Soil erosion Flashcards
What is soil
A thin layer on the surface of the earth and is home to many forms of life.
What would happen without soil
Plants would not grow and animals and humans would not be able to get food from the soil.
At what rate does the natural forms of soil erosion occur
They Takes place at the same rate that soil is formed
What human activities cause soil erosion
Overgrazing and deforestation.
What is the top layer of the soil called
Topsoil
What happens when the topsoil is eroded
The soil will no longer be suitable for agricultural purposes or other vegetation.
What are the negative side effects of soil erosion by water
As water flows over the land, it carries soil and agricultural pollutants into the rivers. This can lead to the silting of dams, poisoning of drinking water, harming of fish and plant life and disruption of the ecosystems found along the course of the river
What are the main causes of man made soil erosion
Agriculture, construction and mining
Why is man made soil erosion a problem
Because humans are stripping soil from the surface of the earth faster than nature can replace it.
What are agricultural practices cause soil erosion (name 7)
Overstocking and overgrazing, removing trees, using pesticides and chemical fertilizers, ploughing up and down the slopes, lack of crop rotation and surface irrigation
How does overstocking and overgrazing cause soil erosion
Plants protect the soil. If there are too many animals on the land the will destroy the plant cover allowing soil to be washed or blown away.
How does removing trees cause soil erosion
Trees removed from agricultural land allows wind to have long, open, distances to travel, increasing the rate of soil erosion.
How does using pesticides and chemical fertilizers cause soil erosion
Pesticides and fertilizers can kill small organisms that bind the soil. The small loose particles can be carried away by water or wind.
How does ploughing up and down cause soil erosion.
This leads to rain washing away the soil
How does lack of crop rotation cause soil erosion
Planting the same crop every year depletes the soil of nutrients and the soil becomes infertile.
How does surface irrigation cause soil erosion.
As the water hits the ground with enough force it causes the soil to erode.
How should farmers prevent soil erosion
- avoid overgrazing
- allow indigenous plants to grow that will bind the soil
- limit the use of pesticides and fertilisers
- use contour ploughing and leave unploughed grass strips between ploughed land.
- use a crop rotation system
- use a drip irrigation system
How does construction cause soil erosion
- When land is cleared of vegetation for building sites or roads, the soil is exposed and is easily eroded by wind and water.
- and when roads, factories or homes are built, large areas of land are covered by tar and concrete. These surfaces cannot absorb the rain, and this increases run-off
What is run-off
Rainfall that doesn’t sink into the soil but runs over the land
What is infiltration
Rainwater that sinks into the ground
What carries run-off water and sediment away from sites
Paved roads, pavement gutters and storm sewers
What is much of the sediment in urban areas contaminated of
Fuel, oil and other chemicals
What does increases run-off do
It erodes the land, washing away more topsoil
How do construction vehicles increase run-off
They compact the soil which reduces infiltration and increases run-off
What does soil and sediment carried off construction sites do
They bury plant and animal habitats needed for healthy rivers and wetlands
How does mining cause soil erosion
large amounts of rock or soil are disturbed by drilling or earth moving. This rock and soil is washed away by rainwater.
What does water that erodes soil because of mining often contain
The water often contains poisons and chemicals from the min and can effect the quality and safety of water for humans and animals.
How does open cast mining do
It destroys landscapes, forests and wildlife habitats at the site of the mine when trees, plants and topsoil are cleared from mining area. This leads to soil erosion and destruction of agricultural land.
What is open cast mining
Mining which does not use shaft or tunnels. The minerals are removed from and open pit.
At what rate is soil formed
1cm every 100 years
How long does it take to form enough soil to create productive land
3000 to 12000 years
Why is soil important (name 7 reasons)
- to grow plants (for food, oxygen and lots of other things)
- to provide income for farmers, families and workers
- to provide food for livestock
- to provide a home for wildlife and insects
- to get rid of pollutants
- to walk on
- as a surface for building
What is windbreak method to conserve soil
Rows of trees planted to slow down the wind and prevent soils from blowing away
What is grassed waterways method to conserve soil
Plant grass and don’t plough low areas where water usually runs
What is the forest and grass areas method to conserve soil
Keep steep hillsides under tree or grass rather than clear cropland
What are terraces method to conserve soil
Wide ridges that go around a hill to prevent water form rushing down the hill too fast
What is the contour planting method to conserve soil
Plant crops around the curve of a hill rather than up and down a hill.
What is arable farming
Growing crops in fields which have usually been ploughed before planting
What is desertification
Formation of deserts through the degradation of soil in arid and semi arid regions
What is degradation
The wearing down of the land by the erosive action of water, wind or ice
What is carrying capacity
The number of cattle or crops that an area can support without environmental degradation
What is a gross domestic product
The amount of money generated by goods and services in a country in a year
What is aquaculture
The cultivation aquatic animals and plants In fresh or marine waters
Why has overfishing become a problem world wide
The massive demand for fish due to a rapidly increasing world population has led to many fish being caught. Very small fish are left behind, meaning that fish are not breeding quickly enough to replace the fish that are being caught
How are fished categorised
According to the red, orange and green lists
What characteristics do the green fish have
Fish in the green list are allowed to be caught in normal quantities
What characteristics do the orange fish have
Fish on the orange list are allowed to be caught in limited quantities
What characteristics do the red fish have
It is illegal to catch or buy fish on the red list
Which fish are labelled as green
Oysters, calamari, mussels, monk, yellowtail, sardines, snoek and rainbow trout
What should we look for, for the best choice in wild capture products
Always look for the MSC eco-labelled products, such as the South African offshore trawled hake
Which fish are labelled as orange
Tuna, hake, kingklip, prawns, spiny lobster, catfish and cape salmon
Which fish are labelled as red
Sharks, galjoen, king fish, potato bass, white stew bras, bronze bream and blacktail
What are the effects of overfishing
- it posses a threat to people as it reduces the amount of food available for people to consume. Many people still rely of fish for sustenance
- many people are employed in the fishing industry. They would lose their jobs if we could no longer catch fish
- extinction fish or a reduction in their quantity will impact the ocean ecosystem negatively
How has the development and improvement of modern technology contributed to overfishing
People are now able to catch fishes in large amounts and be able to preserve them for longer periods because of the development and improvement of modern technology
What some solutions to overfishing
- It is important that people reduce the quantity of fish they eat
- governments must implement strict laws to monitor fishing
- fish farms should be encouraged
- share the real news
- choose certified sustainable sea food
