Response of Maize to Cover Crops, Fertilizer Nitrogen Rates, and Economic Return

Abstract

Leguminous cover crops are considered part of sustainable agricultural systems. With the development of no‐till cropping systems, cover crops have been recognized for their ability to provide N for succeeding crops. The objectives of this study were: (i) to determine the N contribution of summer cover crops and double‐cropped grain crops following winter wheat (Triticum aestivumL.) and N rates to subsequent maize (Zea maysL.) crops’ physiological traits and yield, (ii) to calculate the fertilizer N replacement value, and (iii) to perform economic analyses of the cropping systems. Field experiments were conducted during the 2012–2013 and 2013–2014 growing seasons in Kansas. The grain yield of maize in all the cover crop systems and the double‐cropped soybean [Glycine max(L.) Merr.] system was similar to maize in the fallow system with 45 kg N ha−1. The mean increase in grain yield as a result of including cowpea [Vigna unguiculata(L.) Walp.], pigeonpea [Cajanus cajan(L.) Millsp.], sunn hemp (Crotalaria junceaL.), double‐cropped soybean, and double‐cropped grain sorghum [Sorghum bicolor(L.) Moench] in the rotation over the fallow system with 0 kg N ha−1was 78, 91, 66, 72, and 12%, respectively. Fertilizer N replacement values for cowpea, pigeonpea, sunn hemp, double‐cropped soybean, and double‐cropped grain sorghum were 53, 64, 43, 47, and –5 kg N ha−1, respectively. We conclude that the inclusion of summer leguminous cover crops in a cropping system has the potential to reduce or supplement N requirements and increase the grain yield of subsequent maize crops.