Biochar plus organic fertilizer shrinks rice paddy greenhouse gases
Cao X, Zang Z, Liu J, Zhan G, Shi G
Soil Health
If you've ever wondered why rice farming gets flagged as climate-unfriendly, this shows a simple soil amendment combo can cut the paddy's methane and nitrous oxide output while actually growing more rice.
Rice paddies are a surprisingly big source of greenhouse gases because flooded soil creates perfect conditions for methane- and nitrous oxide-producing microbes. Researchers found that mixing biochar (charred plant material) into the soil along with swapping in a fifth of the usual fertilizer for organic fertilizer shifts which microbes thrive, favoring ones that store carbon and suppress gas-producing pathways. The best combo tested, a moderate dose of biochar with 20% organic fertilizer, grew 12-15% more rice while cutting the farm's climate footprint by double digits.
Key Findings
Combining 20% organic fertilizer substitution with 5 t/hm2 biochar increased rice yield by 11.64-15.44% while reducing global warming potential by 7.58-16.56% and greenhouse gas emission intensity by 17.21-27.72%.
Biochar boosted carbon-fixing microbial genes (PRK, prkB) tied to the Calvin-Benson-Basham pathway while suppressing genes (aclA, aclB, ccsA) linked to an alternative carbon-fixation route that favors emissions.
Soil organic carbon, pH, ammonium nitrogen, and nitrate nitrogen were identified as the main factors shaping which microbial genes dominate, directly linking soil chemistry to nitrogen-cycling genes (nirK, norB, nosZ) involved in denitrification.
chevron_right Technical Summary
Mixing biochar with partial organic fertilizer in rice paddies cuts methane and nitrous oxide emissions while boosting rice yields, offering a practical way to make rice farming less climate-damaging.
Abstract Preview
Original paper
Synergistic effects of biochar and organic fertilizer on the regulation of microbial carbon and nitrogen metabolism in paddy soil to reduce net greenhouse gas emissions.
Biochar and organic fertilizer have been widely applied to improve soil carbon sequestration and mitigate greenhouse gas (GHG) emissions in rice production systems. However, the synergistic mechani...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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