Effect of organic management on soil quality under different land use types

The soil quality of farmlands can be improved by organic management, but this conclusion is unclear under different land-use types. A soil quality survey based on an organically managed farm with diversified land use and nearby conventionally managed farmland was conducted by analyzing differences in the soil quality under two different management measures within five land use types (greenhouse vegetable fields, orchards, open-air vegetable fields, farmland boundaries, and paddy ridge). Analysis of variance (ANOVA) and principal component analysis of 20 indicators of soil nutrients contents, heavy metals contents, and soil animal numbers were used to explore the impact of organic management on soil quality under different land use types. The results showed that the pH value of the organic management was significantly higher than that of conventional farmland overall (the average value of five land use types). Meantime, the organic management overallly significantly decreased soil contents of total P, total K, available P, total Cr, total Cu, total Ni, and total Zn; and increased amounts of soil Araneae, Diplopoda, ground beetle and earthworm, compared with the conventional management. But for the specific land use type, pH increased significantly in the open-air vegetable field and farmland boundary under organic management. The organic matter content and total nitrogen contents of the open-air vegetable fields, and the quantities of Araneae, Diplopoda, ground beetles, and earthworms in the soil under organic management were higher. The total Cr, total Ni, and total Zn contents in the greenhouse vegetable fields, total Zn contents in the open-air vegetable fields and farmland boundaries, total Cu contents in orchards and paddy ridges were lower. The numbers of ground beetles and earthworms in the paddy ridge, and Diplopoda in the orchard were higher under organic management. Principal component analysis indicated that there was a significant difference in soil quality under different management practices. The numbers of Araneae, Diplopoda, ground beetles, and earthworms in the soil were higher, and the pH values and contents of P, Cu, Pb, Zn, and Cr were lower under organic management. These results show that the soil quality was better under organic management, but this was not universal for all land use types due to factors such as the specific management practices, the number of artificial inputs, and the length of organic planting time. The extent to which land quality had been improved under different land use types differed, so it is necessary to take targeted soil improvement measures under diverse land use types.