ISSN:
1432-0789
Keywords:
Soil microbial biomass
;
Chloroform incubation method
;
Initial population
;
Soil organic matter 14C evolved
;
Corrected control
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Estimates of soil microbial biomass are important for both comparative system analysis and mechanistic models. The method for measuring microbial biomass that dominates the literature is the chloroform fumigation incubation method (CFIM), developed on the premise that killed microorganisms are readily mineralized to CO2, which is a measure of the initial population. Factors that effect the CFIM have been thoroughly investigated over the last 15 years. A question that still remains after countless experiments is the use of an appropriate nonfumigated control for accounting for native soil organic matter (SOM) mineralization during incubation. Our approach was to add hot-water-leached 14C-labeled straw to both fumigated and nonfumigated samples assuming the straw would mimic a recalcitrant C substrate fraction of SOM. The ratio of the 14C evolved from the fumigated sample over the 14C evolved from the control sample would provide a corrected control value to be used in calculating microbial biomass. This experiment was conducted on soils from forest, agricultural, grassland and shrub-steppe ecosystems. The results clearly indicate that equal recalcitrant C mineralization during incubation is not a valid assumption. The results with these soils indicate than on the average only 20% of the control CO2 should be subtracted from the fumigated CO2 for the biomass calculation. The correction value ranged from 18% for agricultural soils to 25% for shrub-steppe soil, with the average correction value being 20%. Our experiments show that corrected biomass values will be 1.5–2 times greater than uncorrected biomass values. In addition using a corrected control improved the 1:1 correlation between the CFIM and SIR methods for these soils.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00336096
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