Decomposition rates measuring the speed of disappearance of organic residue or standardized cotton strips. Measuring cellular constituents . The total biomass of all soil organisms or specific characteristics of the community can be inferred by measuring components of soil organisms such as the following. Biomass carbon, nitrogen, or phosphorus measure the amount of nutrients in living cells, which can then be used to estimate the total biomass of organisms. Chloroform fumigation is a common method used to estimate the amount of carbon or nitrogen in all soil organisms.
Enzymes measure enzymes in living cells or attached to soil.
Assays can be used to estimate potential activity or to characterize the biological community. Phospholipids and other lipids provide a fingerprint of the community, and quantify the biomass of groups such as fungi or actinomycetes. DNA and RNA provide a fingerprint of the community, and can detect the presence of specific species or groups. Food web complexity is a factor of both the number of species and the number of different kinds of species in the soil. Complexity can be determined, in part, from a food web diagram such as Figure 4, which represents the soil in an old-growth Douglas fir forest.