Incorporation of rice straw mitigates CH4 and N2O emissions in water saving paddy fields of Central Vietnam

This study evaluated the effects of rice straw and water regimes on CH₄ and N₂O emissions from paddy fields for two rice growing seasons (summer 2014 and spring 2015). Water regimes included alternating wet–dry irrigation (AWD) maintained at three levels (–5 cm, – 10 cm and –15 cm) in comparison to continuous flooding irrigation (CF). Rice straw (5 t ha^–1) was incorporated into the top soil (0 – 15 cm), distributed and burned in situ. Results showed that using burned in situ rice straw was found to reduce seasonal cumulative CH₄ emission (24–34% in summer; 18–28% in spring), N₂O emission (21–32% in summer; 22–29% in spring) and lower rice yield (8–9%) than rice straw incorporation into top soil. AWD methods reduced the amount of CH₄ production (22.6–41.5%) and increased N₂O emission (25–26%) without any decrease in rice yield. Rice straw incorporation into the top soil with AWD had higher water productivity (23–37%) than rice straw when burned in situ with CF. The results conclude that AWD and rice straw management can be employed as mitigation strategy for CH₄ and N₂O emissions from paddy fields in Central Vietnam.