Microbial associations of soil types.

Microorganisms are characterized by wide ranges of distribution. Some groups, however, are known to have zones of active proliferation, and the development of specific populations in discrete zones results in rather specific microbial associations in some soil types. The soils formed in warm climates are richer in microorganisms and contain more bacilli and actinomycetes. The spectrum of dominant microbial groups varies in different soil types.