Transcript hOw do fertilisers affect growth

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How do fertilisers affect plant growth?
Lesson Aims
To review key ideas about plants for
food and study how fertilisers affect plant
Plants for Food
growth.
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Learning outcomes
By the end of the lesson you should
know / be able
• to link ideas about feeding
relationships and photosynthesis
• that plants require a range of
minerals for healthy growth
• that fertilisers supply these minerals
to crop plants
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We need plants !
Write down 3 reasons to
support this statement
Remember: The three main types of
nutrient are:
1. Nitrogen in the form Nitrates – used to
make proteins
2. Phosphorus in the form of Phosphates –
used to provide phosphorus to help
photosynthesis and respiration
3. Potassium – helps the enzymes that are
needed for photosynthesis and
respiration
Remember: Lack of the three
minerals would lead to a “Deficiency
Symptom”:
Lack of nitrates:
Small plant, yellow leaves
Lack of phosphates:
Small roots and purple leaves
Lack of potassium:
Yellow leaves with dead bits
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• On your own :
a)What is a fertiliser?
b)Answer questions 1- 3
• In groups of 3 or 4 :
• Answer questions 4 -11 on newsprint
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1.What is a weed?
2.What is a weedkiller?
3. Why are they used ?
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• Answer question1-4 page 145
• Extension questions 5-11 p\age 146
• Remember your pondweed report is due in
next lesson !
Helping plants to grow
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Farmers can use a number of chemicals to help plants to grow:
Advantages
Disadvantages
1) Fertilisers
Provide nutrients
2) Herbicides
Kill weeds
Too much of it can kill
pond life
Disrupt
food
chains
3) Pesticides
Kill pests
Disrupt food chains
Another disadvantage of pesticides
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Insecticides can wash into a stream or lake where they are
taken up by microscopic water plants. Consider the food chain:
Small plants
Marine insects
Fish
Kingfisher
Although the level of insecticides in the plants is small, it
will build up through the food chain due to the number of
organisms in each stage.