Biochar soil amendment

Phosphorus (P) and sulfur (S) in soil is mostly inaccessible to plants and needs mobilization through microbes into root available forms. In this study, the effect of biochar soil amendment was investigated on the growth of spring barley, the abundance of S and P mobilizing bacteria, bacterial diversity (DNA fingerprinting and next generation sequencing) and S species were identified in soil, feedstock and biochar. Soil amendment with biochar made from Miscanthus x giganteus resulted in significantly increased growth of barley and grain formation. Further significant increases were found for the soil pH, abundances of rhizosphere soil bacteria capable of growing with tri-calcium phosphate, phosphate-esters, phosphonates and aromatic sulfonates, as sole source of S or P. 16S rRNA gene based fingerprint analysis revealed a significant shift in the bacterial community structure upon biochar amendment that correlated significantly with the above mentioned changes (pH, plant growth, bacterial abundances). Increases in genera Flexibacter and Brevundimonas known for P cycling and genera involved in sulfonate desulfurization such as Arthrobacter, Cupriavidus, and Stenotrophomonas were identified under biochar amendment, supporting cultivation dependent findings. However, unlike its feedstock, biochar itself contained no detectable amounts of sulfonate-S, suggesting that soil borne sulfonates are the major source in bacteria S supply.