放牧强度和时期对内蒙古草原土壤压实效应的研究

Study on Grassland Dark Sandy Chestnut Compaction by Grazing Intensity and Grazing Season

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。

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 . 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.