The AGFACE project commenced in June 2007 at Horsham (36°45′07″S, 142°06′52″E; 127 m elevation), Victoria, Australia. Its aim is to quantify the interactive effects of elevated atmospheric carbon dioxide concentration (e[CO2]), nitrogen, temperature (accomplished by early and late sowing times), and soil moisture on the growth, yield, and water use of wheat (Triticum aestivum L.) under Australian conditions. The main engineering goal of the project was to maintain an even temporal and spatial distribution of carbon dioxide (CO2) at 550 μmol/mol within AGFACE rings containing the experimental treatments. Monitoring showed that e[CO2] at the ring-centres was maintained at or above 90% of the target (495 μmol/mol) between 93 and 98% of the operating time across the 8 rings and within ±10% of the target (495–605 μmol/mol) between 86 and 94% of the time. The carbon dioxide concentration ([CO2]) measured inside the rings declined non-linearly with increasing distance downwind of the CO2 source and differed by 3–13% in concentration between the two canopy heights in each ring, but was not affected by wind speed or small variations in [CO2] at the ring-centres. The median values for model-predicted concentrations within the inner 11-m-diameter portion of the rings (>80% of the ring area) varied between 524 and 871 μmol/mol but remained close to target near the centres. The design criteria adopted from existing pure CO2 fumigating FACE systems and new ideas incorporated in the AGFACE system provided a performance similar to its equivalent systems. This provides confidence in the results that will be generated from experiments using the AGFACE system.

The Australian Grains Free-Air Carbon dioxide Enrichment (AGFACE) facility was established at Horsham (36°45′07″S latitude, 142°06′52″E longitude), Victoria, Australia in 2007 to conduct research under Australian conditions with the aim to generate field response data in broad-acre wheat to elevated levels of CO2. Carbon dioxide concentrations within the rings in the AGFACE facility are computer controlled, using inputs of sensed carbon dioxide concentration, wind speed and direction at the centre of each ring. The control system uses a number of pneumatic valves and associated fittings driven by a control algorithm. On average, the control system at the Horsham site has enabled the AGFACE rings to maintain the concentration of CO2 at the centre of the ring at ≥90% of the target (ie. ≥495 ppm) for 97% of the operating time. The typical mean CO2 concentration at the centre of an AGFACE ring was 550 ± 28 ppm and this meets the generally accepted standards for defining FACE systems operating limits.