容许土壤流失量的研究现状及其设想

THE PRESENT SITUATION AND SOME THOUGHTS OF SOIL LOSS TOLERANCE STUDY

成土速率、土地生产力和沟蚀的控制程度是容许土壤流失量(T值)制定中必不可少的因素。国际上现有的T值标准主要是从土层厚度和成土速率出发,并结合实际应用的可能而定。详述了T值的研究历史其主要影响因素,介绍了利用Barth模型和基于风险评价理论的T值的估算方法,对现有T值研究方法和研究结果中存在的问题进行了分析,提出了T值应该从土壤形成速率特性(自然属性)、合理的生产力水平持续性(社会属性)、水土环境的长久安全性(自然和社会属性)几方面属性进行相应的研究。

As the criterion of judging non-erosion and erosion area, the value of soil loss tolerance （T-value） must be determined scientifically and rationally. To assign a T-value soil formation rate, relationship between soil loss and productivity and gully prevention must be considered. Current methods of evaluating the soil loss tolerance mainly include： ①soil profile thickness; ②the geochemistry cycle theory; ③nutrient balance; and ④ according to erosion model. The international existing T-value standards are mainly established according to the soil profile thickness and soil formation rate. The history and the main content of soil loss tolerance study are reviewed in this paper,and the method of using Barth equation and on the basis of the risk assessment are also introduced. In face of the existing problems in the evaluation method and conclusion of T-value research, future T-value study should be concentrated on the characteristic of soil formation（natural attribute） , the durative of rational productivity level （social attribute） and the soil and water environment safety （social and natural attribute）is raised.