Mind-builder # 6• What is the difference between soil and

dirt?

Dirt is just broken down rock, soil contains other sediment including organic material.

ASK Yourself…….• What is the end result of

weathering? Or • What is it that is created by the

breakdown of rocks and minerals?

**SOIL**

Types of Soil

• Sorted by their properties:

~Texture or size of particle~Structure or arrangement

of particle~Fertility or ability to hold

and supply nutrients

SOIL

Most soils are made up of a combination of the three basic soils: sand, silt, and clay.

Loam is soil composed of sand, silt, clay, and organic matter in evenly mixed particles of various sizes.

Basic soils

Sand – largest sized particlesSilt – medium sized particlesClay – smallest size particles

Particle size can affect water and air movement through soil. If there is too much movement nutrients used for plant growth can wash away.

No movement can cause an oversaturation of water in the soil.

Soil Horizons

Types of Soil

• Many different types• Each has a unique

characteristics such as color, texture, structure and mineral content.

• Depth of soil also varies• Kind of soil determines what

type of plants can grow.

HorizonsO Horizon (HUMUS)

top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter).

A Horizon (TOPSOIL)Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus mixed with mineral particles.

E Horizon (ELUVIATION LAYER)light in color; It is made up mostly of sand and silt, having lost most of it minerals and clay as water drips through the soil. Experiences intense leaching.

B Horizon (SUBSOIL)It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above.

• C Horizon (REGOLITH)It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer.• R Horizon (BEDROCK)The solid unweathered rock layer that is beneath all the other layers.

Review: Which layers would you find animals

burrowing? answer: O, A, E and B

horizons What rich organic makes-up horizon A?

answer: humus Where would you find leaf litter?

answer: O horizon What layer experiences extreme

leaching? answer: B horizon

Soil activity:• Students will construct a soil profile complete with parent

material, subsoil, and topsoil using different types of cereals.

• Students will be allow to collect a small cup of each type of cereal.

• Students can crush or otherwise manipulate their soil.

• The profiles will be placed in a clear plastic cup.

• Students are to draw a picture of their soil profiles and explain why they chose the cereal for each layer.

• Students will pour water or milk onto the cereal and record observations.– What happens to the water?– How is pore space taken up?– Do you see evidence of percolation?