Enhanced efficiency nitrogen formulations for bermudagrass–white clover pastures

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AbstractNitrogen fertilizer use is generally restricted in bermudagrass [Cynodon dactylon (L.) Pers.]–white clover (Trifolium repens L.) forage systems because it stimulates grass growth and increases competition with the clover, compromising forage nutritive value and prospective forage accumulation. Enhanced efficiency fertilizer nitrogen (N) products hold potential to improve white clover persistence in bermudagrass–clover pastures while providing supplemental N required by the grass. This study evaluated the effect of different enhanced efficiency N formulations (Environmentally Smart Nitrogen [ESN]; methylene urea; SuperU; and 75% ESN, 25% urea blend) and untreated urea on forage accumulation, nutritive value, and legume persistence in a ‘Wrangler’ bermudagrass and ‘Durana’ white clover mixture. Nitrogen was applied at four rates (0, 112, 224, and 448 kg N ha−1) in two equal applications each year. By the second year, white clover stands were lesser at the greatest N rates. All enhanced efficiency N sources maintained white clover similar to the unfertilized grass–clover control, but only ESN improved white clover persistence over urea. Total season forage accumulation increased linearly with increasing N rates within all three growing seasons, but dry weather conditions in the last 2 yr resulted in less forage accumulation. Nutritive value decreased with maturity throughout the growing season, but ESN maintained clover in the pasture resulted in overall less fiber components and greater digestibility. Although there was no effect of N source on forage accumulation, the ability of ESN to maintain clover could make it a viable option for fertilization in bermudagrass–white clover mixtures.