Table 2.

Mean (±SE) betaproteobacterial (AOB) and archaeal amoA (AOA) gene abundances presented as gene copies per μg DNA or normalized to copies of bacterial 16S rRNA genes in plots receiving different levels of fertilization.

Fertilization	AOA/μg DNA	AOB/μg DNA	AOA: bacterial 16S rRNA	AOB: bacterial 16S rRNA
Control	5.8 ± 2.8 × 106	5.9 ± 5.3 × 104	4.1 ± 2.1 × 10-3	2.3 ± 1.8 × 10-5
LF	2.0 ± 1.1 × 106	1.1 × 104 ± 6.8 × 103	9.2 ± 3.9 × 10-4	5.1 ± 2.2 × 10-6
HF	1.3 × 106 ± 6.0 × 105	2.1 ± 1.5 × 105	4.1 ± 1.9 × 10-4	4.7 ± 1.8 × 10-5
XF	3.5 ± 1.5 × 107	3.2 ± 1.7 × 105	4.12 ± 1.4 × 10-2	2.1 ± 1.1 × 10-4