Effects of biochar application on crop productivity, soil carbon sequestration, and global warming potential controlled by biochar C:N ratio and soil pH: A global meta-analysis

• Published in: Soil & tillage research Vol. 213; p. 105125
• Main Authors: Xu, Hu, Cai, Andong, Wu, Dong, Liang, Guopeng, Xiao, Jing, Xu, Minggang, Colinet, Gilles, Zhang, Wenju
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2021
• Subjects: agroecosystems; application rate; biochar; Biochar properties; carbon nitrogen ratio; carbon sequestration; clay; climate change; Crop yield; data collection; Fertilizer; food security; Greenhouse gas; meta-analysis; Soil carbon; soil organic carbon; soil pH; tillage; Biochar properties; Greenhouse gas; Crop yield; Fertilizer; Soil carbon
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2021.105125

•Biochar plus chemical fertilizer (BF) improved crop yield more than biochar alone (B).•B and BF reduced global warming potential by 27.1 % and 14.3 %, respectively.•Effect sizes of B and BF on crop yield coupled with these on soil organic carbon.•Effect sizes of B & BF on crop yield were controlled by biochar C:N ratio & soil pH. Biochar application has been widely recommended as a potential solution to tackle the challenges of food security and climate change in agroecosystems, but the effect sizes of biochar application on crop yield, soil carbon sequestration, and global warming potential (GWP) shows great uncertainties. To explore the effect variation of biochar application alone (B) and biochar combined with chemical fertilizers (BF) on crop yield, soil organic carbon (SOC), and GWP, this study reviewed updated datasets with 455, 131, and 95 independent experiments globally to identify the key factors influencing the responses of crop yield, SOC, and GWP to B and BF, respectively. Overall, the effect sizes were different between B and BF in both improving crop yield (15.1 % and 48.4 %, respectively) and decreasing GWP (27.1 % and 14.3 %, respectively), whereas there were almost no differences in terms of increasing SOC (32.9 % and 34.8 %, respectively). In addition, the effect sizes of B and BF on crop yield were coupled with these on SOC. Increased biochar carbon to nitrogen ratio (C:N ratio) and soil pH decreased the impact of B and BF on crop yield, while increased SOC promoted the impact of BF on crop yield. The effect size on GWP increased with biochar pH increasing but soil pH decreasing under B and BF. The wetness index, soil properties (SOC, pH, and clay), and biochar properties (type, pH, C:N ratio, and application rate) jointly explained 70 %–79 %, 90 %–93 %, and 70 %–97 % of the effect variations in crop yield, SOC, and GWP, respectively. The biochar C:N ratio and soil pH were the most important factors determining the effect size of biochar application on crop yield, SOC, and GWP. Taken together, biochar application is a tripartite win-win solution for improving crop yield, increasing SOC, and decreasing GWP mainly depending on biochar properties and soil pH.