Directions Drop > Soil Textural Class Determination

How to determine the textural class of a soil sample:

1. Add about 2 Tbsp of loose soil to the palm of your non-dominant hand. Add water drop by drop, working each drop into the soil before adding the next until soil is saturated, but not gooey (if too much water is added, work in some more soil).
2. Feel the soil by squeezing it and rubbing it with your fingers.
· If the soil has a very gritty feel, it is a sandy soil (see Section 1 to determine what type of sandy soil).
· If the sample feels sticky or is firm, it is a clayey soil (see Section 2 to determine what type of clayey soil).
· If the soil feels doughy, smooth, or silky, it is a "silt loam" or a "loam" (see Section 3 to determine which).

Section 1: Sandy Soils
Try to make the sample into a ball by rubbing it in a circular motion between your palms.
· If the sample cannot be rolled into a ball, it is a "sand".
· If the sample can be rolled into a ball, but falls apart extremely easily, it is a "loamy sand".
· If the sample can form a fairly stable ball, try to flatten the ball
· If the ball falls apart, the soil is a "sandy loam"
· If the ball flattens, try forming it into a rope by rolling it back and forth between your palms.
· If the sample cannot form a rope smaller than 1cm in diameter, the soil is a "loamy sand".
· If the sample can form a rope smaller than 1cm in diameter, but not less than .5cm in diameter, the soil is a "sandy loam".

Section 2: Clayey Soils
Smear the sample by rubbing it with your thumb against the side of your index finger using moderate pressure.
· If the surface is shiny with visible sands, the soil is a "sandy clay".
· If the surface is totally smooth and very shiny, the soil is a "clay".
· If the surface is totally smooth and has a dull luster, the soil is a "silty clay".
· If the surface is not totally smooth (few irregularities), try feeling it again by squeezing and rubbing it between your fingers.
· If the sample feels very gritty, the soil is a "sandy clay loam".
· If the sample feels slightly gritty, the soil is a "clay loam".
· If the sample feels doughy, the soil is a "silty clay loam".

Section 3: Silt Loams And Loams
· If the soil feels floury, it is a "silt loam".
· If the soil feels a little gritty but not sticky, it is a "loam"
October 26, 2004 | Unregistered CommenterJulie Hill
Nice to blog. Class is best.
October 27, 2004 | Registered CommenterMarybeth Shea