Effect of post-harvest practices on greenhouse gas emissions in rice paddies: flooding regime and straw management

Abstract

Aims To assess 1) the effect of the combination of flooding (winter flooding vs. non-winter flooding; WFL vs NWF) and timing of straw incorporation (early vs late straw incorporation; ESI vs LSI) in the post-harvest of paddy agrosystem, on a year-round global balance of greenhouse gases (GHG) exchanges, i.e. methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O); 2) the impact on the net ecosystem carbon balance (NECB) and 3) the resulting net global warming potential (GWP). Methods A field experiment was conducted with fortnightly samplings of main GHG emissions. Effect of the studied factors on GHG emissions was seasonally assessed. The net GWP is estimated from the balance between GHG (CH4 and N2O) and NECB. Results NWF-LSI reduced net GWP by 206% compared to conventional post-harvest management (WFL-ESI). NECB was similar in all treatments. Avoiding winter flooding reduced CH4 emissions significantly in the post-harvest and next growing seasons, while delay straw incorporation prevented CH4 and CO2 emissions during post-harvest. None of the treatments increased N2O emission. Environmental implications of post-harvest management options are discussed. Conclusions Post-harvest management affects net GWP of the paddy rice cultivation by modifying GHG emissions in post-harvest and next growing season without compromise sequestration C budget. The combination of non-winter flooding and late straw incorporation strategies were more effective in reducing both CH4 and CO2 emissions, due to avoiding higher temperatures at the time of the straw incorporation during post-harvest and increasing soil Eh conditions at the following growing season.

Agricultural policies against invasive species generate contrasting outcomes for climate change mitigation and biodiversity conservation

“…Alternate wetting and dryings [49] has been already documented as an efficient strategy to reduce methane emission during the growing season as aerobic conditions inhibit methanogenic archaea activity [50]. Our results suggest that implementing field drying in the fallow season can be an efficient strategy to counteract the contribution of rice farming to methane emissions which is aligned with Belenguer-Manzanedo et al [31]. Despite the significant effect of flooding regime on methane emissions, it was remarkable the presence of zero emissions under flooded conditions contrasting with some emissions detected in dry fields (figure 2).…”

“…Despite the significant effect of flooding regime on methane emissions, it was remarkable the presence of zero emissions under flooded conditions contrasting with some emissions detected in dry fields (figure 2). The cluster of zero methane emissions under flooded conditions mainly corresponds to the late autumn or winter period [11,31], when soil temperature in rice fields is below the optimal range (15-30°C) for methanogenesis [51]. This is coherent with the strong positive effect of temperature on methane emission rates found in our study, which is explained by an increased activity of methanogenic microbial activity during warm days [11,52,53].…”

“…Only methane was considered as previous studies showed that emissions of additional greenhouse gases (i.e. nitrous oxide and carbon dioxide) are negligible during the post-harvest season in our study system [12,31]. Three sampling points were established for each rice field, which were randomly distributed across the field.…”

Climate-smart agriculture: Greenhouse gas mitigation in climate-smart villages of Ghana

“…Rice paddies/fields are a major concern to science and policy communities because they produce threatening and long-lasting emissions (CH 4 and N 2 O) (Cheng et al, 2022). Literature (Belenguer-Manzanedo et al 2022;Gupta et al 2021) suggests that 30% CH 4 and 11% N 2 O of global agricultural emissions are from rice fields. Nonetheless, rice cultivation can present large GHG emission removal with simple changes and appropriate management systems (Islam et al 2022;Saha et al 2022).…”

Assessing the methane mitigation potential of innovative management in US rice production

“…The introduction of aerobic events can disrupt anaerobic methane production, reducing growing season methane emissions by at least 60% (LaHue et al 2016, Runkle et al 2019). Additionally, residue management impacts methane production as specific crops can carry larger amounts of field residue, serving as feedstock for methane production during the following growing season (Chidthaisong and Watanabe 1997, Linquist et al 2006, Brye et al 2016, Belenguer-Manzanedo et al 2022. Baseline methane fluxes resulting from various production practices have been synthesized for the MdS and Cal through chamber experiments (Linquist et al 2018).…”