The Experts below are selected from a list of 10491 Experts worldwide ranked by ideXlab platform
A K Guber - One of the best experts on this subject based on the ideXlab platform.
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effect of bovine manure on fecal coliform attachment to soil and soil particles of different sizes
Applied and Environmental Microbiology, 2007Co-Authors: A K Guber, Yakov Pachepsky, Daniel R SheltonAbstract:Manure-borne bacteria can be transported in runoff as free cells, cells attached to soil particles, and cells attached to manure particles. The objectives of this work were to compare the attachment of fecal coliforms (FC) to different Soils and soil fractions and to assess the effect of bovine manure on FC attachment to soil and soil fractions. Three sand fractions of different sizes, the silt fraction, and the Clay fraction of Loam and sandy Clay Loam Soils were separated and used along with soil samples in batch attachment experiments with water-FC suspensions and water-manure-FC suspensions. In the absence of manure colloids, bacterial attachment to soil, silt, and Clay particles was much higher than the attachment to sand particles having no organic coating. The attachment to the coated sand particles was similar to the attachment to silt and Clay. Manure colloids in suspensions decreased bacterial attachment to Soils, Clay and silt fractions, and coated sand fractions, but did not decrease the attachment to sand fractions without the coating. The low attachment of bacteria to silt and Clay particles in the presence of manure colloids may cause predominantly free-cell transport of manure-borne FC in runoff.
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rainfall induced release of fecal coliforms and other manure constituents comparison and modeling
Applied and Environmental Microbiology, 2006Co-Authors: A K Guber, Yakov Pachepsky, Daniel R Shelton, Ali M Sadeghi, Lawrence J SikoraAbstract:Modeling release of fecal coliforms is an important component of fate and transport simulations related to environmental water quality. Manure constituents other than fecal coliforms may serve as natural tracers of fecal contamination provided that their release from manure to runoff is similar to the fecal coliform release. The objectives of this work were to compare release of fecal coliforms (FC), chloride (Cl−), organic carbon (OC), and water-soluble phosphorus (P) from dissolving manure and to assess the performance of three models in describing the observed release. Bovine manure was applied on 0.5- by 0.3-m bare and vegetated subplots with 20% slope on sandy Loam and Clay Loam Soils. Concentrations of Cl−, FC, OC, and P were measured in runoff collected from troughs at the edges of the subplots at 5-min intervals during 1-h rainfall simulations. The one-parametric exponential model and two-parametric Vadas-Kleinman-Sharpley model and Bradford-Schijven model were fitted to the data. The Bradford-Schijven model had uncorrelated parameters, one of which was linearly related to the irrigation rate, and another parameter reflected the presence or the absence of vegetation. Kinetics of the FC release from manure was similar to the release kinetics of P and OC. The Bradford-Schijven model is recommended to simulate the release of manure constituents.
Leonard C. Kibet - One of the best experts on this subject based on the ideXlab platform.
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Long-term tillage impact on soil hydraulic properties
Soil & Tillage Research, 2017Co-Authors: Humberto Blanco-canqui, Brian J. Wienhold, Virginia L. Jin, Marty R. Schmer, Leonard C. KibetAbstract:Abstract An improved understanding of the impact of tillage systems on soil hydraulic properties is necessary to conserve and manage soil water under a changing climate. The objective of this study was to specifically measure soil hydraulic properties (total porosity, water infiltration, saturated hydraulic conductivity, and water retention characteristics) in no-till, chisel plow, disk, and moldboard plow systems under rainfed continuous corn (Zea mays L.) after 35 yr on silty Clay Loam Soils in eastern Nebraska. We measured ponded water infiltration (positive soil water pressure) and tension (−1 kPa matric potential) infiltration to exclude macropore (>125 μm diameter) flow. Tillage treatments affected ponded infiltration only. Moldboard plow significantly increased ponded infiltration rate by 21.6 cm h−1 at 5 min and by 8.8 cm h−1 at 60 min compared with no-till. However, when compared with disk and chisel, moldboard plow increased ponded infiltration rates at all measurements times, which lasted 3 h. Regarding cumulative infiltration, moldboard plow increased cumulative infiltration by 26.9 cm to 39.0 cm after 3 h compared with other tillage systems. Similarities in tension infiltration suggest that the higher ponded infiltration for moldboard plow was most likely due to the presence of voids or fractures (>125 μm) created by full inversion tillage. Total porosity, saturated hydraulic conductivity, and water retention among the treatments did not differ. Overall, soil hydraulic properties did not differ among tillage systems except water infiltration in these silty Clay Loam Soils after 35 yr of management.
