fraction of pulse water in stem xylem decreased more rapidly on the loamy-clay soil than the sandy-loam soil. Similarly, on both soil textures mesquite significantly responded to the 10-mm pulse. However, the magnitude of this response was substantially greater for mesquite on the sandy-loam soil compared to loamy-clay soil. The relationship between psi(pd) and delta13C of leaf-soluble carbohydrates over the pulse period did not differ between plants at the two sites, indicating that differences in photosynthetic response of mesquite trees to the moisture pulses was a function of soil water availability within the rooting zone rather than

  1. Field investigation with regard to the impermeability of clay formations. Helium-4 soil gas surveys in sedimentary basins as a tentative study of secondary permeability in clayey sequences

    International Nuclear Information System (INIS)

    This report deals with a tentative study for the detection of the secondary permeability in clayey formations conducted in several sedimentary basins in Central Italy, by means of geochemical methods. The main purposes are: to try a geochemical method, based on the distribution of deep origin gases in soil gas (4He and 222Rn), to detect buried fault systems and to study the permeability of clay as a potential migration pathway for nuclides of radioactive waste deposits; to verify the effectiveness of this method for the selection of suitable sites for radwaste disposal. This research programme consists in a collaboration between ENEA and the University of Rome within the communitarian programme for the disposal of high level and long-live radwaste. Investigations concerned sedimentary basins filled by sand-clay formations 1000-2000 meters thick and characterized by different tectonic: Era and Chiani-Paglia Valleys (Tuscany and North Latium), structural trenches due to extensive tectonics along the tyrrhenian edge, and Vasto region, a basin in the 'Adriatic foretrench', characterized by compressive tectonics. The investigated areas are near or directly correspond to geothermal fields or to hydrocarbon reservoirs supplying gases which may migrate upward along fractures. Almost 4000 soil gas samples were collected in the three surveyed areas; the sampling density was of about 1.5 points / km2, normally used in the regional scale surveys. The obtained results show that the observed helium anomalies are distributed or elongated according to the main tectonic features of the substratum (fault systems, fractures, deep structures); the magnitude of anomalies seems to correlate with the nature of the deep gas reservoir (i.e. oil in Vasto), geothermal reservoir in the Paglia valley. These observations seem to confirm that the presence of deep origin gases in soils is controlled by tectonics. Clay thickness does not significantly control the uprising of deep gases: in fact a

  2. Estimation of evaporation and drainage losses from two bare soils in Sri Lanka

    Directory of Open Access Journals (Sweden)

    Mehmet Aydin

    2012-01-01

    Full Text Available In this study, evaporation, drainage rates and water storage of two bare soils in the east (Batticaloa and west (Puttalam regions of Sri Lanka, were simulated using the E-DiGOR model. Daily simulations were carried out for each of the years during the periods of 1978 to 1987 in Batticaloa and 1998 to 2007 in Puttalam using standard climate data. The soils in the locations were predominantly sandy loam and/or sandy clay loam. Grass reference evapotranspiration and potential soil evaporation were higher, whereas actual soil evaporation was lower during the dry seasons. The 10-year average annual reference evapotranspiration and potential soil evaporation were 2069.3 mm and 1814.1 mm in Batticaloa, and 1908.8 mm and 1714.5 mm in Puttalam, respectively. Aridity index (precipitation/reference evapotranspiration was 0.685 for Batticaloa and 0.606 for Puttalam. The actual evaporation from bare soil varied between 463.1—725.0 mm in Batticaloa and 543.6—646.3 mm in Puttalam. Annual drainage rates below 150 cm soil depth ranged from 321.7 to 1581.2 mm in Batticaloa and from 346.7 to 957.0 mm in Puttalam. Soil water storage changed daily depending on the intensity and frequency of rainfall events and on evaporation rates.

  3. Nutrient Availability in the Surface Horizons of Four Tropical Agricultural Soils in Mali

    Directory of Open Access Journals (Sweden)

    Verloo, MG.

    2002-01-01

    Full Text Available Studies of nutrient availability are important for the understanding and the estimation of soil fertility in areas like West Africa, where low nutrient availability is still one of the major constraints for food production. Physico-chemical soil analyses were used to assess the fertility status of the surface horizon samples of four Malian agricultural soils, (Bougouni, Kangaba, Baguinéda and Gao abbreviated as Bgni, Kgba, Bgda and Gao. Soil texture was sandy loam for Bgni and Kgba, sandy clay loam for Bgda and loamy sand for Gao. Soil pH values varied from moderately acid for Bgda to neutral for the other sites. Organic carbon ranged from very low (for Gao or low (for Bgni and Bgda to medium (for Kgba. Total N, P and CEC were low for the four soils. Available contents of Fe and Mn in all soils, except Gao, were higher than the critical levels while available Cu and Zn contents (except in Kgba were below or close to it. Results indicated that Kgba soil had a better macronutrient status for plant growth than the other sites.

