ACE Automated Soil CO2 Exchange System

Launched in 2006, the ACE system (Automated Soil CO₂ Exchange System) is designed for long-term, unattended monitoring of soil gas exchange. The automated design means that during analysis cycles, the soil can be exposed to ambient conditions before the chamber closes to take measurements. This means the ACE will continue to collect data without any human intervention for as long as permitted by its battery life. This makes the ACE an ideal research instrument for continuous assessment of below-ground respiration and carbon stores in on-going experiments into the quantitative nature of the carbon cycle.

The unique, single axis opening mechanism, which is mounted at a carefully conceived angle off of vertical, ensures reliability, minimises component costs and reduces weight. The ACE has a highly accurate CO₂ infrared gas analyser housed directly inside the soil chamber, with no long gas tubing connecting the soil chamber and a separate analyser. This ensures accurate and robust measurements, and the fastest possible response times to fluxes in gas exchange. Experimental set-up is much simpler and the system is much more field robust.

Each ACE can function fully independently, or a number can be combined as a network, at one field site. Up to 30 ACE Stations can be connected via an ACE Master control unit. As each ACE has an integral CO₂ IRGA, no long lengths of gas tubing run over the field site. The ACE Master control unit programs, supplies power and monitors all Stations within the network and flags any problems encountered. Data from all ACE Stations is stored at the Master control unit. The ACE network is an invaluable research tool for assessing variations in carbon release across a research site. The rate of soil CO₂ flux is influenced by a variety of environmental parameters, especially organic matter content, moisture content, temperature, and can be used to assess microbial soil activity to characterise the “health” of the soil.