Author_Institution :
Lab. of Karst Dynamics, CAGS, Guilin, China
Abstract :
Notice of Retraction
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The concentration of insoluble matter in carbonate rocks is very low in Southwest karst China. Consequently, soil formation is slow and soil layers are usually thin on hillslope. The results from remote sensing and monitoring sites show that soil loss intensity is mostly weak and light. In fact, the area of rock desertification in karst region, is continuously increasing these years, with the soil eroding, and the ecological situation becoming worse. The traditional standard for soil erosion gradation is confronted with challenge. Risk valuation and intensity classification of soil erosion in karst region should be redefined. Depending on the factors of limestone formation and carbonate rock dissolution, related data and images have been collected. With the help of ArcView3.2, the rate of limestone soil formation can be produced. By also considering a soil loss tolerance, a new standard for soil erosion gradation suitable to karst region can be put forward. The duration of feeble, light, middle, strong, very strong, and acute soil loss gradation, is <;30, 30~100, 100~200, 200~500, 500~1000, and >;1000t/(km2·a), respectively. On the basis of features of soil loss processes and the karst environment, four suggestions for soil protection in karst region are brought forward: 1) depending on the karst hydrological structure, the key part to prevent the soil loss from surface to ground, is the sinkholes and dolines, and effective measurement for soil protection should be taken; 2) on karst hill, in top - art, the carbonate rock is largely exposed with little soil cover, the way to close hillside to facilitate afforestation can be selected; the middle slope part, the rock desertification is middle gradation, to build the wall and prevent the soil loss, and planting the economic plants to increase the land productivity, should be suitable measurement; in the foothill part, thick soil layer and little rock, the farmer land construction, modern agriculture act- vity and food production are taken; 3) in the karst region with thin soil layer, biogenic fence technology is advocated, shrub species are recommended, particularly some shrubs belonging to the C4 plant with high photosynthesis capacity, and, bean family with nitrogen fixation. Moreover, they have flourishing roots to bear the drought and poor habitat; 4) limestone soil is characterized by high calcium content and alkaline. The high calcium level activates much nutrition. The effective soil improvement can enhance agricultural productivity.