  4. Impact of paper mill wastewater on soil properties and crop yield through lysimeter studies.

    Science.gov (United States)

    Singh, P K; Ladwani, K; Ladwani, K; Deshbhratar, P B; Ramteke, D S

    2013-01-01

    Paper and pulp industries produce large quantities of wastewater which can have adverse effects on the receiving water systems. In the present study lysimeters were used and filled with different soils replicating natural soil horizons and provided with a leachate collection system. The physico-chemical characteristics of the soil in each lysimeter and the quality of wastewater before leaching were assessed. Treated wastewater was evaluated for crop irrigation, and was categorized according to the irrigation water class 'Increasing Problem to Severe Problem' with respect to salinity and specific ion toxicity. Sandy loam soils showed 96% chemical oxygen demand (COD) removal while clay loam soils removed 99% of COD, and the colour removal in both the cases was found to be 100%. Application of wastewater resulted in an increase of pH value, ranging from 6.2-7.6; the electrical conductivity (ECe) of saturated extracts was found to be 0.6-1.7 dS m(-1), and exchangeable sodium percentage (ESP) ranged from 7.8-11.1% in soils. Similarly, an increase in the organic carbon, available nitrogen, phosphorus and potash content of soils was observed when irrigated with wastewater. Wastewater irrigation showed increased grain and straw yield of jowar, wheat and moong. These results permit successful utilization of pulp and paper mill wastewater for crop production without damaging the soils. PMID:23837309

  5. Abundance of plankton population densities in relation to bottom soil textural types in aquaculture ponds

    Directory of Open Access Journals (Sweden)

    F. Siddika

    2012-06-01

    Full Text Available Plankton is an important food item of fishes and indicator for the productivity of a water body. The present study was conducted to evaluate the effects of bottom soil textural conditions on abundance of plankton in aquaculture pond. The experiment was carried out using three treatments, i.e., ponds bottom with sandy loam (T1, with loam (T2 and with clay loam (T3. The ranges of water quality parameters analyzed were suitable for the growth of plankton during the experimental period. Similarly, chemical properties of soil were also within suitable ranges and every parameter showed higher ranges in T2. A total 20 genera of phytoplankton were recorded belonged to Chlorophyceae (7, Cyanophyceae (5, Bacillariophyceae (5, Euglenophyceae (2 and Dinophyceae (1. On the other hand, total 13 genera of zooplankton were recorded belonged to Crustacea (7 and Rotifera (6. The highest ranges of phytoplankton and zooplankton densities were found in T2 where low to medium-type bloom was observed during the study period. Consequently, the mean abundance of plankton (phytoplankton and zooplankton density was significantly highest in T2. The highest abundance of plankton in the T2 indicated that pond bottom with loamy soil is suitable for the growth and production of plankton in aquaculture ponds.

  6. 不同质地潮土夏玉米推荐施肥方法研究%Studies on recommended fertilization methods of summer maize in different fluvo-aquic soil texture

    Institute of Scientific and Technical Information of China (English)

    王宜伦; 李慧; 张晓佳; 韩燕来; 谭金芳

    2012-01-01

    Maize is the most cultivated grain crop in China. Realizing high yields of summer maize is important in ensuring food security in the country. There are, however, several known problems with summer maize production (e.g., excessive dosage and unreasonable periods of nitrogen application) that hinder high-yield realization. To increase fertilizer use efficiency and grain yield of summer maize, field experiments were conducted to determine the differences in summer maize yield, economic benefits, N, P and K. Use efficiency between Nutrient Expert (NE) and Agro-Services International Inc (ASI) recommended fertilizations in sand-loam, medium-loam and sticky-loam fluvo-aquic soils in Henan Province. The results showed that NE recommended fertilization treatment significantly increased maize yields in the three different soil textures. Summer maize yield, economic benefits and protein contents were ail significantly different (F medium-loam > sandy-loam soils. The output/input ratio of NE recommended fertilization treatment was higher than that of ASI recommended fertilization. Recommended fertilization treatments significant increased plant nutrient accumulation, which benefited grain protein and yield. Compared with farmer conventional fertilization (CK), maize yield increased by 7.22%, 3.84% and 11.32% for NE recommended fertilization treatment and by 13.44%, 10.60% and 11.20% for ASI recommended fertilization treatment in sandy-loam, medium-loam and clay-loam soils, respectively. N fertilizer increased yield the most under NE recommended fertilization treatment. N agronomic efficiency, use efficiencies of N, P and K fertilizers were in the order of clay-loam > medium-loam > sandy-loam. However, P and K fertilizers agronomic efficiencies were in the order of sandy-loam > clay-loam > medium-loam. Fertilizer agronomic efficiency was in the order of P fertilizer > K fertilizer > N fertilizer in all the three soil textures. NE recommended fertilization was most suitable

  7. Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation: A Soil Column Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI,DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3--N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

  8. Controllability of runoff and soil loss from small plots treated by vinasse-produced biochar.

    Science.gov (United States)

