Biochar effects on yield of cereal and legume crops using meta-analysis

Biochar is a carbon-rich organic material used as soil amendment to improve plant growth. However, its diverse effects on crop performance under field conditions have revealed conflicting results among researchers. Based on published peer-reviewed papers, a meta-analysis was conducted to identify the effects of biochar on grain yield (GY), biological yield (BY), and 1000 grain weight (TGW) of four dominant crops (wheat, maize, rice and soybean). Compared to the control, biochar increased GY of maize and wheat by 28 and 13% respectively, whereas other crops were not significantly affected. Our analysis revealed that the most effective application rates of biochar ranged from 1 to 10 t ha−1, which significantly improved GY (65%), BY (38%) and TGW (23%). Biochar applied to a coarsely textured soil with pH ≤ 7.5 increased GY considerably. Biochar feedstocks of animal waste and crop residues origins had significant effects on GY compared to woody residues. Data suggest that biochar produced at ≤550 °C with the pH of ≤8 more effectively enhanced yield and crop growth than biochar that produced at a higher pyrolytic temperature with a higher pH. Findings from this study suggest the combination of type of biochar, soil, crop, and climate should all be considered to maximize fertility and the organic amendment benefits of biochar for crop production.