Field evaluation of dicyandiamide rates and enhanced efficiency fertilizers to increase corn production and reduce nitrogen loss

There is a need for nitrogen management technology that can reduce environmental N loss mechanisms and to increase nitrogen-use efficiency. While many different technologies exist, it's important that farmers understand how these different products work and for them to see relevant research results in a similar environment. The primary objective was to determine an optimal DCD rate for increasing corn production and reducing N loss and then comparing that rate to commercially available EEFs for farmers in Northeast Missouri on claypan soils. The experimental design was a randomized complete block design with 5 N rates (0, 67, 135, 200, 270 kg ha-1), 5 DCD rates (0, 4, 7.5, 10, 14 g kg-1 formulated with urea), and two EEFs (SuperU and ESN). Optimal DCD rates, based on yield, varied between years and N rates with an overall optimal DCD rate of 8.9 g kg-1. In 2024, 10 g DCD kg-1 and ESN significantly increased (P=0.05) grain yield compared to non-treated urea, 7.5 g DCD kg-1 and SuperU. All DCD rates had significantly lower cumulative (P=0.0878) and yield scaled N2O emissions (P=0.0250) compared to non-treated urea when combined over years. The minimum reduction in N2O emissions from non-treated urea was 65 percent indicating the efficacy of the DCD and EEFs for reducing N2O emissions. At 2, 4, and 6 WAT, 14 g DCD kg-1 had a higher NH4-N to NO3-N ratio than non-treated urea. All DCD rates reduced soil solution nitrate-N concentrations 38 percent compared to non-treated urea. Selected DCD rates and EEFs all had significantly lower nitrate-N content in the soil solution than non-treated urea in 2024 with 7.5 g DCD kg-1 having the highest reduction (51 percent). DCD rates and EEFs were both effective at reducing N loss in this study; however, future economic work should be done to see how these different technologies affect farmer's return on investment.