    Sadeghi, Seyed Hamidreza; Hazbavi, Zeinab; Harchegani, Mahboobeh Kiani

    2016-01-15

    Many different amendments, stabilizers, and conditioners are usually applied for soil and water conservation. Biochar is a carbon-enriched substance produced by thermal decomposition of organic material in the absence of oxygen with the goal to be used as a soil amendment. Biochar can be produced from a wide range of biomass sources including straw, wood, manure, and other organic wastes. Biochar has been demonstrated to restore soil fertility and crop production under many conditions, but less is known about the effects of its application on soil erosion and runoff control. Therefore, a rainfall simulation study, as a pioneer research, was conducted to evaluate the performance of the application of vinasse-produced biochar on the soil erosion control of a sandy clay loam soil packed in small-sized runoff 0.25-m(2) plots with 3 replicates. The treatments were (i) no biochar (control), (ii) biochar (8 tha(-1)) application at 24h before the rainfall simulation and (iii) biochar (8 tha(-1)) application at 48 h before the rainfall simulation. Rainfall was applied at 50 mm h(-1) for 15 min. The mean change of effectiveness in time to runoff could be found in biochar application at 24 and 48 h before simulation treatment with rate of +55.10% and +71.73%, respectively. In addition, the mean runoff volume 24 and 48 h before simulation treatments decreased by 98.46% and 46.39%, respectively. The least soil loss (1.12 ± 0.57 g) and sediment concentration (1.44 ± 0.48 gl(-1)) occurred in the biochar-amended soil treated 48 h before the rainfall simulation. In conclusion, the application of vinasse-produced biochar could effectively control runoff and soil loss. This study provided a new insight into the effects of biochar on runoff, soil loss, and sediment control due to water erosion in sandy clay loam soils. PMID:26410722

  9. Inhibition of nitrification by gamma irradiation in soil under plastic-house conditions

    International Nuclear Information System (INIS)

    An incubation experiment was conducted on sandy clay loam soil treated with ammonium sulfate to study the effect of gamma irradiation (100, 200, and 300 krad) and dicyandiamide (DCD, 5 and 10 ppm) as nitrification inhibitors during 12 weeks of incubation under plastichouse conditions. The nitrification process decreased by either gamma irradiation or DCD treatment of soil. In the soil treated with DCD, there were no significant differences between a concentration of 5 and 10 ppm during the period of incubation. In the soil irradiates with 300 krad, the nitrification rate was significantly lower compared with that in the DCD treatment at concentration of 5 and 10 ppm. Nitrification inhibition was low when the soil was subjected to gamma irradiation and DCD treatment during a period of 4 weeks but the inhibition increased after 6 weeks of incubation. (author)

  10. Enhanced dissipation of oxyfluorfen, ethalfluralin, trifluralin, propyzamide, and pendimethalin in soil by solarization and biosolarization.

    Science.gov (United States)

    Fenoll Serrano, José; Ruiz, Encarnación; Hellín, Pilar; Lacasa, Alfredo; Flores, Pilar

    2010-02-24

    This study was conducted to assess the effects of solarization and biosolarization on the degradation of oxyfluorfen, ethalfluralin, trifluralin, propyzamide, and pendimethalin. The experimental design consisted of 17 L pots filled with clay-loam soil, which were contaminated with the studied herbicides. Then, soil disinfection treatments were applied during the summer season, including a control without disinfection (C), solarization (S), and biosolarization (BS). Soil from five pots per treatment was sampled periodically up to 90 days. Herbicide dissipation rates were higher in both S and BS treatments with regard to the control. Similar dissipation rates were observed under S and BS for most of the herbicides studied, except oxyfluorfen and pendimethalin, which were degraded to a greater extent in the BS than in the S treatment. The obtained results showed that both solarization and biosolarization can be considered, in addition to soil disinfection techniques, such as bioremediation tools for herbicide-polluted soils. PMID:20112907

  11. Salinity control in a clay soil beneath an orchard irrigated with treated waste water in the presence of a high water table: A numerical study

    Science.gov (United States)

    Russo, David; Laufer, Asher; Bardhan, Gopali; Levy, Guy J.

    2015-12-01

    A citrus orchard planted on a structured, clay soil associated with a high water table, irrigated by drip irrigation system using treated waste water (TWW) and local well water (LWW) was considered here. The scope of the present study was to analyze transport of mixed-ion, interacting salts in a combined vadose zone-groundwater flow system focusing on the following issues: (i) long-term effects of irrigation with TWW on the response of the flow system, identifying the main factors (e.g., soil salinity, soil sodicity) that control these effects, and (ii) salinity control aiming at improving both crop productivity and groundwater quality. To pursue this two-fold goal, 3-D numerical simulations of field-scale flow and transport were performed for an extended period of time, considering realistic features of the soil, water table, crop, weather and irrigation, and the coupling between the flow and the transport through the dependence of the soil hydraulic functions, K(ψ) and θ(ψ), on soil solution concentration C, and sodium adsorption ratio, SAR. Results of the analyses suggest that in the case studied, the long-term effect of irrigation with TWW on the response of the flow system is attributed to the enhanced salinity of the TWW, and not to the increase in soil sodicity. The latter findings are attributed to: (i) the negative effect of soil salinity on water uptake, and the tradeoff between water uptake and drainage flux, and, concurrently, solute discharge below the root zone; and, (ii) the tradeoff between the effects of C and SAR on K(ψ) and θ(ψ). Furthermore, it was demonstrated that a data-driven protocol for soil salinity control, based on alternating irrigation water quality between TWW and desalinized water, guided by the soil solution salinity at the centroid of the soil volume active in water uptake, may lead to a substantial increase in crop yield, and to a substantial decrease in the salinity load in the groundwater.

