We also suggest that N suppresses respiration in these organic horizons either by relieving the N limitation of microbial biomass synthesis, or by slowing turnover of C through the microbial pool; concurrent measures of microbial growth and turnover are needed to resolve this question.
Further, although stress and disturbance factors both limited some measures of microbial biomass and activity, the microbial community responded to these two factors in quite different ways.
All measures of microbial activity were significantly greater in the organically farmed soils, including microbial respiration (33.3% more), dehydrogenase (112.3% more), acid phosphatase (98.9% more), and alkaline phosphatase (121.5% more).
The study also contains no measures of microbial exposure or how effective individual hygiene practices may have been in terms of reducing microbial exposure.
Thus, two- to three-fold differences in in situ net N mineralization rates occurred despite the similarity in microbial communities and laboratory measures of gross production and consumption of NH4+ among treatments.
Correlations between measures of microbial functionality (activity, richness, and diversity) and turbidity, total organic carbon (TOC), total nitrogen (TN) were observed in horizontal-flow systems but less so in vertical-flow systems.
Addition of stoichiometric measures and other soil attributes (e.g. soil C N, C P, δ15N) in a multiple regression model explained more of the variation than a single factor plus the land use effect (though soil order still explained a small, but significant amount of variance for measures of microbial biomass).
These studies also lacked measures of microbial abundance.
We do not have credible measures of microbial richness, but development of new technologies will allow us to decide whether this is knowable or not.
