Physico-chemical properties of soil under different tree species

To find out the impact of trees on some physical and chemical properties of soil, nine and eight MPTS were planted at 3x3 m spacing in July month of 1984 and 1985 respectively at AICRP on Agroforestry Farm, SDAU, Sardarkrushinagar. The results obtained from tree plantations of 16 years age and from fallow land indicated striking variation due to tree species with respect to physical and chemical properties of soil. The bulk density (BD) significantly decreased under all the tree plantations. Among the tree species studied, Ailanthus excelsa recorded significantly lower value of BD (1.49 g/cc) and highest water holding capacity (31.32 %) in comparison to other tree species. The organic carbon content in the soil under all the tree species was significantly higher as compared to control (0.17%). Considerable increase in the availability of N, P, and K was observed in the soil samples drawn from the tree plantation as compared to control. Among different species, maximum content of available N (235.5kg/ha), P(45.1kg/ha) and K (403 kg/ha) was recorded under Albizia lebbeck, Prosopis cineraria and Azadirachta indica, respectively. These nutrients decreasing with increase in depth. Among the trees, Azadirachta indica and Ailanthus excelsa were relatively superior in soil amelioration.