The bulk soil samples and aggregate size fractions were ballmilled
and analyzed for total C (Ct) by dry combustion using a CN
elemental analyzer (Elementar Vario El, Heraeus, Hanau,
Germany). As no carbonates were present in the soil, the Ct data
correspond to organic C (Corg). C data for the aggregate-size
fractions are given in percentage of the bulk soil C content.
Microbial biomass C (Cmic) was determined by Chloroform-
Fumigation-Extraction (Vance et al., 1987) on fresh samples
directly after the incubation.