Synthetic nitrogen fertilizers, widely used in agriculture, significantly contribute to nitrous oxide (N₂O) emissions, a greenhouse gas 300 times more potent than CO₂. In the journal Carbon Research, Zhong et al., explored a promising solution: 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. Biochar is a carbon-rich substance derived from organic materials, known for its potential to enhance soil fertility. This meta-analysis examined 550 observations from fertilized croplands to assess how biochar impacts N₂O emissions, nitrification, and denitrification.  

The study revealed that biochar application effectively reduces N₂O emissions from fertilized soils. On average, a biochar application rate of 20 tons per hectare decreased N₂O emissions by 19%. Higher application rates (50+ tons per hectare) led to even more significant reductions, cutting emissions by 48%. The impact of biochar is primarily through denitrification, a microbial process that converts nitrate to nitrogen gas. Biochar influences the abundance of genes involved in this process. For instance, wheat straw biochar increases the genes related to denitrification.  

Moreover, the study found that biochar’s effectiveness is tied to its application rate. At lower application rates (below 20 tons per hectare), biochar preparation conditions and properties have limited effects on N₂O emissions. However, when application rates exceed this threshold, factors like pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperature and biochar properties become more influential. For example, biochar produced at lower temperatures is more effective in reducing N₂O emissions. Biochar with higher pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More content, and cation exchange capacity increases denitrifier abundance and related gene activity.  

These findings highlight biochar’s potential to mitigate climate change by reducing N₂O emissions from fertilized soils. The study underscores that optimizing biochar application could be a key strategy in agricultural management to combat global warming.  

SOURCE: Zhong, L., Wang, P., Gu, Z., Song, Y., Cai, X., Yu, G., … & Kuzyakov, Y. (2025). Biochar reduces N₂O emission from fertilized cropland soils: a meta-analysis. Carbon Research, 4(31).