Ten–Year Assessment Encourages No–Till for Corn Grain and Stover Harvest
Developing a bio-economy by harvesting crop residues from highly productive corn (Zea mays L.) cropping systems requires science-based management decisions to maintain or enhance grain yield and soil, water, and air resources. Which tillage and stover harvest practices are best for accomplishing these goals? Continuous corn grain yield response to either no-till or chisel plowing with two stover harvest rates (3.4 or 5.1 Mg ha -1 yr -1 ) was evaluated for 10 yr in central Iowa. Each tillage and stover removal combination was replicated four times. Year-to-year variation affected grain yield more than tillage practice (0.2 Mg ha -1 ) or stover removal (0.1 Mg ha -1 ). Grain yields were not statistically different (p = 0.33) between tillage systems. Including machinery costs made return on investment for chisel plow and no-till equivalent even though no-till yields were numerically lower. Net stover income per megagram was US $\$2$ to $\$4$ greater at the 3.4 versus 5.1 Mg ha -1 harvest rate because of more efficient harvesting. Among the four practices, no-till with 3.4 Mg ha -1 stover harvest met multiple goals, including providing acceptable corn grain yields, positive net income per megagram stover, and sufficient residues to protect the soil.