Integrated assessment of carbon footprint and economic profit from paddy fields under microbial decaying agents with diverse water regimes in central China

Abstract

Numerous studies have reported effects of straws with microbial decaying agents on greenhouse gas emissions from rice fields. However, studies regarding the effects of microbial decaying agents on carbon footprint and economic profit under diverse water regimes remained unclear. A two-factor field experiment was adopted to assess effects of different straw treatments (straw returning alone abbreviated as S, and straw returning with microbial decaying agent abbreviated as SMD) on CH4 and N2O emissions, rice yield, carbon footprint, economic profit and net ecosystem economic profit (NEEP) from paddy field under different water regimes (continuous flooding abbreviated as F, and alternation of wetting and drying abbreviated as AWD) in central China. Compared with S treatment, SMD treatment significantly enhanced the crop water productivity by 7.9%−8.4% and the rice yield by 7.3%−7.7%. Though SMD treatment increased the economic profit by 9.9%−18.5%, and the NEEP by 9.6%−18.0% relative to S treatment, it also resulted in higher the CH4 emissions by 12.7%−32.4% and global warming potential by 11.2%−21.5% regardless of water regimes. Water regimes had significant effects on the crop water productivity, rice yield, CH4 and N2O emissions, global warming potential, economic profit, NEEP and carbon footprint. Compared with F treatment, AWD treatment improved the crop water productivity by 51.7%−79.4%, maintained rice yield, increased N2O emissions by 17.7%−40.0%, and mitigated CH4 emissions by 33.2%−75.1%, which therefore resulted in lower global warming potential by 31.5%−69.8% and carbon footprint by 32.7%−66.0%. Moreover, AWD treatment significantly increased the economic profit by 25.4%−41.9% and the NEEP by 28.8%−46.6% relative to F treatment. Overall, the straw incorporated with microbial decaying agents is not an environmental friendly practice for the tradeoff of mitigation of CH4 emissions and increase in economic profit. It is necessary to further optimize straw treatment for mitigating CH4 emissions in order to develop rice sustainable production.