Good Science Victorian Curriculum Year 7

BIOLOGICAL SCIENCES: SCIENCE AS A HUMAN ENDEAVOUR
3.6
IMPACT OF
AGRICULTURE
ON ECOSYSTEMS
LEARNING INTENTION
At the end of this lesson I
will be able to describe how
ecosystems can be affected by
agriculture, and how science
and technology can contribute
to finding solutions to a range
of contemporary issues in
agriculture.
KEY TERMS
agriculture
the science or practice of
farming
cultivation
preparing and using land
for crops or gardening
irrigation
supplying water to land or crops
monoculture
the practice of cultivating a
single crop in a given area
selective breeding
breeding organisms with
desirable traits
yield
the amount of something that
is harvested
NUMERACY LINK
DATA
Roscoe recorded the highest
temperature of five consecutive
days in January to be 28°, 28°, 39°,
34° and 32°. Calculate the mean,
median and mode of this data.
What other data might be useful
when analysing these numbers?
1
2
Farming crops for food production is called cultivation. This is
part of the practice of agriculture, where farmers use land to
grow crops and breed animals for food and other products.
Agriculture often has negative impacts on ecosystems.
Farming is one of the main causes of deforestation, and it
often reduces biodiversity.
Scientists work with farmers and governments to come
up with ways of cultivation that improve crop yields and
cause less harm to ecosystems.
Monocultures lead to a loss of biodiversity
Some farms grow only a single crop, such as canola or wheat, that
covers a very large area of land. These crops are called monocultures –
other species are removed so that they don’t compete for nutrients or
feed on the crop. One problem with this loss of biodiversity is that if a
disease or pest affects one plant in a monoculture, it can damage all
of them because they are all the same.
After a crop is harvested, the soil is ploughed (turned over) to remove
the remaining roots of the crop from the soil. This increases seed
germination and removes weeds, but it also increases soil erosion and
removes nutrients stored in decomposing plants.
Many farmers are starting to use agricultural methods that allow
nutrients to remain in the soil. If the plant matter is left in the soil, without
being ploughed, it decomposes, leaving carbon and other nutrients in
the soil. This reduces the amount of fertiliser that needs to be added and
it is a cheaper method of farming.
What is a monoculture?
Chemicals can build up in ecosystems
To give better yields, crops need nutrients. Traditionally, chemical
fertilisers have been added to the soil, but fertiliser runs into waterways
when there’s heavy rain or too much is used. This affects other
ecosystems; for example, it can
cause toxic algal blooms.
Pesticides and herbicides
are used in agriculture to
remove pests and weeds from
crops. These chemicals can
build up in ecosystems, affect
other organisms and enter
waterways. They can be passed
Figure 3.12 Planting canola seeds
into soil without ploughing after
along food chains and cause
the harvest causes less erosion. harm to other organisms.
46 GOOD SCIENCE VICTORIAN CURRICULUM 7