Nitrogen 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.

中文翻译：

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用于百慕大草-白三叶草牧场的高效氮配方

百慕大草 [ Cynodon dactylon (L.) Pers.]-白三叶草 ( Trifolium repensL.) 饲草系统，因为它刺激草生长并增加与三叶草的竞争，损害饲草营养价值和预期饲草积累。提高效率的肥料氮 (N) 产品具有提高百慕大草 - 三叶草牧场中白三叶草持久性的潜力，同时提供草所需的补充 N。本研究评估了不同增效氮配方（环境智能氮 [ESN]；亚甲基尿素；SuperU；和 75% ESN、25% 尿素混合物）和未处理尿素对草料积累、营养价值和豆科植物持久性的影响。 Wrangler' 百慕大草和'Durana' 白三叶草混合物。以四种比率施氮（0、112、224 和 448 kg N ha ^-1) 每年两次相等的申请。到第二年，在最高的 N 率下，白三叶草的数量较少。所有提高效率的氮源都使白三叶草保持与未施肥的三叶草控制相似，但只有 ESN 提高了白三叶草对尿素的持久性。在所有三个生长季节中，总季节草料积累随着 N 率的增加而线性增加，但过去 2 年的干燥天气条件导致草料积累减少。营养价值随着整个生长季节的成熟而下降，但 ESN 将三叶草保留在牧场中，导致总体纤维成分较少，消化率较高。尽管氮源对牧草积累没有影响，但 ESN 维持三叶草的能力使其成为百慕大草-白三叶草混合物施肥的可行选择。