紫色土容许侵蚀量的定位试验确定

Determination of Soil Loss Tolerance for Purplish Soils

容许侵蚀量(T值)是土壤侵蚀程度分级和评价水土保持措施有效性的基础。应用以物质循环理论为基础的Barth模型,估算了不同母质类型,不同种植植被和不同土层厚度下的成土速率,并在田间定位试验点测定了这3种不同处理条件下的成土速率。研究结果表明,用Barth模型估算的成土速率,与田间测定值比较,总体上明显偏小;而且,它所确定的成土速率主要与径流量相关(R=0.639 6,P=0.050 4)。田间测定的成土速率,在不同的条件下差异明显,并都反映出了一定的变化规律;综合考虑田间不同试验条件下的成土速率并分析转换,确定四川丘陵区沙溪庙组和蓬莱镇组紫色土的T值为1 200 t/(km2.a),遂宁组的T值为800 t/(km2.a)。

Soil loss tolerance （T-value） is an important value to judge gradation of soil erosion and efficiency of its control countermeasures. In this study, soil formation rates （SR） of the purple soils （a Regosols） in the hilly area of Sichuan, China were determined by Barth equation （SR-estimated） and field measurements （SR-measured） with the three treatments of soil types （J1 s, J3s, and J3p soils）, vegetations （wheat-maize, loquat tree, and ryegrass）, and soil depths （10, 20, 40, and 60 era）. SR-estimated values are generally smaller than SR-measured values. SR-measured values vary significantly among the treatments. Based on the SR-measured values, the T-value was determined as 800 t/（km^2 ·a） for J3s purple soil, and 1 200 t/（km^2 · a） for Jls and J2s soils in the studied region.