5Smit B.Agroecosystem health:Analysis and assessment[M].Guelph,Ontario:University of Guelph,1998:1-14.
6Kennedy A C,Smith K L.Microbial diversity and sustainabilityof agricultural soils[J].Plant Soil,1995,23(2):69-79.
7Turco R F.Defining soil quality for a sustainable environment[M].Madison:Soil Science Society of America Inc,1994:73-90.
8Hoitink H A,Boehm M J.Biocontrol within the context of soilmicrobial communities:A.substrate-dependent phenomenon[J].Annu Rev Phytopathol,1999,37:427-446.
9Wardle DM,Weller R,Bareson MM.16s rRNAsequences rev-el numerous uncultured microorganisms in a natural community[J].Nature,1992,345:63-65.
10Garland J L,Mills A L.Classification and characterization ofheterophic microbial communities of on the basis of patterns ofcommunity-level sole-carbon-source utilization[J].AppI Envi-ron Microbiol,1991,57:2351-2359.
