Precipitation and not cover crop composition influenced corn economic optimal N rate and yield

Abstract The effects of single species cover crops on corn ( Zea mays L.) N requirement and grain yield are well studied throughout the U.S. Midwest. However, comparing crop mixes that include different compositions grass broadleaf is limited. Fourteen response experiments were conducted in South Dakota from 2018 to 2021. Fall planted after small harvest mixtures dominantly grasses, broadleaves, a 50/50 grass/broadleaf mixture, no control. Compared control, including led differences economic optimal rate (EONR) at zero (0N) EONR 44%, 62%, 83% time, respectively. As spring crop/residue biomass its C content increased, decreased increased when R 2 = 0.36–0.56). Including reduced resulted similar precipitation above 850 mm. When occurred with return N, 3 site‐years (mean decrease US$358 ha −1 ) only 1 site‐year did increase (+US$335 ). Thus, first year growing (i.e., or mix) before corn, growers can normally expect some EONR. appropriate maintained any minimized.