A comparison of methods for soil microbial population and biomass studies

Abstract

A comparison was made of 15 different techniques which are used in assessing soil microbial populations and/or biomasses. These include direct observations (fungal standing crop, fluorescein diacetate active mycelia, acridine orange stained bacteria), cultural methods (bacterial plate counts), physiological methods (total microbial, bacterial and fungal biomasses, O2‐uptake), soil enzyme analyses (dehydrogenase, catalase, alkaline and acid phosphatase, protease, amylase), and ATP‐analyses. The various techniques were applied to six soils known to have different microbial characteristics. The results are discussed with respect to the convertability of counts and measurements into microbial biomasses, the variability of the techniques, the correlations within comparable groups of methods, and the practical limitations in application of individual methods to different soils.

Degradation of Bacteria by Agaricus bisporus and Other Fungi

“…Estimates extrapolated from plate counts and bacterial cell weights indicate that 3-5% of compost dry weight could be bacterial in origin (Fermor & Wood, 1979). Some of the techniques currently employed to (Domsch et al, 1979;Paul & Voroney, 1980) are inapplicable to mushroom compost. The measurement of specific cell constituents is invalid because the concentration of these constituents varies according to the proportions of particular organisms in the very heterogeneous population.…”

Effect of Plant Roots on Chemical and Biochemical Properties of Surrounding Discrete Soil Zones

“…Dehydrogenase activity at week 5 often increased towards the root zone while the phosphatase activity decreased. The former has been shown to correlate with total biomass in the soil (Domsch et al 1979 There is a relationship (r : 0.95) of increased NaHCO3-extractable Po in the zone with increased phosphatase activity (Table 3 vs. Table 2). Similar results were observed by Thompson and Black (1970) and Helal and Sauerbeck (1984) (Oades 1984), the ratio galactose * mannose/arabinose * xylose will be low (< 0.5 (Dormaar and Sauerbeck 1983) and thus creates the potential for the production of diffusable energy rich compounds.…”

Microbial biomass in paddy soil

“…In this study, the average biovolume of bacteria was 0.2-0.3 .um3 which corresponds to the 0.7-O. 8.um diameter class of cocci. This biovolume of bacteria was smaller than that mentioned above, presumably due to the fact that the cocci in the 0.5 .urn diameter class accounted for 60-70% of the total number of bacteria.…”

“…SPARLING (23) attempted to estimate microbial biomass from microcalorimetric determinations of soil microorganisms. In upland and grassland soil, many researchers have determined the microbial biomass using the various methods mentioned above (8,21). In paddy soils, however, there are few data about biomass.…”