喀斯特山区碳酸盐岩土壤抗蚀影响因素研究——以贵州毕节石桥小流域为例

Study on the factor effecting erosion-resistance of calcareous soil in karst mountainous area——A case in the Shiqiao catchment of Bijie city,Guizhou province

对石桥小流域碳酸盐岩土壤进行理化性质分析,结果表明:灌草丛地、水保幼林荒草地、坡耕地土壤砂粒含量依次减少,物理性粘粒含量依次增多,说明坡耕地土壤粘质化最严重;灌草丛地水稳性团粒含量最多,粒级较大,土壤水稳性最好;灌草丛地有机质含量较多,结构破坏率较低,坡耕地土壤分散率、侵蚀率、受蚀指数分别是灌草丛地、水保幼林荒草地的1.11、1.14,1.04、1.13,1.87、1.82倍,耕地土壤团聚度、团聚状况分别是灌草丛地、水保幼林荒草地的0.83、0.84,0.69、0.64倍,说明坡耕地分散率最大,土壤团聚状况最差,土壤抗分散能力弱;小流域内土壤的容重、毛管孔隙度较我国其它地区低,约分别为1.0g/cm3,和39.86%,而非毛管孔隙度则较我国其它地区的高,均值为25.88%。区内碳酸盐岩土壤孔隙的这种组合特征很容易导致上层土壤粘粒向下淋失淀积,堵塞下层土壤孔隙,造成土壤上下层间饱和渗透率的显著差异,对于土壤抵抗流水侵蚀很不利。

It is showed by analysis to physic-chemical property of the calcareous soil in Shiqiao catchment that the sandy content in the soil decreases but the physical clayey content increases successively under the following land with different vegetation form, shrub and grass land, water and soil conservative forest and grass land, slope farmland. Those prove that the development of clayey grain in the soil on slope farmland is most serious. The hydro-stable aggregate content on shrub land is most, the size fraction of soil is largest and the soil water-stable is best. The organic content on shrub land is more and the size fraction of soil are larger, the soil hydro-stability is best. The organic content is more and soil structure is lower on shrub land. The soil dispersing rate on slope farmland, erosion ratio and eroded index is 1.11, 1.14, 1.04, 1.13, 1.87 and 1.82 times that on shrub land and water and soil conservative forest and grass land. The agglomeration degree and agglomeration status of cultivated land is 0. 83,0. 84,0. 69,0. 64 times that on shrub land and water and soil conservative forest and grass land, which shows that the dispersing rate on the slope farmland is maximum, the agglomeration degree on the slope farmland is the poorest and the soil anti-dispersion on the slope farmland is the weakest. The mean value of density and the capillary porosity of catchment, 1.0 g/cm^3 and 39.86%, are lower than that in the other region. The non-capillary porosity, averaged 25.88%, is lager than that in the other region in our country. This kind of combined characteristics of the calcareous soil pore in the catchment is easier leading to the clay at upper soil horizon to be leached downward and to block the pore at lower soil horizon, which causes saturated permeability different significantly between the upper and the lower soil layer, which is very unfavorable for the soil to resist running-water erosion.