Yield and economic potential of spring-planted, pea-barley forage in short-season corn double-crop systems

Double cropping with forages can increase dry matter (DM) yield and N-use efficiency over sole-crop (SC) systems, but reductions in primary crop yield can limit economic return. This study assessed whether a double-crop (DC) system coupling a legume-cereal biculture forage with early maturing corn can reduce fertilizer N input and compete economically with SC corn. Biomass yield, N uptake, residual soil NO₃-N, and economic net return were measured in two DC and one SC systems in four experiments conducted in Minnesota between 2014 and 2016. In DC systems, a field pea (Pisum sativum L.)-barley (Hordeum vulgare L.) forage biculture was double cropped with a dual-purpose hybrid (DP) or semidwarf (SD) corn (Zea mays L.) variety. In SC systems, fullseason hybrid corn (HC) was planted without preceding forage. Six fertilizer N rates (0-224 kg N ha^-1) were applied to corn. Averaged across N rates, DP and SD corn yielded less (8.2 and 1.8 Mg DM ha^-1, respectively) compared to SC (16.4 Mg DM ha^-1). Total system DM yield was similar for the DC-DP and SC-HC systems, averaging 16.6 Mg ha^-1. Economic return for the SC system was greater than that for the DC-DP system, and was maximized with 134 to 224 kg N ha^-1, while return for the DC-DP system was unaffected by N rate. Due to low corn yield and greater production cost, double cropping spring forage with short-season corn is not a profitable alternative to SC corn.