6400-09 Soil CO2 Flux Chamber
Making Soil CO2 Flux Measurements with the LI-6400XT
The 6400-09 Soil CO2 Flux Chamber is an accessory that provides additional versatility for the LI-6400XT system. The 6400-09 attaches directly to the sensor head of the LI-6400XT — the mixing fan in the sensor head is used to move air through a perforated manifold in the 6400-09, thoroughly mixing the air in the chamber. OPEN instrument software includes a configuration for the 6400-09, simplifying the switch between photosynthesis measurements and soil respiration.
The 6400-09 includes a soil temperature probe that connects to the LI-6400XT, which allows for temperature measurements to be integrated into the data set. Also included with the chamber are PVC soil collars, gaskets, and hardware to interface the 6400-09 with the LI-6400XT sensor head.
The LI-6400XT and the 6400-09 address many of the challenges of making soil CO2 flux measurements, including:
- The chamber concentration is automatically scrubbed to just below an ambient target, and then measured as it rises to slightly above ambient. This maintains the CO2 concentration gradient to within a few ppm of the natural, undisturbed value.
- Following each measurement, the intermediate flux data are fit with a regression, which is then used to compute the soil CO2 flux at the target ambient CO2 concentration.
- Automated cycling ensures that CO2 flux measurements are accurate and repeatable.
- A pressure equilibration tube is used to eliminate pressure differentials and avoid chamber leaks.
- Air inside the 6400-09 is thoroughly mixed while maintaining a constant pressure; this, along with a water vapor dilution correction, results in consistently accurate data.
Measuring Soil CO2 Flux?
The LI-8100A Soil CO2 Flux System is ideally suited for this measurement.
Soil CO2 Flux System
- Measures CO2 exchange from soils
- Multiplexed configuration available for larger sampling area
- Useful for survey or long-term measurements