金沙江干热河谷典型区(云南省)土壤退化机理研究 II 土壤水分与土壤退化

The eco-environmental land desertification, as predominated by soil degradation, and shortage of water resources have been the serious problems in the dry and hot valleys of Jinshajiang River Area. The disparities in water property in soils of dif ferent degradation degrees have been investigated in relation to the mechanisms of soil degradation. By comparing the soil water properties of dry red soils in different degradations in Jinshajiang River Area, Yunnan Province, it is found that in degraded soil the PWP increases, and the FC and BCM decrease. The range of water available for plants al so becomes narrow er in the degraded soil. The permeability of degraded soil declines because of the reduction of the soil infiltration rate. Moreover , the increase of the soil water evaporation rate further incuces the water holding capabilities in the soil . It is predicted that the time of water efficiency may exceed 45 days even in rain season, duo to the reduction of available soil water. Thus, the inferiority of the soil water property in this area may result in the occurrence or aggravation of soil degradation.