By analyzing data from more than a thousand experiments, researchers found that targeted composting control measures can simultaneously reduce greenhouse gas emissions, suppress odors, and improve fertilizer quality. The findings demonstrate that composting—often viewed as environmentally friendly but imperfect—can be optimized to retain nutrients while sharply lowering methane, nitrous oxide, and ammonia emissions.
Rapid growth in global consumption is generating unprecedented amounts of organic waste, projected to reach 3.4 billion tons annually by 2050. Much of this waste still ends up in landfills or open dumps, where decomposition releases methane and nitrous oxide—greenhouse gases far more potent than carbon dioxide. Composting has emerged as a key alternative because it converts waste into nutrient-rich fertilizer while reducing landfill pressure. However, poorly managed composting can release large quantities of greenhouse gases and odorous pollutants while losing valuable nutrients, limiting its environmental benefits. Although many mitigation strategies exist, their overall effectiveness has remained unclear due to fragmented and sometimes contradictory experimental results.
A study (DOI: 10.48130/ebp-0025-0022) published in Environmental and Biogeochemical Processes on 27 January 2026 by Dong Liu’s & Fuqiang Yu’s team, Chinese Academy of Sciences, provides evidence-based strategies to make composting more climate-friendly while improving fertilizer quality and resource recycling.
Using a meta-analytic framework, the researchers synthesized results across composting studies and quantified the overall effects of multiple “air-pollution control” interventions (biological, chemical, physical, and mechanical) on process conditions, fertilizer-quality indicators, and gaseous emissions. They calculated response ratios (RR) for core composting variables (temperature, C/N, TOC), maturity/quality metrics (TN, germination index, humic acid), and emissions (CH₄, N₂O, NH₃, CO₂, H₂S, VOCs), and then conducted moderator analyses to test how feedstock type, bulking agents, treatment types (e.g., pressure aeration, biochar), application rate, and composting duration shaped outcomes. The meta-synthesis showed that control measures broadly improved composting performance: temperature increased (RR = 0.48), consistent with intensified and prolonged thermophilic conditions that support pathogen suppression and faster stabilization; simultaneously, C/N decreased (RR = −0.38) and TOC declined (RR = −1.60), indicating more advanced organic matter decomposition and maturation. These process shifts translated into better fertilizer quality, with TN rising sharply (RR = 0.89), GI improving (RR = 0.73) as phytotoxicity fell, and HA increasing (RR = 0.29), reflecting enhanced humification. In parallel, emissions dropped substantially relative to unmanaged composting, including CH₄ (RR = −1.14), N₂O (RR = −1.76), NH₃ (RR = −1.53), CO₂ (RR = −1.51), H₂S (RR = −0.53), and VOCs (RR = −0.54), underscoring dual climate-and-odor benefits. Moderator results highlighted that context often mattered as much as the intervention: feedstock type significantly influenced CH₄ (e.g., sewage sludge showing strong reductions) and CO₂, while bulking agents generally reduced CH₄ (corn straw notably strong) but were less consistently significant across datasets. Treatment type affected CH₄ most clearly, with pressure aeration producing the largest reductions, whereas biochar stood out for suppressing NH₃ and N₂O. Application rate was most consistently linked to lower N₂O, while composting duration showed weaker or mixed relationships across gases. Overall, the analysis suggests optimized controls can improve maturity and nutrient retention while cutting multiple pollutants, but performance depends strongly on feedstock and operating conditions.
This study demonstrates that climate-smart composting can simultaneously reduce emissions and enhance fertilizer quality through strategic feedstock selection, targeted additives, and optimized aeration. By improving nutrient retention and minimizing environmental impacts, optimized composting supports circular bioeconomy principles, promotes soil health, and offers a scalable pathway for climate mitigation in agriculture and waste management systems.
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References
DOI
10.48130/ebp-0025-0022
Original Source URL
https://doi.org/10.48130/ebp-0025-0022
Funding Information
Partial financial support was received from the Caiyun Postdoctoral Project of Yunnan Province, the Yunnan Revitalization Talent Support Program (awarded to Dong Liu), the 'Strategic Priority Research Program' of the Chinese Academy of Sciences (Grant No. XDA26050302), and the Yunnan Technology Innovation Program (awarded to Fuqiang Yu, Grant No. 202205AD160036).
About Environmental and Biogeochemical Processes
Environmental and Biogeochemical Processes is a multidisciplinary platform for communicating advances in fundamental and applied research on the interactions and processes involving the cycling of elements and compounds between the biological, geological, and chemical components of the environment.