Scientists have uncovered practical strategies that can significantly reduce harmful air pollution from composting while improving the quality of organic fertilizers. The findings, based on a large global meta-analysis, provide new evidence to help farmers, waste managers, and policymakers adopt climate-smart composting practices.
The research, published in Environmental and Biogeochemical Processes, analyzed data from 135 scientific studies and 1,683 experimental observations worldwide. The study evaluated how different compost management techniques influence greenhouse gas emissions, odour-causing pollutants, and nutrient preservation during organic fertilizer production.
Composting plays a crucial role in recycling agricultural and organic waste into valuable fertilizers. However, poorly controlled composting can release greenhouse gases such as methane and nitrous oxide, along with ammonia, hydrogen sulfide, and volatile organic compounds that contribute to air pollution and unpleasant odors. These emissions can also reduce the nutrient content and effectiveness of compost products.
"Our analysis shows that composting can be optimized to simultaneously reduce environmental pollution and improve fertilizer quality," said one of the study authors. "By choosing the right management strategies, operators can make composting both environmentally sustainable and agriculturally beneficial."
The research compared four major categories of compost control measures. These included biological methods using microbial additives, chemical approaches such as biochar and gypsum, physical techniques like improved aeration and bulking materials, and mechanical strategies involving mixing and electric field technologies. The results showed that these measures consistently improved composting performance and environmental outcomes.
Overall, the study found that implementing these management practices increased composting temperature by about 48 percent, which helps destroy pathogens and accelerate organic matter breakdown. At the same time, nutrient retention improved significantly. Nitrogen levels increased by nearly 89 percent, and humic acid content rose by roughly 29 percent, both key indicators of high-quality fertilizer. The germination index, which measures plant safety and compost maturity, improved by approximately 73 percent.
Perhaps most importantly, the researchers observed major reductions in harmful emissions. Methane emissions dropped by about 69 percent, nitrous oxide by 83 percent, ammonia by 78 percent, and carbon dioxide by 78 percent. Emissions responsible for strong odors, including hydrogen sulfide and volatile organic compounds, were also reduced by more than 40 percent.
Among all strategies evaluated, biochar emerged as the most effective single solution. Biochar is a carbon-rich material produced from biomass. Its porous structure helps trap pollutants and stabilize nutrients during composting. The study found that biochar consistently reduced ammonia and nitrous oxide emissions while enhancing nitrogen retention and improving fertilizer maturity.
The analysis also highlighted that compost feedstock type plays a major role in determining emission levels and compost quality. Materials such as manure, food waste, and sewage sludge influence chemical balance, moisture, and microbial activity, which directly affect greenhouse gas formation. As a result, the researchers emphasize that composting strategies should be tailored to specific waste materials rather than applying a single universal approach.
Beyond improving fertilizer production, the study underscores composting's broader environmental benefits. Organic waste volumes are rapidly increasing worldwide, and composting offers a circular solution that reduces landfill use while recycling nutrients back into agricultural soils. However, maximizing these benefits requires better control of gaseous emissions and nutrient losses.
The researchers suggest that combining strategies such as optimized aeration with chemical additives could further improve results. They also call for future research to expand datasets across different climates and geographic regions to refine global composting recommendations.
By providing a comprehensive, evidence-based evaluation of compost management practices, the study offers clear guidance for developing sustainable waste recycling systems. These findings support efforts to reduce agricultural emissions, enhance soil fertility, and promote environmentally responsible fertilizer production.
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Journal reference: Abdellah YAY, Gao J, Shi Z, Shi X, Liu W, et al. 2026. Synthesis of air pollution patterns and nutrient composition during organic fertilizer production: a meta-analytical study. Environmental and Biogeochemical Processes 2: e005 doi: 10.48130/ebp-0025-0022
https://www.maxapress.com/article/doi/10.48130/ebp-0025-0022
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About the Journal:
Environmental and Biogeochemical Processes (e-ISSN 3070-1708) 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.
