河北省表层土壤可侵蚀性K值评估与分析

Assessment and Analysis of the Topsoil Erodibility K Values in Hebei Province

利用河北土系调查成果中的土壤颗粒组成、土地利用及土壤化学性质等资料，利用EPIC模型中土壤可蚀性K值算法以及结合地统计学方法，研究了不同土壤类型、不同质地及不同土地利用类型的土壤可侵蚀性K值和土壤可侵蚀性K值的空间变异特征。结果表明：①河北土壤可侵蚀性K值平均为0．27，其变化范围为0．12～0．40，土壤可蚀性K值在0．30～0．35之间易蚀性土壤面积占总土地面积的63．71％，土壤可蚀性K值在0-25～0．3之间较易蚀性土壤面积占总土地面积的21．52％，这说明该省易蚀性土壤面积较大。②不同质地的K值之间显著性差异，粉砂黏壤质的可侵蚀性K值最大，为0．37；壤砂质的可侵蚀性K值最小，为0．13。而在不同的土地利用类型之间的K值差异性不显著，耕地的K值最大，为0．33；草地的K值最小，为0．22。③河北土壤可侵蚀性K值存在较强的变异性，其变异系数为29％。因此，在土壤侵蚀定量监测、评价水土流失时，应考虑土壤可蚀性K值的这种空间变异状况。块金值／基台值为37．3％，表明在变程内具有中等强度的空间相关性。步长为23km，变程为440km，变程远大于步长，表明在小流域尺度下有较好的空间相关性，进行Kriging插值能得到较准确的结果。④河北土壤可蚀性K值大体呈现南高北低的空间分布特征，南部主要是耕作栽培区，北部主要是自然植被区。该研究结果为宏观大尺度土壤资源可持续利用与制定水土保持规划提供科学依据。

According to soil mechanical compositions, land-use types and soil physicochemical properties in the soil survey, soil erodibility K values of different soil groups, different textures and different land use types and spatial variability characteristics of soil erodibility K values can be studied by using the method of the EPIC model and geostatistics. The results showed that： 1） Soil erodibility K value ranged from 0.12 to 0.40 and mean value was 0.27 in Hebei. The area of soil erodibility K value ranging from 0.30 to 0.35 was 63.71% of the total soil area and that of soil erodibility K value ranging from 0.25 to 0.30 was 21.52% of the total soil area. This indicated that the area of easy erosion soil was larger. 2） The differences were significant between different textures. Soil erodibility K value of silt-clay-loam was maximum （0.37） while that of loamy sand was minimum （0.13）. However, there was no significant difference between different land-use types. K value of cultivated land was the largest （0.33） while that of grass was the smallest （0.22）. 3） Soil erodibility K values existed strong variability and variation coefficient was 29%. Spatial variability of erodibility K value should be considered when soil erosion was monitored and soil and water loss was evaluated. The ratio of nugget and sill value was 37.3%, which showed that K value had the spatial correlation of moderate intensity within the variable range. Lag size was 23 km and the range was 440 kin, which indicated that there was better spatial correlation in the small watershed scale so that Kriging interpolation can get more accurate result. 4） Soil erodibility K value was lower in the north which was mainly natural vegetation region but higher in the south which was mainly the cultivation region. The results of this study can provide scientific basis for sustainable utilization of soil resources and planning of soil and water conservation in larger scale in Hebei Province.