Department of Animal Science, São Paulo State University, Jaboticabal, SP, Brazil.
Embrapa Agrobiologia, Antiga Rodovia Rio-São Paulo, Seropédica, RJ, Brazil.
PLoS One. 2021 Mar 3;16(3):e0247931. doi: 10.1371/journal.pone.0247931. eCollection 2021.
Palisadegrass [Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster cv. Marandu] is widely used in Brazil and is typically managed with little or no N fertilizer, which often leads to pasture decline in the long-term. The current relationship between beef price and fertilizer cost in Brazil does not favor fertilizer use in pastures. Legume inclusion is an alternative to adding fertilizer N, but often legumes do not reach a significant proportion (> 30%) in pasture botanical composition. This study evaluated herbage responses to N inputs and pasture species composition, under intermittent stocking. Treatments included palisadegrass-forage peanut (Arachis pintoi Krapov. & W.C. Greg. cv. Amarillo) mixture (mixed), unfertilized palisadegrass (control), and palisadegrass fertilized with 150 kg N ha-1 yr-1 (fertilized). Treatments were applied over two rainy seasons with five growth cycle (GC) evaluations each season. Response variables included herbage biomass, herbage accumulation, morphological components, total aboveground N of forage peanut (TAGNFP), and contribution of biological N2 fixation (BNF). Herbage biomass was greater for fertilized palisadegrass [5850 kg dry matter (DM) ha-1] than for the palisadegrass-forage peanut mixture (3940 kg DM ha-1), while the unfertilized palisadegrass (4400 kg DM ha-1) did not differ from the mixed pasture. Nitrogen fertilizer increased leaf mass of palisadegrass (2490 kg DM ha-1) compared with the control and mixed treatments (1700 and 1310 kg DM ha-1, respectively). The contribution of BNF to the forage peanut ranged from 79 to 85% and 0.5 to 5.5 kg N ha-1 cycle-1. Overall, benefits from forage peanut were minimal because legume percentage was less than 10%, while N input in the system by N-fertilizer increased palisadegrass herbage biomass.
雀稗[Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster cv. Marandu]在巴西被广泛应用,通常在管理上几乎不施或不施氮肥,这往往导致长期牧场退化。巴西目前的牛肉价格和肥料成本之间的关系不利于在牧场使用肥料。豆科植物的加入是添加肥料氮的一种替代方法,但通常豆科植物在牧场植物组成中所占比例不到 30%。本研究评估了间歇放牧条件下氮投入和牧场物种组成对牧草的响应。处理包括雀稗-饲用花生(Arachis pintoi Krapov. & W.C. Greg. cv. Amarillo)混播(混播)、不施肥雀稗(对照)和每公顷每年施 150 公斤氮(施肥)。这些处理在两个雨季进行,每个季节进行五次生长周期(GC)评估。响应变量包括牧草生物量、牧草积累、形态组成、饲用花生地上总氮(TAGNFP)和生物固氮(BNF)的贡献。施肥雀稗的牧草生物量(5850 公斤干物质(DM)公顷-1)大于雀稗-饲用花生混播(3940 公斤 DM 公顷-1),而不施肥雀稗(4400 公斤 DM 公顷-1)与混播牧场无差异。与对照和混播处理(分别为 1700 和 1310 公斤 DM 公顷-1)相比,氮肥增加了雀稗的叶片质量(2490 公斤 DM 公顷-1)。生物固氮对饲用花生的贡献范围为 79%至 85%,为 0.5 至 5.5 公斤 N 公顷-1周期-1。总的来说,饲用花生的效益很小,因为豆科植物的比例不到 10%,而系统中通过氮肥投入增加了雀稗的牧草生物量。