GreenHouse Gases Emissions from Soils

This protocol addresses the measurement of greenhouse gases (GHGs) soil effl ux by soil chamber methodology. The GHGs considered are CO2, N2O or CH4. The two most used chamber based methods are presented: the Non-Steady-State Through-Flow System (NSS_TFS, also referred as closed dynamic chamber) and the Non-Steady-State Non-Through-Flow closed system (NSS_NTFS, also called closed static chamber). The difference between the two methods is related only to the presence (Through-Flow), or not presence (Non-Through-Flow), of an in-situ analyzer connected to the chamber by a closed pneumatic circuit. The NSS_TFS has the best performance in term of precision and accuracy, but the availability of in-fi eld operated analyzer limits its use. At present time, only CO2 soil effl ux is normally measured using the closed dynamic system, thanks to the availability of low cost CO2 IRGAs (Infrared Gas Analyzer). N2O and CH4 fluxes are normally measured using closed static systems by collecting gas samples to be analyzed later in the laboratory. It is expected that all three gases will be measured routinely in-fi eld (e.g. using NSS_TFS) once non dispersive close-path GHG analyzers become more affordable (Venterea et al. 2009). The protocol considers the most important precautions to guarantee accurate measure-ments of soil GHGs effl ux. These include: 1) Chamber design and deployment.2) Sampling frequency and intensity. 3) Data collection and quality check of flux calculations.