金沙江支流冲沟侵蚀区四种土地利用方式下土壤入渗特性研究

Soil Infiltration Under Different Patterns of Land Use in Gully Erosion Area of the Jinshajiang River Basin

在保持原有植被条件下,采用野外双环入渗法对金沙江支流安宁河谷冲沟侵蚀发生区4种土地利用条件下(荒草地活动沟、荒草地稳定沟、裸地活动沟、耕地)土壤入渗性进行研究。试验表明,前21．5 min土壤平均渗透率和累计入渗量均以荒草地稳定沟为最大,以裸地活动沟为最小,其余二者居中。4种土地利用条件下的入渗过程相似,并且可以用考斯恰可夫(костяковАН)公式f(t)=at-b得到很好的表达。植被能够有效增加土壤有机质的含量,而后者对改善土壤结构起着显著作用。土壤中>0．25 mm水稳性团聚体,尤其是其中的大粒径团聚体(>3 mm)含量较高,有利于提高土壤入渗性能。根量是能反映入渗性能强弱的重要生物学指标之一。具有良好入渗性的土壤,其地表径流减少,冲沟侵蚀得到有效遏制。

With the original vegetations kept undisturbed, the field double-ring method was used to examine soil infiltration under 4 different patterns of land uses （P-1, waste grassland with active gullies, P-2, waste grassland with stable gullies, P-3, bare land with active gullies, and P-4, farmland） in gully erosion area of Anning River Valley of the Jinshajiang River Basin of Xichang, Southwest China. Results showed P-2 was the highest in average infiltration rate in the initial 21.5 mins and in cumulative infiltration and P-3 was the lowest with the others standing in between. The process of infiltration under 4 different patterns of land use can be described with the equation of KOCTЯKOB A.H： f（t）=at^-b. Vegetation could increase the soil organic matters effectively, and the latter could improve soil structure notably. The higher content of water-stable aggregates 〉 0.25mm, especially of aggregates 〉 3mm increased soil infiltration rate. Root weight is an important biological indicator of soil infiltration. High soil infiltration reduces surface runoff and hence in turn suppresses formation of gullies.