incubated at 25 C where the CO2 cumulatively respired after the
first four weeks accounted for 59% (control) to 79% (manure) of the
total amount of respired CO2 (cumulative after eight weeks). This
effect is less pronounced for the CO2 amounts emitted within the
first four weeks at 15 C and 5 C incubation temperature. The
emission rates account for 48% (slurry) to 71% (manure) of the total
amount of the respired C at 15 C and for 47% (control) to 66%
(slurry) at 5 C. Only for the treatments with organic soil additives
at 25 C incubation temperature, did the higher emissions rates
measured within the
first four weeks compared to those of weeks
five to eight correspond with higher concentrations of the
microbial biomass C measured after four rather than after eight
weeks. For the samples incubated at 15 C (except slurry) and at
5 C (except control and biochar), the CO2 emission rates were
higher within the
first four weeks but the microbial biomass C
concentration was higher after eight weeks than after four weeks
(3% to 68%). The data imply that the microbial biomass seems to
become less active or less efficient over time in terms of
decomposition processes and CO2 production at incubation
temperatures of 5 C and 15 C compared with 25