Wednesday, November 7, 2007
308-8

The Effect of Landscape Restoration on Soil Properties Influencing Crop Productivity.

Diane Smith1, David Lobb1, Thomas E. Schumacher2, and Sharon Papiernik3. (1) Soil Science, University of Manitoba, 13 Freedman Cres., Winnipeg, MB R3T 2N2, Canada, (2) Plant Science Department, South Dakota State University, NPB 247A, Brookings, SD 57007, (3) USDA-ARS-NPA-SPNRU, USDA-ARS, 803 Iowa Avenue, Morris, MN 56267

In cultivated hilly landscapes, tillage is a dominant soil erosion process and is responsible for local soil redistribution and displacement within the landscape. Organic-rich topsoil is lost from convex upper slope positions and accumulates in the concave lower slope positions or depressions. The loss of topsoil from these hilltops greatly reduces topsoil depth, nutrient supply, water infiltration, and available water-holding capacity. Evidence of tillage erosion can be seen throughout hilly landscapes by increased stoniness and carbonates at the soil surface and decreased soil organic matter; resulting in localized areas of poor crop growth. The combination of these factors ultimately leads to an overall reduction in crop productivity throughout the landscape. Landscape restoration is the practice of removing accumulated topsoil from depositional areas in the landscape and replacing it on the hilltops where it had originated. Studies have shown landscape restoration to increase crop yield by 24 to 128% on severely eroded hilltops which have been restored with 10 cm added topsoil. The purpose of this study is to determine the soil physical and chemical properties that are improved by landscape restoration and contribute to increased crop productivity. A large field-scale study was established in southwestern Manitoba to monitor bulk density, soil texture, plant available water, and soil fertility on eroded hilltops and hilltops that were restored with 10 cm of added topsoil. Initial results have shown bulk density is not significantly different between restored and unrestored hilltops. Further analyses of the other soil properties have yet to be determined. However, a companion study in Morris, Minnesota has found significant increases in soil fertility on restored hilltops. These trends indicate that landscape restoration can provide producers with a practical and agronomically effective management practice to restoring the productivity and sustainability to eroded landscapes.