Changes in the Distribution of Soil Particle and the Content of Soil Nutrients During Reversal of Desertification:a case study in Yanchi County,Ningxia Hui Autonomous Region

Based on field investigation and laboratory analysis,the changes of the distribution of soil particle and the content of soil nutrients were examined by the method of time-space mutual substitution at a site exhibiting the reversal of desertification in enclosed area for many years of Yanchi County;and by adopting statistic analytical methods,the quantitative relationship between the soil particle distribution and the soil nutrient was discussed.The results showed that with the reduction of the degree of desertification,the content of coarse-fine sand decreased and the silt + clay increased,and the dominant soil particle class changed;the composition of soil particle was always that the content of sand was the first,silt in the second place,and the clay was the least,the deterioration of desertification was possible.The contents of soil organic matter,total N,total P,available N,available P,and available K showed the increasing tendency with the decrement of desertification;at the same time,the desertification reversion improved the ability of soil carbon sequestration.Correlation analysis indicated that the essential characteristic of desertification reversion was the process of the fineness of soil texture accompanying the enrichment of soil nutrients.The fineness of particle size distribution was the direct cause of the improve of soil nutrient contents,and the silt + clay content contributed most to the increasing soil nutrient contents,and thus appeared to be the main factor of the improved soil quality and the key factor of desertification reversal.