Crop Rotation Affects Corn, Grain Sorghum, and Soybean Yields and Nitrogen Recovery

Long-term cropping system and fertilizer N studies are essential to understanding production potential and yield stability of corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merr.] in rain-fed environments. A no-till experiment (2007–2013) was conducted in eastern Nebraska to evaluate crop rotation (continuous corn, continuous grain sorghum, continuous soybean, corn–soybean, grain sorghum–soybean, corn–soybean–grain sorghum–oat [Avena sativa (L.)]/clover mixture [80% Melilotus officinalis Lam. + 20% Trifolium pretense L.], and corn–oat/clover–grain sorghum–soybean) and fertilizer N (corn and grain sorghum: 0, 90, 180 kg N ha–¹; soybean and oat/clover: 0, 36, 67 kg N ha–¹) on grain yield, plant N uptake, and N recovery efficiency. Diversified crop rotations increased corn and grain sorghum yields and improved yield stability. A positive corn grain yield response to fertilizer N was consistent across crop rotations, but fertilizer N addition with corn–soybean–grain sorghum–oat did not increase grain sorghum yield. Yield stability of soybean was less sensitive to management; all treatment combinations were found to be stable. Fertilizer N addition decreased soybean grain yield in 2 of 7 yr, but yields were similar in the remaining 5 yr. These results indicate that adoption of 2- and 4-yr crop rotations in rain-fed environments can result in high-yielding, more stable corn, grain sorghum, and soybean grain production compared with shorter rotations or continuous cropping.