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This article in SSSAJ

  1. Vol. 54 No. 1, p. 55-59
    Received: Mar 29, 1989

    * Corresponding author(s):
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Steady-State Procedure for Determining the Effective Particle-Size Distribution of Soil Carbonates

  1. R. C. Hartwig,
  2. R. H. Loeppert  and
  3. T. J. Moore
  1. Dep. of Soil & Crop Sciences, Texas A&M Univ., College Station, TX 77843
    ARCO Oil and Gas Co., 2300 W. Plano Parkway, Plano, TX 75075



A pH-stat procedure in conjunction with the equal-diameter reduction model was used to estimate the effective particle-size distribution of soil carbonates. Samples were titrated by pH-stat at pH 3 and 5. The cumulative dissolution data and rate constants for the dissolution of Iceland-spar calcite were incorporated into simultaneous equations to obtain estimates of the effective particle-size distributions of soil carbonates. Results obtained by this method from 23 calcareous soils were compared with results obtained by a sieving and sedimentation procedure. The pH-stat procedure resulted in the estimation of a higher proportion of clay-size carbonates than was obtained by the sieving and sedimentation procedure. This difference was attributed predominantly to the higher reactivity of soil carbonates compared with Iceland-spar calcite. The pH-stat procedure was especially useful for obtaining quantitative estimates of the proportion of highly reactive clay-size carbonate with <0.2-µm effective particle diameters.

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