The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Francesco Morari - One of the best experts on this subject based on the ideXlab platform.
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errors in water retention curves determined with pressure plates effects on the soil water balance
Journal of Hydrology, 2012Co-Authors: R Solone, Marco Bittelli, Fausto Tomei, Francesco MorariAbstract:Pressure plates apparatus are very common experimental devices utilized to measure the soil water retention curve. Many studies have demonstrated the lack of reliability of pressure plates apparatus when they are used to measure the soil water retention curve in the dry range, due to low plate and soil conductance, lack of hydrostatic equilibrium, lack of soil–plate contact and soil dispersion. In this research, we investigated measurements of soil water retention curves obtained with a combination of Stackman’s tables, pressure plates apparatus and the chilled-mirror dew point technique. Specifically, the aim of this research was: (a) to investigate the differences in the measured soil water retention curves by the different experimental methods, (b) evaluate relationships between the experimental differences and soil texture, (c) analyze the effect of experimental differences on hydraulic properties parameterization and (d) investigate the effects of the different parameters set on water transport computation. The results showed differences in measurements made by the combination of Stackman’s tables and Richards’ pressure plates apparatus as compared to the dew point method, for fine textured Soils, while no significant differences were detected for coarse textured Soils. Computed cumulative drainage and evaporation displayed lower values if soil water retention curves were obtained from data obtained with the Stackman’s tables and Richards’ pressure plates apparatus instead of the dew point method. In Soils, where the soil water retention curve was measured with traditional methods (Stackman’s tables and Richards’ pressure plates apparatus) average cumulative drainage was 173 mm, with respect to a combination of methods including the dew point methods, where the average cumulative drainage was 184 mm. Average cumulative evaporation was 77 mm for the traditional methods, while it was 91 mm, for the combination of methods. Overall, when simulation models are used for studies related to solute transport, polluted soil remediation, irrigation management and others, erroneous measurement of the SWRC for fine textured Soils, may lead to erroneous computation of the soil water balance.
D C Coleman - One of the best experts on this subject based on the ideXlab platform.
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long term effects of earthworms on microbial biomass nitrogen in coarse and fine textured Soils
Applied Soil Ecology, 1998Co-Authors: Paul F Hendrix, A C Peterson, M H Beare, D C ColemanAbstract:Abstract We conducted field studies of the effects of earthworms on microbial biomass-N in sandy clay loam vs. sandy Soils under no-tillage management on Ultisols of the southern Appalachian Piedmont in Georgia, USA. 15 N -labeled crop residue was applied to the surface of plots with or without the addition of earthworms (principally Lumbricus rubellus and Aporrectodea caliginosa). Microbial biomass N and 15 N levels were measured at intervals over five years. Microbial N concentrations increased in both Soils but more so at the surface of the sandy soil and in deeper soil layers in the clay soil. Microbial N concentrations were consistently lower in earthworm treatments than in controls in the clay soil and to a lesser extent in the sandy soil. In deeper layers of the clay soil, earthworm additions increased 15 N enrichment of the microbial pool, suggesting that earthworms increased transport of crop residue N into the subsoil. In the sandy soil the microbial pool was half as large as in the clay soil, but showed a 100–300% increase in 15 N enrichment during the first year, indicating substantially higher microbial turnover. Although earthworm activity reduced standing stocks of microbial biomass, particularly in the Fine-Textured soil, it appeared to increase the turnover of the microbial-N pool as indicated by 15 N measurements. Observed changes in microbial biomass reflected rapid cycling of labile organic matter pools in response to biological activity, soil texture and soil management.
R Solone - One of the best experts on this subject based on the ideXlab platform.
