MEASUREMENT TIME ESTIMATION OF CO2, CH4, N2O AND NH3 IN CLOSED CHAMBERS AND RECIRCULATION SYSTEM WITH PICARRO G2508 ANALYSER.

The European Union has set a target to cut its greenhouse gas emission levels by 80% to 95% until 2050, if compared to 1990. Agricultural soil is an important carbon store and food provider in the world as well as greenhouse gas emission reducer via carbon sequestration. In order to assess the climate change mitigation effectiveness of the measures, it is necessary to obtain statistically significant data before and after the implementation. The greenhouse gas measurements from soil are commonly determined using static chamber-based method in which the gas sample is collected at regular intervals and stored for later analysis by gas chromatography. Picarro G2508 performs measurements in field or laboratory directly from the chamber with the interval of one second. The aim of the study was to determine the optimal measurement time for greenhouse gas measurements in different soil types by using mobile ring-down spectrophotometer Picarro G2508. N₂O, CH₄, CO₂, NH₃ and measurement data from four chambers and laboratory experiments were used. Field measurements were carried out using static chambers with the diameter of 23 cm and volume of 3 litres, which was connected to the Picarro G2508 via tube with an outer diameter of 0.125 inches. Recirculation system with the chamber volume of 2 litres was used to make the laboratory experiment. The linear regression was used to evaluate the measurement time and to compare the stability of emission coefficients. The results showed that statistically significant optimum measurement time is 8-10 minutes on a field and 2-4 minutes in laboratory. [ABSTRACT FROM AUTHOR]