Soil Carbon and Nutrient Status Under Different Vegetation Types in a Mountain Watershed of Nepal

The carbon stored in soils is more than one trillion tons, which is twice the quantity contained in the atmosphere and three times the quantity contained in terrestrial vegetation. Upon land use conversion to agricultural ecosystems, soil loses about 25–40 Mg C ha −1 from their original pool, which is a common problem in Nepal. Through carbon trading, aside from contributing to climate change mitigation, Nepal can earn monetary income. This study aims to quantify soil carbon and nutrients status under different vegetation types with respect to soil depth. The study was conducted at the National Zoological Garden; Bhaktapur. Pinus , Schima , and Rhododendron vegetation types were taken as vegetation types for consideration; and random sampling was carried out to collect soil samples. Soil depths of 0–10 cm, 10–20 cm, and 20–30 cm were sampled. Altogether 27 soil samples were tested at the soil lab of Central Department of Environment Science, Kirtipur. ANOVA tests indicated that the variance in SOC% between soil depths was statistically significant for soils under Rhododendron ( p = 0.03), whereas it was insignificant for Pinus ( p = 0.45) and Schima ( p = 0.73). When comparing mean SOC% across all vegetation types, the difference was statistically insignificant ( p = 0.14). Variations in total nitrogen (TN) across depths were highly significant ( p < 0.001) for all vegetation types. TN% was highest in the 0–10‐cm depth under Schima (0.36%). Mean available phosphorus was also highest under Schima (91.36 kg/ha), while available potassium was highest under Rhododendron (196.46 kg/ha). Observed mean bulk density was highest under Pinus (1.40 g/cm 3 ) at 20–30‐cm depth, though the overall variance between vegetation types was insignificant ( p = 0.30). The soil pH under the different vegetation types was acidic with a mean of 4.5. Soil under Schima vegetation was noted to be more acidic than that under Pinus and Rhododendron . Future research should focus on examining the long‐term impacts of different land use practices on soil carbon sequestration and nutrient dynamics across varying soil depths and vegetation types. Additionally, studies should investigate the potential economic and ecological benefits of implementing carbon trading schemes and sustainable land management practices in Nepal.