Laboratory incubation experiments show that lime, applied in the field or immediately before incubating, increases the rate at which Sitka spruce needles and forest floor litter decompose. Increases in CO 2 production caused by lime were accompanied by the rapid assimilation of both native and added mineral N. Added mineral N also increased CO 2 , produced from lime-treated spruce needles. Results are related to field data reported in the first paper of this series.