Corn Grain Yield Response to Stover Removal Under Variable Nitrogen, Irrigation, and Carbon Amendments.

Demand for corn (Zea mays L.) stover either for livestock or cellulosic ethanol production have increased the importance of determining stover removal effects on biomass production. The objectives of this study was to evaluate yield response and N use from continuous stover removal under two irrigation rates (full and deficit irrigation), two N fertilization rates (125 kg N ha^-1 and 200 kg N ha^-1), and two carbon amendment treatments [manure application; winter cereal rye (Secale cereale L.) cover crop]. The study was initiated in 2010 and is a managed as a no-till, continuous corn system irrigated with a linear-move sprinkler system. The study is located near Clay Center, NE at the University of Nebraska-Lincoln’s South Central Agricultural Laboratory (40.58 N, 98.14 W; 552 m asl). Soil type is a Hastings silt loam (Fine, smectitic, mesic Udic Argiustolls) with <3% slope. Grain yield response have trended higher over time with highest dry matter grain yields (13.4 Mg ha^-1) occurring under full irrigation with stover removal at the 200 kg N ha^-1 rate (averaged over five growing seasons). Grain yields were similar (P = 0.7418) between irrigation treatments when stover was retained but full irrigation had higher yields (P = 0.0291) than deficit irrigation when stover was harvested. Grain yields were higher when stover was harvested for both deficit (P = 0.0200) and full (P <0.0001) irrigation treatments compared with stover retained treatments. Carbon amendment practices did not result in yield differences (P = 0.5802) when stover was retained but cereal rye and manure treatments resulted in higher yields from no carbon amendment practices when stover was harvested. Results from five growing seasons indicate that stover removal resulted in higher yields than stover retention under a no-till, irrigated, continuous corn system. Carbon amelioration practices further increased grain yields when stover was harvested.