Portable soil respirometer system

After having great success with the laboratory multi-chamber soil respirometer system, we built a portable version that could be deployed in the field for in-situ measurements.  It still uses the same Licor LI-840 gas analyzer system and a smaller Arduino controller, based on the Sparkfun ArduinoPro board since it has better power efficiencies than the Uno, which is important for battery-powered operation.  Data is still displayed on an LCD screen and recorded to an SD card.  The Arduino controls 3 pairs of solenoids, and a small circulation pump provides the air flow through the remote chambers and through the gas analyzer.  The entire control and measurement  system is mounted in a waterproof toolbox, and the air and power connections go through bulkheads in the case wall.  It is powered by a set of deep-cycle marine batteries mounted in a separate case.