Stepwise time response of corn yield and economic return to no tillage

The adoption of no tillage (NT) in crop production has been encouraged primarily due to its more significant benefits to the environment compared with other conservation tillage systems. There are nevertheless concerns about NT corn (Zea mays L.) performance from both short- and long-term perspectives. This study was conducted near Burlington, Nashua, Newell, Sutherland, and Crawfordsville in Iowa from 1978 through 2001 to evaluate corn production in 4- to 5-year phases under long-term NT management. Field experiments were conducted using a complete randomized block, or split-plot design. Seven tillage systems including NT, moldboard plow (MP), ridge tillage (RT), chisel plow (CP), reduced tillage (RDT), field cultivation (FC), and tillage-plant (TP) were evaluated in terms of corn yield and economic return. Differences between NT and other tillage systems in either corn yield or economic return did not change with the 4- to 5-year phases within the entire study period. The competitiveness of NT over MP, RT, CP, or other tillage systems in the early years (first 4–5 years) since tillage adoption, was as strong as that after 8–10 years. This finding is encouraging to those corn producers who are reluctant to use NT, because of their concern about the poor performance of NT corn during the early years. Yield differences between NT and other tillage systems in each 4- to 5-year phase, or averaged over the entire study period, were mostly within 5% in a corn–soybean (Glycine max (L.) Merr.) rotation. No tillage generally had equal or greater economic return than other tillage systems in each 4- to 5-year phase and over the entire study period. The yield and economic return benefits of a corn–soybean rotation relative to continuous corn remained generally the same over time under long-term NT management. Therefore, the adoption of a NT system can be accomplished without lowering the economic return from both short- and long-term perspectives.