Baljit SinghJagmanjot Singh2021-01-142021-01-142020Jagmanjot Singh (2020). Soil carbon and nitrogen pools in different tree based systems (Unpublished M.Sc. thesis), Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810160074Agroforestry systems improve carbon sequestration and regulate nutrients in the soil. The present study was conducted to investigate carbon and nitrogen pools, nutrient status and physico-chemical properties of soil in seven land use systems namely poplar (Populus deltoides) + fodder wheat, eucalyptus (Eucalyptus tereticornis) + fodder wheat, sole fodder wheat rotation, poplar + citrus, eucalyptus + citrus, sole citrus and fallow land at four depths (0-15, 15-30, 30-45 and 45-60 cm) in Hoshiarpur district of Punjab. Poplar + fodder wheat system had highest soil organic carbon (SOC) and total carbon (TC). In citrus based systems, poplar + citrus had higher SOC and TC than eucalyptus + citrus and sole citrus. The highest concentrations of very labile, labile, less labile and recalcitrant carbon were 2.75, 2.37, 2.97 and 2.69 g kg-1, respectively in poplar + fodder wheat and lowest were 0.51, 0.41, 0.91 and 0.33 g kg-1, respectively in fallow land. Water soluble carbon and microbial biomass carbon decreased with depth and ranged from 11.14-17.74 and 0.042-0.147 mg kg-1, respectively in 0-15 cm depth. Total nitrogen, NH4+-N, NO3--N, available N, P and K were higher in tree based systems. The DTPA extractable Zn, Cu, Fe, and Mn increased by 64.8, 54.0, 50.9, 46.1%, respectively in poplar + fodder wheat in surface depth over control. The WHC, EC, CEC reduced while pH and bulk density increased with soil depth. Hence, long term tree based systems enhanced soil carbon and nitrogen pools and improved nutrient status and physico-chemical properties of soil.EnglishThesis