SoilAn important product

of

Weathering.

Soils

Weathering produces a layer of rock and mineral fragments called – Regolith

Soil – The part of regolith that supports plant growth.

Soils

Soil Composition – Soil has 4 major components.

1. Mineral Matter - broken rocks

2. Organic Matter - Humus

3. Water

4. Air

Fill in the percentages using your book on page 133.

Soils

Soil Texture - Refers to the proportions of different particle sizes.

US Department of Agriculture has established categories base on the percentages of these in Soil

Clay

Silt

Sand

Texture

Texture STRONGLY influences soil’s ability to support plants.Sandy soils dry out to quickClay rich soils drain slowlyLoam soils Best for plant growth

Soils

Soil Formation – The most important factors in soil formation are

1. parent material, 2. time, 3. climate, 4. organisms and 5. slope

Soils - Soil Formation 1. Parent Material – The source of the mineral matter in soil. (pg. 135)* 2 Types:

a. Transported > What is the b. Residual > Difference

2. Time – The longer a soil has been forming = Thicker it becomes. 3. Climate – Climate has the greatest effect on soil formation.

Variation in temperature and precipitation influence the rate, depth, and type of weathering.

Residual - If soil stays on top of the parent rock that it formed from it is called residual soil.  Residual soil will be made of the same materials as the original rock. 

ResidualResidual

Transported soil has been moved from another location. Most soil on the Earth's surface is transported.

Soil Names? Page 136

Sometimes soils are named based on the soil’s natural vegetation. What are some of those names?

What is the main source of organic matter?

What increases soils fertility?

Soils - Soil Formation

4. Organisms – The types of organisms and how many there are in a soil have a major impact on its physical and chemical properties.

Soils – Soil Formation

5. Slope –5. Slope – Variations in slope Variations in slope can result in very different soil can result in very different soil types. Many of the differences types. Many of the differences are related to the amount of are related to the amount of erosion and the water content erosion and the water content of the soilof the soil

What type of slope accelerates What type of slope accelerates erosion? erosion? (Pg137)(Pg137)

Soil Profiles

Soil varies in composition, texture, structure and color at different depths.

A vertical section through all of the soil horizons is called a Soil Profiles.

Soil Profiles Page 138

A Horizon - is commonly known as “Topsoil.” Its upper part consists mostly of organic matter HUMUS.

B Horizon “Subsoil” – Contains fine clay particles washed out of the A horizon by water.

C Horizon – Contains partially weathered parent material.

A Horizon

C Horizon

B Horizon

D Horizon

(Bedrock)

Soil Types Page 139

Three common types of soil are pedalfer, pedocal, and laterite.

Honors look up these 3 and put them into a graphic organizer NOW!Include several places or states where these types of soil can be found.

SoilTypes

Pedalfer – Forms in temperate areas that receive more than 30” or 63 cm of rain each year. The eastern US falls within this type.

Acidic in Composition

Us

Soil Types

Pedocal – are found in the drier western US in areas that have grasses and brush vegetation.

They also contain abundance of limestone (Calcium Carbonate).

Alkaline in Composition

Soil Types

Laterite – Laterites form in hot, wet tropical areas.

Chemical weather is intense within these regions.

Usually DEEEEEEP soils.

Calcite & Silica are removed by lots of H2O and Iron Oxide and Aluminum are left giving the soil a RED Color

Were any of your soil samples acidic?

Some plants require acid soils to grow and thrive. For example, pine trees, azaleas, rhododendrons, cranberries, blueberries, potatoes, and tomatoes prefer acid soils. However, most plants thrive only in soils of pH 6 to 7.

Were any of your soil samples basic? Some soils, such as in many midwestern United States, contain a lot of limestone and are alkaline. In those locations, people often add sulfate, such as ammonium bisulfate to soil to make it less basic.

Were there any big differences between the plant and animal life at each location?

Some types of plants and animals are able to live in acid soils, while others are not. Be aware, however, that many factors, not just the soil acidity, determine the types of plants and animals that occur at a particular site

Soil Erosion

Soil Erosion is a natural part of the constant recycling of earth materials known as the rock Cycle.Rates of Erosion In the past, soil eroded more slowly than it does today because more land was covered by trees, grasses, and other plants.Human activity has accelerated this process.Farming – Logging – Construction -- Deforestation

Soil Erosion

Sediment Deposition – Another problem caused by excessive soil erosion is the deposition of sediment.

Rivers that collect sediment, need to be dredged to remain open for shipping.

Soil Erosion

Controlling erosion – Although we cannot completely eliminate soil erosion, we can significantly slow it by using soil conservation measures.

List some of these METHODS!

Soil Erosion