Can biochar play a role in crop protection?

Biochar is the solid coproduct of biomass pyrolysis, a technique used for biofuel production. Biochar can be applied as a soil amendment and has potential to help mitigate climate change, as it permanently sequesters carbon from the atmosphere. In addition, biochar soil amendments have proven to be beneficial for soil tilth, nutrient retention and crop productivity. However, to date little is known about the effect of biochar soil amendments on plant pathogens and plant disease resistance. The effect of biochar soil amendments on the plant‐parasitic nematodes Meloidogyne chitwoodi on bean and carrot, Globodera rostochiensis and G. pallida on potato and the fungal plant pathogens Rhizoctonia solani, Sclerotinia sclerotiorum and Verticillium dahliae on lettuce and Botrytis cinerea on strawberry were evaluated in bio‐assays. The effect of biochar varied with the plant‐pathogen system, the type of biochar, the biochar dose, and whether it was combined with compost. In addition, we investigated if the biochar effect was correlated with changes in plant biomass, soil chemical and physical properties (water retention, N, P, K, pH, EC, etc.) and overall soil and rhizosphere microbiology. The latter was done using phospholipid‐derived fatty acids (PLFA) and denaturing gradient gel electrophoresis (DGGE) analysis.