Soil Physical Properties

Bluish gray spots or patches as a result of oxidation and reduction of iron.

Mottles

Reflects the composition and the past and present oxidation-reduction conditions of the soil

Soil color

The relative distribution of sand, silt and clay particles.

Soil texture

There are ____________ soil textural classes in the Soil Textural Triangle

12

Analysis used to determine the textural class of soils. The principle is based on the Stoke’s Law where settling velocity (v) for spherical particles, in a viscous medium is equal to the square of the diameter (D) of the particles.

Particle Size Analysis

“settling velocity (v) for spherical particles, in a viscous medium is equal to the square of the diameter (D) of the particles multiplied by a constant (K)”

Stoke’s Law

Refers to the arrangement of particles and pore spaces

Soil structure

Soil density that refers to mass per volume of solids

Particle Density

For general calculations concerning arable mineral surface soils (1%–5% organic matter), a particle density of about ____________may be assumed if the actual particle density is not known.

2.65 g/cm³

Soil density that is known as an index of compaction.

Bulk density

A method used for measuring the bulk density of soils using a cylinder with known volume.

Core method

Pore sizes that range from 0.08 to 5mm and above.

Macropores

Pores that are filled with water in field soils, too small to permit air movement and water movement is slow

Micropores

Pores with size less than 0.0001 mm. It excludes all microorganisms, too small for large molecules to enter.

Cryptopores

Soil physical property which indicates how much of the bulk volume is compacted by pores

Porosity

The maximum amount of moisture the soil can hold after drainage in a given period. Moisture equivalent is attained at 1/3 bar.

Field capacity

Moisture equivalent is attained at 15 bars.

Permanent Wilting Point

The suction of water at this moisture condition is about 31 bars.

Hygroscopic Coefficient

Solve for the %Moisture content of the soil using the following:
FW = 85 grams
ODW = 78 grams

8.97%

Defined as the manifestation of the physical forces of cohesion and adhesion acting within the soil at various moisture contents including behavior towards gravity and pressure.

Soil Consistence

The attraction of dissimilar objects, in the soil, it refers to the attraction of water to soil solids

Adhesion

The result of attractive forces between similar objects

Cohesion