Attachment_6_Soil_Moisture_Content.pdf

Soil Moisture Content

Soil indicators for dry soil are detailed below in Table A. If the soil forms a clod from the upper six inches of soil it is too wet to work. Table A provides visual clues to discern when operation on soils should be avoided or mitigated by a slash mat.

Table A. Dry and wet soil designation. Protocol for determining operability of soils based on soil moisture at 4 to 8 inch depth. Yellow highlights soil conditions to avoid.

Soil

Moisture

Increases

Downward

Coarse Soils

Loamy sands, fine sandy loam, very fine sands, coarse sands

Light Soils

Fine sandy loams, sandy loams, very fine sandy loam

Med. Soils

(<35% clay)

Sandy clay loam, loam, silt loam, sandy clay loam, clay loam

Heavy Soils

(>35% clay)

Clay loam, sandy clay, silty clay loam, clay

Dry soils

Dry, loose, single grained flows thru fingers

Dry, loose, flows thru fingers

Powdery, dry, sometimes slightly crusted but breaks down into powdery conditions

Hard, baked, cracked sometimes has loose crumbs on surface

Slightly moist soil

Still appears dry, will not form a ball with pressure

Still appears to be dry; will not form a ball

Somewhat crumbly, but will hold together from pressure

Somewhat pliable;

will form ball under pressure. At plastic limit.

Moist soil

Still appears dry, will not form a ball with pressure

Tends to ball under pressure but seldom will hold together

Forms a ball and is very pliable, sticks readily if high in clay.

Easily ribbons out between fingers, has a slick feeling.

At plastic limit.

Very moist soil

Tends to stick together slightly, sometimes forms a very weak ball

Forms a weak ball breaks easily, will not stick. Plastic limit or nonplastic.

Forms a ball and is very pliable, sticks readily if high in clay.

Exceeds plastic limit.

Easily ribbons out between fingers, has a slick feeling.

Exceeds plastic limit.

Wet soils

Upon squeezing, free water may appear.

Wet outline is left on hand. Nonplastic.

Upon squeezing free water may appear. Wet outline left on hand.

Can squeeze out free water. Wet outline left on hand.

Puddles and free water forms on surface. Wet outline left on hand.