黄土高原水蚀风蚀交错带不同土地利用方式坡面土壤水分特性研究

Soil water properties in a slope of different land use in the wind-water erosion crisscross region on the Loess Plateau

为分析不同土地利用方式下坡面土壤水分特性的差异和规律,对黄土高原水蚀风蚀交错带典型坡面上农地、林地和草地的土壤水分特性进行了分析。结果表明：（1）苜蓿地土壤的持水能力和供水能力最强,其次是杏树林和长芒草地,谷子地最差;（2）通过土壤水分有效性分析发现,水蚀风蚀交错带田间持水量相当于-0.2×105Pa土壤基质势时的土壤含水量,永久凋萎点则低于-2.0×106Pa土壤基质势对应的土壤含水量;（3）苜蓿地有效水含量最高,谷子地有效水含量最低,而且苜蓿地土壤有效水含量的提高主要是提高了迟效水部分;（4）对不同土地利用方式下的土壤比水容量变化曲线研究表明,土壤比水容量在田间持水量附近随土壤含水量的降低减小的很快,而当土壤水分降低到田间持水量的50%~60%以下时,土壤比水容量基本不变。

Different land use has an important effect on soil moisture and soil quality. In order to describe the differences and features of soil water characteristics on a slope-land under different land uses, a research on soil water characteristics of farmland, woodland and grassland was carried out in the Wind-water Erosion Crisscross region. The results showed that： （1） the capacity of soil water retention and supply of alfalfas was the best, then almonds, and then stipa bungeana, and the capacity of millets was the worst; （2） in the region the field capacities （FC） corresponded to soil moisture content with soil matrix potential of - 0.2 ×10^5 Pa, the permanent wilting points （PWP） corresponded to soil moisture content with soil matric potential lower than -2.0 × 10^5 Pa; （3） the available water of alfalfas was the greatest, the available water of millets was the least, and the increase of the available water of alfalfas can be attributed to the increase of slowly available water; （4） the specific water capacity decreased quickly with soil moisture content around FC, while it retained relatively constant in 50 % ~ 60 % of FC.