小嵩草高寒草甸的土壤养分因子及水分含量对牦牛放牧率的响应 Ⅱ冬季草场土壤营养因子及水分含量的变化

Responses of Soil Nutrient Contents and Water to Stocking Rates for Yaks in Kobrecia parva Alpine Meadow Ⅱhange of Soil Nutrient Contents and Water on Winter Pasture

牦牛放牧试验结果表明:随着放牧率的增加, 冬季草场不同土层有机质、有机碳、全氮的含量和C/N值下降,它们的含量与放牧率呈显著的线性回归关系, 全磷和速效氮的含量与放牧率呈显著的二次回归关系, 各土壤营养因子平均含量与放牧率也有类似的关系;当放牧率分别达到0.81头 hm-2 和1.00 头 hm-2,1.03 头 hm-2 和1.03头 hm-2, 1.36头 hm-2和1.30头 hm-2时, 0～5cm, 5～10cm, 10～20cm土层全磷和速效氮的含量分别依此达到最大,若放牧率继续增强,它们的含量依此开始减小;而且0～20 cm土层全磷和速效氮平均含量达到最大的放牧率分别是1.03头 hm-2和1.06头 hm-2.放牧率和土壤深度的交互作用对土壤各养分因子含量的影响极显著(P<0.01);放牧率对各土壤层含水量有极显著的影响(P<0.01),不同年度间同一土壤层含水量的差异极显著(P<0.01).

The result of grazing trial for yaks on winter pasture of Kobrecia parva alpine meadow indicated that contents of organic matter, total N and C/N decreased in the same soil layers with the increase of stocking rates, and there was a significant linear regression relationship between the contents, value of C/N and stocking rates.Besides, the interactions of stocking rates and grazing time had an extremely significant effect on the contents of every nutrient in different soil layers (P<0.01). Effect of stocking rates on the water contents of every layers was very significant (P<0.01), and the annual change for water contents of every stratum was also very significant (P<0.01).