Abstract: Soil bulk density,surface hardness,0-20cm hardness and capillary capacity were tested in grazing gradient in temperatural zone semi-arid steep.The soil type is dark sandy chestnut.Thc grazing intensity range is from 0 to 6.67 shecps/ha.The research result showed:(1)It is limited(0-10cm)soil bulk density change influenced by grazing intensity.The mathematics model between soil bulk density and grazing intensity is Y=1.236＋0.595x－7.764*10^-3x².Soil compaction is the light grazing in summer(15-25.July),the heavy grazing in autumn(3-13,September),the middle grazing in spring with same grazing intensity(20 sheeps/ha).(2)Soil hardness(0-20cm)increased with grazing intensity increaes from 0 to 4(sheeps/ha),while soil hardncss(0-20cm)decreased with grazing intensity from 4 to 6.67(sheeps/ha).(3)Soil surface hardness and capillary capacity changes are not notable with grazing intensity.(4)Based research result,author divide grazing range into two stages,grazing intensity from 0 to 4(sheeps/ha)is called the resilience stage of able retum,other is called real degeneration stage that grazing intensity is from 4 to 6.67 sheeps/ha.In first stage,soil and vegetation can be returned under it's returnability,but secend stage,natural return is difficult unless taked some artifical ameliorate measures.(5)Author proposed 4sheeps/ha would be high limite that grazing on the sandy dark chestnut steep.

Key words: Inner Mongolia, Temperatural steppe, Grazing presure, Soil compaction, Grassland degradation

摘要： 在不同牧压下,测定土壤容重(0-20cm)、硬度(地表和0-20cm)、孔隙度、毛管持水量等与土壤压实作用的有关物理指标。结果表明,供试放牧强度(0-6.67羊/hm²)对土壤容重的影响仅局限于0-10cm,其中以0-5cm最显著。0-10cm土壤容重的数学模型为y＝1.236＋0.595x－7.764*10^-3x²,R＝0.978。相同放牧强度(20羊/hm²)不同放牧时期(春牧5月22日-6月1日,夏牧7月15-25日,秋收9月3-13日),对土壤容重的影响表现在夏季放牧对于土壤的压实作用最轻,秋季最重,春季居中。每公顷0-4只羊,土壤硬度随着放牧强度的增加而增大,每公顷4-6.67只羊,土壤硬度随着放牧强度的增加而降低。放牧强度对土壤表面硬度和毛管持水量的影响不显著。

关键词: 内蒙古, 温带草原, 放牧强度, 压实效应, 草原退化