Effects of Swine Manure Application Time and Instinct On Corn Growth and Mineralizable Nitrogen On Two Indiana Soils.

The growing concern of N loss due to nitrate leaching, denitrification, and the rising cost of N fertilizers has led to increased interest in the use nitrification inhibitors with manure. A field study was initiated in 2011 to evaluate the impact of swine manure application timing and Instinct^TM, a microencapsulated form of the nitrification inhibitor nitrapyrin, on corn growth and yield at two locations in Central Indiana. Treatments in this field study were: manure application in August, September, October, March, and April; manure plus Instinct^TM (2.6 L/ha) application in October, March and April; and three commercial fertilizer application rates (134 kg N/ha, 179 kg N/ha, 224 kg N/ha) applied in the spring either as preplant anhydrous ammonia (location 1) or sidedress injected urea ammonium nitrate solution (location 2). Swine manure was subsurface injected at 65,500 L/ha at both locations. Due to differences in manure analyses, total N and estimated potentially available N application rates were 420 kg/ha and 340 kg/ha at location 1 and 240 kg/ha and 200 kg/ha at location 2. Whole plant samples were taken at the V6 growth stage and ear leaves were collected at the R1 growth stage. We also collected soil samples (0-30 cm and 30-60 cm) in December 2011 from treatments that had received manure and one treatment that had not yet received manure, and we conducted an incubation study to determine differences in soil N mineralization potential from these samples. Additional soil samples were collected in April and June of 2012. The results of both field and incubation studies will be presented in this poster.