Recent studies suggested that soil applied biochar, the solid carbon-rich co-product of biomass pyrolysis, reduce severity of foliar diseases and soilborne diseases in various crops. However, there is no research conducted what would be effect of different biochar produced from different feedstock and temperature on disease suppression, as there is a profound variability in the physical and chemical properties of biochar depending on the initial feedstock and production parameters. Furthermore, understanding the mechanisms will surely assist in setting more general sets of rules for optimizing disease suppression by biochar. The aim of our research is to explore the influence of various biochar types on suppression of soilborne disease caused by Rhizoctonia solani in bean and understanding the mechanisms responsible for suppression or promotion of disease. Four different types of biochar prepared from two feedstocks (eucalyptus wood and greenhouse wastes) each produced at 350 and 600 oC were used.
We found that biochar has the ability to suppress the disease caused by R. solani in bean. In general, biochar addition at relatively lower concentrations suppressed damping-off and root rot caused by R. solani, whereas, at higher concentrations, biochar was ineffective (U-shaped biochar dose/disease response curves). Biochars produced at both low and high temperatures were equally effective against disease. However, suppression of disease was affected by the feedstock type and concentration interaction. Some possible mechanisms of biochar such as direct toxicity, soil microbial population and systemic induced resistance are under study. Till now we found that biochar has direct toxic effect on pathogens, effect its survival in soil and also bring changes in soil microbial population.