W E Curnoe - One of the best experts on this subject based on the ideXlab platform.
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slurry application implement tine modification of soil hydraulic properties under different soil water content conditions for silt Clay Loam Soils
Soil & Tillage Research, 2007Co-Authors: K M Turpin, G. C. Topp, M Edwards, W E Curnoe, David R Lapen, M J L Robin, Edward Topp, Neil B Mclaughlin, Ball B Coelho, M PayneAbstract:Abstract Tillage action associated with liquid slurry application systems/management practices can modify soil infiltration properties. The degree or nature of such modification will depend largely on the type of tillage implement used, and the soil conditions at time of tillage activity. The specific objective of this study is to evaluate differences in soil infiltration properties, as measured using pressure infiltrometers and Guelph permeameters, resulting from the immediate tine action of two commonly used slurry application tillage implements (Kongskilde Vibro-Flex (S-tine) and the AerWay SSD (rolling aerator-type tine)) over a variety of silt–Clay Loam soil water content conditions. The results indicated that there were consistent negative correlations between field saturated hydraulic conductivity and soil water content for all tine-disturbed and undisturbed soil treatments. For Kongskilde, field-saturated hydraulic conductivity was, on average, lower in tine-influenced furrow bottoms, relative to those measured in undisturbed conditions at similar depths for most water content conditions. Generally, the Kongskilde tine-action reduced macropore-based infiltration in the bottom of the furrow for most soil conditions, albeit, this effect was most pronounced at the higher soil water contents. For AerWay, the tine-disturbed Soils had generally higher field saturated hydraulic conductivities than undisturbed soil treatments over the observed water content range. This effect was manifested to a greater degree at higher, relative to lower observed water contents.
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combination cone penetration resistance water content instrumentation to evaluate cone penetration water content relationships in tillage research
Soil & Tillage Research, 2004Co-Authors: D R Lapen, G. C. Topp, M Edwards, E G Gregorich, W E CurnoeAbstract:Cone penetration resistance (PR) is generally regarded as one of the best tools to assess soil strength. However, effects of soil water content (WC) on measured PR can mask or confound interpretations of treatment effects on soil strength. Correction of PR data to common water contents, via empirical PR versus WC relationships, could help reduce such problems. This study used a portable combination PR/WC instrument to evaluate and formalize growing season (multiple year) changes in cultivation zone PR versus WC relationships for different tillage (conventional and no-till), trafficked, and corn (Zea mays L.) cropping systems on Clay Loam Soils in eastern Ontario, Canada. The results indicated expected negative linear and piecewise linear relationships between PR and WC for no-till Soils. There was generally greater potential for higher PR at a specified water content for preferentially trafficked no-till Soils, relative to no-till not receiving such a treatment. For tilled Soils, negative linear relationships between bulk PR and WC were not as strong. Significant interactions between PR, WC, and days after planting (DAP), however, were uncovered using multivariate adaptive regression spline analyses. For non-preferentially trafficked tilled plots, linear negative relationships between PR and WC changed over the growing season and achieved strength/stability at approximately 90 days after planting; roughly 50 days after bulk density after planting effectively stabilized. For preferentially trafficked tilled plots, there were similar PR versus WC relationships, however, there were stronger interacting positive relationships between PR and DAP. The results from this work are promising for elucidating soil structural evolution over growing seasons for different tillage, trafficked and corn cropping systems on Clay Loam Soils.
