Nitrogen, Stover, and Tillage Management Affect Nitrogen Use Efficiency in Continuous Corn

Improving nitrogen use effciency (NUE) in corn (Zea mays L.) is critical for optimizing yield and reducing environmental impact. Stover removal in continuous corn (CC) for biofuel production, coupled with reduced-tillage systems, could alter NUE and residual soil nitrate-N. Experiments were conducted in Minnesota over 3 yr to determine how N uptake, NUE, and residual soil nitrate-N are affected by stover (remove and retain), tillage (chisel-[CT], strip-[ST], and no-till [NT]), and fertilizer N (0, 45, 89, 134, 179, and 224 kg N ha(-1)) management. There was a linear response of grain and total aboveground N uptake to fertilizer N across stover management and tillage treatments. Stover removal increased recovery effciency for ST and NT at fertilizer N rates <= 134 kg N ha(-1), but did not enhance N recovery in plots fertilized at rates > 134 kg N ha(-1). Internal efficiency was 5% greater with stover removal with no fertilizer N, but did not change with fertilizer N application. Stover removal did not affect agronomic efficiency in CT but did enhance it in ST and NT at fertilizer N rates <= 134 kg N ha(-1). Residual soil nitrate-N to a depth of 1.2 m was 10 to 16 kg NO3-N ha(-1) greater with stover removal at fertilizer N rates of 134 to 224 kg N ha(-1). Greater residual soil nitrate-N with stover removal indicates a need for judicious management of N when stover is removed in intensively-managed Upper Midwestern CC systems.