Effect of Water Regimes and Organic Matter Strategies on Mitigating Green House Gas Emission from Rice Cultivation and Co-benefits in Agriculture in Vietnam

Abstract

Agriculture sector in Vietnam is not only affected by climate change but it also emits a high proportion of greenhouse gas (GHG) - especially rice, which is the main source of GHG emissions in this sector. Many GHG mitigation options have been transferred to rice cultivation in the world with biochar measure, compost measure and applying Alternative Wet and Dry (AWD) measures having high potential to reducing GHG emissions. This study assesses the co-benefits of greenhouse gas emission mitigation options above in comparison with traditional farmers' practice (applying flooding irrigation (PF) in combination with farmyard manure fertilizer (FYM)) to find a climate-smart agriculture system for Vietnam ensuring both economic benefits and maintain Global Warming Potential. Therefore, a field experiment was conducted in Hanoi city, located in Northwest Vietnam. The experiment was divided into two blocks with different water regimes: AWD and PF. Each block was designed with four different types of fertilizer: 1) NPK (i.e. irorganic fertilizer) only; 2) NPK and FYM; 3) NPK and straw compost; and 4) NPK and straw biochar. The result showed that rice yield was significantly different among mitigation treatments compared to traditional farming practise. In addition, the block with AWD irrigation method and NPK+ straw biochar fertilizer showed potential to mitigate GHG emissions significantly with 53.4% CO2eq per grain yield reduction compared to traditional farmers' practice. Furthermore, this mitigation option also helped to save 43.24% of water irrigation, increase soil fertilit and reuse Vietnam’s agricultural residue.