  12. Effects of shrub encroachment on soil organic carbon in global grasslands.

    Science.gov (United States)

    Li, He; Shen, Haihua; Chen, Leiyi; Liu, Taoyu; Hu, Huifeng; Zhao, Xia; Zhou, Luhong; Zhang, Pujin; Fang, Jingyun

    2016-01-01

    This study aimed to evaluate the effect of shrub encroachment on soil organic carbon (SOC) content at broad scales and its controls. We conducted a meta-analysis using paired control data of shrub-encroached grassland (SEG) vs. non-SEG collected from 142 studies worldwide. SOC contents (0-50 cm) were altered by shrub encroachment, with changes ranging from -50% to + 300%, with an effect size of 0.15 (p soils but increased in sand, sandy loam and sandy clay loam. The SOC content increment was significantly positively correlated with precipitation and temperature as well as with soil bulk density but significantly negatively correlated with soil total nitrogen. We conclude the main effects of shrub encroachment would be to increase topsoil organic carbon content. As structural equation model revealed, soils properties seem to be the primary factors responsible for the extent of the changes, coarse textured soils having a greater capacity than fine textured soils to increase the SOC content. This increased effect appears to be secondarily enhanced by climate and plant elements. PMID:27388145

  13. Effects of dissolved organic matter from the rhizosphere of the hyperaccumulator Sedum alfredii on sorption of zinc and cadmium by different soils.

    Science.gov (United States)

    Li, Tingqiang; Di, Zhenzhen; Yang, Xiaoe; Sparks, Donald L

    2011-09-15

    Pot experiments were conducted to investigate the changes of the dissolved organic matter (DOM) in the rhizosphere of hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of Sedum alfredii and its effects on Zn and Cd sorption by soils. After planted with HE, soil pH in the rhizosphere reduced by 0.5-0.6 units which is consistent with the increase of DOM. The hydrophilic fractions (51%) in DOM from the rhizosphere of HE (HE-DOM) was much greater than NHE-DOM (35%). In the presence of HE-DOM, Zn and Cd sorption capacity decreased markedly in the following order: calcareous clay loam>neutral clay loam>acidic silty clay. The sorption isotherms could be well described by the Freundlich equation (R(2)>0.95), and the partition coefficient (K) in the presence of HE-DOM was decreased by 30.7-68.8% for Zn and 20.3-59.2% for Cd, as compared to NHE-DOM. An increase in HE-DOM concentration significantly reduced the sorption and increased the desorption of Zn and Cd by three soils. DOM derived from the rhizosphere of the hyperaccumulating ecotype of S. alfredii could significantly reduce metal sorption and increase its mobility through the formation of soluble DOM-metal complexes. PMID:21782330

  14. Dispersão de argila em microagregados de solo incubado com calcário Clay dispersion in microaggregates of soil incubated with limestone

    Directory of Open Access Journals (Sweden)

    Silvio Tulio Spera

    2008-12-01

    incubated with 0, 1.9, 3.8, 5.7, 7.6 and 15.2 Mg ha-1. After the incubation period, the micro and macro porosity, soil density, clay dispersion, hydraulic conductivity and concentration of exchangeable Al, Ca and Mg and soil organic matter were evaluated. Soil density, clay dispersion, pH and Ca and Mg concentration increased with lime application, while macro porosity, hydraulic conductivity, soil organic matter, and Al decreased. The increase of pH and hydraulic conductivity were higher in the sterilized soil. Liming effects were more evident at a rate of 3.8 Mg ha-1. Soil sterilization increased the pH value and decreased the organic matter content and Ca, besides the hydraulic conductivity. Micro- aggregate dispersion in limed soils can, at least partially, contribute to soil compaction.

  15. Spatial variability in the soil water content of a Mediterranean agroforestry system with high soil heterogeneity

    Science.gov (United States)

    Molina, Antonio Jaime; Llorens, Pilar; Aranda, Xavier; Savé, Robert; Biel, Carmen

    2013-04-01

    Variability of soil water content is known to increase with the size of spatial domain in which measurements are taken. At field scale, heterogeneity in soil, vegetation, topography, water input volume and management affects, among other factors, hydrologic plot behaviour under different mean soil water contents. The present work studies how the spatial variability of soil water content (SWC) is affected by soil type (texture, percentage of stones and the combination of them) in a timber-orientated plantation of cherry tree (Prunus avium) under Mediterranean climatic conditions. The experimental design is a randomized block one with 3 blocks * 4 treatments, based on two factors: irrigation (6 plots irrigated versus 6 plots not irrigated) and soil management (6 plots tillaged versus 6 plots not tillaged). SWC is continuously measured at 25, 50 and 100 cm depth with FDR sensors, located at two positions in each treatment: under tree influence and 2.5 m apart. This study presents the results of the monitoring during 2012 of the 24 sensors located at the 25 cm depth. In each of the measurement point, texture and percentage of stones were measured. Sandy-loam, sandy-clay-loam and loam textures were found together with a percentage of stones ranging from 20 to 70 %. The results indicated that the relationship between the daily mean SWC and its standard deviation, a common procedure used to study spatial variability, changed with texture, percentage of stones and the estimation of field capacity from the combination of both. Temporal stability analysis of SWC showed a clear pattern related to field capacity, with the measurement points of the sandy-loam texture and the high percentage of stones showing the maximun negative diference with the global mean. The high range in the mean relative difference observed (± 75 %), could indicate that the studied plot may be considered as a good field-laboratory to extrapolate results at higher spatial scales. Furthermore, the

