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Conserving Land and SoilSec. 4-1
Objectives
E.4.1.1 Explain how people use land.
E.4.1.2 Describe the structure of fertile soil.
E.4.1.3 Identify problems that occur when soil is not properly managed.
What are some things land is used for?
Agriculture-Growing food to feed the World population.
Mining-Extracting ores and fossil fuel from the ground.
Development-We need homes to live in and buildings to work and go to school in.
Recreation-People connect with nature as part of our natural evolution.
Agriculture
Land is used to grow food for people and livestock to feed a growing population on Earth.
Without farming there would not be enough food and people would starve.
What else, besides land, do we use a lot of to grow food?
Average Water Use 20th Century
What happened around the 1980’s to cause the graph to decline?
Efficiency
Water
Rain does not provide anywhere near enough water to generate the amount of crops we need!
Where do we get water from?
Irrigation from surface and ground water.
Water
Is this an efficient method of irrigation?
No
Why not? Where does most of the water go?
80%-85% evaporates and never makes it to the plants roots where it’s needed.
Drip Irrigation
Hoses right on the ground deliver water directly to the roots of the plant. What does this help reduce?
Evaporation!
What does this do to water use efficiency?
Increases it from 15%-20% up to as much as 90% or more.
Drip Irrigation
Drip Irrigation
Which Is More Efficient?
Drip Sprinkler
Strip Mining
Earth is removed, the valuable material extracted and then the earthen material is replaced.
Underground Mining
Development
This Becomes This
Or This
Recreation
What Land Uses Do You See?
Soil Structure
How thick is the rich top layer of soil that supports life?
Not very!
The top layer contains all the richness needed to support plant life. What happens if that layer is lost?
The soil will no longer support plant life.
Soil Profile
Look at the roots. Where are most of them?
In the top layer.
Soil Management
Poor soil management can result in three problems:
Erosion
Nutrient depletion
Desertification
Fortunately, damaged soil can sometimes be restored.
Erosion
Erosion is the wearing away of top layers of soil by water and wind.
Rich Soil and Plants Can Reduce Erosion
Terracing
Soil Nutrient Depletion
Soil Nutrient Depletion
Desertification
When desert like conditions move into areas that were once fertile it’s called:
DESERTIFICATION
Why is this is a major problem?
Because it reduces the land area available for growing food.
Land Reclamation
When nutrient rich topsoil is depleted or stripped off, then the area will lose its ability to grow plants and the area will essentially “die.”
Fortunately we are able to reclaim many of these areas by bringing in nutrient rich compost and plants.
Compost
Compost is decomposed natural grass, leaves, wood, vegetables and manures that release their nutrients back into the soil so plants can start to grow again.
Compost
This Turns Into This
I Did This For 10 Years
What Compost Can Do
Before After
Land Reclamation
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