R. B. Somawanshi - One of the best experts on this subject based on the ideXlab platform.
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unsaturated flow of different quality irrigation waters through Clay Clay Loam and silt Loam Soils and its dependence on soil and solution parameters
Agricultural Water Management, 2004Co-Authors: S.k. Chaudhari, R. B. SomawanshiAbstract:Abstract The effect of total electrolyte concentration (TEC) and sodium adsorption ratio (SAR) of irrigation water on unsaturated hydraulic properties, viz. unsaturated hydraulic conductivity, wetting front advancement and soil-water diffusivity of Clay (Typic Haplustert), Clay Loam (Vertic Haplustept) and silt Loam (Lithic Haplorthent) soil was studied in a laboratory experiment. Twenty-four types of irrigation waters, encompassing four TEC levels, viz. 5, 10, 20 and 50 me l −1 and six SAR levels, viz. 2.5, 5, 10, 15, 20 and 30 m mol 1/2 l −1/2 were synthesised to equilibrate the soil samples using pure chloride salts of calcium, magnesium and sodium at Mg:Ca=1:2. Unsaturated hydraulic conductivity ( K θ ), was determined both directly (by ‘inflow–outflow’ vertical infiltration method for water potentials of −5 and −10 kPa) and indirectly (from diffusivity functions and soil-water retention curves) in two different water potential ranges. Wetting front advancement and diffusivity ( D θ ) were determined by the horizontal infiltration method. Water quality had larger impacts on the unsaturated hydraulic conductivities of the silt Loam soil than on the Clay and Clay Loam Soils. The effects of TEC and SAR were both large for the silt Loam soil whereas the effects of SAR were predominant for the Clay and Clay Loam Soils. At a water potential of −5 kPa (50 cm suction), the hydraulic conductivity of Clay and Clay Loam Soils was approximately 10 times smaller than at saturation under different quality waters. However, the hydraulic conductivity of silt Loam soil was approximately 10 and 100 times smaller than at saturation for low SAR (up to 10 m mol 1/2 l −1/2 ) and high SAR (15 m mol 1/2 l −1/2 and above) waters, respectively. Influence of irrigation water quality on K θ increased with decreasing water content. SAR of water and exchangeable sodium percentage (ESP) of Soils influenced K θ significantly. Besides SAR, TEC also influenced K θ of silt Loam significantly. D θ increased with increase in TEC and/or decrease in SAR of water. The Clay soil was found to be the most sensitive soil to unsaturated flow above SAR 15 m mol 1/2 l −1/2 . At higher and lower water contents, the dependence of D θ on SAR of water and ESP of soil was found to be highly significant. However, in silt Loam soil it was significantly dependent on TEC of water also.
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Modelling pF curve of Clay, Clay Loam and silt Loam Soils under different quality waters.
2000Co-Authors: S.k. Chaudhari, R. B. SomawanshiAbstract:Water retention curve of Clay (Typic Haplusterts), Clay Loam (Vertic Haplustepts) and silt Loam (Lithic Ustorthents) Soils were modelled hy six ditlerent approaches. A modified exponential form with log of suction (pF) as the dependent and relative water content (water content as a fraction of saturation water content) as the independent variahle, predicted this relationship very satisfactorily under differ ent water quality comhinations in Clay and Clay Loam Soils with an average R2 values of96.6 and 98.9 per cent, respectively. An inverse polynomial fonn predicted this relationship very satisfactorily with an average R2 value of 98.3 per cent in silt Loam soil. Rise in sodium adsorption ratio under low electrolyte solutions declined the R2 values of various models, however under high electrolyte solu tions R2 values remained almost constant.
S.k. Chaudhari - One of the best experts on this subject based on the ideXlab platform.