  16. Soil transference patterns on bras: Image processing and laboratory dragging experiments.

    Science.gov (United States)

    Murray, Kathleen R; Fitzpatrick, Robert W; Bottrill, Ralph S; Berry, Ron; Kobus, Hilton

    2016-01-01

    soil moisture content that would not have been possible otherwise. Soil type (e.g. Anthropogenic, gravelly sandy loam soil or Natural, organic-rich soil), clay mineralogy (smectite) and soil moisture content were the greatest influencing factors in all the dragging soil transference tests (both naked eye and measured properties) to explain the eight categories of soil transference patterns recorded. This study was intended to develop a method for dragging soil transference laboratory experiments and create a baseline of preliminary soil type/property knowledge. Results confirm the need to better understand soil behaviour and properties of clothing fabrics by further testing of a wider range of soil types and clay mineral properties. PMID:26679633

  17. Lixiviação e inativação do metribuzin em dois tipos de solos Leaching and inactivation of metribuzin in two soil types

    Directory of Open Access Journals (Sweden)

    J. Ferreira da Silva

    1981-12-01

    Full Text Available Com o objetivo de avaliar a lixiviação e a inativação do herbicida metribuzin (4-amino-6-tertbutil-3-(metiltio-as-triazina-5-(4Hona em materiais de um solo franco-argiloso e de outro solo franco-argilo-arenoso de duas regiões de Minas Gerais, um em laboratório e outro em casa de vegetação. O solo franco-argiloso era um Latossolo Roxo, com 2,8% de matéria orgãnica e o solo franco-argilo-arenoso era um Podzólico Vermelho-Amarelo; fase terraço, em 2,17% de matéria orgânica. Em laboratório estudou-se a lixiviação do metribuzin em colunas de 5, 10 e 15 cm de altura, com 7,5 cm de diâmetro, enchidas com materiais dos solos franco-argiloso e do solo franco-argiloarenoso. Usou-se o ensaio biológico de discos de cotilédones de melancia para detectar o metribuzin no lixiviado. Em casa de vegetação, estudou-se a inativação do metribuzin com materiais dos mesmos solos utilizados para o estudo de lixiviação. Para este ensaio foram utilizadas as doses de 0, 50, 80, 110, 140, 170 e 200g do i.a./ha do produto, e em areia lavada, as doses foram de 0, 4, 6, 8, 10, 12 e 16 g do i.a./ha do metribuzin, usando o pepino como planta teste, que foi cortado rente ao solo e pesado aos 14 dias após o plantio. Informações adicionais são necessárias para explicar porque o solo franco -argiloso inativa mais o metribuzin que o solo franco-argilo-arenoso.Laboratory and greenhouse experiments were made to evaluate the leaching and the inactivation of the metribuzin in clay loam and sand clay loam soils. The clay loam soil was a dark, red latosol with 2,8% organic matter and the sand clay loam soil was a reddish-yellow podzol with 2,17% organic matter. Leaching of metribuzin was studied in the laboratory in colums of 5, 10 and 15 cm high, 7.5 cm diameter, filled with soil. Watermelon cotiledon discs were used to measure the metribuzin leached. The inactivation of metribuzin was estudied in a greenhouse using doses of 0, 50, 80, 110, 140, 170 and 200

  18. Mineralization of 14C-labelled aromatic pesticide molecules in Egyptian soils under aerobic and anaerobic conditions

    International Nuclear Information System (INIS)

    The mineralization of 2,4-D, carbofuran and pirimiphos-methyl in Egyptian soils was studied over a period of 90 days. Laboratory studies under aerobic and anaerobic conditions were conducted using 14C-ring labelled pesticides. Under anaerobic conditions 10-14% of applied ring labelled 2,4-D mineralized during 90 days with no significant variations due to soil type. Under aerobic conditions, 2,4-D mineralized more readily in clay soil to reach 29-34% of applied dose within 90 days. In clay loam soil, 14C-carbofuran and 14C-pirimiphos-methyl mineralized at a rather slow rate to reach 12-14% and 12-13% of applied dose in 90 days, respectively under aerobic conditions. Generally, soils repeatedly treated with pesticides gave a slightly lower percentage of mineralization than control soils. In all studies, the soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding affinity of about 26-29% was observed with 2,4-D in clay soil under aerobic conditions in 90 days. Carbofuran, and pirimiphos-methyl, on the other hand, had lower binding capacity that did not exceed 16% of applied radioactivity. (author)

  19. Soil Nitrogen-Cycling Responses to Conversion of Lowland Forests to Oil Palm and Rubber Plantations in Sumatra, Indonesia.

