The Formation of Soil Earth Science Mr. Cloud

Soil Formation Soil: is a mixture of rock particles and organic matter on Earth’s surface that supports rooted plants

How do soils form? Soils form from the weathering of bedrock, over time soil develops horizontal layers with distinct profile Physical and chemical weathering are vital to the formation of soil Living things play a significant role in soil formation

Soil Composition 25% 45% 25% 5%

What are some factors that affect the type of soil found in a region? 1. Climate: temperature and moisture conditions affect the rate of weathering i.e. more water available, faster weathering, faster soil development i.e. Too much water can be harmful; waste away nourishment from the soil i.e. Too little water, little vegetation, less soil development

What are some factors that affect the type of soil found in a region? 2. Gradient: steep slopes will cause rock to fall under the force of gravity; runoff of precipitation tends to amplify erosion Moderate slopes and valleys encourage the formation of deep soils 3. Organisms: animal/plant life affects the soil

Soil Organisms Earthworms provide many soil services One teaspoon of fertile soils contains millions of microorganisms such as bacteria, fungi, algae, microscopic worms, and protozoa! Ecosystem Services: organisms help maintain soil fertility, prevent soil erosion, breakdown toxic materials, cleanse water, and affect the composition of the atmosphere. Earthworms provide many soil services

Soil Horizons

Mature Soil Profile: temperate location Mollisol: similar to the mature organic-rich soils of the American “bread-basket”

Immature Soil Profiles Alfisol Immature Soil Profiles Aridisol