LaMotte SOIL TEXTURE UNIT 1067 - Manual (Page 3)

12. Calculate volume of clay as shown above. To calculate percent clay in
the soil, divide value by 15. Multiply by 100. Record as % clay.
CAL CU LA TION
EX AM PLE:
Soil Separation Tube “A” reads 2.
Soil Separation Tube “B” reads 8.
Percent Sand =
Reading A x 100 = 2 x 100 = 13%
Total Volume 15
Percent Silt = Reading B x 100 = 8 x 100 = 53%
Total Volume 15
Percent Clay = Calculated Volume x 100 = 5 x 100 = 33%
Total Volume 15
Since the scientific basis of the test is the particle size and its mass, as
related to its settling time when dispersed in solution, the following table
is included for reference.
Soil Particle Diameter In mm
Very Course Sand 2.0 – 1.0
Course Sand 1.0 – 0.5
Medium Sand 0.5 – 0.25
Fine Sand 0.25 – 0.10
Very Fine Sand 0.10 – 0.05
Silt 0.05 – 0.002
Clay Less than 0.002
IN TER PRE TA TION
Sandy soil is described as soil material that contains 85% or more sand.
The percentage of silt plus 1.5 times the percentage of clay shall not
exceed 15.
Silt soil is described as soil material that contains 80% or more silt and less
than 12% clay.
Clay soil is described as soil material that contains 40% or more clay, less
than 45% sand and less than 40% silt.