ABSTRACT:
Intensive tillage moves large quantities of soil, resulting in a pattern of soil redistribution where topsoil is depleted from convex slope positions and deposited in concave positions. In these experiments, the variation in erosion estimates, properties of the surface soil, and crop yield (four years) were determined in an undulating landscape that is subject to annual moldboard plowing. Results indicated that areas with high tillage erosion (shoulder slope positions) had high inorganic carbon contents in the surface soil due to the incorporation of calcareous subsoil material. Wheat yields in 2000, 2001, and 2003 were lowest in these areas, demonstrating yield reductions of 50 percent or more. Conversely, wheat yields were highest in areas in which soil translocation by tillage and water results in a net deposition of soil (depressions). These areas had a deeper A horizon, and the surface soils had higher organic carbon contents, lower pH and lower inorganic carbon contents. Soybean yields in 2002 did not show a strong dependence on location within the landscape. These results indicate that the observed variation in crop yield in undulating landscapes may be significantly influenced by removal of topsoil through repeated intensive tillage, and point to opportunities for landscape restoration to reduce yield losses.
Footnotes
Sharon K. Papiernik and Michael J. Lindstrom (retired) are soil scientists with the U.S. Department of Agriculture Agricultural Research Service, North Central Soil Conservation Research Laboratory in Morris, Minnesota. Joseph A. Schumacher is a research engineer and Thomas E. Schumacher is a professor in the Plant Sciences Department at South Dakota State in Brookings, South Dakota. Annemieke Farenhorst and David A. Lobb are associate professors of soil science at the University of Manitoba in Winnipeg, Manitoba, Canada. Kristian D. Stephens received his MS degree at the University of Manitoba and is currently employed as a municipal conservation technologist with the County of Two Hills in Alberta, Canada.
- Copyright 2005 by the Soil and Water Conservation Society