An improved technique for measuring concentration of soil gases at depth in situ

Measurements of gas fluxes at the soil surface are useful for determining exchanges of gases between the soil and the atmosphere, but they may not be representative of total gas production below the surface. Here we present an improved technique that enables sampling of soil atmosphere gas from ally depth in the soil profile, regardless of soil moisture status. The method utilises the equilibration of gas from the soil pore space with that in a small headspace probe by means of diffusion through a silicone rubber membrane. The method demonstrated is capable of 98 +/- 1% recovery of soil-entrapped CH4 and N2O and has potential for use in a wide range of circumstances.