Table 3. Two-way ANOVA indicating the effects of N addition and management type (intensive or conventional) on the Chao 1 index of soil microbial community composition.

Source of variation	SS	df	MS	F	P-value
N addition	1295767.9	3	431922.6	9.4	0.0008
Management type	8005801.7	1	8005802	175.2	<0.0001
Interaction	840578.7	3	280192.9	6.1	0.006
Within	730924.5	16	45682.8
Total	10873072.9	23

SS: sum-of-squares; df: degrees of freedom; MS: mean square.