Wu, et al (2024) Recycling annual self-straw as biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More reduces long-term greenhouse gas emissions from paddy fields economically. Nature Portfolio. https://doi.org/10.21203/rs.3.rs-3923418/v1

In recent years, the environmental impact of paddy fields, particularly in terms of greenhouse gas (GHG) emissions, has been a critical focus in global efforts towards carbon neutrality. A new study by Weixiang Wu and colleagues provides a compelling look at how recycling rice straw into biochar, rather than the common one-time application, can significantly reduce GHG emissions from paddy fields while yielding substantial economic benefits.

Traditionally, paddy fields have been a major contributor to agricultural methane (CH4) emissions. The conventional approach involves a one-time application of biochar (termed as high single, HS), which initially reduces GHG emissions effectively but suffers from diminishing returns over time due to biochar ageing. This ageing leads to higher soil ammonium concentration which inhibits methanotrophic activity essential for methane mitigation, ultimately reducing soil carbon content.

The study introduces an alternative annual low (AL) method, where biochar is recycled yearly. This approach not only addresses the ageing issue but also increases CO2 reduction by 58% and financial gains by 16% compared to the HS method. Over an eight-year field experiment, the AL method demonstrated a reduction of 197 tonnes of CO2-eq per hectare and a net financial benefit of US$ 4,568 per hectare, proving its superior sustainability and cost-effectiveness.

Implementing the AL method globally could potentially reduce up to 4 billion tonnes of CO2-eq GHG annually, translating to an economic benefit of approximately $90 billion. This significant reduction aligns well with the Sustainable Development Goals and illustrates the economic attractiveness of sustainable practices in paddy field management.

By shifting from a one-time application to a sustainable yearly recycling of biochar, researchers underscore the potential for a global reduction in greenhouse gases, offering a practical, economically viable method that enhances the long-term sustainability of paddy farming while supporting global carbon neutrality goals.