Agricultural waste is often seen as a disposal problem, but new research suggests it could be a powerful tool for climate change mitigation. A study published in Agricultural Ecology and Environment finds that converting cotton straw and discarded agricultural plastic film into biochar through a process known as co-pyrolysis could significantly reduce greenhouse gas emissions while improving the sustainability of farming systems in Xinjiang, China.
Xinjiang is China's largest cotton producing region and one of its most important agricultural areas. Every year, millions of tons of cotton straw and plastic mulch film are generated after harvest. Much of this material is either burned, discarded, or poorly recycled, contributing to air pollution, soil degradation, and so called white pollution from residual plastic in farmland.
The research team evaluated how much of this agricultural waste could realistically be collected and converted into biochar, a carbon rich material produced by heating organic matter in the absence of oxygen. Biochar can be used to improve soil fertility, retain nutrients, and store carbon in soils for long periods. Using a life cycle assessment approach, the researchers quantified the potential climate benefits of different waste management strategies.
"Our goal was to understand whether these agricultural residues could be transformed from an environmental burden into a climate solution," said corresponding author Ronghua Li. "The results show that integrated treatment of cotton straw and plastic mulch film can deliver substantial carbon emission reductions while addressing long standing pollution challenges in cotton producing regions."
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