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unsaturated flow of different quality irrigation waters through Clay Clay Loam and silt Loam Soils and its dependence on soil and solution parameters
Agricultural Water Management, 2004Co-Authors: S.k. Chaudhari, R. B. SomawanshiAbstract:Abstract The effect of total electrolyte concentration (TEC) and sodium adsorption ratio (SAR) of irrigation water on unsaturated hydraulic properties, viz. unsaturated hydraulic conductivity, wetting front advancement and soil-water diffusivity of Clay (Typic Haplustert), Clay Loam (Vertic Haplustept) and silt Loam (Lithic Haplorthent) soil was studied in a laboratory experiment. Twenty-four types of irrigation waters, encompassing four TEC levels, viz. 5, 10, 20 and 50 me l −1 and six SAR levels, viz. 2.5, 5, 10, 15, 20 and 30 m mol 1/2 l −1/2 were synthesised to equilibrate the soil samples using pure chloride salts of calcium, magnesium and sodium at Mg:Ca=1:2. Unsaturated hydraulic conductivity ( K θ ), was determined both directly (by ‘inflow–outflow’ vertical infiltration method for water potentials of −5 and −10 kPa) and indirectly (from diffusivity functions and soil-water retention curves) in two different water potential ranges. Wetting front advancement and diffusivity ( D θ ) were determined by the horizontal infiltration method. Water quality had larger impacts on the unsaturated hydraulic conductivities of the silt Loam soil than on the Clay and Clay Loam Soils. The effects of TEC and SAR were both large for the silt Loam soil whereas the effects of SAR were predominant for the Clay and Clay Loam Soils. At a water potential of −5 kPa (50 cm suction), the hydraulic conductivity of Clay and Clay Loam Soils was approximately 10 times smaller than at saturation under different quality waters. However, the hydraulic conductivity of silt Loam soil was approximately 10 and 100 times smaller than at saturation for low SAR (up to 10 m mol 1/2 l −1/2 ) and high SAR (15 m mol 1/2 l −1/2 and above) waters, respectively. Influence of irrigation water quality on K θ increased with decreasing water content. SAR of water and exchangeable sodium percentage (ESP) of Soils influenced K θ significantly. Besides SAR, TEC also influenced K θ of silt Loam significantly. D θ increased with increase in TEC and/or decrease in SAR of water. The Clay soil was found to be the most sensitive soil to unsaturated flow above SAR 15 m mol 1/2 l −1/2 . At higher and lower water contents, the dependence of D θ on SAR of water and ESP of soil was found to be highly significant. However, in silt Loam soil it was significantly dependent on TEC of water also.
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Dependence of Saturated Hydraulic Conductivity on Dispersion, Swelling and Exchangeable Sodium under Different Quality Waters
Journal of the Indian Society of Soil Science, 2001Co-Authors: S.k. ChaudhariAbstract:Effects of water quality on saturated hydraulic conductivity, dispersion, swelling and exchangeable sodium build-up in Clay (Typic Haplustert), Clay Loam (Vertic Haplustept) and silt Loam (Lithic Ustorthent) Soils were studied. Soil samples were equilibrated with twenty-four water quality combinations encompassing four electrolyte concentrations (TEC) ranging between 5 and 50 me L−1; and six sodium adsorption ratios (SAR) ranging between 2.5 and 30 m mol½ L−½. Saturated hydraulic conductivity ranged from 0.009 to 0.157, 0.016 to 0.235; and 0.453 to 22.76 cm h−1, dispersion index from 11.6 to 26.0, 8.3 to 24.9 and 5.7 to 13.2 per cent, coefficient of linear extensibility from 0.05 to 0.21, 0.03 to 0.14; and 0.007 to 0.032; and exchangeable sodium percentage from 2.23 to 20.0, 3.18 to 24.55; and 4.26 to 32.4 in Clay, Clay Loam and silt Loam Soils, respectively. Dependence of saturated hydraulic conductivity on water quality parameters (TEC and SAR) and soil properties (dispersion, swelling and exchangeable sodium) was also studied. Clay and Clay Loam Soils were equally sensitive to the changes in TEC only. Multiple regression equations indicated the significant dependence of saturated hydraulic conductivity on ESP in all the Soils. Dispersion and swelling were found to be the important processes governing the changes in saturated hydraulic conductivity of Clay and Clay Loam Soils. However, changes in saturated hydraulic conductivity were mainly governed by dispersion in silt Loam soil.
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Modelling pF curve of Clay, Clay Loam and silt Loam Soils under different quality waters.
2000Co-Authors: S.k. Chaudhari, R. B. SomawanshiAbstract:Water retention curve of Clay (Typic Haplusterts), Clay Loam (Vertic Haplustepts) and silt Loam (Lithic Ustorthents) Soils were modelled hy six ditlerent approaches. A modified exponential form with log of suction (pF) as the dependent and relative water content (water content as a fraction of saturation water content) as the independent variahle, predicted this relationship very satisfactorily under differ ent water quality comhinations in Clay and Clay Loam Soils with an average R2 values of96.6 and 98.9 per cent, respectively. An inverse polynomial fonn predicted this relationship very satisfactorily with an average R2 value of 98.3 per cent in silt Loam soil. Rise in sodium adsorption ratio under low electrolyte solutions declined the R2 values of various models, however under high electrolyte solu tions R2 values remained almost constant.