7.2 Soil Formation and Characteristics

Humus

Decayed organic matter in soil. It is essential for nutrient retention, soil structure, and moisture retention, providing vital nutrients to plants.

Components of Soil

Includes minerals, organic matter, water, air, and living organisms. These components work together to support plant growth and soil health.

Factors of Soil Formation

Parent material, organisms, climate, time, and slope of the land. These factors influence the composition and characteristics of the soil.

Soil Particle Sizes

Order from smallest to largest: clay, silt, sand and gravel. Soil particle sizes are classified based on their diameter, ranging from very fine clay particles to larger gravel pieces, affecting soil texture and water retention.

Plants

Help form soil by breaking up rocks with their roots. They contribute organic matter through leaf litter and decay, enriching the soil and providing nutrients for other organisms.

Soil Color

Indicates the types and amounts of minerals and organic matter. Soil color can reveal information about soil drainage, fertility, and overall health. Dark soils often indicate high organic content, while lighter soils may suggest leaching or low nutrient levels.

Soil Development Time

Soils in cold, dry areas take a longer amount of time to develop than soils in warm, wet areas.

Dirt

Not as valuable as soil. Dirt lacks organic matter and structure, making it less suitable for supporting plant life and ecosystems.

Importance of Soil

Provides food and support for plants. Helps regulate water, nutrients, and supports diverse ecosystems. Essential for agriculture and sustaining life.

Soil

A natural resource composed of mineral particles, organic matter, water, and air, which supports plant growth and sustains ecosystems. Nonrenewable resource. It forms through processes of weathering, decomposition, and biological activity over time.