Journal of Research

A study was conducted to evaluate the effect of pure stands of tree species and poplar-based agroforestry system on soil organic carbon (OC) and available N, P and K contents. Depthwise soil samples were taken from 13-year-old Eucalyptus tereticornis (eucalyptus), Azadirachta indica (neem), Melia azedarach (dek), Dalbergia sissoo (shisham), Albizia lebbeck (siris), Leucaena leucocephala (subabul) and Acacia nilotica (kikar) spaced at 6 x 3 m and adjoining open area (control) from PAU Regional Station at Bathinda. Similarly, samples were taken from an agroforestry system having poplar at 5 x 4 m spacing intercropped with pearlmillet-wheat rotation for six years and sole pearlmillet-wheat rotation from PAU Ludhiana. Soil OC and available nutrients were significantly higher in the surface soil depth (0–15 cm) than the lower depths irrespective of tree species. Organic carbon and available nutrients were significantly more under all the tree species compared to control in the surface layer. Organic carbon increased by 90.3 per cent under siris followed by kikar (84.5%), shisham (82.2%) and subabul (80.8%) over control (3.81 g/kg). The available N, P and K contents in surface layer were higher under subabul, siris, shisham and kikar than the other tree species. In poplar-based agroforestry system, the average contents of OC, N, P and K were higher by 22.2, 10.2, 33.6 and 4.5% respectively, than pure pearlmillet-wheat rotation. However, the interaction effects of soil depths and cropping systems were significant only for OC and available P.