A review of the movement and fate of N2O in the subsoil

Understanding the fate of N2O in the subsoil is important in accurately assessing the direct and indirect fluxes of N2O to the environment. The production, movement and ultimate fate of N2O in the subsoil are all poorly understood. Movement of N2O in the subsoil occurs predominantly via diffusion but convective fluxes can also occur. Diffusion gradients in the soil have been used to determine N2O surface fluxes with varying success. Infiltration of water into the soil may lead to entrapment, and the temporary storage of N2O, ebullition, or the transport of dissolved N2O in soil leachates. The reduction of N2O to N-2 is potentially enhanced when N2O is entrapped. Few studies have examined the effect of infiltrating water on a previously known N2O concentration in the soil. Future studies are required to better establish the consumption and movement of N2O in the subsoil during water infiltration. This paper reviews past work on the movement and fate of N2O in the subsoil and makes suggestions for future studies.