Table 7.

The main effect of year on soil microbial community biomass and indices determined by phospholipid fatty acid analysis (PLFA) for cover crop systems in Reno, Nevada, USA.

Year	TMBa	TBB	ACTB	Gram (−)	Gram (+)	TFB	AMFB	SB	UND	FBR	DI
	-------------------------------------------------------------------------ng g soil−1-------------------------------------------------------------
1	877	299	49	111	188	53	17	35	525	0.19	1.3
2	3760	1533	376	449	1084	368	74	295	1848	0.23	1.5
SEb	196	99	24	52	63	38	6	29	85	0.02	0.02
P-valuec	<0.001	<0.001	<0.001	0.01	<0.001	<0.001	<0.001	<0.001	<0.001	0.053	<0.001

^aTMB; total microbial biomass, TBB; total bacteria biomass, ACTB; actinomycetes biomass, (−) gram-negative bacteria biomass, (+) gram-positive bacteria biomass, TFB; total fungi biomass, AMF; arbuscular mycorrhizal fungi biomass, SB; saprophytes biomass, UND; undifferentiated microbial biomass, FBR; fungi-bacteria ratio, and DI; diversity index.

^bSE; standard error.

^cP-value; indicates significance within each column.