Soil Composition (Copy)
3.1 Soil Composition – Cheat Sheet
Components of Soil
| Component | Description | Importance |
|---|---|---|
| Mineral Particles | Weathered rock fragments (sand, silt, clay) | Provide structure, determine texture |
| Organic Content (Humus) | Decomposed remains of plants, animals & microorganisms | Improves fertility, water retention, soil binding |
| Living Organisms | Earthworms, bacteria, fungi, insects, roots | Break down organic matter, aerate soil, recycle nutrients |
| Air | Spaces between particles | Supplies oxygen for respiration of roots & organisms |
| Water | Occupies pores; carries dissolved nutrients | Essential for plant growth and chemical processes |
Soil Particle Sizes
| Particle Type | Size | Characteristics |
|---|---|---|
| Sand | Largest particles | Coarse texture, drains quickly, poor nutrient retention |
| Silt | Medium particles | Smooth, retains water better than sand |
| Clay | Smallest particles | Sticky when wet, high water & nutrient retention, poor drainage |
Quick Pointers
- Loam soil (balanced mix of sand, silt, clay + humus) → best for agriculture.
- Texture affects aeration, drainage, and fertility.
- Healthy soils need balance of minerals, organic matter, air, and water.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Environmental Management Full Scale Course