Pathways of nitrogen utilization by soil microorganisms - a review
GEISSELER, D., HORWATH, W.R., JOERGENSEN, R.G., LUDWIG, B.
Soil Biology and Biochemistry 42, 2058-2067 (2010)
A soil-column experiment with maize-straw application at different depths was carried out to investigate the accuracy of CO(2)-measurement systems in a greenhouse experiment with sandy and loamy soils. The classical approach of CO(2) absorption in NaOH solution was compared with three other methods using dynamic chambers. These methods were gas chromatography (GC), a portable infrared analyzer (IR), and a portable photo-acoustic system (PAS). The cumulative CO(2) production over the 57-day incubation period was significantly affected by the method and soil-specifically by the treatments. The NaOH and GC method always formed a pair of lowest cumulative CO(2) production in all treatments with maize-straw addition. In the treatments with bottom application of the maize straw, IR and PAS methods gave values at identical levels in both soils. In the treatments with top application of the maize straw, the IR method gave significantly highest values in the sandy soil and the PAS method in the loamy soil. The correlation coefficients between the cumulative CO(2) production of the three dynamic-chamber methods (GC, IR, and PAS) and the static NaOH method were all significant, with r values between 0.90 and 0.93. The C balance can be used for testing the plausibility of CO(2)-production data. Roughly 102% (NaOH and GC) and 114% (IR and PAS) were recovered, including the CO(2)-production data in the C balance of the sandy soil. The respective data were 97% (NaOH and GC) and 104% (IR and PAS) for the loamy soil.