中文摘要：

为探寻该区域Ks的最优测定方法,应用Guelph入渗仪测量了川中低山丘陵区的林地和坡耕地土壤的饱和导水率,对比分析单水头法（LA法、USH法）和双水头法（TH法、BH法）所测得饱和导水率（Ks）的差异,同时比较了田间原位Guelph法与室内降水头法测定结果的差异。对于同一土层深度,不同方法估算所得的Ks有较大的差异：1）双水头TH法测得的值最大（坡耕地土层〉20～40cm除外）,林地0～20cm,〉20～40cm土层的Ks值分别为0.134,0.266mm/min,坡耕地0～20cm土层的Ks值为0.860mm/min。单水头USH法5cm水头所得值最小,林地0～20和〉20～40cm土层的Ks值分别为0.015和0.022mm/min,坡耕地对应土层则分别为0.040和0.022mm/min;2）单水头USH法10cm水头（USH2）测得的Ks大于5cm水头（USH1）所得值,采用前者所测得林地0～20和〉20～40cm土层、坡耕地0～20和〉20～40cm土层的Ks值分别为0.031,0.056,0.211,0.031mm/min;3）田间原位BH法和USH2法（压力水头为10cm）测定的Ks均大于室内降水头法所测得的值,这可能与室内环刀法在采样中对土壤大孔隙通道的切断与破坏、所测定土壤样品的体积较小有关。综合上述结果,并考虑到单水头法操作简便,故而该研究推荐在川中低山丘陵紫色土地区使用单水头USH2法,压力水头为10cm。

英文摘要：

Soil hydraulic properties are key factors controlling water and solute movement in soil. Soil hydraulic properties estimated from a laboratory experiment use commonly on relatively small soil cores, and they are often not representative of field condition. Ideally, the estimation of soil hydraulic parameters for the simulation of flow dynamics should be based as far as possible on field measurements. Reliable determination of saturated hydraulic conductivity is critical for modeling and predicting soil moisture pattern in soil under various field conditions. In this study, soil saturated hydraulic conductivity （Ks） of a forest land and a sloping farmland, located at Yanting Agro-ecological Experimental Station of Purple Soil （105°27＇E, 31°16＇N）, Sichuan, Southwest China, was determined with a Guelph infiltrometer using different methods, including single head methods （e.g., Laplace analysis, updated single head analysis） and two-head methods （e.g., two-head analysis, Bohne analysis）. Differences in measured saturated hydraulic conductivity between in situ Guelph constant head methods and laboratory falling head method were also compared. We aimed to select a reliable method for determining Ks for the soils in this studied region. The Ks values obtained for the forest land at the 0-20 cm depth were lower than those obtained at the 20-40 cm depth; however, the results obtained from the sloping farmland were contrary to those measured in the forest land. For the same layer, the measured Ks value was related to the method adopted. Results showed that： 1） the Ks values using the two-head analysis were the greatest （except for the 20-40 cm layer of the sloping farmland）. The Ks value in the forest land at the 0-20 cm and 20-40 cm depth was 0.134 and 0.266 mm/min, respectively. In the sloping farmland, the Ks value at the 0-20 cm depth was 0.86 mm/min. However, the updated single head analysis under a 5cm head was the smallest values. The Ks value at the 0-20 cm and 20-40 cm depth was 0.015