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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1105

J.P.E. Anderson and K.H. Domsch; A physiological method for the quantitative measurement of microbial biomass in soils. Water Research :215-221, 1978

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A method is described for the rapid and objective estimation of the amount of carbon in the living, non-resting microbial biomass of soils. The method, which is based on the initial respiratory response of microbial populations to amendment with an excess of a carbon and energy source, was quantified using an expanded version of Jenkinson's technique. The simultaneous application of the two methods to 50 soil samples showed a highly significant correlation (r=0.96) between both. From this correlation it could be deduced that at 22 degrees C, a substrate-induced maximal respiratory rate of 1 ml CO2/hr corresponds to ca. 40 mg microbial biomass C. Evidence supporting these results was obtained from pure culture studies. The various soil types investigated were collected from agricultural as well as forest sites and they contained between 15 to 240 mg microbial C/100 g dry soil. The respiratory method provides reproducible estimates of biomass size within 1-3 hr after soil amendment. It can be combined without difficulty with a selective inhibition method for determination of bacterial and fungal contributions to soil metabolism.