However, the model overestimated CO2 fluxes for manure at 5 C. The microbial biomass C concentration in the control and biochar treatments accounted for 84–176 mg C kg 1 soil after four weeks and for 101–165 mg C kg 1 soil after eight weeks (Fig. 2). In the slurry and manure treatments, the microbial biomass C concen- tration was between 192–468 mg C kg 1 soil after four weeks and between 267 and 497 mg C kg 1 soil after eight weeks.
3.2. Macro-aggregate yield and associated C
The concentration of macro-aggregates was mostly higher at lower than at higher temperatures, while the duration of the experiment (four or eight weeks) did not result in large differences.
For 5 C, 15 C and 25 C incubation temperatures, the macro- aggregate dry mass concentration ranged from 233 to 606 g kg 1 soil, from 91 to 637 g kg 1 soil, and from 100 to 383 g kg 1 soil (Fig. 2), respectively, with the highest value from the slurry or biochar + slurry treatment and the lowest from the biochar treatment. The macro-aggregate associated C concentrations had a similar distribution among the treatments as the macro- aggregate dry mass concentrations. The macro-aggregates sepa- rated from the biochar treatments accounted for 5–22% of bulk soil C (Table 1). Those separated from the control and from the slurry or manure treatments accounted for 14–34% and for 25–66% of bulk soil C, respectively.