OBJECTIVES - Describe soil by physical, chemical, and biological properties of the soil.
- Distinguish among physical, chemical, and biological properties of the soil.
- Distinguish between homogenous and heterogeneous mixtures in soil.
Objective 1: TERMS TO KNOW: - Clay- The smallest soil particle
- Sand - The largest soil particle
- Silt - An intermediate sized soil particle
- Structure - The way individual soil particles are grouped together
- Texture - A physical property of the soil referring to the relative percentages of sand, silt, and clay
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Objective 1: TERMS TO KNOW: (Cont’d) - Topsoil - The upper part of the soil profile that is normally cultivated
- Subsoil - the area in the soil profile below the topsoil which accumulates clay
- Subsoiling - A method of breaking up the compacted layers of the soil that restrict air and water movement and root growth using farm machinery
- Tillage pan - areas of compacted soil in the plant root zone created by repeated plowing of heavy soils especially when wet; also called a plow pan
- Mottling - Spots of color in the soil that indicates internal drainage and aeration
Texture - physical property of soil considered rather permanent
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- refers to the relative percentages of the three types of soil particles
Textural Triangle Light Soils vs Heavy Soils - Light Soils - sandy or coarse texture
- Heavy Soils - clay or fine texture
- Loamy Soils - medium textured
Light Soils vs Heavy Soils - When comparing light soils to heavy soils, the light soil will:
- require less energy to cultivate
- heat and cool faster
- usually lighter in color
- wet and dry faster
- usually subject to greater erosion
- usually lower in fertility
Four Main Types of Soil Structure - Platy - thin horizontal sheets overlapping each other
- Prismatic - long vertical columns without rounded tops
- Block-like - irregular shaped cubes
- Spheroidal - rounded and often referred to as granular or crumb; usually found in the topsoil
Biological Properties of Soil – Food Web
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