Author
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Unger, Paul |
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Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/5/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Much semiarid southern Great Plains cropland was covered by Conservation Reserve Program (CRP) contracts. One purpose of the program was to take highly erodible land out of crop production. Because the land was highly erodible, would erosion become a problem when the land was again used for dryland crops? A study on Pullman soil determined what effects treatments used to prepare CRP grassland for crop production had on the potential for soil erosion. Treatments were no-, sweep, disk, and moldboard + disk tillage with CRP grass kept on the land or removed by mowing and baling, and grass burning followed by sweep or disk tillage. Potential for wind erosion was based on the percentage of dry aggregates >0.84-mm and their mean weight diameter (MWD) in soil samples taken 2-3 years after applying the treatments. Potential for water erosion was based on the MWD and percentage of <0.25 mm water-stable aggregates, and water stability of 1-2 mm aggregates in soil samples taken at crop planting and harvest. Few differences in wind and water erosion potentials resulted from the treatments. In all cases, >60% of dry aggregates were >0.84-mm and MWD was >10 mm, showing a low wind erosion potential. Some water stable aggregate and MWD values showed that water erosion could occur. Although the erosion potentials were low, continued use of tillage methods that eliminated crop residues on the soil surface could lead to greater erosion potentials. Because of low potentials during the first 2-3 years, this study shows any tillage method could be used to prepare CRP land for crops on the Pullman and similar soils in this region. A conservation tillage system (for example, no-tillage) could then be started on the land before wind or water erosion became a serious problem. Technical Abstract: Extensive cropland areas were covered by Conservation Reserve Program (CRP) contracts in the semiarid southern Great Plains. Because soils were highly erodible, would erosion become a problem when contracts expired and the land reverted to cropland? This study on Pullman soil (Torrertic Paleustoll) determined erosion potential due to treatments used to convert CRP grassland to cropland. Treatments were no-, sweep, disk, and moldboar + disk tillage with CRP grass retained or removed (mowing and baling), and grass burning followed by sweep or disk tillage. Wind erosion potential was based on percentage of >0.84-mm and mean weight diameter (MWD) of dry aggregates in samples obtained 2 to 3 years after applying treatments. Water erosion potential was based on MWD and percentage of <0.25 mm water-stable aggregates, and water stability of 1- to 2-mm aggregates in samples obtained at crop planting and harvest. Few differences due to treatments were significant regarding erosion potentials. With all treatments, more than 60% of dry aggregates were >0.84-mm and MWD was >10 mm, indicating a low wind erosion potential. Water stable aggregate and MWD values at some sampling times indicated water erosion could occur. Although the erosion potential was low, continued use of residue- incorporating tillage could lead to greater potentials. Because of initially low potentials, CRP land could be converted to cropland in this region using any tillage method. Then, a conservation tillage system (e.g., no-tillage) could be implemented before erosion by wind or water became a serious problem. |
