Bio-slurry has potential value as good quality organic fertilizer and an agent of soil carbon sequestration through build up of soil organic matter level. Cowdung and poultry manure had the higher organic carbon content as well as higher nutrient concentration compared to Cow-dung and poultry bio-slurry. Nutrient concentration particularly N, P and S in CD and CB was found lower than the PM and PB. The highest carbon mineralization in Balina soil was found in poultry manure amended soil followed by cow dung, poultry bio-slurry and the lowest in cow dung bio-slurry. Carbon mineralization of manures in Noadda soil also followed the similar trend like Balina soil. However, Carbon mineralization of poultry manure and poultry bio-slurry was lower and cow dung and cow dung bio-slurry was higher in Noadda compared to Balina soil. Thus, decomposition of manure does not depend only on the quality of soil rather both the quality of manure and soil. Decomposition of manure was found slightly higher (around 5%) in Balina soil compared to Noadda soil when averaged over four manures. Among the manure, around three to four times less amount of CO2 was evolved during the decomposition of cow-dung and poultry bio-slurry as compared to cow-dung and poultry manure. Thus, this study indicate that soil application of bio-slurry had high potential in the mitigation of the greenhouse effect as well as short-term benefits in terms of improving soil organic matter stock, as compared to manure.