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This article in SSSAJ

  1. Vol. 49 No. 1, p. 25-28
    Received: Apr 12, 1984
    Accepted: Sept 13, 1984

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Gas Displacement and Aggregate Stability of Soils1

  1. W. D. Kemper,
  2. Russell Rosenau and
  3. Sheldon Nelson2



When surface soils are dry, O2 and N2 are adsorbed on the external mineral surfaces. In the process of wetting the soil, water molecules displace the adsorbed O2 and N2 molecules to the gas phase where they can be measured, as was done in this study. These gases, released from the adsorbed phase, join entrapped air in the gaseous phase as the primary factor disintegrating aggregates when soils are wet quickly. Adsorption of N2 and O2 occurs on surface soils during hot dry afternoons as the water molecules leave the surface. During cool nights, relative humidities commonly rise above 50%, allowing more strongly adsorbed H2O molecules to displace adsorbed O2 and N2. Release of this adsorbed N2 and O2 causes aggregates wetted by immersion during hot afternoons to be less stable than aggregates of the same soil wetted in the morning.

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