Microgranular biochar improves soil fertility and mycorrhization in crop systems

Intensive agricultural practices have accelerated soil organic carbon mineralization, compromising soil health and function. This study evaluated the efficacy of microgranular biochar (MicroCHAR) and powdered biochar as soil additives enhancing soil function, and pea, maize and wheat growth and yield. We carried out a series of experiments with degraded drought‐prone soils in greenhouse and field conditions, combining biochar addition with arbuscular mycorrhizal fungi (AMF). The combination of amendments variously impacted soil nutrient status; availability of extractable potassium (K) increased in all cases, whilst that of calcium (Ca) was reduced when AMF inoculation was applied alone but not in combination with biochar. MicroCHAR positively affected root biomass and pea P content compared with the control, but biochar did not enhance N or K. Crop yield was not significantly increased by MicroCHAR amendment. MicroCHAR enhanced the mycorrhization rate of crop roots by 260%, an effect seen in the greenhouse and field conditions. This study suggests that credible benefits in some crops can be gained by the application of MicroCHAR to some soils. Observed effects may be soil and crop specific; future study of optimal nutrient and microorganism coatings on microgranular biochar opens exciting avenues for the improvement of crop yields in degraded agricultural soils.