The conversion of forestland into agricultural land without appropriate measures to conserve SOM leads to the degradation of physical and rheological soil properties

This study was conducted to compare soil particle density (rho (s)), soil total porosity (TP), liquid limit (LL), plastic limit (PL), and plasticity index, and their relations with soil organic matter (SOM), of non-carbonate silty clay Fluvisols under different land uses. Three neighboring land uses were studied: native deciduous forest, arable land, and meadow, managed in the same way for more than 100 years. Soil was collected from 27 soil profiles and from three depths (0-15, 15-30 and 30-45 cm). Land use caused statistically significant but different impacts on soil properties, particularly in the topsoil. The forest topsoil measured the lowest rho (s) and bulk density (rho (b)) but the highest SOM and soil water content at PL, compared to meadow and arable soil. Statistically significant linear relationship was observed with the SOM content and rho (s) (-0.851**), rho (b) (-0.567**), calculated TP (0.567**) and measured TP (-0.280**). There was a nonlinear relationship between SOM and LL (0.704**) and PL (0.845**) at the topsoil. The findings suggested that SOM content strongly affected rho (s), rho (b), TP, LL and LP. This regional study showed that the conversion of forestland into agricultural land without appropriate measures to conserve SOM leads to the degradation of physical and rheological soil properties.