Intermittent drainage in paddy soil: ecosystem carbon budget and global warming potential

Abstract

Intermittent drainage of rice fields alters soil redox potential and contributes to the reduction of CH 4 emission and thus may reduce net global warming potential (GWP) during rice cultivation. Incorporation of green biomass helps maintaining soil organic matter, but may increase CH 4 emission. We investigated net ecosystem carbon budget (NECB) and net GWP under two water management regimes-continuous flooding and intermittent drainage-having four biomass incorporation levels (0, 3, 6 and 12 Mg ha -1 ). Water management and biomass incorporation level demonstrated significant (P \ 0.05) interaction effect on the NECB and GWP. Intermittent drainage decreased the NECB by ca. 6-46 % than continuous flooding under same rates of cover crop biomass (CCB) incorporation. Moreover, intermittent drainage reduced seasonal CH 4 -C fluxes by ca. 54-58 % and net GWP by 35-58 % compared to continuous flooding. There was also no significant reduction in rice yield because of intermittent drainage under similar CCB. This implies that incorporation of 3 Mg ha -1 CCB and intermittent drainage could be a good option for reducing net GWP and higher grain yield.

Quantitative synthesis on the ecosystem services of cover crops

“…On annual basis, the GWP of submerged rice cultivation increases by 400% with cover crops compared to fallow (Haque et al, 2015). The GWP was found to increase linearly with the amount of cover crop biomass (Haque et al, 2017), and especially with high C/N ratio of non-leguminous cover crops (Kim et al, 2013).…”

“…To reduce the amount of GHG emission from rice cultivation, using cover crops with low C:N ratio (i.e., legume) (Kim et al, 2013) is recommended, apart from using intermittent, instead of continuous flooding (Haque et al, 2017). In addition to fertilizer management, alternate wetting and drying methods, and midseason drainage have successfully been used to reduced CH4 emission from rice fields without negatively affecting yield (Liang et al, 2017).…”

Global benefits of non‐continuous flooding to reduce greenhouse gases and irrigation water use without rice yield penalty

“…However, it is much difficult to include SOC changes in this study for two reasons. On the one hand, only four studies from two sites were found that synchronously investigated effects of non-continuous flooding practices on GHG emissions and SOC changes to allow analyzing effects on net GWP (Haque et al, 2016(Haque et al, , 2017(Haque et al, , 2021Wu et al, 2018). Therefore, it is not feasible to conduct reliable global predictions based on RF modelling approach.…”

Recarbonizing global soils: A technical manual of recommended sustainable soil management

“…Using cover crops with low C/N ratios (i.e. legume) and practicing intermittent, instead of continuous flooding, is recommended to reduce methane emission with minimum impact on yield (Haque et al, 2017). When it comes to biochar application, one should carefully consider the appropriate rate and method (e.g.…”