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 e xchanges of gases between the soil and the atmosphere, but they may not be representative of total gas production below the surface. Here we present a n 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 s mall headspace probe by means of diffusion through a silicone rubber membra ne. The method demonstrated is capable of 98 +/- 1% recovery of soil-entrap ped CH4 and N2O and has potential for use in a wide range of circumstances.