Optimizing stubble returning rate in mulched farmland to balance trade-offs between greenhouse gas emission and maize yield under climate change

Context
Plastic film mulching (PM) is a widely adopted technique for enhancing crop yield in arid and semiarid regions. However, the improved soil hydrothermal conditions under PM may accelerate the mineralization of soil organic carbon (SOC) and increase greenhouse gas (GHG) emissions. Concurrently, crop stubble return, while widely recognized for its benefits in improving soil properties and mitigating GHG emissions, has demonstrated inconsistent effects on crop yield. Given the individual advantages of these practices, their combined application may offer a sustainable agricultural approach to achieving high yields and low GHG emissions. It is important to investigate the long-term combined effects of stubble return and PM on SOC dynamics, crop productivity, and GHG emissions under future climate change scenarios.
Objective
We aim to investigate the novel synergy of PM combined with stubble return as a strategy to achieve high yield and environmental sustainability under future climate change.
Methods
The SPACSYS model was calibrated using seven years of field trial data to evaluate its precision in simulating yield, SOC dynamics, and GHG emissions in Yangling, northwest China. Our simulations utilized an ensemble of 27 global climate models across two emission scenarios (SSP245 and SSP585) from Coupled Model Intercomparison Project Phase 6 to drive the model. We explored multiple agronomic strategies, including 11 stubble return levels (from 0 % to 100 % in 10 % increments) and two mulching practices (no mulching and PM), to identify the optimal management practice under future climate change.
Results
The yields of the reference management (CK, without mulching and stubble return) are projected to decline by 20.3 % and 60.0 % under SSP245 and SSP585, respectively, during the 2080 s (2061–2100), compared to the baseline period (1981–2020). Additionally, SOC under the CK is expected to decrease by 23.6–29.7 % in the 2040 s and by 43.0–58.1 % in the 2080 s. An optimal scenario involving 100 % stubble return with PM (PM_R100) increases yields in the 2040 s and mitigates yield losses in the 2080 s under SSP585, compared to CK during the baseline. Furthermore, PM_R100 leads to an increase of 11.1–23.6 % in SOC during the 2040 s and alleviates SOC decomposition in the 2080 s under SSP585. PM_R100 also reduces global warming potential (GWP) compared to CK, transforming the dryland maize system into a carbon sink in the 2040 s.
Conclusions
PM combined with 100 % stubble return is the optimal practice to increase yield and SOC stock while reducing GWP. This approach effectively ensures high yields and promotes sustainable agriculture under climate change.
Significance
Our study underscores the significance of adopting stubble return practices in dryland rainfed areas where PM is applied. Our results are anticipated to assist farmers and policymakers in formulating effective mitigation and adaptation strategies to promote low-carbon sustainable agricultural development in dryland maize-growing regions under climate change.