Soil flux: an important component of total carbon  budget

Rapidly rising atmospheric CO2  concentration and its potential impact on future  climatic conditions is an issue of increasing global economic and political significance.

Soil respiration can be defined as the  net  CO2  production of a soil. The amount of gas  exchange taking place  is frequently used as an indicator of microbial soil activity and so is used to characterise the “health” of that  soil.  The rate  of soil flux is influenced by a variety of

environmental parameters especially organic  matter content, soil moisture and soil temperature.

Natural biomass respiration from soil is a major carbon  source. Understanding soil flux and its relationship with other  sources and sinks  within the  carbon  cycle are currently  subject to increasing scientific  scrutiny in relation  to global climatic change.

The ADC BioScientific ACE system (Automated Soil CO2  Exchange System) is designed for the  long-term, unattended  monitoring of soil flux for both  temporal and spatial  studies. Individual ACE Stations can be used independently or as part of an ACE Network of multiple

ACE Stations.

Integral  CO2 analyser inside  soil chamber assembly

- designed for superior  soil flux measurements

Each ACE Station  features a highly accurate CO2  infrared  gas  analyser housed directly inside  the  soil chamber assembly. There  are therefore no long gas  tubing  connections between the  soil chamber and a separate analyser.

The close  proximity of the  analyser ensures accurate, straightforward and robust field measurements. The fastest possible response times to CO2  changes is assured. Any potential gas “hang-ups” or water vapour  drop out in long lengths of tubing  is avoided.  Experimental set-up is much  simpler  and the  system is much  more  field robust. The ACE Station  is also very power efficient  as there is no requirement to pump  gas  from the  chamber to the  analyser that  could be several metres of tubing  away.

Typically a 40Ah car battery will run an ACE Station  continuously for around  28 days.

The gas  circuitry of the  ACE Station  includes a permeation drier that  prevents the  water vapour  concentration increasing inside  the  chamber and so removes the  need to measure or compensate for water vapour  within the  system.