Ponciroli, G., S. Halstead, H. Collins, and G.P. Robertson
Presented at the All Scientist Meeting (1996-07-16 to 1996-07-17 )
Substrate Induced Respiration (SIR) provides a sensitive means for assessing soil microbial activity at a given moment in time. CO2 production under glucose-amended and control conditions respectively provide measures of potential and actual soil heterotrophic activity. Potential activity can be used to estimate microbial biomass.We used the SIR method to examine the heterotrophic potential of soils from all LTER treatments in June 1996. Twenty five grams of field moist soil amended with 25 mL of a 55 mmol glucose solution was incubated at 22 C for 2 hours on an orbital shaker. Headspace CO2 was analyzed using an infra-red gas analyzer.The forested sites, native succession (T7), and native treatment (T8) exhibited significantly more heterotrophic activity then the other treatments (Figure 1). The amount of activity may be attributed to differences in soil moisture, soil temperature, soil texture, and the amount and quality of carbon returned to the system.
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