    Science.gov (United States)

    Allen, Kara; Corre, Marife D; Tjoa, Aiyen; Veldkamp, Edzo

    2015-01-01

    Rapid deforestation in Sumatra, Indonesia is presently occurring due to the expansion of palm oil and rubber production, fueled by an increasing global demand. Our study aimed to assess changes in soil-N cycling rates with conversion of forest to oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations. In Jambi Province, Sumatra, Indonesia, we selected two soil landscapes - loam and clay Acrisol soils - each with four land-use types: lowland forest and forest with regenerating rubber (hereafter, "jungle rubber") as reference land uses, and rubber and oil palm as converted land uses. Gross soil-N cycling rates were measured using the 15N pool dilution technique with in-situ incubation of soil cores. In the loam Acrisol soil, where fertility was low, microbial biomass, gross N mineralization and NH4+ immobilization were also low and no significant changes were detected with land-use conversion. The clay Acrisol soil which had higher initial fertility based on the reference land uses (i.e. higher pH, organic C, total N, effective cation exchange capacity (ECEC) and base saturation) (P≤0.05-0.09) had larger microbial biomass and NH4+ transformation rates (P≤0.05) compared to the loam Acrisol soil. Conversion of forest and jungle rubber to rubber and oil palm in the clay Acrisol soil decreased soil fertility which, in turn, reduced microbial biomass and consequently decreased NH4+ transformation rates (P≤0.05-0.09). This was further attested by the correlation of gross N mineralization and microbial biomass N with ECEC, organic C, total N (R=0.51-0. 76; P≤0.05) and C:N ratio (R=-0.71 - -0.75, P≤0.05). Our findings suggest that the larger the initial soil fertility and N availability, the larger the reductions upon land-use conversion. Because soil N availability was dependent on microbial biomass, management practices in converted oil palm and rubber plantations should focus on enriching microbial biomass. PMID:26222690

  20. Soil and applied sulphur utilization by sunflower grown on vertisol under rainfed conditions

    International Nuclear Information System (INIS)

    In a field experiment, conducted with sunflower genotypes viz., Morden, APSH-11, and EC 68414 grown on a local black clay loam soil, fertilizer sulphur (labelled with 35S) was applied at the rate of 0, 20, 40 and 60 kg S/ha through gypsum and ammonium sulphate. Among the sunflower genotypes, EC 68414 utilized maximum sulphur from the sources at any given growth stage i.e., star, bud, flowering and maturity. Sulphur applied through ammonium sulphate resulted in highest S utilization by all the genotypes at all the stages of growth. Though, sulphur uptake showed an increase, the S utilization decreased with increase in levels of S. The S uptake was highest at 60 kg S/ha level applied through any of the sources. The soil S uptake was higher than fertilizer S uptake at any given stage of crop. Maximum yields were recorded at 40 kg S/ha level signifying that this dose is optimum for sunflower grown on black clay loam soils. (author). 17 refs., 3 tabs

  1. Soil carbon dioxide and methane fluxes from lowland forests converted to oil palm and rubber plantations in Sumatra, Indonesia

    Science.gov (United States)

    Preuss, Evelyn; Corre, Marife D.; Damris, Muhammad; Tjoa, Aiyen; Rahayu Utami, Sri; Veldkamp, Edzo

    2015-04-01

    Demand for palm oil has increased strongly in recent decades. Global palm oil production quadrupled between 1990 and 2009, and although almost half of the global supply is already produced in Indonesia, a doubling of current production is planned for the next ten years. This agricultural expansion is achieved by conversion of rainforest. Land-use conversion affects soil carbon dioxide (CO2) and methane (CH4) fluxes through changes in nutrient availability and soil properties which, in turn, influence plant productivity, microbial activity and gas diffusivity. Our study was aimed to assess changes in soil CO2 and CH4 fluxes with forest conversion to oil palm and rubber plantations. Our study area was Jambi Province, Sumatra, Indonesia. We selected two soil landscapes in this region: loam and clay Acrisol soils. At each landscape, we investigated four land-use systems: lowland secondary rainforest, secondary forest with regenerating rubber (referred here as jungle rubber), rubber (7-17 years old) and oil palm plantations (9-16 years old). Each land use in each soil landscape was represented by four sites as replicates, totaling to 32 sites. We measured soil-atmosphere CH4 and CO2 fluxes using vented static chamber method with monthly sampling from November 2012 to December 2013. There were no differences in soil CO2 and CH4 fluxes (all P > 0.05) between soil landscapes for each land-use type. For soil CO2 fluxes, in both clay and loam Acrisol soil landscapes oil palm were lower compared to the other land uses (P life-cycle analysis of these economically important crops.

  2. Statistical analyses of soil properties on a quaternary terrace sequence in the upper sava river valley, Slovenia, Yugoslavia

    Science.gov (United States)

    Vidic, N.; Pavich, M.; Lobnik, F.

    1991-01-01

    Alpine glaciations, climatic changes and tectonic movements have created a Quaternary sequence of gravely carbonate sediments in the upper Sava River Valley, Slovenia, Yugoslavia. The names for terraces, assigned in this model, Gu??nz, Mindel, Riss and Wu??rm in order of decreasing age, are used as morphostratigraphic terms. Soil chronosequence on the terraces was examined to evaluate which soil properties are time dependent and can be used to help constrain the ages of glaciofluvial sedimentation. Soil thickness, thickness of Bt horizons, amount and continuity of clay coatings and amount of Fe and Me concretions increase with soil age. The main source of variability consists of solutions of carbonate, leaching of basic cations and acidification of soils, which are time dependent and increase with the age of soils. The second source of variability is the content of organic matter, which is less time dependent, but varies more within soil profiles. Textural changes are significant, presented by solution of carbonate pebbles and sand, and formation is silt loam matrix, which with age becomes finer, with clay loam or clayey texture. The oldest, Gu??nz, terrace shows slight deviation from general progressive trends of changes of soil properties with time. The hypothesis of single versus multiple depositional periods of deposition was tested with one-way analysis of variance (ANOVA) on a staggered, nested hierarchical sampling design on a terrace of largest extent and greatest gravel volume, the Wu??rm terrace. The variability of soil properties is generally higher within subareas than between areas of the terrace, except for the soil thickness. Observed differences in soil thickness between the areas of the terrace could be due to multiple periods of gravel deposition, or to the initial differences of texture of the deposits. ?? 1991.

