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This article in SSSAJ

  1. Vol. 31 No. 2, p. 244-247
    Received: Feb 7, 1966
    Accepted: Nov 28, 1966

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Sampling for Pedographic Modal Analysis of an Argillic Horizon1

  1. C. J. Milfred,
  2. F. D. Hole and
  3. J. H. Torrie2



Pedographic modal analysis expresses soil composition in terms of the relative amounts of constituents observed in thin sections. Data are presented on the sampling density necessary for pedographic modal analysis of an argillic horizon. Thirty-one randomly selected samples (100cc cores) were obtained from a 61 cm by 61 cm vertical exposure of the horizon. Four thin sections were made from each core. Six constituents were counted in each thin section by the point count method of modal analysis. Constituents less than 50 µ in diameter were classified as matrix, while those larger than 50 µ were classified as glaebules, pores, papules, argillans, or skeleton grains.

Results indicate that a sample adequate to measure these constituents in an argillic horizon with a standard error 10% of the mean would involve taking 21 cores, making 2 thin sections per core, and counting 1,000 points per thin section.

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