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8.2: Activity 1 - Aggregate Stability

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    Slake Test

    1. Carefully select one in-tact soil aggregate from the available soil.
    2. Place the soil aggregate on the sieve.
    3. Fill the beaker with approximately 1.5 inches of water, or so that the soil aggregate will be just immersed in water when lowered into the beaker.
    4. Lower the sieve into the beaker of water. Observe the soil aggregate for 5 minutes and keep track of the timing of structural loss. Refer to the stability class table below to determine class 1 and 2.
    5. Once stability class 1 and 2 are determined, raise the sieve + aggregate out of the water for one second, and immerse again for another second.
    6. Repeat immersion 4 times. Refer to the stability class table below to determine and record stability classes 3 through 6.

    Table 1. Stability class table (Source: USDA NRCS Soil Quality Test Kit)

    Screen Shot 2021-06-24 at 07.46.40.png


    1. Aggregates of soils high in organic matter are more stable than are those low in OM. Which soil aggregates fall apart when wetted, and which will maintain their stability?
    2. Discuss the positive and negative impacts of tillage on soil structure. What is a physical consideration in deciding whether to utilize this practice on agricultural land?
    3. What are 3 management strategies to support and promote soil aggregation?

    This page titled 8.2: Activity 1 - Aggregate Stability is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Anna R. Schwyter & Karen L. Vaughan (UW Open Education Resources (OER)) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.