1. Texture: This refers to the relative proportions of sand, silt, and clay particles in the soil. It's determined by feeling the soil and analyzing its particle size distribution. Texture influences:
* Water holding capacity: Clay holds more water than sand.
* Drainage: Sandy soils drain quickly, while clay soils drain slowly.
* Aeration: Sandy soils have good aeration, while clay soils have poor aeration.
* Workability: Clay soils are more difficult to work than sandy soils.
2. Structure: This refers to the arrangement of soil particles into aggregates. Good structure allows for:
* Better drainage: Water can easily move through well-structured soil.
* Improved aeration: Air can easily move through well-structured soil.
* Increased root growth: Roots can easily penetrate well-structured soil.
3. Color: Soil color can indicate:
* Organic matter content: Darker soils generally have more organic matter.
* Drainage: Well-drained soils are often lighter in color than poorly drained soils.
* Mineral content: Certain minerals can impart specific colors to the soil.
4. Consistence: This refers to the resistance of the soil to deformation or crushing. It's influenced by:
* Moisture content: Wet soil is more cohesive than dry soil.
* Organic matter content: Soils with high organic matter content are more friable (crumbly) than those with low organic matter content.
* Clay content: Soils with high clay content are more plastic and sticky than those with low clay content.
5. Density and Bulk Density: These properties relate to the mass of soil per unit volume. They influence:
* Water infiltration: Dense soils have poor infiltration, while loose soils have good infiltration.
* Root growth: Dense soils are difficult for roots to penetrate.
6. Porosity: This refers to the amount of pore space in the soil. It's important for:
* Water storage: Porous soils hold more water than non-porous soils.
* Aeration: Porous soils have good aeration.
* Root growth: Porous soils allow for easy root growth.
In addition to these physical properties, chemical and biological properties also play a role in soil classification. However, the emphasis is on physical properties when classifying soils based on the USDA soil taxonomy system.
