Sharon Papiernik1, Michael Lindstrom1, David Lobb2, Thomas Schumacher3, Joseph Schumacher4, and Diane Smith2. (1) USDA-ARS-MWA-NCSCRL, 803 Iowa Ave., Morris, MN 56267, (2) Department of Soil Science, University of Manitoba, Ellis Bldg., University Crescent, Winnipeg, MB R3T 2N2, Canada, (3) Box 2140C, South Dakota State Univ., South Dakota State University, Brookings, SD 57007, (4) Plant Science Dept., South Dakota State University, 247A NPB, Box 2140C, Brookings, SD 57007
In hilly landscapes, tillage and water erosion can combine to induce large variability in soil productivity at the field scale. Approaches to manage this variability have been proposed, including restoring the landscape by physically moving soil from areas of net deposition to areas of net soil loss. We evaluated the variability in soil properties and crop yield in an eroded landscape that has been cultivated for the past 100 years and in portions of the same landscape subject to restoration. In highly-eroded positions (summit, shoulder, and upper backslope), the surface soil is comprised of exposed subsoil high in inorganic carbon. Deep accumulation (>40 cm) of high-organic-matter soil was observed in the footslope and toeslope. Surface soil organic carbon, Olsen phosphorus, nitrate-N, and total nitrogen concentrations in the toeslope were more than twice that in the summit, shoulder, and upper backslope positions prior to restoration. After moving accumulated topsoil from the footslope and toeslope to the eroded upper landscape positions, surface soil organic carbon, phosphorus, and total nitrogen concentrations in upper slope positions were similar to those in the toeslope. In the first year following restoration, soybean yields were uniform from the summit through the footslope in the restored plots: minimum soybean yields (in the upper backslope) were within 10% of yields in the footslope. In unrestored plots, minimum yields (in the upper backslope) were only 40% of yields in the footslope. These first-year results indicate that soil movement from areas of net deposition to areas of topsoil depletion may reduce the spatial variability in soil properties that affect productivity in eroded landscapes. The project will continue for another four years to more completely evaluate the productivity and profitability of this restoration approach.