Southeast Research and Demonstration Farm
The goal was to compare yields of three different tillage systems on a sloping, moderately well drained soil (Nira) and on a nearly level, poorly drained soil (Kalona) in a continuous corn and a corn-soybean system. These plots were begun in 1990.
Iowa State University
Brenneman, Greg and Van Dee, Kevin, "Conservation Tillage Study" (2009). Iowa State Research Farm Progress Reports. 610.