Forage mass, botanical composition and stocking density of bermudagrass overseeded with forage legumes

ABSTRACT Pastures of the genus Cynodon are being cultivated alone in conventional production with high rates of nitrogen fertilizer. Information and research about its use on mixed-pasture system is scarce. The objective of this study was to evaluate three grazing systems with coastcross-1 (CC) + 100 kg N ha-1 year-1 + common vetch; CC + 100 kg N ha-1 year-1 + arrowleaf clover; and CC + 200 kg N ha-1 year-1. The experiment was carried out from May 2013 to April 2014. The sward height, forage mass, botanical composition, leaf:stem ratio, and animal stocking density were evaluated. Experimental design was completely randomized with three treatments (grazing systems) and three replicates (paddocks) in completely split-plot time (grazing cycles). The average stocking rate was 7.0, 6.8, 6.8 cows ha-1 day-1 for the respective forage systems. Better results were found with coastcross-1 mixed with common vetch + 100 kg N ha-1 year-1 in winter and spring and coastcross-1 alone + 200 kg N ha-1 year-1 in autumn.

摘要：常规牧草生产中，狗牙根属（Cynodon）牧草多以单播方式种植，且氮肥施用量较高。目前关于其在混播牧场系统中应用的相关研究与资料仍较为匮乏。本研究旨在评估3种放牧系统：①岸杂1号狗牙根（coastcross-1，CC）+ 年施100 kg·hm⁻²氮肥 + 普通野豌豆；②岸杂1号狗牙根（coastcross-1，CC）+ 年施100 kg·hm⁻²氮肥 + 箭叶三叶草；③岸杂1号狗牙根（coastcross-1，CC）+ 年施200 kg·hm⁻²氮肥。本试验于2013年5月至2014年4月开展，测定指标包括草层高度、牧草生物量、群落植物学组成、叶茎比以及动物载畜密度。试验采用完全随机设计，设置3个放牧处理组，每组设置3个重复试验小区，并以放牧周期作为裂区时间因子。对应3个牧草系统的平均载畜率分别为7.0、6.8、6.8 头·hm⁻²·d⁻¹。研究结果显示，岸杂1号狗牙根与普通野豌豆配施年施100 kg·hm⁻²氮肥的组合在冬、春季表现更优，而单独种植岸杂1号狗牙根并配施年施200 kg·hm⁻²氮肥的组合在秋季表现更佳。