Southeast Research and Demonstration Farm
The project 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 started in 1990 and have continued to the present.
Iowa State University
Brenneman, Greg and Rees, Myron, "Conservation Tillage Study" (2015). Iowa State Research Farm Progress Reports. 2238.