  3. Resistance of soil-bound prions to rumen digestion.

    Directory of Open Access Journals (Sweden)

    Samuel E Saunders

    Full Text Available Before prion uptake and infection can occur in the lower gastrointestinal system, ingested prions are subjected to anaerobic digestion in the rumen of cervids and bovids. The susceptibility of soil-bound prions to rumen digestion has not been evaluated previously. In this study, prions from infectious brain homogenates as well as prions bound to a range of soils and soil minerals were subjected to in vitro rumen digestion, and changes in PrP levels were measured via western blot. Binding to clay appeared to protect noninfectious hamster PrP(c from complete digestion, while both unbound and soil-bound infectious PrP(Sc proved highly resistant to rumen digestion. In addition, no change in intracerebral incubation period was observed following active rumen digestion of unbound hamster HY TME prions and HY TME prions bound to a silty clay loam soil. These results demonstrate that both unbound and soil-bound prions readily survive rumen digestion without a reduction in infectivity, further supporting the potential for soil-mediated transmission of chronic wasting disease (CWD and scrapie in the environment.

  4. Clay matrix voltammetry

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS2), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

  5. Neutron investigation of the rate of water seepage from irrigation channels and reservoirs in loessial loams

    International Nuclear Information System (INIS)

    The author discusses the results of experimental field studies on moisture conditions in the ground near an irrigation channel and a reservoir and the area of ground affected that were carried out in 1968 with neutron moisture gauges and gamma-gamma densimeters. Observations of the moisture movement and soil density were made in permanent boreholes up to 16.5 m deep lined with 2-in. steel tubes sealed at the bottom. To measure the moisture use was made of an all-purpose probe with a high-efficiency slow-neutron detector of the LDNM type (ZnS(Ag ) + B2O3), which was contained in the probe alongside a Pu + Be neutron source, thereby making it possible to obtain a linear dependence between the thermal neutron count and soil moisture. A portable scaler was used as the measuring instrument. When recording soil density, the LDNM scintillation crystal in the probe was replaced by a NaI(Tl) single crystal and a lengthener with a steel screen was screwed onto the probe casing. The conical end of the lengthener contained a gamma source (137Cs) with an activity of 2 meq of radium. In this case the length of the probe was 35 cm. On the basis of these studies the author determines the rate at which the soil near the reservoir is moistened and establishes the areas of loessial loams moistened by the irrigation channel. (author)

  6. Neutron Investigation of the Rate of Water Seepage from Irrigation Channels and Reservoirs on Loessial Loams

    International Nuclear Information System (INIS)

    The author discusses the results of experimental field studies on moisture conditions in the ground near an irrigation channel and a reservoir and the area of ground affected that were carried out in 1968 with neutron moisture gauges and gamma-gamma densimeters. Observations of the moisture movement and soil density were made in permanent boreholes up to 16.5 m deep lined with 2-in. steel tubes sealed at the bottom. To measure the moisture use was made of an all-purpose probe with a high-efficiency slow-neutron detector of the LDNM type (ZnS(Ag) + B2O3), which was contained in the probe alongside a Pu + Be neutron source, thereby making it possible to obtain a linear dependence between the thermal neutron count and soil moisture. A portable scaler was used as the measuring instrument. When recording soil density, the LDNM scintillation crystal in the probe was replaced by a Nal(Tl) single crystal and a lengthener with a steel screen was screwed onto the probe casing. The conical end of the lengthener contained a gamma source (137Cs) with an activity of 2 meq of radium. In this case the length of the probe was-35 cm. On the basis of these studies the author determines the rate at which the soil near the reservoir is moistened and establishes the areas of loessial loams moistened by the irrigation channel. (author)

  7. Combined effects of short-term rainfall patterns and soil texture on nitrogen cycling -- A Modeling Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C.; Riley, W.J.

