Estimating soil erosion after 100 years of cropping on Sanborn Field

Abstract

ABSTRACT: Sanborn Field, established in 1888, is the oldest agricultural experiment field west of the Mississippi River. It provides an excellent opportunity to document how longtime crop rotations and soil management, including annual additions of manure, influence soil erosion and, thus, the sustainability of these practices. Analysis of topsoil remaining after 100 years of continuous cropping in plots sown to continuous corn; to continuous timothy; and to a 6-year rotation cropped sequentially to corn, oats, wheat, clover, and 2 years of timothy are presented. Remaining topsoil was significantly less for the continuous corn versus the 6-year rotation or timothy plots after the 100th year of cropping. Corn plots had only 44% as much topsoil and the rotation plots had only 70% as much topsoil as the timothy plots. The amount of clay in the plow layer was significantly higher in the corn plots compared to that in either the rotation or timothy plots, suggesting that mixing of clay subsoil within the plow layer has occurred in the corn plots. Productivity estimates indicate that 60% reductions in corn yield can occur for an eroded soil compared to an uneroded soil even when the eroded soil is managed with high fertility. Thus, if long-term production is to be sustained, improved management for row crops is necessary.