Through a comprehensive life cycle assessment (LCA) , the team demonstrated that converting these wastes into biochar via pyrolysis—particularly by co-processing cotton straw with recycled mulch film—could cut carbon emissions by millions of tons annually while simultaneously addressing the region’s persistent “white pollution” from residual agricultural plastics.
Agricultural residues in Xinjiang pose both environmental pressures and climate opportunities. In 2023, maize, wheat, and cotton production exceeded 24 million tons, generating about 33.9 million tons of straw, of which 26.4 million tons are collectible. While wheat straw is mostly returned to fields and maize straw used as feed, cotton straw—produced in a region accounting for 85% of China’s cotton area—is often underutilized or burned. Plastic mulch film, covering over 60% of cropland, adds to the challenge; despite an 81% recovery rate, more than 200,000 tons remain recyclable annually. Converting these wastes into biochar via pyrolysis could enhance carbon sequestration and cut emissions, yet integrated regional assessments remain limited.
A study (DOI:10.48130/aee-0025-0016) published in Agricultural Ecology and Environment on 28 January 2026 by Ronghua Li’s & Jianchun Zhu’s team, Northwest A&F University, provides a regionally grounded, life cycle–based framework showing how integrated co-pyrolysis of crop straw and plastic mulch can simultaneously reduce carbon emissions, mitigate agricultural plastic pollution, and enhance soil sustainability.
Using regional agricultural statistics, crop-specific straw-to-grain ratios, collection coefficients, and mulch film recovery rates, the researchers first quantified the available biomass resources in Xinjiang, and then applied a LCA framework to evaluate net CO₂e balances from feedstock collection, pyrolysis, transport, renewable energy substitution, soil carbon sequestration, N₂O mitigation, fertilizer savings, and associated emissions. The analysis showed that in 2023 maize, wheat, and cotton production generated 1.36 × 10⁷, 7.68 × 10⁶, and 1.25 × 10⁷ t of straw, respectively, with 2.64 × 10⁷ t collectively recoverable; meanwhile, mulch film use reached 2.5 × 10⁵ t, of which 2.03 × 10⁵ t was recyclable. If all collectible straw were pyrolyzed, biogas could generate 5.39 × 10⁹ kWh of electricity, offsetting 4.54 × 10⁶ t CO₂, while 8.76 × 10⁶ t of biochar could be produced, sequestering 4.62 × 10⁶ t of stable carbon (1.70 × 10⁷ t CO₂). Additional benefits included a 241.53 t reduction in N₂O emissions (7.2 × 10⁴ t CO₂e) and 8.06 × 10³ t CO₂e avoided from reduced fertilizer use, even after accounting for 1.12 × 10⁶ t CO₂e from logistics, yielding a net reduction of 2.05 × 10⁷ t CO₂e. Considering current uses of wheat and maize straw, cotton straw alone (9.29 × 10⁶ t) could deliver a net reduction of 1.01 × 10⁷ t CO₂e. In contrast, mulch film pyrolysis alone produced limited biochar (3.35 × 10³ t) and a net reduction of 2.67 × 10⁵ t CO₂e. However, co-pyrolyzing all recyclable mulch film with cotton straw at a 1:4 ratio significantly improved performance, generating 2.24 × 10⁵ t of biochar and achieving a net reduction of 3.43 × 10⁶ t CO₂e, with further potential reductions of 9.34 × 10⁶ t CO₂e from treating the remaining cotton straw.
Overall, this study demonstrates that integrating cotton straw and plastic mulch management through co-pyrolysis can convert two persistent agricultural wastes into a powerful climate mitigation solution. Compared with treating plastic alone, co-pyrolysis significantly boosts biochar yield and carbon reduction efficiency. In addition to lowering emissions, biochar enhances soil quality and resource use efficiency, supporting sustainable cotton production and offering a scalable model for residue valorization in cotton-growing regions worldwide.
###
References
DOI
10.48130/aee-0025-0016
Original Souce URL
https://doi.org/10.48130/aee-0025-0016
Funding information
This study was funded by the Shaanxi Science and Technology Innovation Team Project (Grant No. 2025RS–CXTD–032).
About Agricultural Ecology and Environment
Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.