    2009-11-01

    Precipitation variability and magnitude are expected to change in many parts of the world over the 21st century. We examined the potential effects of intra-annual rainfall patterns on soil nitrogen (N) transport and transformation in the unsaturated soil zone using a deterministic dynamic modeling approach. The model (TOUGHREACT-N), which has been tested and applied in several experimental and observational systems, mechanistically accounts for microbial activity, soil-moisture dynamics that respond to precipitation variability, and gaseous and aqueous tracer transport in the soil. Here, we further tested and calibrated the model against data from a precipitation variability experiment in a tropical system in Costa Rica. The model was then used to simulate responses of soil moisture, microbial dynamics, nitrogen (N) aqueous and gaseous species, N leaching, and N trace-gas emissions to changes in rainfall patterns; the effect of soil texture was also examined. The temporal variability of nitrate leaching and NO, N{sub 2}, and N{sub 2}O effluxes were significantly influenced by rainfall dynamics. Soil texture combined with rainfall dynamics altered soil moisture dynamics, and consequently regulated soil N responses to precipitation changes. The clay loam soil more effectively buffered water stress during relatively long intervals between precipitation events, particularly after a large rainfall event. Subsequent soil N aqueous and gaseous losses showed either increases or decreases in response to increasing precipitation variability due to complex soil moisture dynamics. For a high rainfall scenario, high precipitation variability resulted in as high as 2.4-, 2.4-, 1.2-, and 13-fold increases in NH{sub 3}, NO, N{sub 2}O and NO{sub 3}{sup -} fluxes, respectively, in clay loam soil. In sandy loam soil, however, NO and N{sub 2}O fluxes decreased by 15% and 28%, respectively, in response to high precipitation variability. Our results demonstrate that soil N cycling

  8. Change effects in the land use about the mineral clay

    International Nuclear Information System (INIS)

    The Pampas land changes during the Quaternary, left their mark on the mineralogy of soil clays. This work is oriented to compare the mineralogical composition of the clays and the value of potassium in an eucalyptus forestation. These results show that the mineralogical illite alteration is the cause of its destruction. This clay is the main reservoir of potassium for the agricultural soils

  9. Effects Of Irrigation With Saline Water, And Soil Type On Germination And Seedling Growth Of Sweet Maize (Zea Mays L.)

    International Nuclear Information System (INIS)

    Germination and early growth of maize Sweet Maize (Zea mays L.), var. (SEL. CONETA) under irrigation with saline water were investigated in a pot experiment with different soil types. Seven salinity levels of irrigation water up to 12 dS/m were used on a Clay soil (C) and a Sandy-Loam (SL). Emergence of maize was delayed under irrigation with saline water, and the final percentage of germination was reduced only at 8 dS/m or above. Seedling shoot and root growth were reduced starting at 4 dS/m of irrigation water. Salts accumulated more in the C soil but reductions in final germination rate and seedling growth were larger in the SL soil, although differences were not always significant. Data indicate that germination is rather tolerant to salinity level in var. SEL. CONETA whereas seedling growth is reduced at moderate salinity levels, and that soil type affects plant performance under irrigation with saline water

  10. Fracture mapping in clays: the design and application of a mobile gas geochemistry laboratory for the analysis of soil gases

    International Nuclear Information System (INIS)

    Integrated soil gas analyses for helium, radon, carbon dioxide, oxygen and organic gases allow the accurate interpretation of soil gas signatures as indicators of underlying structure. The most important features observed in the patterns of soil gas behaviour are large variations over faults and fractures. Structures such as these provide channelways for fluid movement in the upper crust. The construction of a mobile gas geochemistry laboratory for the analysis of soil gases at field investigation sites, and the subsequent trials carried out to evaluate the laboratory, clearly show that the soil gas investigation technique is accurate and viable as an independent site investigation method for the study of fracturing and groundwater movement around potential waste repository sites. (author)

  11. Effect of land management on soil properties in flood irrigated citrus orchards in Eastern Spain

    Science.gov (United States)

    Morugán-Coronado, A.; García-Orenes, F.; Cerdà, A.

    2015-01-01

    Agricultural land management greatly affects soil properties. Microbial soil communities are the most sensitive and rapid indicators of perturbations in land use and soil enzyme activities are sensitive biological indicators of the effects of soil management practices. Citrus orchards frequently have degraded soils and this paper evaluates how land management in citrus orchards can improve soil quality. A field experiment was performed in an orchard of orange trees (Citrus Sinensis) in the Alcoleja Experimental Station (Eastern Spain) with clay-loam agricultural soils to assess the long-term effects of herbicides with inorganic fertilizers (H), intensive ploughing and inorganic fertilizers (P) and organic farming (O) on the soil microbial properties, and to study the relationship between them. Nine soil samples were taken from each agricultural management plot. In all the samples the basal soil respiration, soil microbial biomass carbon, water holding capacity, electrical conductivity, soil organic matter, total nitrogen, available phosphorus, available potassium, aggregate stability, cation exchange capacity, pH, texture, macronutrients (Na, Ca and Mg), micronutrients (Fe, Mn, Zn and Cu), calcium carbonate equivalent, calcium carbonate content of limestone and enzimatic activities (urease, dehydrogenase, β-glucosidase and acid phosphatase) were determined. The results showed a substantial level of differentiation in the microbial properties, which were highly associated with soil organic matter content. The management practices including herbicides and intensive ploughing had similar results on microbial soil properties. O management contributed to an increase in the soil biology quality, aggregate stability and organic matter content.

  12. Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Polymerase chain reaction (PCR) was used to amplify a 600-base pair (bp) sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil (Alfisol) and Red soil (Ultisol), and three different minerals (goethite, kaolinite, montmorillonite). DNA bound on soil colloids, kaolinite, and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted, 10- and 20-fold. The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected. DNA bound on goethite was amplified irrespective of whether the complex was used directly, or diluted 10- and 20-fold. The amplification of mineral-bound plasmid DNA