微型小区在土壤可蚀性估算中的应用

Soil erodibility estimation using micro-plots

土壤可蚀性反映土壤对侵蚀的敏感程度,是评价土壤侵蚀程度和预报土壤流失量的重要指标。方便可行且可信的土壤可蚀性测定与估算方法在土壤可蚀性的研究中具有重要意义。采用微型小区对黑土、褐土、黄土、紫色土和红壤5种土壤可蚀性K值进行估算,并基于标准小区天然降雨的径流泥沙观测资料,判断微型小区能否代替标准小区进行土壤可蚀性的估算。结果表明:微型小区估算的土壤可蚀性K值比标准小区估算K值小,但具有很好的规律性,可以进行校正。黑土、紫色土、褐土和红壤在天然降雨条件下微型小区计算的K值与标准小区间存在良好的线性关系,可对微型小区条件下的K值进行修订以达到标准小区的要求;容易产生细沟的黄土不宜采用微型小区进行K值的估算。

Soil erodibility reflects the vulnerability or susceptibility of soil to erosion and is frequently used in the evaluation of soil erosion and the prediction of soil loss. A feasible and reliable method for soil erodibility measurement and estimation is critically required in the research of soil erosion. The objectives of the current study were to estimate the erodibilities of five typical soils in China using micro- plots and to compare the results with those obtained with the traditional unit plot method. Each of the five soils, i.e. , purple soil, black soil, red soil, cinnamon soil and loess soil, was packed into a 20 m × 2. 1 m unit plot and a 1 m× 1 m micro-plot, with continuously in a clean-tilled fallow condition and tillage performed upslope and downslope. Runoff and sediment yield were measured for the unit plots in 61 natural rainfall events during the years 2006--2011 and for the micro-plots in 47 events during 2007-- 2011. Annual soil erodibilities of each soil were calculated as the K values in the Chinese Soil Loss Equation （CSLE） for both unit plot and micro-plot. And, the calculated formula of K value was presented as K =A/（R·LS·B·E·T）. The results showed that the mean annual K values generated with the micro-plots were all lower than those obtained with the unit plots. However, both plot methods yielded generally the highest K values for the purple and black soils, followed by the red soil, and the lowest values for the cinnamon and loess soils. In addition, significant correlations of annual K value were detected between the two methods for all the soils except for the loess soil, because rills were prone to develop in the unit plot of loess soil but not in the micro-plot due to the short slope length. Significant linear regression equations between two K values, i. e. , obtained with the unit plot and the micro-plot methods, were generated for purple soil, black soil, red soil and cinnamon soil. These findings suggest that micro-plots are applicable in soil erobibility estimation for five typical soils in China except for the loess soil.