Estimating the effect of biological nitrification inhibition-enabled sorghum on nitrogen fertilizer consumption, life cycle GHG emissions, farmer's benefit and fertilizer subsidy from Indian sorghum production

Biological nitrification inhibition (BNI) effectively curtails nitrogen (N) loss and enhances N utilization efficiency. BNI is increasingly important as a technology for mitigating greenhouse gas emissions and water pollution in countries with high N fertilizer consumption. This study aimed to evaluate the potential impacts of BNI-enabled sorghum varieties with a 30 % soil nitrification inhibition rate for a major sorghum-growing state (Maharashtra, India). We analysed the farm survey data collected for Rabi sorghum in 2020–2021 (n = 250) and for Kharif sorghum in 2022 (n = 209). Life cycle greenhouse gas (LC-GHG) emissions were estimated using a life cycle assessment with a cradle-to-farm gate perspective. The results showed that adoption of BNI-enabled sorghum reduced N fertilizer application in the Rabi and Kharif seasons by 8.0 % and 7.4 % and area-scaled/yield-scaled LC-GHG emissions by 15.6 % and 11.2 %, respectively, while increasing farmers' benefits slightly. These changes could reduce the government's expenditure on urea fertilizer subsidies by 9.1 %. However, many farmers indicated that they would not change N fertilizer application even if the yield per N fertilizer application increased. Even under these circumstances, area-scaled/yield-scaled LC-GHG emissions will be decreased by 11.3 % and 13.5 % in the Rabi season and 8.1 % and 10.2 % in the Kharif season, respectively. The yield and farmers' benefit will increase by 2.5 % and 4.9 % in the Rabi season and by 2.4 % and 6.5 % in the Kharif season, respectively, but the government's expenditure on fertilizer will not decrease. These results indicate that BNI-enabled sorghum can be introduced into countries where fertilizer use is low. This study shows the potential impacts of BNI-enabled sorghum under two scenarios; N fertilizer consumption is reduced or maintained. Discussions on the N fertilizer consumption under BNI-enabled sorghum are needed to establish a sustainable food system, especially in countries with high N fertilizer consumption.