my dear,.A number of methods are currently available for

studies on soil microbial communities. The use of

molecular techniques for investigating microbial diversity

in soil communities continues to provide

new understanding of the distribution and diversity

of organisms in soil habitats. The use of SSU

rRNA or rDNA sequences, combined with fluorescent

oligonucleotide probes provides a powerful approach

for studying soil microorganisms that may not be

amenable to current culturing techniques.

Despite the utility of culture-independent techniques

such as SSU rRNA or rDNA analyses, there

remains a general need to cultivate microorganisms

from soil habitats to better understand their role in soil

processes. Future studies of soil microbial communities

must necessarily rely on a combination of both

culture-dependent and culture-independent methods

and approaches. Only then will we be able to develop

a more complete picture of the contribution of specific

microbial communities to the overall quality and

health of agricultural soils.

please check the below link:

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regards,

The practical way to quantify the microbial population in soil samples would be as described by Ricker (1972) using "bean-sampler method".

Macro organisms (I am referring to soil invertebrates) can be collected from soil samples with the Berlese apparatus and then counted with the aid of a dissecting microscope.