Soil

What is the average composition of soil?

45% mineral, 25% water, 25% air, and 5% organic matter

What is normally the most productive layer of soil?

A Horizon

What is the second layer of the soil profile?

A Horizon

How do living organisms influence soil formation?

As they die, organic matter incorporates with weathered parent material and becomes part of the soil.

What is the third layer of the soil profile?

B Horizon

What is under the C Horizon?

Below the C horizon the unweathered bedrock will be found.

What is the fourth layer of the soil profile?

C Horizon

What type of soils are often found on hillsides?

Drier, well drained soils are often found in sloping hillsides.

What is often a problem with the soils on hillsides?

Erosion is often a problem here and can lead to lose of topsoil.

What is the soil profile?

In a cross-section of soil, various zones are formed.

What type of soils are in low areas?

In many regions, moist, poorly drained soils are located in low areas.

What is in the O Horizon?

It consists of leaf litter and other organic material lying on the surface of the soil.

What is the is the top layer of the soil profile?

It consists of leaf litter and other organic material lying on the surface of the soil.

How long does it take soil to form?

It takes hundreds of years to form one inch of soil from parent material.

What is soil?

Mixture of weathered rock, organic matter, mineral fragments water, and air that supports the growth of vegetation

How much of the soil can support plant growth?

Only the top few centimeters are productive in the sense of being able to sustain plant growth.

What is true of the soils in the B Horizon?

Subsoil are usually lighter in color, dense and low in organic matter.

How do moles, earthworms, bacteria, and other organisms like them, in particular, influence soils?

The actions of moles, earthworms, bacteria, fungi, and round worms mix and enrich the soil.

What type of topography has a major influence on soils? How does it influence them?

The slope or hilliness of a region can have a major influence on the moisture and erosion of soils

What is in the A Horizon?

This layer is usually loose and crumbly with varying amounts of organic matter.

Describe the C Horizon.

This layer of transition is almost completely void of organic mater and is made up of partially weathered parent material.

In what way does climate influence soil formation?

Weathering processes like the cycles of freezing and thawing, along with wetting and drying vary with each region.

What is parent material?

mainly mineral matter or small pieces of rock, broken down over thousands of years (bedrock)

What are two examples of parent material?

materials from volcanoes and sediment transported by air

What are the three noticeable parts of soil?

sand, clay and silt