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Soil Science Society of America Journal Abstract -

Infrared Dehydration Method for Determining Gypsum Content of Soils1


This article in SSSAJ

  1. Vol. 47 No. 6, p. 1089-1091
    Received: Dec 6, 1982
    Accepted: Aug 1, 1983

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  1. A. M. Elprince and
  2. A. M. Turjoman2



A Mettler drying unit (Model LP12) and a top-loading balance (Model PL60) were used for determining gypsum in soils. Plotting the rate of weight loss against time upon heating by infrared (IR) radiation (at 123 or 156°C) gave a dehydration curve made of two peaks. The first peak was due to soil moisture and the second to the crystal water of gypsum. Percent gypsum was determined by extrapolation the dehydration curve (vida infra) to rate = 0. The use of computer graphics in developing the curves made this method very rapid (about 15 min per determination). The reproducibility of the IR method (σ = 0.48) was better than the barium sulfate method (σ = 0.61) over the 2 to 58% gypsum range studies. The accuracies of the two methods were comparable and estimated to be ± 0.3% gypsum when the average of triplicate determinations was used and ± 0.5% gypsum with single determinations.

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