FIELD CHAMBER MEASUREMENTS OF CO2 FLUX FROM SOIL SURFACE

Abstract

Rates of carbon dioxide exchange were determined using an infrared gas analyzer in an open chamber system in a field. During 1971 a fan was used to draw air through the chamber; the measured CO2 flux was approximately 40 percent greater than the highest rate reported in the literature. In 1972 two chambers were used: one under slight suction and the other under a slight pressure (compared with atmospheric pressure). The CO2 flux from the soil surface inside the “pressure” chamber was nearly an order of magnitude lower than inside the “suction” chamber. Dispersion equations were used to separate mass flow and diffusion components of the total flux. Simplified analysis showed that mass flow could account for the large CO2 flux with slight negative pressures inside the chamber.