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.
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