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errors in water retention curves determined with pressure plates effects on the soil water balance
Journal of Hydrology, 2012Co-Authors: R Solone, Marco Bittelli, Fausto Tomei, Francesco MorariAbstract:Pressure plates apparatus are very common experimental devices utilized to measure the soil water retention curve. Many studies have demonstrated the lack of reliability of pressure plates apparatus when they are used to measure the soil water retention curve in the dry range, due to low plate and soil conductance, lack of hydrostatic equilibrium, lack of soil–plate contact and soil dispersion. In this research, we investigated measurements of soil water retention curves obtained with a combination of Stackman’s tables, pressure plates apparatus and the chilled-mirror dew point technique. Specifically, the aim of this research was: (a) to investigate the differences in the measured soil water retention curves by the different experimental methods, (b) evaluate relationships between the experimental differences and soil texture, (c) analyze the effect of experimental differences on hydraulic properties parameterization and (d) investigate the effects of the different parameters set on water transport computation. The results showed differences in measurements made by the combination of Stackman’s tables and Richards’ pressure plates apparatus as compared to the dew point method, for fine textured Soils, while no significant differences were detected for coarse textured Soils. Computed cumulative drainage and evaporation displayed lower values if soil water retention curves were obtained from data obtained with the Stackman’s tables and Richards’ pressure plates apparatus instead of the dew point method. In Soils, where the soil water retention curve was measured with traditional methods (Stackman’s tables and Richards’ pressure plates apparatus) average cumulative drainage was 173 mm, with respect to a combination of methods including the dew point methods, where the average cumulative drainage was 184 mm. Average cumulative evaporation was 77 mm for the traditional methods, while it was 91 mm, for the combination of methods. Overall, when simulation models are used for studies related to solute transport, polluted soil remediation, irrigation management and others, erroneous measurement of the SWRC for fine textured Soils, may lead to erroneous computation of the soil water balance.
Paul F Hendrix - One of the best experts on this subject based on the ideXlab platform.
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long term effects of earthworms on microbial biomass nitrogen in coarse and fine textured Soils
Applied Soil Ecology, 1998Co-Authors: Paul F Hendrix, A C Peterson, M H Beare, D C ColemanAbstract:Abstract We conducted field studies of the effects of earthworms on microbial biomass-N in sandy clay loam vs. sandy Soils under no-tillage management on Ultisols of the southern Appalachian Piedmont in Georgia, USA. 15 N -labeled crop residue was applied to the surface of plots with or without the addition of earthworms (principally Lumbricus rubellus and Aporrectodea caliginosa). Microbial biomass N and 15 N levels were measured at intervals over five years. Microbial N concentrations increased in both Soils but more so at the surface of the sandy soil and in deeper soil layers in the clay soil. Microbial N concentrations were consistently lower in earthworm treatments than in controls in the clay soil and to a lesser extent in the sandy soil. In deeper layers of the clay soil, earthworm additions increased 15 N enrichment of the microbial pool, suggesting that earthworms increased transport of crop residue N into the subsoil. In the sandy soil the microbial pool was half as large as in the clay soil, but showed a 100–300% increase in 15 N enrichment during the first year, indicating substantially higher microbial turnover. Although earthworm activity reduced standing stocks of microbial biomass, particularly in the Fine-Textured soil, it appeared to increase the turnover of the microbial-N pool as indicated by 15 N measurements. Observed changes in microbial biomass reflected rapid cycling of labile organic matter pools in response to biological activity, soil texture and soil management.
J. Hassink - One of the best experts on this subject based on the ideXlab platform.
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density fractions of soil macroorganic matter and microbial biomass as predictors of c and n mineralization
Soil Biology & Biochemistry, 1995Co-Authors: J. HassinkAbstract:Macroorganic matter of arable Soils which had received different inputs of organic residues for 25 y and grassland Soils that had been under grass for at least 8 y was fractionated into light, intermediate and heavy fractions using a stable silica suspension as heavy liquid. For all residue treatments, the C-to-N ratios of organic matter decreased in the order light, intermediate, heavy macroorganic matter (fraction > 150 μm) and non-macroorganic matter (fraction < 150 μm). Residue application had a stronger effect on the amount and C-to-N ratio of macroorganic matter fractions than on the amount and C-to-N ratio non-macroorganic matter. Textural effects were apparent with the proportions of soil N in the light and intermediate fractions being higher in coarse-textured grassland Soils than in Fine-Textured grassland Soils. C and N mineralization were positively correlated with the amount of C and N in the light fraction and the active microbial biomass. The correlation with mineralization decreased with increasing stability of the organic matter fractions. C and N mineralization per unit of total microbial biomass were lower in Fine-Textured Soils than in coarse-textured Soils. This is ascribed to a greater physical protection of the organic matter in Fine-Textured Soils than in coarse-textured Soils.