Colorimetric method for CO2 measurement in soils

A sensitive and versatile method for the measurement of CO2 is described that involves equilibration with a dilute bicarbonate solution containing a pH indicator dye. Although the method is not as sensitive as those based upon IR gas analysis and GC, it does not require expensive equipment and has several advantages involving convenience and reliability over methods based on alkali absorption. Coarse adjustment of the sensitivity and range is achieved by varying the concentration of NaHCO3, while the volume of gas analysed and the sampling frequency provide fine tuning.