In grass-legume pastures, grazing management strategies are an essential factor affecting nitrogen (N) cycling. This study assessed the impact of grazing management on N cycling in rotationally-stocked mixed pastures of ‘Marandu’ palisadegrass (Brachiaria brizantha) and ‘Comum’ calopo (Calopogonium mucunoides). Treatments included three grazing management strategies, defined by interruption of the rest period when the canopy reached 90 (90LI), 95 (95LI) and 100% (100LI) of the interception of photosynthetically active radiation. A 2-yr experimental period was adopted. Plant litter responses, forage intake and livestock excretion were evaluated. No differences between grazing management were obtained for existing (294 g OM m⁻²) and deposited litter (6.7 g OM m⁻² d⁻¹, P > 0.10). Compared to the dry season, the litter decomposition rate increased 24.0%, and the half-life decreased 37.8% in the rainy season (P < 0.10). The N cycling via litter (553 g ha⁻¹ d⁻¹) was similar in all grazing management (P > 0.10). Less frequent defoliation (100LI) resulted in reduced proportion of legume intake (P < 0.10, 94.4 vs. 168.5 g kg⁻¹; an average of 90LI and 95LI, respectively), lower N intake (123.1 vs. 194.1 g animal unit⁻¹ d⁻¹) and a lower input of N from biological fixation (73.2 vs. 97.8 kg ha⁻¹ yr⁻¹). Less frequent defoliation should be avoided because it reduces the N intake and N retained by animals, which caused a reduction in N utilisation efficiency by heifers. Thus, 95% light interception is the maximum limit to interrupt the regrowth in palisadegrass-calopo pastures.

在豆科牧草中，放牧管理策略是影响氮 (N) 循环的重要因素。本研究评估了放牧管理对 'Marandu' palisadegrass ( Brachiaria brizantha ) 和 'Comum' calopo ( Calopogonium mucunoides )轮作放养混合牧场中氮循环的影响。处理包括三种放牧管理策略，定义为当树冠达到光合有效辐射拦截的 90% (90LI)、95% (95LI) 和 100% (100LI) 时中断休息期。采用了 2 年的实验期。评估了植物凋落物反应、草料摄入量和牲畜排泄量。现有 (294 g OM m ^-2 ) 和堆积的垫料 (6.7 g OM m ^-2 ) 的放牧管理之间没有差异^-2  d ^-1，P  >  0.10 )。与旱季相比，雨季凋落物分解率提高24.0%，半衰期降低37.8%（P  <  0.10）。通过垫料（553 g ha ^-1  d ^-1）循环的氮在所有放牧管理中都相似（P  >  0.10）。不太频繁的落叶 (100LI) 导致豆类摄入量的比例降低（P  <  0.10, 94.4 vs. 168.5 g kg ^-1；平均分别为 90LI 和 95LI），氮摄入量降低（123.1 vs. 194.1 g 动物单位^-1  d ^-1) 和来自生物固定的较低 N 输入（73.2 与 97.8 kg ha ^-1  yr ^-1）。应避免不频繁的落叶，因为它减少了动物的氮摄入量和保留氮，从而导致小母牛对氮的利用效率降低。因此，95% 的光拦截是中断 palisadegrass-calopo 牧场再生的最大限制。