ISSN:
1432-0789
Keywords:
Flow-microcalorimeter
;
CO2
;
Cal/CO2 ratio
;
N2O
;
Aggregates
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Heat output can be used as an indicator of microbial activity and is usually measured in a microcalorimeter with closed ampoules. In long-term experiments particularly, interpretation of the data is hindered by the changing environment in the closed ampoules because of O2 consumption and CO2 enrichment. We used a combination of a flow-microcalorimeter and a gas chromatograph to measure the heat flux and CO2 and N2O production rates under controlled conditions. Simultaneous detection of the heat output and CO2 emission allowed calculation of the calorimetric: CO2 (Cal/CO2) ratio. A mean ratio of-435 kJ mol-1 CO2 was detected in six different soils amended with glucose and incubated under aerobic conditions. This ratio indicated that CO2 was the end-product of catabolism. In wet 10–12 mm soil aggregates of a gleyic vertisol amended with glucose, values of-285 kJ mol-1 CO2 under an aerobic and-141 kJ mol-1 CO2 under a N2 atmosphere was determined. These findings indicated that fermentative metabolism occurred. The Cal/CO2 ratio was not affected when enough NO inf3 sup- was available and denitrification processes (N2O production) were possible.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00336160
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