Mitigation of greenhouse gases emission through value-added straw amendments in rice-green gram system

Mitigation of greenhouse gas (GHG) emission and reduction of straw burning are two major environmental challenges faced by rice production systems. Open-field straw burning causing air pollution, health hazards, nutrients and biodiversity losses needs to be tackled through management practices. Emissions of methane and nitrous oxide are issues in rice that must be reduced to mitigate GHGs emission. To address these two challenges, our hypothesis is to use the value-added straw byproducts for reduction of GHGs emission. Four straw management practices, i.e. residue retention through zero tillage, rice straw-compost (RSC), rice straw-mushroom spent (MW) and rice straw-biochar as soil amendments and two other established mitigation options (methanotrophs and phosphogypsum addition), were compared with conventional practice in two seasons (kharif and rabi) of 2019-20. Methane emissions were higher under RSC in rice and MW treatment in green gram as compared to RDF (8.4 and 1.8%, respectively), while lowest emission was recorded under methanotrophs treatment. The seasonal and annual N2O emissions were highest under RDF in both rice and green gram. The annual nitrous oxide emission (1.27 kg ha(-1)) was lowest under zero tillage, whereas, methane (59.9 kg ha(-1)) and global warming potential (611 kg ha(-1)) recorded lowest in methanotroph treatment. The CH4 and N2O emissions were positively correlated with the soil labile carbon pools and enzymatic activities. The GHG intensities lower in straw management practices (except rice straw-compost) indicated the potentiality of GHGs emission mitigation. Therefore, straw-mushroom spent and straw-biochar could be considered as soil amendment for the mitigation of GHGs emission in rice which were comparable with methanotrophs and phosphogypsum (industrial waste amendments) and also give the options of straw management in eco-friendly manner. [GRAPHICS] .

Automated summary

Mitigating greenhouse gas emissions and reducing straw burning are two major challenges in rice production. Through management practices and soil amendments, such as straw-mushroom spent and straw-biochar, the emissions can be effectively reduced.