Submitted to: Proceedings of the International Symposium on Wind Erosion
Publication Type: Proceedings
Publication Acceptance Date: June 3, 1997
Publication Date: N/A
Technical Abstract: Crop residue cover decreases the risk of erosion by wind and water. For the USDA, ARS, Wind Erosion Prediction System (WEPS), crop residues are predicted for three pools: standing, flat, and buried. The residue submodel accounts for mass change within each pool including standing residues that weaken and fall to the surface as they decompose. Climatic indices based on rainfall and temperature represent decomposition environments. To predict decomposition of above-ground biomass and rate that standing residues fall to the soil surface, daily precipitation and air temperature are used. When daily precipitation exceeds 4 mm, the moisture index for above-ground processes is optimum. The temperature coefficient is optimum at 32 degrees C and decreases at warmer or cooler temperatures. Decomposition of below-ground residues is based on soil temperature and water content, simulated in the hydrology submodel. The daily climate index is the minimum of the daily moisture or temperature index and is accumulated through time as decomposition days. Decomposition is predicted as a first-order decay process, with crop-specific decomposition rate coefficients based on residue quality. On days that wind is potentially erosive, the erosion submodel uses percent soil cover, based on standing and flat residue biomass, and Stem Area Index, based on number, height, and diameter of standing stems per unit area. The decomposition model was developed for application across diverse climate conditions and cropping systems.