Effects of different grazing intensity of Tan sheep on the grasslands in Yanchi county

A Tan sheep grazing experiment with five different grazing intensities and of 150 days was carried out.The results showed that:(1) there were extremely negative correlation and extremely significant regression between grazing intensity and the standing crop of gramineous pasture,and the varying tendency of the standing crop of gramineous pasture was first increased and then decreased.The standing crop of the gramineous pasture was the highest when grazing intensity was 0.45 sheep/(hm~2·d).(2) The rate of standing crop of gramineous pasture in gross pasture decreased with increased grazing intensity.The rate of standing crop of the gramineous pasture was the highest when grazing intensity was 0.45 sheep/(hm~2·d).(3) The rate of standing crop of leguminous pasture decreased with increased grazing intensity.And the varying tendency line shaped like Vcurve.(4) the varying tendency line liked N when grazing intensity increased.(5) The rate of gramineous pasture decreased and the rate of leguminous pasture increased with increased grazing intensity.The vegetation constitutes changed.From the present situation of grassland in Ningxia,the grazing intensity can not surpass 0.45 sheep/(hm~2·d).