Gas Flux

Gas flux measurements were conducted using the chamber technique, whereby the open end of a container was placed on the soil surface and measurements of CO2 concentrations were made every second via a connected infra-red analyser. The non-destructive analyser was connected to the chamber via an inlet and an outlet tube such that air was recycled through the chamber via a pump in the instrument, thereby guaranteeing a constant internal pressure during the measurement. In the present study a 13 x 13 x 9 cm Plexiglas chamber was used along with a Draeger Multiwarn infrared analyser equipped with CO2 (0-25%), H2 (0-1000ppm) and H2S (0-

100ppm) sensors. Measurements were conducted for no more than 75 seconds in order to ensure that the natural flux rate from the soil was not affected. Data was then transferred to a PC and the flux rate was calculated using the following formula from Hutchinson and Livingston (1993)

Where f is the flux in m3 m-2 s-1, V is the volume of the chamber (m3), A is the surface area measured (m2) and At is the time difference (sec) between the first and last measurements of the CO2 concentrations (ml/ml). Values were then converted into kg m-2 d-1.

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