Great Potential of Biochar Application in Reducing Greenhouse Gases While Increasing the Yield in Acidic Soil of Global Cropland

Biochar's ability to mitigate greenhouse gas emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), and its impact on yield remain unclear due to the variation in biochar properties, initial acidic soil properties, and experimental and climatic conditions. This study aimed to determine the biochar potential in mitigating GWP and GHGI while simultaneously increasing yield in acidic soils through a meta-analysis of 288 publications combined with a random forest regression structure model and global predictions. The results showed that in soil pH < 7, biochar produced at pyrolysis temperature < 550°C typically decreased the GWP (−11%) and GHGI (−24%) by reducing CH₄ (−16%), N₂O (−13%), while increasing CO₂ (12%). Biochar application in tropic climates (mean annual temperature: 18°C–32°C, mean annual precipitation: 1000–3000 mm) is highly effective in increasing yield by 31%. The relatively most important factor influencing biochar potential was initial soil cation exchange capacity (24%) for GWP, soil organic matter (19%) for GHGI, and biochar nitrogen (29%) for yield. The random forest regression model predicted that biochar increased maximum yield (effect size (lnRR) = 0.393–0.651) in 15% and decreased maximum GWP (lnRR = −0.911 to −0.422) in 6.4% of acidic soils globally. However, biochar was least effective in increasing yield in acidic soils with high organic matter (> 2%) and led to increased GWP (lnRR = 0.023–0.236) in areas with high mean annual temperatures (> 20.9°C). For GHGI reduction, biochar was most effective in acidic soils with low total nitrogen (< 1%). Overall, the study highlighted and predicted the biochar potential to mitigate GWP and GHGI and increase production in acidic soils of diversified geographical regions.