Soil Organic Carbon Sequestration after Biochar Application: A Global Meta-Analysis

• Published in: Agronomy (Basel) Vol. 11; no. 12; p. 2474
• Main Authors: Gross, Arthur, Bromm, Tobias, Glaser, Bruno
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.12.2021
• Subjects: Agricultural land; Agroforestry; agronomy; biochar; Biomass; C sequestration; Carbon; Carbon sequestration; Carbon/nitrogen ratio; Charcoal; Climate change; climate change mitigation; Datasets; Experiments; feces; Fertilizers; Field tests; Grain size; Greenhouses; Incubation; Laboratories; Meta-analysis; Organic carbon; Organic fertilizers; organic soil amendments; Organic soils; Paris Agreement; pyrogenic C; Raw materials; Soil characteristics; soil organic carbon; Soil texture; soil treatment; Soils
• DOI: 10.3390/agronomy11122474
• ISSN: 2073-4395

Biochar application to soil has the potential to sequester carbon in the long term because of its high stability and large-scale production potential. However, biochar technologies are still relatively new, and the global factors affecting the long-term fate of biochar in the environment are still poorly understood. To fill this important research gap, a global meta-analysis was conducted including 64 studies with 736 individual treatments. Field experiments covered experimental durations between 1 and 10 years with biochar application amounts between 1 and 100 Mg ha−1. They showed a mean increase in soil organic carbon (SOC) stocks by 13.0 Mg ha−1 on average, corresponding to 29%. Pot and incubation experiments ranged between 1 and 1278 days and biochar amounts between 5 g kg−1 and 200 g kg−1. They raised SOC by 6.3 g kg−1 on average, corresponding to 75%. More SOC was accumulated in long experimental durations of >500 days in pot and incubation experiments and 6–10 years in field experiments than in shorter experimental durations. Organic fertilizer co-applications significantly further increased SOC. Biochar from plant material showed higher C sequestration potential than biochar from fecal matter, due to higher C/N ratio. SOC increases after biochar application were higher in medium to fine grain textured soils than in soils with coarse grain sizes. Our study clearly demonstrated the high C sequestration potential of biochar application to agricultural soils of varying site and soil characteristics.