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Geosciences LibreTexts

1.5: Activity 4 - Soil Texture

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    14433
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    Section: _____________________________

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    Read through and complete the following activity and questions. All questions should be answered and completed labs are due at the end of the laboratory period. No late work will be accepted.

    Known Soil Samples to be Identified:

    Sample Soil Characteristics (grittiness, stickiness, ribbon length, etc.) USDA Textural Class

    1

    2
    3

    Unknown Soil Samples to be Identified:

    Sample Soil Characteristics (grittiness, stickiness, ribbon length, etc.) USDA Textural Class

    1

    2

    1) Define soil texture.

    2) What differences do you notice between the feel of the sand and the feel of the silt separates?

    3) Which soil separate will settle most rapidly to the bottom of the lake?

    4) Practice determining the textural class for these soils:

    Soil Sample Sand % by mass Silt Clay USDA Soil Textural Class
    A 65 25 10 Sandy Loam
    B 40 40 20
    C 50 25 25
    D 10 70 20
    E 40 10 50
    F 17 46 37

    5) What is the lowest clay percentage allowed for a texture to be classed as:

    clay = clay loam =
    sandy clay loam = sandy clay =

    6) What is the lowest silt percentage allowed for a texture to be classed as:

    loam = silt loam = silt =

    7) A dry soil sample weighing _25_ grams in total contains _8_ grams of sand, _15_ grams of clay, and the remainder is silt. Calculate the percentages of sand, silt and clay and determine the soil's textural class. Show the appropriate units and complete setup for each calculation of this problem.

    % Sand =

    % Silt =

    % Clay =

    USDA Textural Class =

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