Carryover of N-fertilization from corn to pasture in an integrated crop-livestock system

Nutrient-use efficiency in pasture-crop rotations is not well understood. The hypothesis of this research is that nitrogen (N) cycled from the corn crop to the following pasture is not enough to supply the N demand of the pasture, independent of pasture height management. Our goal was to assess the carryover effect of N-fertilization from corn crop to a mixed pasture of black oat and ryegrass managed with two sward heights in an integrated crop-livestock system. The experimental design was a factorial arrangement (2 × 2) of sward height (10 and 25 cm) and N pasture fertilization: 0 kg N ha−1 (representing the carryover of N-fertilization from the corn crop) and 200 kg N ha−1. Accumulated forage dry matter and N concentration increased by 62% and 40%, respectively, in the pasture-fertilized compared with fertilization only in the previous crop phase. The residual effect of N applied to the previous corn crop was not enough to adequately meet the N requirements of the subsequent pasture, thereby reducing forage dry matter accumulation compared with the pasture-fertilized system. Our data suggest that fertilization of the pasture phase is key to better nutrient use efficiency in integrated crop-livestock systems.