Donald J. Graper, James J. Camberato, Brad C. Joern and Shaun Casteel, Purdue University, West Lafayette, IN
Animal production, especially swine and poultry has increased in the United States prompting the need to manage the larger volume of manure beyond land applications to supply nitrogen (N) for corn production. Soybean uses large amounts of N and takes up nearly four times more in the grain than corn on a kg basis. Applying swine manure to soybean has been shown to increase grain yield due to N supply. The goal of the research is to determine if swine manure applications for double crop soybean following wheat can limit manure N loading to the soil, increase soybean biomass and grain production, and increase N removal rates. Two field-scale trials were initiated in 2012 near Russiaville, IN and Farmland, IN. Three rates of swine manure were applied to equal 170, 340, and 510 kg of total N ha-1. Fertilizer UAN was also applied in three matching rates of N. An untreated control (UTC) was included to equal the seven treatments. Biomass and nutrient accumulations were determined with plant samples at full bloom (R2) and full seed (R6), and grain subsamples at harvest. Soybean biomass at R2 and R6 was highest with the top rate of manure. The remaining manure and UAN treatments produced more soybean biomass by R6 than the UTC. Grain yield followed a similar trend with manure treatments producing 155 to 512 kg ha-1more than UTC. The low and medium rates of manure and UAN yielded very similarly with each pairing. Grain yields were limited due to the drought, but manure and UAN applications were positive. This research has continued in 2013 in addition to tracking soil N movement. Double crop soybean appears to be a successful crop to manage swine manure with the benefit of increased grain yield.
