Comparison of greenhouse gas emissions monitored with a photoacoustic infrared spectroscopy multi-gas monitor and a gas chromatograph from a Crosby silt loam

The photoacoustic infrared spectroscopy multi-gas monitor (PAS) method is a promising technique for in situ monitoring of gaseous emissions in agricultural soils. However, few studies have been done to evaluate its accuracy and precision under different management practices, soil and environmental conditions. Thus, the objectives of this study were to provide information regarding the PAS method, and compare it to the gas chromatograph (GC) method's results for GHG emission, and to discuss the PAS and GC methods in terms of operation simplicity and time, precision, cost and efficiency of gaseous flux measurements. Emissions of CO2 by PAS and GC methods were within 1.4 to 7.5% and 0.3 to 5.1% of each other in 2012 and 2013, respectively. Similarly emissions of N2O measured by PAS and GC methods for 2012 and 2013 were within 18.4 to 30.7%, and 3.4 to 10.6% of each other, respectively. The accuracy and precision of GHG emissions with the PAS and GC methods are similar and comparable. For field measurement of GHG emission, the PAS method is better than the GC method in terms of ease of operation, time required, cost and sample variation.