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Calculators

Soil Classification Calculator LEL


The USDA classifies soils into twelve types which it calls textures. This classification is based on the relative percentages of sand, silt and clay. This can be visualized by the use of the USDA Soil Textures Triangle (below).

(Please read disclaimer below before using this form)
Collect 2 shovels full of soil to a depth of 8-12 inches in a large bucket at the desired location. Remove all rocks and loose vegetative matter-twigs, etc. Mix up the remainder thoroughly. Place 2-4 cups of this material into a jar. Add water to completely cover. Add non-foaming detergent (dishwasher soap). Shake vigorously until the material has gone into solution. Set jar aside and allow the material to settle into distinct layers.
Figure 1
Sediment Measurement
Using a ruler determine the location of the top of the SAND (A), the SILT (B), and the CLAY (C). Note: if any of the layers is missing use the reading from the lower sediment. The readings may be entered in either decimal or fraction notation, i.e. 2.5 or 2 1/2. Enter the values into the Classification Calculator below and click the CALCULATE button. The percentage of each material and the soil Classification will be shown.
SOIL CLASSIFICATION CALCULATOR
Measurement A
(SAND)
  UNITS
Measurement B
(SILT)
  UNITS
Measurement C
(CLAY)
  UNITS
ANSWER


Disclaimer: This determination is based on the use of the USDA Soil Textures Triangle and is only meant to assist the Master Gardener in determining the approximate soil type in a desiginated area. The results are only as accurate as the data entered. The measurement technique described is not designed or intended to serve as a substitute for USDA standard measurement techniques to determine particle size and types or the use of calibrated equipment. For more accurate determination you should act in accordance to the standard practices involved in the determination of soil texture.

Note: The system for determining USDA texture is significantly different from the Unified and the American Association of State Highway and Transportation Officials (AASHTO) systems that are traditionally used by engineers. The USDA texture depends entirely on particle size; the Unified and AASHTO designations depend not only on particle sizes (with differing cutoffs between particle sizes among the three systems) but also on other properties such as Atterberg limits (liquid limit and plasticity index). There is, unfortunately, no way to translate directly from the USDA system to the other systems and back.


USDA Soil Textures Triangle

USDA classification

Sand
Soil particles between 0.05 and 2.0 mm in size
Can be further divided into coarse, medium, and fine sand with a sieve test
Silt
Soil particles between 0.002 mm and 0.05 mm
Clay
Soil particles smaller than 0.002 mm (2 microns) in size