Replacing N fertilizer with forage legumes may increase sustainability of grazing systems. The objectives were to evaluate herbage and animal responses and to quantify the water footprint associated with beef production in N-fertilized grass or grass–legume systems during 4 yr under continuous stocking. The three year-round forage systems were: Grass+N which included N-fertilized bahiagrass (Paspalum notatum Flüggé) during summer which was overseeded with N-fertilized cereal rye (Secale cereale L.) and oat (Avena sativa L.) during winter; Grass+Clover included bahiagrass without N fertilizer during summer which was overseeded with rye, oat, and a mixture of clovers (Trifolium spp.) during winter; and Grass+Clover+RP included rhizoma peanut (Arachis glabrata Benth.)–bahiagrass mixture during summer which was overseeded with a similar rye–oat–clover mixture as for Grass+Clover. Clover inclusion improved uniformity of herbage distribution throughout the winter. Including rhizoma peanut increased cattle average daily gain (ADG) by 74% during summer. The ADG in Grass+Clover+RP was 0.61 kg d⁻¹ compared with 0.35 kg d⁻¹ on Grass+N and Grass+Clover. The water footprint during summer was less in Grass+Clover+RP than Grass+Clover (18 and 25 m³ kg⁻¹ bodyweight, respectively). Gain per area (GPA) was similar across all treatments through the year, indicating similar productivity in grass–legume and N-fertilized grass systems. The N-fertilizer inputs were reduced from 224 to 34 kg N ha⁻¹ yr⁻¹ in Grass+Clover+RP, compared to Grass+N. Inclusion of rhizoma peanut and clovers contributes to developing sustainable grazing systems with reduced levels of off-farm inputs.

中文翻译：

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施氮草和草豆类放牧系统的水足迹、牧草和牲畜响应

用牧草豆类代替氮肥可能会增加放牧系统的可持续性。目标是评估牧草和动物的反应，并量化与连续放养 4 年期间在施氮肥的草或草-豆科植物系统中牛肉生产相关的水足迹。三个全年饲草系统是： Grass+N，包括夏季施氮的巴伊亚草 ( Paspalum notatum Flüggé)，冬季播施施氮的谷物黑麦 ( Secale creame L.) 和燕麦 ( Avena sativa L.) ; Grass+Clover 包括在夏季不施氮肥的巴伊亚草，它与黑麦、燕麦和三叶草的混合物（三叶草spp.) 在冬天; Grass+Clover+RP 包括在夏季加入花生根（Arachis glabrata Benth.）-bahiagrass 混合物，与 Grass+Clover 类似的黑麦-燕麦-三叶草混合物进行播种。三叶草的加入提高了整个冬季牧草分布的均匀性。在夏季，包括根茎花生在内的牛平均日增重 (ADG) 增加了 74%。Grass+Clover+RP 的 ADG 为 0.61 kg d ^-1，而Grass+N 和 Grass+Clover的 ADG为 0.35 kg d ^-1。Grass+Clover+RP 的夏季水足迹小于 Grass+Clover（18 和 25 m ³ kg ^-1体重）。全年所有处理的单位面积增益 (GPA) 相似，表明草豆科植物和施氮肥草系统的生产力相似。与 Grass+N 相比，Grass+Clover+RP 中的 N 肥料输入从 224 kg N ha ^-1  yr ^-1减少到 34 kg N ha ^-1 yr ^-1。加入花生和三叶草有助于发展可持续的放牧系统，减少非农投入。