Abstract:
The effects of three common land use patterns (abandoned land, Al; corn field, CF; fruit tree land, FD) on soil aggregate stability and organic carbon (C) distribution in rocky desertification area were analyzed, which will provide theoretical basis for farmland restoration and soil fertility improvement in karst rocky desertification area. Soil samples were collected from different land use patterns in the same area, and dry sieving method and wet sieving method were used for aggregate classification. The soil nutrient content, particle size distribution, structural stability and organic C distribution characteristics of soil aggregates under different land use patterns were compared and analyzed. The results showed that the soil nutrient indices of FD were higher than those of Al and CF. The soil organic C of FD was significantly increased by 25.45% and 21.86% compared with Al and CF, and the total nitrogen was significantly increased by 22.42% and 29.76%. The content of mechanical and water stable aggregates in FD > 5 mm was significantly higher than that in Al and CF, while the content of water stable aggregates < 0.25 mm was significantly lower than that of Al and CF. The aggregate content (R
0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) of > 0.25 mm in different land use patterns were FD > AL > CF, while the aggregate failure rate (PAD) and unstable aggregate index (E
LT) were opposite. Compared with Al and CF, the organic C content of FD aggregates with different particle sizes increased by 4.39% ~ 36.69% and 8.11% ~ 27.51% respectively, and the contribution rate of organic C of aggregates with particle size > 5 mm to soil organic C significantly increased by 6.03% and 9.64% compared with Al and CF, while the contribution rate of organic C with particle size < 0.25 mm decreased by 46.02% and 57.42%. Correlation analysis showed that soil organic C content was significantly positively correlated with MWD, GMD and R
0.25, and soil organic C content was the most important soil nutrient index affecting soil aggregate stability. Returning farmland to forest in the areas with serious karst rocky desertification can improve soil nutrients, soil aggregate structure, and promote the improvement of ecological environment of karst rocky desertification.