Unit

Sedimentation Test of Soil Texture

1. Describe the concept of soil texture and its importance.

2. Identify the classes of soil separates.

Objectives

3. Use a soil textural triangle to identify fine, medium, and coarse textured soils.

5. Explain why it is difficult to change the soil texture.

4. Identify the texture of a sample of soil.

Objectives

Bulk densityClayCoarse textureFine textureLoamMedium texture

Particle densityPore spaceSandSiltSoil separates Soil texture

Terms

- Soil texture is the comparison of soils due to their separates.

- Sand is the largest soil particle, as it offers the most drainage.

What is soil texture and why is it important

- Clay is the smallest soil separate, as it offers the least drainage.

- Silt is a medium sized soil particle that drains between fast and slow.

- Loam is a mixture of relatively equal amounts of sand, silt or clay.

Soil Texture/importance

- The soil texture also affects pore

space, a portion of the soil not occupied

by solid material but filled with air or

water. The larger the soil particle the

larger the pore spaces. Small particles

have more spaces but they are smaller

in size.

Soil Texture/importance

- Particle density is the mass per unit

volume of the soil and is determined

largely by the texture. The Bulk density of

the soil is the particle density after the

water has been dried. The density is a

major factor in dealing with root movement

and stability of the soil.

Soil Texture/importance

- Soil separates are classes of soil material less than 2 millimeters in diameter.

What are the classes of soil separates?

- Medium texture soils have intermediate amounts of sand and clay, with a large representation of silt.

- Fine texture represents soils that are composed mainly of clay.

- Coarse texture represents those soils that are largely composed of sand.

Classes of soil separates

How can soil textural triangle determine fine,

medium and coarse textured soils?

- The soils can be separated into their separates by mixing the soil with water and letting the particles settle. Once settled the percentages of each can be evaluated using the texture triangle.

-is a tool that is used to determine soil texture.

Soil texture triangle

Soil texture triangle

- The triangle will separate the soil into classes as well as coarse, fine and medium textured soils.

Textural Triangle

Texture Classification

- Soil texture can be determined in many ways.

How can you identify the texture of a soil sample?

- The ribbon method where soil is pressed between the thumb and index finger is a quick method of determining soil texture. If a long ribbon can be formed the soil is fine in texture. If no ribbon is formed the soil is coarse in texture.

- The sedimentation method using the texture triangle is the most detailed method.

Identify the texture of a soil sample?

- Soil texture is a natural characteristic of soil.

Why is it difficult to change soil texture?

A. The relative components of the soil separates are established by the soil early in formation. They do not change without major environmental conditions.

B. Agricultural land is very large and an attempt to mix soil separates manually would be impossible. Texture cannot be mixed without nature. Organic matter can help change texture but takes many years to begin to work.

Soil Texture Characteristic

Particle Sizes.

Soil Separates