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ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #90922
Title: MODELING SPATIAL VARIATION IN PRODUCTIVITY DUE TO TILLAGE AND WATER EROSION

Author
item SCHUMACHER, T - SOUTH DAKOTA STATE UNIV.
item Lindstrom, Michael
item SCHUMACHER, J - SOUTH DAKOTA STATE UNIV.
item LEMME, G - UNIVERSITY OF MINNESOTA

Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soil movement from erosion processes causes many changes in soil properties that affect long-term soil productivity. A study was conducted to examine the relationship between soil redistribution by tillage and water erosion over a typical landscape in the western Corn Belt and the resulting changes in soil productivity. Soil redistribution due to tillage and water erosion was determined from established models. Soil productivity was determined from a productivity index model with changes in soil productivity based on changes in topsoil thickness due to soil redistribution by the erosion processes. Tillage erosion was the dominant erosion process at the top and crests of the hillslopes while water erosion was dominant in landscape positions with the steepest slope gradients. Deposition from both erosion processes occurred in the lower landscape positions where slope gradients began to decline. The reduction in soil productivity was greatest when both erosion processes were combined compared with either process acting alone. Soil productivity increased in areas where soil deposition took place but the net effect of soil redistribution over the landscape from the combined effects of tillage and water erosion was a decline in overall soil productivity. Conservation planners can use the results from these analyses to show the adverse effects of soil erosion by tillage and/or water on soil productivity.

Technical Abstract: The large variation in yields across many producer fields demonstrated by yield-monitor-equipped combines has generated concern about management-induced causes of spatial variation in soil productivity. Soil translocation from erosion processes may result in variation in soil properties across field landscape positions that produce long-term changes in soil productivity. The objective of this study was to examine the relationship between soil redistribution caused by tillage and water erosion and the resulting spatial variability of soil productivity in a soil catena in eastern South Dakota. An empirical model developed to estimate tillage erosion was used to evaluate changes expected in the soil profile over a fifty-year period on a typical toposequence found in eastern South Dakota and western Minnesota. Changes in the soil profile due to water erosion over a fifty-year period were evaluated using the WEPP hillslope model. The tillage erosion model and the WEPP hillslope model were run concurrently for a fifty-year period to evaluate the combined effect of the two processes. The resulting changes in soil properties of the root zone were evaluated for changes in productivity using a productivity index model. Tillage erosion resulted in soil loss in the shoulder position while soil loss from water erosion occurred primarily in the lower backslope position. Water erosion contributed to nearly all the decline in soil productivity in the backslope position when both tillage and water erosion processes were combined. The net effect of soil translocation from the combined effects of tillage and water erosion is an increase in spatial variability of crop yields and a likely decline in overall soil productivity.