Sandy soil leaks water and fertilizers,the structure is loose,and the soil and water loss is serious.The effective improvement of the weathered material of the soft rock can improve the soil structure, quality and promote the utilization efficiency of resources.In order to screen out the compounding ratio with better improvement effect on sandy land,four kinds of compound soils with mixed soft rock to sand ratios of 0∶1 (CK),1∶5 (C1),1∶2 (C2) and 1∶1 (C3) were selected as research objects.The soil organic carbon content, active organic carbon content, bulk density, organic carbon storage and carbon pool management index of 0—30 cm soil layer (10 cm interval)were measured and evaluated.The results showed that,soil organic carbon content showed significant differences only in the 10—20 cm soil layer.Compared with CK, the organic carbon content of the soft rock treatment was significantly reduced by 30.00%—46.36%,and there was no significant difference among the C1,C2 and C3 treatments.In each soil layer,the compounding ratio had a significant effect on the content of soil active organic carbon.Among them,the C2 and C3 treatments significantly increased the content of active organic carbon by 325.00%—491.67% (0—10 cm), 775.00%—787.50% (10—20 cm) and 490.91%—509.09% (20—30 cm).The soil bulk density in each soil layer increased with the increase of the ratio of soft rock.The average bulk density of 0—10 cm soil layer was 1. 77 g/cm³ ,and compared with 0—10 cm soil layer,the bulk density of 10—20 cm and 20—30 cm soil layers increased by 12.43% and 23.16%,respectively.There was no significant difference in soil organic carbon storage in each soil layer.The organic carbon storage in C1 treatment was 13.89% lower than that of CK,and the organic carbon storage in C2 and C3 treatments increased by 4.40% and 3.22% compared to CK in 0—30 cm soil layer.The change of carbon pool management index was consistent with the rule of active organic carbon content,increasing in the 10—20 cm and 20—30 cm soil layers with the increase of soft rock,and in the 0—10 cm soil layer, C2 had the largest carbon pool management index.Therefore,in the process of using soft rock to improve sandy soil,the improvement effect of sandy soil is better when the ratio of soft
rock to sand is 1∶2 to 1∶1.