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Soil Science Society of America Journal Abstract -

Non-Steady-State Moisture, Temperature, and Soil Air Pressure Approximation With an Electric Simulator1


This article in SSSAJ

  1. Vol. 24 No. 4, p. 247-252
    Received: Nov 16, 1959
    Accepted: Mar 30, 1960

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  1. R. J. Hanks and
  2. S. A. Bowers2



An electric simulator was used to approximate the non-steady-state, one-dimensional solution of several moisture, temperature, and air pressure problems in soil. The simulator consists of a resistance-capacitance network with accessory units for setting initial conditions and recording or indicating the simulated variable with time and depth. Time and distance can be scaled to convenient magnitudes. Provision for changing the simulated diffusivity with distance and time allows for the approximate solution of several types of moisture problems. An example of absorption, redistribution after absorption, and evaporation from Yolo light clay is given. The absorption solution compares favorably with the mathematical solutions of Klute and Philip.

Comparison of mathematical and simulated solution of temperature distribution in a soil with constant diffusivity and temperature varying sinusoidally at the surface shows excellent agreement. The soil temperature (fluctuating with time) between two measured depths is estimated. The solution agrees reasonably with actual field measurements. The solution of the problem of air pressure fluctuation within the soil due to fluctuation at the surface is given where an impermeable layer exists at a specified depth.

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