Explain how the resources soil provides help in supporting life; Explain how the resources soil provides help in supporting life; Explain the contents.

The Nature of Soil

Explain how the resources soil provides help in

supporting life; Explain the contents of soil; Describe the biological nature of soil; and Describe four ways plants use soil.

Objectives

Soil provides many resources to life

They make it possible for plants and animals to grow

We will list five of them

Soil Supports Life

Oxygen

In the soil Needed for root growth

Temperature Soil absorbs heat from the sun Soil radiates heat into the atmosphere

This cycle regulates the temperature so seeds can germinate and grow

Soil Supports Life

Water

Used by growing plants

Carbon The base of all life forms Most essential element to life

Nutrients Minerals that are absorbed and used by the

plant

Soil Supports Life

Soil is composed of four primary components

Mineral matter Organic matter Air Water

In addition, there are numerous living organisms

Contents of Soil

Soil is 50/50 solid and porous

What is porous?

Solids Mineral matter and organic matter

Contents of Soil

Solids

Mineral matter 45%of the soil Broken down rocks Sand, Silt, Clay

These three things determine water holding capacity and fertility of the soil

Contents of Soil

Solids

Organic Matter 5% of the soil Mostly from leaves, roots and stems Contributes to water holding capacity and fertility Gives soil a dark color

Contents of Soil

Pore Spaces

Space occupied by air and water

Air ≈25% of soil

Water ≈25% of soil

Contents of Soil

Air

Constantly fluctuating More water = less air Less water = more air

Contents of Soil

Water

It can do two things with soil Run off Soak in

Contents of Soil

Terms to know

Infiltration Water soaking into the soil

Percolation Water moving downward through the soil

Permeable Quality of soil when water can both infiltrate and percolate

Leaching Movement of dissolved minerals and chemicals and salts

downward with water

Contents of Soil

3 types of soil water

Gravitational water Water pulled down by gravity Causes leaching

Capillary water Water held in pore spaces May move sideways or up

Hygroscopic water Water that forms a thin film around soil particles Not available to plants

Contents of Soil

What life forms would you find in the soil?

Worms Insects Bacteria Fungi Other organisms

Biology of Soil

Bacteria and fungi have an important role in

the soil. They break down organic matter and release

nutrients.

Biology of Soil

Earthworms, ants, crawfish, moles, and other

organisms improve the soil tilth, Tilth: the ease at which soil can be worked. These organisms create openings in the soil as

they tunnel. This enhances drainage and improves air

exchange.

Biology of Soil

What are they?

Anchorage Water Oxygen Nutrients

4 ways plants use soil