© Boardworks Ltd 20061 of 18
These icons indicate that teacher’s notes or useful web addresses are available in the Notes Page.
This icon indicates the slide contains activities created in Flash. These activities are not editable.
For more detailed instructions, see the Getting Started presentation.
Environmental Impacts of Farming
1 of 18 © Boardworks Ltd 2006
© Boardworks Ltd 20062 of 18
Lea
rnin
g o
bje
ctiv
es How does the use of chemicals affect the environment?
Other environmental issues in farming.
© Boardworks Ltd 20063 of 18
Globally, over a hundred million tonnes of artificial fertilizers and pesticides are used every year.
The use of mineral fertilizers and pesticides have vastly increased global agricultural yields.
How has food production been increased?
© Boardworks Ltd 20064 of 18
What are artificial (or mineral) fertilizers?
Fertilizers generally encourage plant growth.
They come in salt or liquid form and are mixed with water so that plants can absorb them as a weak solution.
Artificial fertilizers are specifically designed for a particular crop. For example, a plant grown mainly for its leaves will need a fertilizer with a high nitrogen content.
Farmers spray about 150-200 kg of fertilizer onto every hectare of cereal crop. This can be washed into rivers and lakes causing eutrophication.
Fertilizers
© Boardworks Ltd 20065 of 18
Eutrophication
© Boardworks Ltd 20066 of 18
Eutrophication
© Boardworks Ltd 20067 of 18
What are pesticides?
A pesticide is a substance used to prevent, destroy or repel a pest.
The pests you want to control could be insects, mice and other animals, weeds, fungi or micro-organisms (bacteria or viruses).
Insecticides kill insects Herbicides kill plants Fungicides kill fungi (mildews, molds, etc.)
Pesticides
© Boardworks Ltd 20068 of 18
One problem with pesticides it that they can poison wildlife. This is because pesticides accumulate along the food chain.
Corn is sprayed with pesticide.
The pesticide is transferred to caterpillars on
the corn.Each shrew eats lots of caterpillars, so the poison accumulates in their bodies.
Each owl eats lots of shrews, so they get an even higher dose.
Pesticides cause owls to produces weak eggs that break easily.
Problems with pesticides
© Boardworks Ltd 20069 of 18
Producing artificial fertilizers uses fossil fuels. Energy is also used by the machinery spraying the pesticides.
Artificial fertilizers and pesticides can also end up in our water supply. It costs Britain £121 million each year to monitor and remove pesticides from the water.
Today, it takes about 1.2 barrels of oil to produce a single tonne of grain in more developed countries. This is some 7 times greater than in 1950!
Other problems with fertilizers and pesticides
© Boardworks Ltd 200610 of 18
Types of pesticide
© Boardworks Ltd 200611 of 18
Lea
rnin
g o
bje
ctiv
es How does the use of chemicals affect the environment?
Other environmental issues in farming.
© Boardworks Ltd 200612 of 18
Since 1949, the UK has lost:95% of its lowland grassland
40% of its lowland heaths on acid soils 30-50% of its ancient lowland woods…
Agriculture causes the destruction of important habitats for wildlife.
…and 1949-1974, 140,000 miles of its hedgerows.
Destruction of habitat
© Boardworks Ltd 200613 of 18
Why are hedgerows important?
They provide a habitat for animals and birds.
They reduce soil erosion.
They act as windshields, stopping the wind from blowing away the topsoil. The roots of the hedgerows also help by binding the soil together.
Hedgerows
© Boardworks Ltd 200614 of 18
The effect of hedgerows on soil erosion
© Boardworks Ltd 200615 of 18
What are genetically modified (GM) foods?
All organisms have genes. Genes contain a sort of code that tells each organism how to develop. GM crops have had their genes altered by scientists.
Some farm animals and crops have been ‘genetically modified’ for
centuries using selective breeding.
However, modern genetic engineering allows scientists to mix genes from plants and animals that would never normally be able to breed together. For example, a gene from a fish could be put into a tomato.
Pedigree cows have been selectively bred.
Genetically Modified (GM) foods
© Boardworks Ltd 200616 of 18
Better crops are needed to feed the world’s rapidly
growing population.
GM crops are more resistant to insectsand diseases, so farmers won’t need
to use as much insecticide.
GM crops can be made that don’t need as much water or
fertilizer, so droughts would no longer cause famine.
Crops can be engineered to give health benefits. ‘Golden Rice’ has
been engineered to contain large quantities of vitamin A.
Crops can be engineered to last longer after harvesting, so less food will be wasted.
The argument for GM foods
© Boardworks Ltd 200617 of 18
We can’t predict what
effects GM crops could have on human health.
GM crops are resistant to herbicides, so stronger weed-killers can be used – this could wipe out many wild plants.
GM crops could spread uncontrolled through cross-pollination. Wild plants and non-GM crops could be pollinated by nearby GM crops.
We don’t need GM. There’s enough food
in the world for everyone, it’s just
that many people can’t afford to buy it.
Bio-tech businesses would control agriculture. They can make plants that produce barren seeds, forcing farmers to buy new seeds every year.
The argument against GM foods
© Boardworks Ltd 200618 of 18
Plenary
Top Related