Textural Triangle
Scientists created the textural triangle to classify soil into 12 texture categories. The
categories include clay, sandy clay, sandy clay loam, clay loam, silt, silty clay, silty
clay loam, sand, loam, loam and silt loam. The textural triangle is a diagram which
helps determine the 12 categories based on what percentage of sand, silt and clay is
in the soil. There are three sets of lines on a textural triangle. The diagonal lines
which reach the bottom and lean to the left represent sand. The horizontal lines
represent clay. The diagonal lines which reach the bottom and lean to the right
represent silt.
S
T
U
D
E
N
T
H
A
N
D
O
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T
Using the Textural Triangle
For this example, the soil sample contains 50 percent sand and 40 percent clay.
1. First, determine the percentage of sand, silt and clay in the soil.
2. Next, determined the percent of sand and mark a line at the percent determined.
Accompanies: Soil Formation & Evaluation
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Textural Triangle
3. Then, mark a line at the percent of clay which has been determined.
S
T
U
D
E
N
T
H
A
N
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O
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T
4. The intersection of the sand and clay lines will give the percentage of silt in the
soil, as well as the category of soil.
The intersection shows the soil is
a sandy clay and 10 percent silt.
Accompanies: Soil Formation & Evaluation
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