soil

SOILThe soil is the source of life, creativity, culture, and real independence.

David Ben Gurion (1886-1973),

Hazon VeDerek, 1951

It is where life and life processes begin on land.

It is the material that constitutes the outermost solid layer of our planet.

It is a naturally-occurring mixture of minerals, air, water and organic ingredients.

It is formed by the dynamics of chemical and physical weathering.

Just What Is Soil?

Soil Composition

Soil is composed of four major components: Minerals or rock particles – 45% Water – 25% Air – 25% Organic matter such as leaves –

5%

Soil Components

Minerals 45%

Water 25%

Air 25%

Organic Matter 5%

The Soil’s Ecosystem Soil is a home for many

living things such as worms and many microorganisms that you cannot always see with your eye.

The soil’s ecosystem is a source of food for the organisms that live there.

The soil’s ecosystem is a protective area.

Soil Properties How do soils differ?

Composition Texture Color Porosity – the ability to retain water Permeability – the ability of water to

move through the soil Nutrients – the ability to support plant

growth

Soil Composition

Observing the sample with a hand lens

Touching the dry sample Rolling the moist sample Smearing Settling

Soil Texture

The way soil “feels” is called the soil texture.

Soil’s texture depends on the amount of each component and the size of its particles: Sand are the largest particles and they feel

gritty Silt are medium-sized and they feel soft or

silky like flour Clay are the smallest-sized particles and they

feel sticky and hard to squeeze.

Soil Texture

In the Classroom Coffee Grounds, Flour and Modeling Clay

In the Environment Sand, Silt and Clay

Dichotomous Key Guide to Soil Texture by Feel

BarrelSand

(feels gritty)(2.00 - 0.05 mm, USDA)

(2.00 - 0.02 mm, ISSS)  

PlateSilt

(feels floury)(0.05 - 0.002 mm, USDA) (0.02 - 0.002 mm, ISSS)

CoinClay

(feels sticky)(< 0.002 mm, USDA) (< 0.002 mm, ISSS)

Relative Size Comparison of Soil Particles

Soil

Text

ure

Tria

ngle

Soil Colors

Hue

Value Degree of lightness

or darkness of a color

Black: 0/ White: 10/ Gray: halfway

between black and white 5/

Water Relationship Porosity – the ability of soil to hold

water Permeability – the ability of water to

move through the soil Dependent on soil particle size The larger the particle size the more

movement Saturation Rate – the point where no

more water can be absorbed or moved through the soil

Soil Provides Nutrients

Washed down from the O and A horizons.

Held in the B Horizon by presence of clay

Absorbed by the plant’s roots to provide food to the plants.

Soil Profile

A soil profile is a slice of earth several feet deep.

By studying soil profiles, scientist learn about the soils characteristics and how to use and protect it.

Soil profiles are made up of several layers called horizons - each with their own job.

The Soil’s Horizons The surface layer or the O Layer is made up of

organic material like leaves and grass. The A horizon is a mixture of decayed organic

material and minerals. The B horizon is the most active layer. It is

where the nutrients and moisture is stored. The B horizon is also called the root horizon.

This is where plants’ roots reach out and pull nutrients and water into the plants.

The C horizon is the area of parent material that helps to make the soil.

Types of Existing Bedrock – the solid rock beneath a layer of soil

Soil is Formed by Weathering

Physical/Mechanical: Freezing water Wind Running water Frost

Chemical: Acid rain Minerals are

dissolved

Biological: Roots of plants Lichen Burrowing and

digging by animals and insects

What are the ingredients???

Soil Conservation

Apple Demonstration Soil Stories Soil Is Not Trivial Enviroscape Cookie Mining From Apple Cores to Healthy Soil Composting (Presented by Solid Waste

Management Authority)

Once you step out onto a piece of ground, you step out onto something that is alive. Soil is not just a piece of dirt. Soil is made up of living and nonliving material spread as a very thin layer over the entire surface of the planet we call Earth.

Respect the Soil

• Missi Zender-SakachScience Consultant Summit County Educational Service Center

• Sandy BarbicEducation SpecialistSummit Soil & Water Conservation District

• Debbie RohrConsultantSummit County Educational Service Center

Summit County Educational Service Center Standards-Based Science Curriculum Includes:Model Curriculum-Content Statement(s)Model Curriculum-Content Elaboration ConceptsModel Curriculum-Visions Into Practice (V)A Framework for K-12 Science Education: Practices , Crosscutting Concepts, and Core Ideas (F) → Next Generation (Next Gen) Science Education Standards Strategies for Teaching and Learning

OMS science teachers thank the following for their assistance with this unit.