Formation of Soil

Formation of Soil

1. Five major influences on soil formation

   • nature of the original parent material, weathering, climate, land surface features, and the action of plants and animals
     • These factors determine the physical and chemical properties of various kinds of soil.

2. Temperature and precipitation are the main weathering and climatic factors that affect soil development.

3. Parent material is the basic mineral and organic material from which the soil is formed.

   • There are three kinds of parent material: transported, residual, and organic.
   • The residual parent material from which soil is formed is loose, slightly weathered rock called regolith.

4. The greater the weathering processes at work, the finer the particles of soil that result.

   • These particles range from gravel to sand, silty material, and, finally, clay.

5. Soil is enriched by the wastes and decayed bodies of animals.

   • Many insects directly enrich the soil by fertilizing flowers, thus aiding the spread of plant life.
   • Some animals—ants and earthworms, for example—help by mixing the soil.

6. Plants and animals also help develop soil.

7. Land surface features affect soil development by controlling the amount of erosion of topsoil and by influencing how water drains into the soil.