Reducing carbon footprint and acquiring carbon credits in intensively cultivated rice wheat system by tillage and residue management

• CH 4 , N 2 O, CO 2 & SOC changes quantified in 9-year-old zero-tilled rice-wheat system • ZT+ crop residue retention lowered the net C-footprint by 64-78% than conventional tillage • Field burning of rice residue emitted 2.56, 0.3 & 1035 g kg −1 of CH 4 , N 2 O, CO 2 , respectively • Residue retention along-with ZT was essential for positive net ecosystem carbon balance • Triple ZT-system reduced GHG 53%, energy-input 24%, carbon-intensity 64% & NECB 105% • Triple ZT Rice-Wheat-Greengram system with residue generated 11.4 C-credits ha −1 y −1 The conventional rice-wheat cropping system of the northern-Indo-Gangetic Plains is tillage, energy, and water-intensive leading to greenhouse gases emission (GHG) and soil-carbon loss. Practices such as direct seeding, zero-tillage, and residue-retention are promoted for sustainable-farming and environmental-benefit, however the impact on the net-carbon footprint (NCF) has been less evaluated. Measurement of GHG emission and soil organic carbon was carried out for three consecutive years in a long-term experiment in rice–wheat system. Six treatment combination of zero-till direct-seeded rice (ZTDSR), transplanted-puddled rice, zero-tilled wheat (ZTW), conventionally-tilled wheat (CTW), summer-fallow, zero-tilled green-gram (ZTGG), rice-residue retention (RS), rice residue burning (RRB), and green-gram residue (GGR) were field experimented. The zero tillage (ZT) and crop residue retention significantly reduced energy input and net carbon footprint (NCF) of rice wheat system through energy saving, water saving and net positive ecosystem carbon balance (NECB). The CH 4 , N 2 O and CO 2 emissions from the field burning of rice residue were 2.56±0.52 gkg −1 , 0.3±0.05 gkg −1 and 1035±0.82 g kg −1 , respectively. The NCF differed significantly (p<0.001) among the treatments, and ZT-systems with and without residue retention, had 64-78% lower NCF than conventional-system due to lower methane emission with significantly higher net ecosystem carbon balance (NECB). Residue retention in ZT-treatments reduced NCF by 7-39% varying with type of residue and frequency of application. The triple ZT treatment of ZTDSR+GGR–ZTW+RS–ZTGG significantly reduced GHG emissions (on-farm+off-farm) by 52.6%, energy input by 23.5%, carbon intensity by 64.1%, and NECB by 105% compared to conventional rice-wheat-fallow system. Higher Dehydrogenase activity in the triple ZT-treatments indicated better microbial activity and soil health. Additionally, this approach of triple ZT based rice-wheat-green gram system can yield up to 11 carbon credits per hectare annually, providing additional income for smallholder farmers of the region. However, policymakers need to invest in strengthening agricultural extension services to provide farmers with the necessary knowledge, training, and technical support to adopt these practices and participate in carbon markets.