Table 2.

P values and F values from two-way ANOVA of urea levels (N), salt gradients (S)/salt-alkali gradients (A) and their interaction (N × S/N × A) on denitrifying gene abundances and denitrification rates.

Source	df	nirK		nirS		nosZ Clade I		Denitrification rate
		P	F	P	F	P	F	P	F
Na	2	0.00**	10.97	0.00**	12.59	0.00**	6.50	0.00**	324.59
S	4	0.00**	52.86	0.00**	19.17	0.00**	69.22	0.00**	190.38
N × S	8	0.10	1.91	0.31	1.25	0.76	0.62	0.00**	11.63
Nb	2	0.00**	14.82	0.10	3.67	0.00**	14.76	0.00**	49.11
A	4	0.00**	52.30	0.00**	60.97	0.00**	94.90	0.00**	475.57
N × A	8	0.14	1.69	0.97	0.29	0.04*	2.43	0.00**	17.06

N^a and N^b represent the effect of urea on the dependent variables when interacting with salt and alkali, respectively. Significance levels: *P < 0.05, **P < 0.01.