Kellman and Kavanaugh 2008

Kellman L, Kavanaugh K. 2008. Nitrous oxide dynamics in managed northern forest soil profiles: is production offset by consumption? Biogeochemistry 90: 115-128.

These authors measured surface flux and subsurface profiles of N2O at a number of paired sites in the managed forest of Nova Scotia. Half of the sites were clear-cut harvested three years before the study, the other half more than 50 years previously. Climate factors such as air temperatures and solar radiation were consistent across the study area. Fluxes and profiles were measured periodically through a 9-month snow-free period in 2005, from early March to late November.

Surface fluxes were measured by pulling samples into evacuated containers from chambers mounted on permanent collars. Similarly, profiles were measured by sampling from permanent probes buried in the walls of soil pits. Actual measurement of gas concentrations were in the laboratory using a gas chromatograph system.
The soil probes consist of 50cm PVC tubes, covered with a “water resistant porous membrane” (could they be using Gore-tex?) and buried in the walls of pits at depths of 0, 5, 20, and 35cm, with 0 at the mineral soil-organic layer interface. This provides a 50cm-long sampling space at four depths, replicated across 40 sites.

The relationship between profile N2O concentrations and surface flux was almost always non-significant. These authors attribute this lack of correlation to consumption of N2O in the soil profile. In contrast, the studies that have linked CO2 profiles to surface flux have relied on the (probably true) assumption that CO2 is not consumed in the soil, and moves through diffusion in a manner that can be predicted from soil physics. N2O profiles that include regions of consumption are complicated by the biological and chemical factors that control production and consumption, as well as movement. All of this leads to a disconnection between soil N2O cycling and surface-atmosphere exchange.

This paper should almost certainly be included in the introduction, methods, and/or discussion section(s) of my pits & probes manuscript. This is one of the few studies I have found that examined N2O in soil profiles; most others appear to focus on CO2 or in some cases the biogeochemistry of CH4.