Yield and Nitrogen Uptake of Rotated Corn in a Ridge Tillage System

Abstract Information is scant on the response of corn ( Zea mays L.) following legumes seeded with small grains in reduced tillage systems in the upper Midwest. Our objective was to determine yield and N uptake response of ridge‐tilled corn planted after soybean [ Glycine max (L.) Merr.], wheat ( Triticum aestivu L.) alone, wheat with alfalfa ( Medicago sativa L.), or wheat with hairy vetch ( Vicia villosa Roth), compared with continuous corn. Field studies were conducted from 1991 through 1994 at two southern Minnesota locations on a poorly drained Webster clay loam (fine‐loamy, mixed, mesic Typic Endoaquoll) soil. At Freeborn, corn grown in rotation with soybean yielded highest (6.8 Mg ha −1 ) in 2 of 3 yr, while continuous corn usually yielded less than corn grown after other crops. Corn grown after other crops accumulated 23 to 36 kg ha −1 more N than continuous corn in 2 of 3 yr at all fertilizer‐N rates up to 135 kg N ha −1 . At Waseca, corn grain yields and N uptake were generally similar among rotations, except that yields were 1.5 to 1.9 Mg ha −1 lower and total N uptake was 16 to 18 kg ha −1 less following wheat alone in 2 of 3 yr, compared with other rotations at fertilizer‐N rates up to 135 kg N ha −1 . Regression analysis indicated that significant, positive, non‐N‐related rotation effects were present at Freeborn, but not at Waseca, where there was a negative effect of wheat alone on subsequent corn yield. The potential fertilizer‐N savings due to including annual alfalfa or hairy vetch could not be calculated because the N rates used in this study were insufficient to determine the economically optimum N rate. However, neither the alfalfa nor hairy vetch provided a consistent source of available N for the subsequent corn crop in this study.