The measuring concept is actually quite simple. We place a chamber on a small soil surface area and follow the change in CO2 concentration of the air in this chamber. The efflux of carbon dioxide from soil is usually higher than the photosynthetic uptake of ground vegetation and thus, the concentration of carbon dioxide starts to increase in the chamber. From the rate of the concentration change in a given time, we can calculate the rate of CO2 exchange between the soil surface and air.
This is a very widely used technique in plant physiology to measure soil respiration. We use an automatic system that works with minimal assistance. The chambers are transparent and ventilated, and the conditions inside follow the natural daily and seasonal changes of light, temperature and air humidity. The chambers open and close automatically. When it is closed, we follow the change in CO2 concentration and calculate the CO2 exchange rate.