Greenhouse gas emissions from integrated nutrient management practices in pearl millet + Melia dubia agri-silvi system

Climate change induced due to the magnitudinal rise in proportions of carbon dioxide (CO₂) and nitrous oxide (N₂O) in the environment has emerged as an indubitable concern across the globe. Hence, the impact of various organic forms of manure on greenhouse gas (GHG) emissions from the soil and global warming potential (GWP) was studied in pearl millet + Melia dubia agri-silvi system. Replacing 25% of nitrogen with farmyard manure (FYM), poultry manure and pongamia green leaf manure (PGLM) elevated CO₂ emissions by 8.81%, 12.39%, 15.88% and N₂O emissions by 47.5%, 49.8% and 55.8% respectively, compared to full recommended dose of fertilizer through neem-coated urea treatment. Also, 100% recommended dose of fertilizer (RDF) using neem-coated urea is effective in reducing GWP by 19% over 100% RDF through normal urea. GWP of all the treatments ranged from 1029 (unfertilized) to 1807 kg CO₂ eq. ha–1 (sole crop without trees). The study also reported lower CO₂ and N₂O emissions under the tree compared to sole crop without trees, which suggests that agroforestry would reduce the overall GHG emissions. Also, use of organic manure along with inorganic fertilizers showed better carbon efficiency ratio and soil fertility status in spite of increase in GWP.