Periodic Response of Soybean Yields and Economic Returns to Long‐Term No‐Tillage

Abstract

Farmers have been encouraged to adopt no‐tillage (NT) because of its positive environmental effects compared with other conservation tillage systems. Nevertheless, poor crop performance under NT management has been reported in both short‐ and long‐term experiments. This study was conducted on six different soils (a poorly drained Taintor soil near Burlington, a moderately well‐drained Kenyon soil near Nashua, a well‐drained Clarion soil near Newell, a well‐drained Galva soil near Sutherland, and a well‐drained Nira soil and a poorly drained Kalona soil near Crawfordsville) in Iowa during 1978 to 2001. Soybean [Glycine max (L.) Merr.] response to long‐term NT management was evaluated by 5‐yr periods and on the average over the entire study in terms of grain yields and economic returns. The design of the field experiments was a randomized complete block or split plot. Eight tillage systems, including NT, moldboard plow, chisel plow, ridge tillage, alternative tillage, reduced tillage, field cultivation, and tillage‐plant were investigated in a corn (Zea mays L.)–soybean rotation. Differences between NT and other tillage systems in both soybean grain yields and economic returns remained the same over the entire period of each study, ranging from 8 to 15 yr. No‐tillage generally had less than 5% yield decrease and equal or greater economic returns compared with other tillage systems on well‐drained soils during each 5‐yr period and when averaged over the entire study. Therefore, economic returns favor the adoption of NT for soybean production from both short‐ and long‐term perspectives for well‐drained soils in Iowa.