摘要
本试验中,放牧绵羊对草地的实际利用率(采食率)各为40％、60％、70％、80％左右以及适时刈割这五种处理方法,对多年生黑麦草、红三叶、白三叶混播草地不同季节牧草地上生物量、全年产量和植物组分动态等均产生了明显的处理效应。试验期内(1987～1989年),连续刈割条件下,草群中多年生黑麦草和白三叶草比例逐年下降,而红三叶草比例逐年上升;中等偏高的放牧强度(实际利用率为70％左右)下,多年生黑麦草和白三叶在草群中的比例相对稳定,豆、禾比率保持在1:2左右;放牧本身有降低红三叶在草群中的比例的作用,各放牧处理中红三叶比例仅达10％左右。在实际放牧强度为40％～70％的范围内,草地牧草产量较高(各年份情况相似),其中以适度放牧强度(利用率60％左右)下草地产量最高;过度放牧强度(利用率80％左右)明显降低了草地牧草产量,并产生了不可逆转的年度间变化。本试验中,割草处理产生的综合效应与过度放牧强度类似。不同放牧强度对春、夏、秋各季节牧草地上生物量都产生了极显著处理效应,春、秋二季,以适度放牧强度(利用率60％左右)下牧草地上生物量最高;夏季以割草处理下牧草地上生物量最高;过度放牧强度(利用率80％左右)下,春、夏、秋季测得的牧草地上生物量均极显著低于适牧处理。本试验为当地选出的适宜放牧强度是实际利用率为60％左右,相应的牧后地上牧草剩余量约为900公斤干物质/公顷左右。
The experiment with five treatments, i.e. four grazing intensities by sheep grazing (40%, 60%, 70%, and 80%) and continuous fixed cutting in height, showed significant treatments effects on the seasonal above ground biomass (AGBM), annual dry matter yield and pasture composition of perennial ryegrass+ red clover + white clove mixed sown pasture. During the experimental period (1987—1989) .continuous fixed cutting in height resulted in the gradual decline of perennial ryegrass and white clover on the sown pasture, but increase of red clover on the mixture | under grazing , heavey utilization intensity (70%) could maintain a relative stable composition of the ryegrass and white clover on the sown pasture where the dry matter weight ratio of legume and grass was about 1:2; The proportion of red clover decreased, which was only accounted for 10 % due to grazing. Within the range of grazing intensities (40%～70%) , high pasture production was achieved with highest pasture yield by moderate grazing intensity (60%). However, high grazing intensity (80%) had marked decrease in pasture production, and long—term negative effect on the sown pasture. In this experiment, long—term negative effect by continuous cutting was the same as by over grazing(80%). In general, different grazing intensities had significant effects on the AGBM in spring ,summer and autumn. Moderate grazing intensity(60%) had the highest AGBM during spring and autumn; cutting treatment had the highest AGBM during summer; overgrazing (80%) significantly resulted in lower AGBM than the moderrate grazing intensity(60%) throughout the year. The optimal grazing intensity recommended based on the results of this trial is the moderate grazing intensity, about 60% of utilization rate ( the residual dry matter is about 900 kg/ha).
出处
《草业学报》
CSCD
1993年第3期1-10,共10页
Acta Prataculturae Sinica
关键词
强度
混播草地
产量
组分动态
utilization intensity mixed pasture herbage yield dynamic composition
