Harris, D., authorVoroney, R. P., authorPaul, Eldor A., authorAgricultural Institute of Canada, publisher2007-01-032007-01-031997-11Harris, D., R. P. Voroney and E. A. Paul, Measurement of Microbial Biomass N:C by Chloroform Fumigation-Incubation. Canadian Journal of Soil Science 77, no. 4 (November 1997): 507-514. https://dx.doi.org/10.4141/S96-064.http://hdl.handle.net/10217/80890We present a calculation for soil microbial biomass N:C ratio determined from a 10-d incubation following chloroform fumigation. The calculation is based on a mathematical model of the N content of the pre- and post-fumigation soil microbial biomass and the growth yield of the biomass that develops after fumigation. Biomass N is calculated from the N:C ratio and biomass C. The mineralization of bacteria and fungi, with different N contents, added to fumigated soils was used to establish the model parameters. The model was tested against an independent set of measurements and considers two assumptions: 1) The ratio of N:C mineralized from killed biomass is equal to the ratio of N:C mineralized from soil non-biomass constituents. 2) More realistically, the N and C mineralization in the fumigated soil, from sources other than killed biomass, is a residual fraction of the N and C mineralization in the unfumigated soil. Biomass C:N ratios calculated without a control correction (assumption 1) were, on average, 20% wider than corrected values (assumption 2). Biomass N calculated as the product of N:C and biomass C was compared with published values for several data sets. The new calculation method was robust even when net immobilization of N followed fumigation.born digitalarticleseng©1997 Agricultural Institute of Canada.Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.soil microbial biomassC:N ratiochloroform fumigationnitrogenTexthttps://dx.doi.org/10.4141/S96-064