Ryegrass (Lolium perenne L.) was seeded and plant growth was monitored. Soil microbial activity, quantifier using the dehydrogenase activity (DHA) assay, was significantly increased (P < 0.01) under all biochar treatments. This increase was in excess of 100% after 30 d of treatment and was significantly higher (P < 0.05) than the control throughout the trial for 350 ◦ C amended soils