Soil Science

Skip Navigation LinksHome > September 2012 - Volume 177 - Issue 9 > Soil-Gas Phase Transport and Structure Parameters for a Soil...
Text sizing:
Soil Science:
doi: 10.1097/SS.0b013e318267ec85
Technical Article

Soil-Gas Phase Transport and Structure Parameters for a Soil Under Different Management Regimes and at Two Moisture Levels

Eden, Marie1; Moldrup, Per2; Schjønning, Per1; Scow, Kate M.3; de Jonge, Lis W.1

Collapse Box


Abstract: Measurements of diffusive and convective gas transport parameters can be used to describe soil functional architecture and reveal key factors for soil structure development. Undisturbed 100-cm3 soil samples were sampled at the Long-term Research on Agricultural Systems experiment located at the University of California, Davis. The 18 plots used in this study represented fairly wide ranges in organic carbon (0. 0072–0.0153 kg kg−1) and clay (0.30–0.44 kg kg−1). Soil-air permeability, ka, and soil-gas diffusivity, DP/D0, were determined at field-moist conditions (fm) and, subsequently, after saturation and drainage to −100 cm of matric potential (pF2). Gas diffusivity in intact samples at fm conditions exhibited a general, linear relationship with air-filled porosity ([Latin Small Letter Open E]), independent of soil texture and treatment. Comparing intact and repacked samples drained to pF2, repacked soil displayed markedly lower DP/D0 values at similar air-filled porosity, illustrating soil structure effects on DP/D0. The Currie tortuosity-connectivity parameter, X = Log(DP/D0)/Log([Latin Small Letter Open E]), decreased with increasing bulk density in the intact samples at both moisture conditions, suggesting less tortuous and well-connected pathways for gas diffusion at higher bulk density. Pore organization, PO = ka / [Latin Small Letter Open E], showed a treatment effect with typically higher values for the organic plots, implying that an improved possibility for formation of organomineral soil aggregates resulted in better-connected macropore networks. Fitting a linear model to DP/D0 versus [Latin Small Letter Open E] measurements revealed different slopes at the two moisture conditions, suggesting short-term nonsingularity (hysteretic) effects after rewetting and drainage. Defining the ratio of slopes at the fm and pF2 moisture conditions as a nonsingularity index (α), the nonsingularity in DP/D0 increased with lower bulk density and higher organic carbon content.

© 2012 Lippincott Williams & Wilkins, Inc.




Article Tools


Article Level Metrics

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.