SOILIntroduction

SoilSoil is a very important component of any terrestrial ecosystem.

Soil provides support and nutrients for plant growth.

Healthy Soil Is Essential for…

- Agriculture & Forestry- The cycles of matter- The flow of energy that

keep Earth’s ecosystems running.

A Renewable ResourceSoil is a renewable resource. Once its nutrients are used up, it can

renew itself over time.

(It takes a very long time, though. It can take hundreds -- or thousands -- of years for just one inch of topsoil to form.)

A Renewable ResourceSoil is a renewable resource. Once its nutrients are used up, it can

renew itself over time.

(It takes a very long time, though. It can take hundreds -- or thousands -- of years for just one inch of topsoil to form.)

If we deplete soil by using up all of its nutrients, we ruin it not just for ourselves, but also for future generations to come.

How Does Soil Form?

How Does Soil Form?WEATHERING, EROSION, AND

DEPOSITIONWEATHERING

-breaks down rocks into smaller particles.

-can be caused by weather, water, or living things.

How Does Soil Form?

EROSION

-moves sediment and particles of rock to new places.

-is usually done by wind and water, but also by ice (eg: glaciers).

WEATHERING, EROSION, AND DEPOSITION

How Does Soil Form?

DEPOSITION

-occurs when the transported particles of sediment and fragments of rock fall out of the transporting medium and settle in place.

WEATHERING, EROSION, AND DEPOSITION

There are five components of soil:

• 1. Rock• 2. Sand• 3. Silt• 4. Clay• 5. Humus

RockRock is solid and made of minerals.

SandSand is made of tiny grains of worn down

rock. Sand doesn’t hold water, nor does it have

many nutrients.

SiltSilt is even smaller than sand (but larger than clay

particles). Silt is powdery when dry.

Sand ------------Silt---------------Clay (larger particles) (smaller particles)

ClayClay holds water well. It is made of very tiny particles.

Clay is sticky and can be shaped when it is wet. But it is very hard when dry.

Clay has many nutrients.

Humus

Humus is made of leaves, twigs, small animals, or other decayed substances.

Humus adds many nutrients to the soil.

Humus is always foundin the topsoil.

3 Layers of Soil(Soil Horizons)

1. Topsoil

2. Subsoil

3. Bedrock

Three Main Types of Soils

• Sandy soils tend to drain quickly (nutrients wash away before plants can absorb them).

Three Main Types of Soils

• Clay soils hold water well, and are rich in nutrients, but pack too tightly and lack organic matter.

Three Main Types of Soils

• Loamy soils are the most fertile soil. • Loamy soils are a mixture of sand, silt and clay.

They have a lot of organic matter.