Author
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ZHANG, J - Northwest Agricultural & Forestry University |
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Wagner, Larry |
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Hagen, Lawrence |
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Submitted to: International Conference on Aeolian Research
Publication Type: Abstract Only Publication Acceptance Date: 7/1/2014 Publication Date: N/A Citation: N/A Interpretive Summary: Flat crop residue often contributes to wind erosion control, but it may be rearranged or removed from fields during high wind events. The influence of standing residue stems on flat residue loss and thus wind erosion susceptibility is evaluated. Data were collected in laboratory wind tunnel experiments using three typical crop residues including soybeans, winter wheat and grain sorghum. The effects of standing residue combined with reductions in flat residue cover on soil loss by wind were simulated with the Single-event Wind Erosion Evaluation Program (SWEEP). Results showed that erosion decreased with increases in standing residue stem height and stem population density. The variation was greater among lower population densities than higher ones. This was observed regardless whether flat residue existed or not. The amount of simulated soil loss decreased with increases of flat residue cover. Potential soil loss differences among the residues with similar SAI (product of stem height, population density and stem diameter) implied that stem height played the most significant role, followed by population density, with stem diameter being the least effective in controlling wind erosion. Technical Abstract: Flat crop residue often contributes to wind erosion control, but it may be rearranged or removed from fields during high wind events. This paper reports the influence of flat residue loss on soil wind erosion susceptibility when standing stems co-existed. Data were collected in laboratory wind tunnel experiments using three typical crop residues including soybeans (Glycine max), winter wheat (Triticum aestivum) and grain sorghum (Sorghum bicolor). The effects of standing residue combined with reductions in flat residue cover on soil loss by wind were simulated with the Single-event Wind Erosion Evaluation Program (SWEEP). Results showed that potential erosion decreased with increases in standing residue height and population density. Obviously, the variation was greater among lower population densities than higher ones. This was observed regardless whether flat residue existed or not. The amount of simulated soil loss decreased with increases of flat residue cover. Potential soil loss differences among the residues with similar SAI (product of stem height, population density and stem diameter) implied that stem height played the most significant role, followed by population density, with stem diameter being the least effective in controlling wind erosion. The comparison of Critical Friction-Velocity Ratio among residues indicated that winter wheat was a little better than soybeans, and both of them were much better than grain sorghum in controlling soil erosion. The SWEEP simulations showed that saltation and creep particles were the main components which took 69.4% on average, the rest was suspension particles with only a small fraction of PM10 being emitted. Contents of these components were stable in eroded soil, which had narrow range regardless the variation of height and population density of standing stems, cover of flat residue and residue type. Soil erosion intensity decreased along the wind direction in simulation for the impact of standing residue and redistribution of sheltered flat residue. The change of near-surface wind is illustrated by the zero-plane displacement and near-surface wind profile. Values of zero-plane displacement increased with stem height and population density of standing residue, and initial flat residue biomass. Near-surface wind profile showed the impact of residue to near-surface wind velocity clearly. There was a critical stem population density above which zero-plane displacement increased little for each residue type. This density is related to the residue type only. |
