This system consisted of pneumatically operated static chambers (non-steady-state, non-through-flow), linked to an automated sampling system and a gas chromatograph. The clear acrylic glass chambers covered a surface area of 0.25 m2 (500 mm x 500 mm) with a height of 150 mm and were secured to stainless steel bases inserted permanently into the soil to a depth of 100 mm. Three replicate sampling chambers were randomly placed within an area roughly 5 x 4 metres within a larger 20 m x 30 m experimental plot. A transparent tinted plastic coating was placed on the lids to reduce heat build-up within the chambers when closed. A tipping bucket rain gauge (Davis Instruments Corp. CA, USA) connected to the system allowed for automated opening of the lids during rainfall events.

Nitrous oxide and CH4 concentrations were determined using a gas chromatograph (SRI GC8610, Torrance, CA, USA) equipped with 63Ni Electron Capture Detector for N2O and a Flame Ionisation Detector for CH4. Carbon dioxide was measured continuously with a non dispersive infrared CO2 analyser (LI-820; LI-COR, Lincoln Nebraska, USA). To minimize interference from moisture vapour and CO2 on N2O measurement, a precolumn filled with sodium hydroxide coated silica was installed ahead of the analytical column and changed regularly.A full measurement cycle for flux determination commenced with lid closure and finished when the lids opened 48 minutes later. The lids remained open for a further 96 minutes before the commencement of the next cycle. Fluxes of N2O, CH4 and CO2 were calculated from the slope of the linear increase or decrease in concentrations within the chambers over the closure time. An optimization function was used that selected the best regression coefficient (r2) from either 3 or 4 of the measured gas concentrations. Flux rates were discarded if the r2 was <0.81 for N2O and CH4 and <0.90 for CO2. The flux rate was then calculated and corrected for air temperature during measurement and site pressure using the procedure outline by Barton et. al. (2008).

A FDR (EnviroSCAN Sentek, Stepney, South Australia) moisture probe located centrally to the chambers recorded half-hourly readings of volumetric water content (5-10 cm) while soil temperature (10 cm) was measured at 5 minute intervals (Hobo Pendant temperature/light data logger, Onset Computer Corporation).

For climate data an automatic weather station (Davis Instruments Corp. CA, USA) installed nearby recorded half-hourly rainfall, temperature, relative humidity and wind speed and direction values