Effects Of Land Preparation Measures On Soil Particle Size And Soil Moisture In Rocky Desertification Slope

Due to improper farming management methods and the unique hydrogeological structure of karst areas,soil and water loss on the slope is serious.Bedrock is gradually exposed,and the problem of rocky desertification is becoming increasingly prominent.Based on the current farming situation of the rocky desertification slope,we have constructed reverse slopes and flat terraces.In this study,the fractal theory was used to study soil particle size and water-storage capacity.Classical statistical and geostatistical methods were used to explore the spatial variation characteristics of soil moisture in the surface layer（0～20 cm）.Based on the long-term monitoring of soil moisture and atmospheric rainfall,the response process of soil moisture to rainfall was analyzed.In addition,this study analyzed the effects of different land preparation measures（reverse slope,flat terrace,and natural slope）on soil particle size and soil moisture,and provided basic data and a theoretical basis for sustainable farming of rocky desertification slopes.The main conclusions are as follows:（1）The clay content（38.68%）of the reverse slope and the sand content（29.25%）of the flat terrace was the highest.The soil particle size distribution of the reverse slope was relatively more concentrated,while the soil particle size distribution range of the flat terrace was relatively smaller and more symmetrical.The soil total water-storage capacity,non-capillary water-storage capacity,and capillary water-storage capacity of the reverse slope were the largest.Land preparation measures can affect soil water-storage capacity by changing the distribution of soil particle size,and fractal parameters can be used as potential indicators to evaluate soil water-storage capacity.（2）During the rainy and dry seasons,the soil moisture content of different land preparation measures showed strong spatial autocorrelation（C₀/（C₀+C）≤0.25）,moderate spatial variability（10.00%≤CV≤100.00%）,and extremely significant（P<0.01）spatial aggregation.The soil moisture content of the reverse slope was the highest,while the spatial continuity,aggregation,total and structural variability of soil moisture content of the flat terrace were the strongest.Soil mechanical composition was the main factor that affected soil moisture content,and the reverse slope was more conducive to improved soil moisture conditions on rocky desertification slopes.（3）The average soil moisture content of the reverse slope（39.73%）was higher than that on the natural slope（34.03%）and the flat terrace（32.05%）,but the time variability of soil moisture content of the flat terrace was higher than that on the natural slope and the reverse slope.Rainfall and soil depth were the main factors that affect the dynamic change and amplitude of soil moisture content in the rocky desertification slope,respectively.The overall amplitude of soil moisture content of the reverse slope was the smallest.In light rain and moderate rain events,the amplitude of soil moisture content of the different land preparation measures was consistent,but the response speed of soil moisture to rainfall of the reverse slope was the fastest.In rainstorm and heavy rainstorm events,the response speed of soil moisture to rainfall of the different land preparation measures was faster,but the amplitude of soil moisture content of the reverse slope was the smallest.In light rain and heavy rainstorm events,the effective replenishment amount,rate,and efficiency of soil moisture on the flat terrace were the largest.In moderate rain,heavy rain,and rainstorm events,the effective replenishment amount,rate,and efficiency of soil moisture of the natural slope were the largest.