Relationships among soil components
This chart is broadly used for determining what type
of soil we are dealing with. It is possible to estimate
texture of soil “on the field” (Portland Cement
Association. 1962. PCA Soil Primer)
Sand: Individual grains can be seen and felt readily.
Squeezed in the hand when dry, this soil will fall
apart when the pressure is released. Squeezed when
moist, it will form a cast that will hold its shape
when the pressure is released but will crumble when
Sandy loam: Consists largely of sand, but has
enough silt and clay present to give it a small
amount of stability. Individual sand grains can be
seen and felt readily. Squeezed in the hand when dry,
this soil will fall apart when the pressure is released.
Squeezed when moist, it forms a cast that will not
only hold its shape when the pressure is released but
will withstand careful handling without breaking. The
stability of the moist cast differentiates this soil from
Loam: Consists of an even mixture of the different
sizes of sand and of silt and clay. It is easily
crumbled when dry and has a slightly gritty, yet fairly
smooth feel. It is slightly plastic. Squeezed in the
hand when dry, it will form a cast that will withstand
careful handling. The cast formed of moist soil can
be handled freely without breaking.
Silt loam: Consists of a moderate amount of fine
grades of sand, a small amount of clay, and a large
quantity of silt particles. Lumps in a dry, undisturbed
state appear quite cloddy but they can be pulverized
readily; the soil then feels soft and floury. When wet,
silt loam runs together and puddles. Either dry or
moist casts can be handled freely without breaking.
When a ball of moist soil is pressed between thumb
and finger, it will not press out into a smooth,
unbroken ribbon but will have a broken appearance.
Clay loam: A fine-textured soil which breaks into
clods or lumps that are hard when dry. When a
ball of moist soil is pressed between the thumb
and finger, it will form a thin ribbon that will break
readily, barely sustaining its own weight. The moist
soil is plastic and will form a cast that will withstand
Clay: A fine-textured soil that breaks into very
hard clods or lumps when dry, and is plastic and
unusually sticky when wet. When a ball of moist soil
is pressed between the thumb and finger, it will form
a long ribbon.
Concerning texture, agricultural use of soils has
limit only for sand and loamy sand soils. Of course,
other limits exist depending on factors as slope,
permeability, climate, rock presence and others.