Sedimentation Test of Soil Texture Unit Sedimentation Test of Soil Texture

Objectives 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. 4. Identify the texture of a sample of soil. 5. Explain why it is difficult to change the soil texture.

Terms Bulk density Clay Coarse texture Fine texture Loam Medium texture Particle density Pore space Sand Silt Soil separates Soil texture

What is soil texture and why is it important - Soil texture is the comparison of soils due to their separates. - Sand is the largest soil particle, as it offers the most drainage.

Soil Texture/importance - 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.

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

Classes of soil separates - Fine texture represents soils that are composed mainly of clay. - Medium texture soils have intermediate amounts of sand and clay, with a large representation of silt. - Coarse texture represents those soils that are largely composed of sand.

How can soil textural triangle determine fine, medium and coarse textured soils?

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

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

Textural Triangle

Texture Classification

How can you identify the texture of a soil sample? - Soil texture can be determined in many ways.

Identify the texture of a soil sample? - The sedimentation method using the texture triangle is the most detailed method. - 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.

Why is it difficult to change soil texture? - Soil texture is a natural characteristic of soil.

Soil Texture Characteristic 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.

Particle Sizes.

Soil Separates