Title : Rice Residue Biochar Transfigures Carbon Footprint under Rice-Wheat System of Indian Indo-Gangetic Plains
Alongside economical produce the India produce 501.73 MT of agricultural residue every year as co-products and140.84 remains unutilized or burned. On-farm burning cause problem of GHGs emission, particulate matters, smoke and volatile matters worsening global environmental and human health. The considering the adversities caused be burning as well as decarbonisation technologies in agriculture as a goal of net zero equation, present experiment was planned to evaluate the residue management as biochar to emission reduction and increase carbon capture under rice-wheat cropping sequence (RWCS) of Indian Indo-Gangetic plains, India. Three residue management treatments viz., No residue (NR), Rice straw incorporation (RI) and Rice straw biochar (BC) were taken into consideration. After two cycles of cropping pattern, the analysis revealed that BC application reduces the CO2 emission by 24.3 % over RI, however, CH4 and N2O emissions by 21.4 % and 12.5 % over RI and 9.8 % and 29.2 % over NR, respectively. Considering the emissions of present experiment and emissions from rice straw burning (MoEFCC, 2021), overall carbon footprint under residue incorporation, residue burning and residue incorporation as biochar for whole IGP (10 Mha) was calculated to calculate the climate mitigation potential. The annual carbon footprint (CF) (sum of all the emissions and inputs in CO2-Ce) under RI increased by 37.2 % and 30.8 % over BC and NR, respectively. Whereas net CF [(Total emissions + Inputs) – Carbon sequestration] under residue burning was estimated to be highest (194.07 Tg-CO2-Ce) followed by RI (45.65 Tg-CO2-Ce) showing net positive emissions however, net negative emissions were found under biochar-based system. The estimated annual carbon offset potential of biochar system over predominant residue incorporation and burning may increase upto 112.3 and 260.7 Tg-CO2-Ce, respectively.
It is concluded that rice straw management as biochar amendment and slow-release biochar fertilizer significantly reduced carbon footprint in RWCS compared with predominant open field burning and conventional in-situ straw management with synthetic fertilizers, mainly benefiting from lower CH4 and N2O emissions and substantial soil carbon storage. This study also indicated that biochar-based RWCS along IGP, India could have significant carbon offset effect and may contribute to achieve net zero emission goal in addition to its function in the agroecosystem restoration.