不同放牧强度下奶牛对多年生黑麦草/白三叶草地土壤特性的影响

本文作者在湖南南山牧场通过放牧试验研究了不同放牧强度下奶牛对多年生黑麦草／白三叶人工草地土壤物理和化学特性的影响。结果表明：放牧强度直接影响着多年生黑麦草／白三叶人工草地土壤的物理结构。随放牧强度增加，奶牛对草地土壤的践踏加剧，导致土壤紧实度增加，容重上升，通气性变差，含水量下降。放牧强度对土壤物理特性的影响随土层深度增加而减轻。土壤中全磷、速效磷、碱解氮和有机质随放牧强度的增加而减少，而全氮、速效钾则随放牧强度的增加而增加。土壤中各养分含量随季节变化波动很大。

Effects of Different Grazing Intensity for Dairy Cows on Soil Characteristics of Perennial Ryegrass/White Clover Sward

The effects of grazing dairy cow on physical and chemical characteristics of soil for the swards of Loium pernne/Trifolium repens were studied at Nanshan Ranch. The result showed that grazing intensity directly influenced the physical structure of soil for the swards of Lolium perenne/Trifolium repens. The soil bulk density increased along with the increament of grazing intensity, while water content and pority were decreased both for 0~10 and 10~ 30cm layer, The impact of grazing intensity on soil physical characteristics decreased with the increament of soil depth. The contents of gross phosphorus, quick available phosphorus, alkaline hydrolytic nitrogen and organic matter in the soil decreased with the increament of grazing intensity, while the contents of gross nitrogen, quick available potasium in the soil increased with the increament of grazing intensity. An the nutrients in the soil nucted greatly from month to month.