Enhanced Efficiency Nitrogen Fertilizers on the Production and Nutritive Value of Bermudagrass Pastures.

Bermudagrass (Cynodon dactylon L.) is a perennial, warm-season grass that is common in pastures of the southeastern U.S. and responsive to high rates of N fertilization. However, excessive N applications may have negative environmental consequences and are prone to losses during the summer months. Enhanced efficiency (EE) forms of N offer potential benefits that include: fewer applications, increased availability during the growing season, and fewer N losses. The objective of this study was to determine the effects of different EE formulations of urea on the yield and nutritive value (crude protein, NDF, ADF, IVTD) of bermudagrass pastures.  Urea, SuperU (urea formulated with agrotain and dicyandiamide), ESN (Environmentally Smart Nitrogen, a polymer-coated urea), and BCMU (branched-chain methylene urea) were applied to ‘Wrangler’ bermudagrass pastures at rates of 50, 200, and 400 lbs N acre^-1 in two equal split applications.  Despite higher forage yields during the initial harvest, there was no difference in the total forage yield for urea and the two slow-release formulations (BCMU and ESN). SuperU provided maximum total yields at 200 lbs N acre^-1, while seasonal forage yields increased linearly to 400 lbs N acre^-1 for the other fertilizer types. Fertilizer type and rate had little effect on the estimated parameters of forage nutritive value except crude protein (CP). Urea had a tendency to increase CP concentrations with higher fertilizer rates, while the effects of the EE fertilizers on CP were inconsistent across the season. Enhanced efficiency fertilizers may producer higher or similar forage yields as traditional forms without sacrificing forage nutritive value. However, more research is needed to validate these observations across multiple growing seasons.