Using Sweep to Simulate Soil Wind Erosion Under Different Crop Residue Removal Levels.

Residue removal for livestock and biofuel production at large scales may degrade soil productivity and properties. Among all the negative impacts, wind erosion is a major concern in the central Great Plains. We conducted the on-farm study by removing crop residue at five levels (0, 25, 50, 75, and 100%) to determine the effects of crop residue removal on soil wind erosion parameters such as dry aggregate size distribution including soil wind erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) and geometric standard deviation (GSD), dry aggregate stability, and soil surface roughness. Five crop residue removal treatments with four replications were established after wheat harvest in 9 m by 9 m plots on six farmers’ no-till fields in western Kansas in summer 2011. Crop residue was cut with a forage harvester at different heights corresponding to the five treatments. Soil samples from the 0- to 5-cm depth were taken in fall 2011, spring 2012, fall 2012, and spring 2013 for evaluation of wind erosion parameters. A part of the Wind Erosion Prediction System (WEPS) model developed by the USDA-ARS, known as the Single-event Wind Erosion Evaluation Program (SWEEP) is a stand-alone companion software package that can be applied to simulate soil loss and dust emission from a single windstorm event given known surface characteristics. We applied measured data (i.e. EF, GMD, GSD, and roughness) to SWEEP to predict the wind velocity that can initiate wind erosion.  We also simulated soil loss under each crop residue removal condition with a constant wind velocity at 13 m·s^-1. Results showed the threshold wind velocity to initiate wind erosion generally decreased with increase in crop residue removal levels. Wind erosion was only simulated for plots with residue removal larger than 75%. The total amount of soil loss ranges from about 0.2 to 2.5 kg·m^-2 and depends on soil condition and crop residue cover.