Document Type : Research Article
Soil Science Department,, Faculty of Agriculture, University of Zanjan, Zanjan, Iran.
Department of Soil Science, Faculty of Agriculture, University of Zanjan, Zanjan, Iran.
Rangeland soils have always been of interest due to their high organic content, while the change of land use influences the amount of organic carbon, which plays a key role in soil quality. In this research, the quantification of soil quality in Sahand rangeland, East Azarbaijan province and its possible relationship with soil organic carbon were investigated. Soil samples were collected from two land uses, including undisturbed rangeland and agricultural land using the transect method. Twelve physical and chemical characteristics of the soil were measured, and then compared by statistical analyze. Principal component analysis (PCA) method was used to extract the minimum data set (MDS) affecting soil quality. Then, the soil quality index was estimated using non-linear scoring functions. Finally, the relationship patterns between the most effective identified indicator and other soil characteristics were investigated using multivariate regression. Results showed that the value of soil quality index in rangeland (0.78) was significantly higher than agricultural land (0.63). The highest score value used to estimate soil quality index was related to organic carbon indicator (0.73). The mean weight diameter (0.72), clay percentage (0.93), bulk density (-0.24), and saturated water content (0.04) in rangeland soil, and acidity (-0.13) and electrical conductivity (-0.48) in agricultural land soil showed a significant effect on soil organic carbon (highest regression coefficient). It can be concluded that different land use systems play an important role in changing the soil quality by affecting the soil attributes, and thus changing the input and preservation of organic carbon to the soil.