Chapter 3 Lesson 3

Essential Question: What is soil made up of?

TYPES OF SOIL & PARTICLES

Lesson 3 Vocabulary•soil•topsoil•subsoil•contour plowing•terrace farming

Observations

Facts

Silt

Sand

Loam

Clay

What is soil made up of?

• moderate size• smooth floury

texture

• largest particle• gritty feel

• smallest particle

• feels sticky

combination of sand, silt, and clay

Sizes of Soil Particles

smallest to largest:claysiltfine sandmedium sandcoarse sand

Try This!Identifying Soil Texture

1. Spread soil on newspaper. Remove all rocks, trash, roots, etc. Crush all lumps.

2. Fill a tall, slender jar ¼ full of soil.3. Add water until the jar is ¾ full.4. Add a teaspoon of non-foaming dishwasher

detergent.5. Put on a tight fitting lid and shake hard for 10-15

minutes. This shaking breaks apart the soil aggregates and separates the soil into individual mineral particles.

6. Set the jar where it will not be disturbed for 2-3 days.7. Soil particles will settle out according to size.8. After 1 minute, mark on the jar the depth of the

sand.9. After 2 hours, mark the depth of silt.10.When the water clears (1-3 days or more), mark

the clay levels.11.Measure the thickness of sand, silt, and clay layers

and calculate the percentages of each.12.Refer to the soil texture triangle and identify your

soil.

Soil Texture Experiment

Measure the thickness of the sand, silt, and clay.

thickness of sand = ______ inches

thickness of silt = _______ inches

thickness of clay = _______ inches

TOTAL = _______ inches

Calculate the percentage of sand, silt, and clay.

sand thickness / total thickness = ______ percent sand

silt thickness / total thickness = ______ percent silt

clay thickness / total thickness = ______ percent clayIdentify soil texture using the soil

texture triangle.

Soil Texture Triangle

For example, a soil with 30% clay, 50% sand, 20%silt is called a sandy loam.

A natural resource made up of minerals and small rocks, gases, water, and organic matter = soil

topsoil

subsoil

bedrock

Georgia’s soil

• looks red because it contains lots of iron• Cotton

grows well in our soil.

Flashback to the 1930’s:Drought caused big problems for farmers. Without rain, land was extra dry. Because

farmers planted their crops in long, straight lines, the wind blew through their fields more strongly and blew their topsoil away. Crops

could not grow!

Protecting TopsoilContour plowing: soil is plowed in curved rows that follow the shape of the land. This decreases wind and water damage to the land.

Farmers keep soil in place by planting cover crops. This is what happens: Soil sticks to plant roots. Stems & leaves protect the soil from wind.

Farmers protect soil that is lost from moving down hills by using terrace farming. Crops are planted on level sections.