An Automated Laboratory Method for Measuring CO2 Emissions from Soils

Abstract

A gas chromatography (GC) headspace method was developed for soil microbial respiration (CO emission) analysis after a 24-h incubation of a rewetted soil. The GC method was compared with the Solvita CO burst method by analyzing 18 different soils that were air-dried (22°C) or dried at 45, 65, and 105°C for 24 h before rewetting. A strong exponential relationship between the Solvita color number and GC headspace CO–C emission was observed. Compared with air-dried soils, drying at 65°C led to increased CO emission and reduced variation among sample replicates, while drying at 105°C led to a reduction in CO emission and an increase in variability. The GC method does not require sample dilution, provides data that is highly correlated to the Solvita method, and has a wider dynamic test range than the Solvita method. The developed GC method could be adapted to automation for commercial laboratory use.