Good Science Victorian Curriculum Year 7

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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
CHAPTER 3: ECOSYSTEMS 3 Reducing and improving chemical use is important in agriculture. Organic fertilisers such as compost and manure add nutrients without causing the same harm as chemical fertilisers. When chemicals are used, they must be registered and controlled. Farmers are required to record their use, including the date, type of chemical and the amount being used. What is an example of an organic fertiliser? Irrigating crops uses large amounts of water Figure 3.13 Micro-irrigation systems are replacing traditional spraying methods for some crops. 4 Have you ever seen a jet of water shooting up high to spray downwards on a crop at a farm? These types of irrigation waste a lot of water – some of the water evaporates or doesn’t reach the plant, so a large amount needs to be used to soak into the soil. Micro-irrigation systems are replacing some traditional irrigation sprayers. They are water pipes sitting just above the crops, allowing water to drip slowly on the plants. Scientists also use scheduling tools to work out the best time to irrigate a particular crop based on rain forecasts, plant stress and temperature. This gives better plant growth and prevents water from being wasted when irrigation isn’t needed. What is irrigation? Selective breeding is used to develop new crops Some scientists study different species of crop to increase yield and find varieties that can resist drought, pests and diseases. This can be done as part of selective breeding programs. When a disease destroys a crop, a few plants usually survive because they are naturally resistant. Scientists can then breed more of those plants to create an entire crop that’s resistant to the disease. Blackleg is a fungus that damages canola crops in New South Wales and Victoria. Farmers usually use chemical sprays to kill and prevent the spread of blackleg, but the chemicals also affect the ecosystems. Scientists have studied varieties of canola that can resist blackleg. Growing these varieties of canola is the best way to control the effects of blackleg in Australia. What is selective breeding? CHECKPOINT 3.6 1 Define agriculture in your own words. 2 Give two examples of crops grown in Australia. 3 Give one example of how scientific knowledge has influenced agriculture. 4 Explain why chemicals are often used in agriculture. 5 Suggest why some farmers are starting to use organic fertilisers. 6 Why do farmers usually grow monocultures rather than a variety of crops? 7 Describe why deforestation is necessary for agriculture. INQUIRY 8 Undertake some research to suggest one way farmers could improve the productivity of wheat in times of drought. SUCCESS CRITERIA I can explain what agriculture is with at least two examples. I can describe how science and technology can contribute to finding solutions to a range of contemporary issues in agriculture. 47
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INVESTIGATIONS KEY SKILLS Writing a
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INVESTIGATIONS Investigation 5.6A E
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INVESTIGATIONS 30 min Level 2 TO MO
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INVESTIGATIONS METHOD 1 Copy the re
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fractional distillation a method th
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INDEX Aboriginal and Torres Strait
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photosynthesis 30, 31, 36, 42, 109
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Good Science Victorian Curriculum Year 7

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