Table 1. The relative abundance of the nitrite reductase gene and transcript responsible for N₂O emission in a soil microcosm.

	Treatmentsa	nirK in Cluster Ib	nirK in Cluster II	nirK in Cluster III	nirK in Cluster IV	Total nirK	nirS in Cluster I	nirS in Cluster II	Total nirS	Total Nitrite reductase gene
Gene	NF-8	0.506	0.717	2.191	0.027	3.441	1.863	0.498	2.36	5.802
	OF-8	5.631	5.272	1.282	0.014	12.199	1.344	0.275	1.619	13.818
Transcript	NF-8	0.002	0.003	0.001	—c	0.006	—	—	—	0.006
	OF-8	0.010	0.049	0.002	—	0.062	0.001	—	0.001	0.063

^aNF-8 and OF-8 represent the control and organic fertilized soil on the eighth day of N₂O flux in the soil microcosm, which corresponds to the curve in Supplementary Figure S3.

^bRelative abundance of the nitrite reductase gene or transcript copies calculated as a percentage of the total bacterial 16S rRNA gene copies (for the mean and s.d. of replicates by treatment see Supplementary Table S4).

^cNot detected.