Effect of fertilizer regime, sample time and the interaction between them on the relative abundance (%) of abundant bacterial classes (subgroups) ^£ (relative abundance >1%).

Values are means ± standard deviation (n = 6 or n = 18). NS: no significant (P>0.05). Means followed by the same letter for a given factor are not significantly different (P<0.05; Turkey's HSD test where there are more than two treatment levels). Actinobaceria, Gemmatimonadetes, Nitrospira were not included in this analysis as they had only one class. Fertilizer regimes as described in Table 1.