Figure 2.

Potential (a) and relative enzyme activities (b) for nitrogen fixation, mineralization, nitrification and denitrification are displayed (n=5, error bars represent standard error of means). Only significant differences as revealed by one way ANOVA on ranks (P<0.05) are indicated by different letters. n.d. indicates that all five replicates of potential N fixation were below the detection limit of 0.2 pmol N h⁻¹ g⁻¹ soil.