Spatial Variation of CO2 Inside Australian Grains Free Air Carbon Dioxide Enrichment (AGFACE) Rings

AGFACE facilities are being used to investigate the interactive effects of CO₂, temperature, water supply and nitrogen on wheat growth, yield and quality. One of the engineering goals of AGFACE was to describe the extent of spatial variation of CO₂ concentrations [CO₂] inside AGFACE rings and factors affecting it. Monitoring has shown that [CO₂] is highly variable near the ring-edge where CO₂ is emitted and declines non-linearly with the distance downwind of the ring-edge corroborating the findings of others. The spatial variation of [CO₂] depends on ring size and the gap between ring and canopy heights but not wind speeds.