Agronomic impacts of production scale harvesting of corn stover for cellulosic ethanol production in Central Iowa

This thesis investigates the impacts of corn stover harvest in Central Iowa with regards to nutrient removal, grain yield impacts and soil tilth. Focusing on phosphorus and potassium removal due to production of large, square bales of corn stover, 3.7 lb P2O5 and 18.7 lb K2O per dry ton of corn stover were removed in 2011. P2O5 removal remained statistically the same in 2012, but K2O decreased to 15.1 lb per ton of dry corn stover. Grain cart data showed no statistical difference in grain yield between harvest treatments, but grain yield monitor data showed a 3 – 17 bu/ac increase in 2012 and hand samples showed a 4 – 21 bu/ac increase in 2013. Corn stover residue levels decreased below 30% coverage when corn stover was harvested the previous fall and conventional tillage methods were used, but incorporating reduced tillage practices following corn stover harvest increased residue levels back up to 30% coverage. Corn emergence rates increased by at least 2,470 more plants per acre within the first three days of spiking, but final populations between harvest and nonharvest corn stover treatments were the same. Inorganic soil nitrogen in the form of ammonium and nitrate were not directly impacted by corn stover harvest, but it is hypothesized that weather patterns had a greater impact on nitrogen availability. Lastly, soil organic matter did not statistically change from 2011 to 2013 due to corn stover removal, even when analyzed withing single soil types