Meta-analysis of yield-emission trade-off in direct seeded vs. puddled transplanted rice: Towards a cleaner and sustainable production

Le résumé fourni par la source

Conventional rice production through puddled transplanted rice-PTR is tillage, water, energy, and capital intensive. Furthermore, it is a major contributor to greenhouse gas (GHGs) emissions. In this regard, Direct seeded rice-DSR can be a potential alternative to PTR for reducing GHGs emissions, while sustaining yields. However, depending upon agroclimatic situation, whether the effect of DSR on GHGs emission and yield are consistent or not, as compared to PTR need a comprehensive analysis. To bridge this knowledge gap, we performed a meta-analysis synthesizing 876 paired measurements from 54-peer-reviewed studies to understand how DSR impacts N 2 O and CH 4 emissions, global warming potential-GWP (heat-trapping potential of greenhouse gases compared to CO 2 ), yield and C-footprint-CF P (environmental impact in CO 2 eq. due to concerned activity). Compared to PTR, DSR decreased CH 4 emissions by 70%, GWP by 37% and CF P by 34%, despite 85% increase in N 2 O emissions. However, this shift comes with 11% decrease in yield. To decipher the primary factors driving these outcomes, we conducted subgroup analyses by taking environmental conditions and management practices as predictors in a random effect model. Low to medium pH soils, zero tillage, puddled soil (wet DSR), conventional flooding, and high nitrogen rates (>200 kg/ha) are found to be favorable for DSR with comparable yields but posing a discrepancy with environmental sustainability benefits. Therefore, further research to evaluate DSR across agro-ecologies, management practices are needed to optimize yields with lower GWP and CF P . • DSR significantly reduced CH 4 emissions by 69.9% over PTR. • DSR showed a substantial increase in N 2 O emissions by 84.6% over PTR. • Overall, DSR reduced GWP by 37% and carbon footprints by ∼34% compared to PTR. • A modest reduction in grain yield of 10.8% was observed in DSR compared to PTR. • DSR adoption across diverse agro-ecologies offers yield-emission co-benefits.

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