Bacterial growth was measured using 3H-leucine incorporation into extracted bacteria (Bååth et al., 2001), which uses an estimate for protein synthesis as an index for in situ bacterial growth rate. Briefly, soil was mixed with water by vortexing and subjected to a low speed centrifugation. The leucine incorporation of the extracted bacteria in the supernatant was then measured during
1 h at 17 C. The amount of Leu incorporated into extracted bacteria per h and g dry soil was used as a measure of bacterial growth.