GPE Chapter 12
Terms
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- Parent material
- The source of the weathered fragments of rock from which soil is made; solid bedrock or loose sediments that have been transported from elsewhere by the action of water, wind, or ice.
- Litter
- The collection of dead plant parts that accumulate at the surface of the soil.
- Humus
- A dark-colored, gelatious, chemically stable fraction of organic matter on or in the soil.
- Illuviation
- The process by which fine particles of soil from the upper layers are deposited at a lower level.
- Leaching
- The process in which gravitational water dissolves soluable materials and carries them downward in solution to be redeposited at lower levels.
- Soil-water balance
- The relationship between gain, loss, and storage of soil water.
- Field Capacity
- The maximum amount of water that can be retained in the soil after the gravitational water has drained away.
- Wilting Point
- The point at which plants no longer able to extract moisture from the soil because the capillary water is all used up or evaporated.
- Soil-water budget
- An accounting that demonstrates the variation of the soil-water balance over a period of time.
- Separates
- The size groups within the standard classification of soil particle sizes.
- Loam
- A soil texture in which none of the three principal soil separates - sand, silt, and clay - dominates the other two.
- Ped
- A larger mass or clump that individual soil particles tend to aggregate into and that determines the structure of the soil.
- Colloids
- Organic and inorganic microscopic particles of soil that represent the chemically active portion of particles in the soil.
- Cation Exchange Capacity
- Capability of soil to attract and exchange cations.
- Horizon
- The more or less distinctly recognizable layer of soil, distinguished from one another by differing characteristics and forming a vertical zonation of the soil.
- Soil Profile
- A verticle cross section from Earth's surface down through the soil layers into the parent material beneath.
- Solum
- The true soil that includes only the top four horizons: O, the organic surface layer; A, the topsoil; E, the eluvial layer; and B, the subsoil.
- Pedogenic regimes
- Soil-forming regimes that can be thought of as environmental settings in which certain physical/chemical/biological processes prevail.
- Soil Taxonomy
- The system of soil classification currently in use in the U.S. It is genetic in nature and focuses on the existing properties of the soil rather than on environment, genesis, or the properties it would possess under virgin conditions.