Rotating alfalfa with corn can increase corn yield potential due to improved soil physical properties that enhance water infiltration and root extension, altered soil microbial communities, and reduced pest pressure. In addition, fertilizer nitrogen (N) requirements are commonly reduced by about 100% for first-year corn and 50% for second-year corn following a good stand of alfalfa. However, N guidelines for corn after alfalfa vary among Corn Belt states and growers have questioned the reliability of alfalfa N credits in high-yield environments. In this presentation, results are shared from 33 recent on-farm N rate trials in first-year corn after alfalfa in the Upper Midwest. This presentation will help viewers understand factors that affect the response of first-year corn to fertilizer N, and will address related issues such as alfalfa termination timing, alfalfa regrowth prior to termination, and side-dressing of N.
