Transcript Land and Soil Conservation

Land and Soil
Conservation
3 main land uses
• Agriculture- less than 1/3 of land on earth can be used for
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farming. The rest is too dry, salty, wet, or mountainous.
To have more room we clean forests, drain wetlands, and
irrigate deserts. When we make the changes organisms
must leave.
The land is usually used for grazing or pastures.
Development – the construction of buildings, roads, dams,
and other structures.
People first settled near good soil and water. As the pop.
grew they turned into cities. More structures were built.
In the us an area ½ the size of New Jersey is developed
each year.
It destroys farmland and habitats.
3 Main uses of land
Mining – the removal of nonrenewable resources like
iron, copper, and coal from the land.
 Strip Mining – is when you remove a strip of land to get to
minerals and replacing the strip. It exposes soil which can
be blown or washed away. It stays free of vegetation for
years
 Underground mining – the process of digging shafts or
tunnels to mine minerals deep underground.
How land is Used in the Usa
 We use land in the
usa for forests, woodland, cropland,
rangeland, grassland, cities, wilderness parks, wildlife refuges,
wetlands, tundra, and deserts.
forest and
woodland 30%
rangeland and
grassland 29%
cropland 17%
wetlands,
tundra, and
desert 13%
wilderness parks
and wildlife
refuges 9%
cities 2%
What layers make up fertile soil?
 The 1st layer of soil from the top is called litter. It is a
mixture of dead leaves and grass.
 The 2nd layer of soil is called the topsoil. It is a mixture of
rock fragments, nutrients, water, air, and decaying animal
and plant matter. Most water absorbed by plants is in this
layer.
 The 3rd layer of soil is called subsoil. It contains rock
fragments, water, air, but less decaying matter than topsoil.
 The final layer is bedrock. It is the rock that makes up the
Earth’s crust. Freezing and thawing gradually break apart
the bedrock.
Why is it important?
• It takes hundreds of years to form a
few centimeters of soil.
• Poor soil management can result in
three problems: erosion, nutrient
depletion, and desertification.
What is erosion?
• Erosion- the process by which water, wind or ice moves
particles of rocks or soil.
• Mostly plant roots hold the soil in place but when exposed
to wind it erodes rapidly.
• Logging, mining, and farming expose soil and helps cause
erosion.
• Some types of farming reduce erosion.
Nutrient Depletion
• Nutrient Depletion – the situation that arises when more soil nutrients
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are used than the decomposers can replace.
Plants need nitrogen, phosphorus, potassium and other nutrients to
grow. The get them from the soil.
Decomposers make these nutrients from the remains of dead
organisms.
Farmers that plant the same crops over and over uses up the nutrients
and causes nutrient depletion.
A way to prevent it is to fallow, or leave clear of crops. You can also
leave the what is left of the plants so the can decompose.
Desertification
Land Reclamation
The End