The absence of nutrient replacement, especially nitrogen (N), is one of the main causes of grazing system underutilization and tropical climate pasture degradation. Therefore, N is a very important nutrient in the pasture maintenance; however, it is necessary to know the maximum limit to be used of this nutrient, since fertilization increases production cost. Thus, the objective of this study was to identify the N dose that provides the highest production of marandu palisadegrass (Brachiaria brizantha cv. Marandu), and the fertilization effect on pasture degradation process and forage nutritive value. Treatments consisted in the application of : 0 (control), 25, 50, 75 and 100 kg N ha⁻¹ cycle⁻¹ of regrowth. The evaluations were carried out during the summers (November to April) of 2015/2016 and 2016/2017. The highest dry matter yield (DMY) and forage accumulation rate (FAR) occurred between doses of 50 and 75 kg ha⁻¹ cycle⁻¹, with no change in productive potential at higher doses. The reduction in mineral content and the increase in crude protein (CP) are the main changes in the nutritional value of marandu palisadegrass, with no pronounced effect on in vitro dry matter digestibility (IVDMD), indigestible neutral detergent fiber (iNDF) and potentially digestible dry matter proportions of CP in the cell wall (CP_CW) and in cellular content (CP_CC).The productive effect of nitrogen fertilization under marandu palisadegrass is the increase in DMY and FAR. Thus, the use of nitrogen fertilizers in pasture systems with marandu palisadegrass has a greater impact on the area gain than the individual gain, assuming these systems, the use of nitrogen doses of 50 to 75 kg ha⁻¹ cycle⁻¹.

中文翻译：

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马兰杜草的施肥中最大氮含量是多少？

没有营养替代物，特别是氮（N）的缺乏是放牧系统利用不足和热带气候牧场退化的主要原因之一。因此，氮是牧场维护中非常重要的营养素。但是，由于施肥会增加生产成本，因此有必要知道该养分的最大限量。因此，本研究的目的是确定能提供最高产量的马兰杜鹃（Brachiaria brizantha cv。Marandu）的氮剂量，以及对牧场降解过程和牧草营养价值的施肥作用。处理包括：0（对照），25、50、75和100 kg N ha ^-1 循环^-1再生。评估是在2015/2016年夏季（11月至4月）和2016/2017年夏季进行的。最高干物质产量（DMY）和饲料积累率（FAR）发生在50至75 kg ha ^-1 周期^-1剂量之间，高剂量时生产潜力没有变化。矿物质含量的减少和粗蛋白（CP）的增加是马兰杜草营养价值的主要变化，对体外干物质消化率（IVDMD），难消化的中性洗涤剂纤维（iNDF）和潜在的消化率没有明显影响细胞壁（CP _CW）和细胞含量（CP _CC）中CP的干物质比例（Marandu palisadegrass）下氮肥的生产效应是DMY和FAR的增加。因此，在具有马兰杜草的牧草系统中使用氮肥对面积增加的影响要大于对个体收益的影响，假设这些系统使用50至75 kg ha ^-1 循环^-1的氮剂量。