Soils

Soil Composition

Comparing Soil Types

Soil and Roots

Ecosystem

Living and non living things and their interactions

Ecology

The study of the Ecosystem

What is soil made of?

Weathering of parent rock

Organic material

Open spaces

Water

Particles larger than 2 mm are calledgravel.

Particles between 2 mm and 0.05 mmare called sand.

Particles between 0.05 mm and 0.002mm are called silt.

Particles less than 0.002 mm arecalled clay.

Soil made up of a mixture of all three sizes of particles is called loam

All soil originates from parent rock. Parent rock is broken down by weatheringinto small mineral particles. The sizes of the mineral particles determine the

texture of the soil. One way of classifying soils is by their texture.

Soil Defined:

Soil is the total mixture of mineral particles of many

sizes, organic matter, open spaces, water, and salt

solutions in a defined structure.

Formation of Soil

Parent Rock begins to break down into smaller and smaller pieces.

Organic matter (dead plant and animal material) accumulates at the surface

Over time the weathering process forms soil at deeper levels and the layer of soil on the top becomes thicker.

As separate layers of soils become identifiable they are known as Horizons

Horizon A is known as topsoil

Horizon B is known as subsoil

Horizon C most closely resembles parent rock

All of the Horizons together are known as a soil profile

Although different locations and types of parent material will form soils at varying rates, it is believed to take centuries to form a complete profile

Some scientists believe that it takes 200 to 300 years toform one centimeter of soil form parent rock and some well formed soil profiles can be hundreds of centimeters thick.

How do roots effect soil?

1) Pictures provided by: Google Images

2) Fast 1 Curriculum; University Hawaii

3) General Science: A Voyage of Adventure, Chapter 20 Soils; Prentice Hall; 1989