Assessments of soil carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) emissions are critical for determination of the agricultural practices' potential to mitigate global warming. This study evaluated the photoacoustic spectroscopy (PAS) for the assessment of soil greenhouse gases (GHG) fluxes in comparison to the standard gas chromatography (GC) method. Two long-term experiments with different tillage and cropping systems over a Paleudult were evaluated using static chambers. PAS measurements of CO 2 and N 2O concentrations showed good relationship and linearity (R 2=0.98 and 0.94, respectively) with GC results. However, CH 4 measurements were significantly affected by air sample moisture which interfered on CH 4 detection by PAS. Overestimation of CO 2 and N 2O concentrations in air samples determined by PAS (14.6 and 18.7%, respectively) were also related to sampling moisture. CO 2 and N 2O fluxes showed good agreement between methods (R 2=0.96 and 0.95, respectively), though PAS overestimated fluxes by 18.6 and 13.6% in relation to GC results, respectively. PAS showed good sensitivity and was able to detect CO 2 and N 2O fluxes as low as 332 mg CO 2 m -2 h -1 and 21g N 2O m -2 h -1. PAS analyzer should be detailed calibrated to reduce humidity interference on CO 2, CH 4 and N 2O concentrations measurements avoiding overestimation or erroneous determination of soil GHG fluxes.
