Fang and Moncrieff 1998

Fang C, Moncrieff JB. 1998. Simple and fast technique to measure CO2 profiles in soil. Soil Biology and Biochemistry 30: 2107-2112.

These authors present a method they developed to measure sub-surface CO2 concentrations in soil. Their test environment was a slash pine (Pinus elliotti) plantation in Florida, with sandy soil subject to a broadly fluctuating water table that occasionally comes to the surface.

Their method, essentially, involves burying a perforated aluminum probe connected to the surface with flexible tubing, waiting several weeks for the disturbance to settle, and then measuring recirculated gas samples by injecting them with a syringe into an IRGA. Recirculation breaks the trade-off between errors associated with the syringe sucking air out of surrounding soils at depths different from the intended sample, and large buffer volumes inside probes become dead spaces with internal gas concentration gradients.

This is an interesting approach to soil gas probes, but is fundamentally unsuitable for my own studies because of the necessity of waiting weeks before sampling due to the disturbance of burying the probes.