| 原文摘要 | The effects of biochar application to calcareous soils are not well documented. In a laboratory incubation study, a hardwood‐based, fast pyrolysis biochar was applied (0, 1, 2, and 10% by weight) to a calcareous soil. Changes in soil chemistry, water content, microbial respiration, and microbial community structure were monitored over a 12‐mo period. Increasing the biochar application rate increased the water‐holding capacity of the soil–biochar blend, a trait that could be beneficial under water‐limited situations. Biochar application also caused an increase in plant‐available Fe and Mn, soil C content, soil respiration rates, and bacterial populations and a decrease in soil NO3–N concentration. Biochar rates of 2 and 10% altered the relative proportions of bacterial and fungal fatty acids and shifted the microbial community toward greater relative amounts of bacteria and fewer fungi. The ratio of fatty acid 19:0 cy to its precursor, 18:1ω7c, was higher in the 10% biochar rate soil than in all other soils, potentially indicating an environmental stress response. The 10% application rate of this particular biochar was extreme, causing the greatest change in microbial community structure, a physiological response to stress in Gram‐negative bacteria, and a drastic reduction in soil NO3–N (85–97% reduction compared with the control), all of which were sustained over time. |