Bacterial biomass (×108 cells∙g−1)

NH+ 4 oxidation activity (point)

NO− 2 oxidation activity (point)

N circulation activity (point)

P circulation activity (point)

Black soil

n.d ± 0z

7.0 ± 0.82

27.0 ± 1.63

1.0 ± 0

0 ± 0.0