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This article in SSSAJ

  1. Vol. 59 No. 1, p. 218-223
    Received: Nov 24, 1993

    * Corresponding author(s):
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Freeze-Drying Effects on Wet and Dry Soil Aggregate Stability

  1. J. A. Staricka  and
  2. G. R. Benoit
  1. Southwest Experiment Station, P.O. Box 428, Lamberton, MN 56152
    USDA-ARS North Central Soil Conservation Research Lab., Morris, MN 56267



Freeze-drying of soil aggregates may reduce aggregate size and increase erosion potential. We investigated whether freeze-thaw frequency, water content, and initial aggregate size influences the freeze-drying disruption of soil aggregates, as measured by dry and water-drop-impacted wet sieving. Aggregates of two western Minnesota soils, Barnes loam (a fine-loamy, mixed Udic Haploboroll) and Hamerly clay loam (a fine-loamy, mixed, frigid Aeric Calciaquoll) were tested. Vulnerability to wet sieving was increased much more by freeze-drying than was vulnerability to dry sieving. Freeze-drying decreased wet aggregate stability in 85 of 96 cases and dry aggregate stability in 56 of 96 cases. Initial water content largely determined whether freeze-drying decreased aggregate stability. For water contents of 0.05, 0.15, 0.25, and 0.35 kg kg−1, the mean weight diameters (water-drop-impacted wet sieving method) of freeze-dried aggregates were 93, 64, 48, and 46%, respectively, of their non-freeze-dried values. For dry sieving, values for the same four water contents were 100, 103, 90, and 88%, respectively. The detrimental effects also generally increased as aggregate size increased. Freeze-thaw frequency and soil type had less effect on freeze-drying disruption than did water content and initial aggregate size. Thus soil surface resistance to breakdown by freeze-drying and raindrop impact would be expected to decline as initial aggregate size and soil water content increases.

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