The Department of Agriculture defines soil particles as having the following diameters in millimeters: very coarse sand 2 to 1; coarse sand 1 to 0.50; medium sand 0.50 to 0.25; fine sand 0.25 to 0.10; very fine sand 0.10 to 0.05; silt 0.05 to .002; and clay below .002 millimeter.
of Wetted Area
Sand is loose and single grained. The individual grains can be seen or felt. Squeezed 5 sq.ft
in the hand when dry, it will fall apart when pressure is released. Squeezed when moist,
it will form a cast, but will crumble.
A sandy loam is a soil containing mostly sand but which has enough silt and clay to make 21 sq. ft.
it somewhat coherent. Squeezed when dry, it will form a cast which will fall apart; but if
squeezed when moist, a cast can be formed that will bear careful handling without crumbling.
A loam is a soil having a mixture of the different grades of sand, silt, and clay in such 36 sq. ft.
proportion that the characteristics, of no one predominate. Squeezed when dry, it will form
a cast that will bear careful handling, while the cast formed by squeezing the moist soil can
be handled quite freely without crumbling.
A silt loam is a soil having a moderate amount of the fine grades of sand and only a small 45 sq. ft.
amount of clay over half of the particles being of the size called "silt".When dry, it may appear
quite cloddy, but the lumps can be readily broken; and when pulverized, it feels smooth, soft,
and floury. When wet, the soil readily runs together. Either dry or moist, it will form casts than
can be freely handled without breaking.
A clay loam is a fine textured soil which usually breaks into clods or lumps that are hard when 65 sq. ft.
dry. When the moist soil is pinched between the thumb and finger, it will form a thin "ribbon
" which will break barely sustaining its own weight. The moist soil is plastic and will form a
cast that will bear much handling. When kneaded in the hand, it does not crumble easily.
A clay is a fine textured soil that usually forms very hard lumps or clods when dry and is quite 161 sq. ft.
plastic and usually sticky when wet. When the moist soil is pinched out between the thumb
and finger, it will form a long, flexible "ribbon".
*Watering time and flow rate can alter these patterns significantly.