我国西南岩溶区土壤侵蚀强度分级标准研究

Grading of soil erosion intensity in Southwest karst area of China

中国西南岩溶区碳酸盐岩成土物质先天不足，沿用水利部颁布的SL190--1996《土壤侵蚀分类分级标准》，显然与岩溶区的实际情况不适应。在分析影响西南岩溶区碳酸盐岩风化成土因素的基础上，收集相关的资料、数据和图层，估算西南岩溶区碳酸盐岩的风化成土速率，并将成土速率作为土壤允许流失量，厘定西南岩溶区土壤侵蚀强度的分级标准，结果表明，微度、轻度、中度、强度、极强度和剧烈侵蚀标准分别为〈30、30—100、100～200、200～500、500～l000、〉1000t／（km2·a）。根据西南岩溶区土壤侵蚀过程的基本特点，对该地区以后的水土保持工作提出以下建议：1）抓住土壤侵蚀过程关键环节重点防治，2）不同岩溶石漠化区采取不同水土保持对策，3）积极推进生物篱技术，4）加强岩溶区土壤改良技术研究，提高基本农田的生产效率。

The concentration of acid insolvable matter in carbonate rock is very low in Southwest area of China. Consequently, the formation of limestone soil is slow and the soil layer is usually thin on karst slope, and the soil loss intensity is mostly weak and light. In fact, the area of rocky desertification in karst region, is continuously increasing these years, and with the soil erosion, the ecological situation is going to worse. The traditional standard for soil erosion gradation is confronted with challenge. The risk valuation and intensity classification of soil erosion in karst＇region should be redefinition. Depending on the factors on the limestone soil formation and carbonate rock corrosion, related data and images have been collected. With the help of ArcView3.2, the rate of limestone soil formation image can be produced. When the rate of limestone soil formation considered as the soil loss tolerance, a new standard for soil erosion gradation suitable to karst region was put forward. The duration of feeble, light, middle, strong, very strong, and acute soil loss gradation is 〈 30, 30 - 100, 100 - 200,200 - 500, 500 - 1 000, and 〉 1 000 t/（km2·a） respectively. Meanwhile, on the basis of features of soil loss process and karst environment, four suggestions for soil conservation in karst region are also put forward： 1 ） depending on the karst hydrological characters, the sinkholes and dolines is the key part to prevent the soil loss, and effective measurement for soil protection should be taken ; 2） on top part of karst hill, the carbonate rock is largely exposed and there is a little soil cover, the way to close hillside to facilitate afforestation should be selected; on the middle part of slope, the rocky desertification of which is mid- dle gradation, the economic plants to increase the land productivity, should be planted; in the .foothill part, there are thick soil layer, the farmland construction, modern agriculture activity and food production should be taken;3） in the karst region with thin soil layer, biogenic fence technology is recommended; 4） the research of soil melioration technology should be strengthened.