الأسبوع 12 · الفصل 9: تدريبات على ورق عباد الشمس والتبخير، مقال «العين الكيميائية التي ترى القوى الخفية» · 3 دروس
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Healthy farm soil and a healthy Nile
Science P6: Term 1, Chapter 9, pp. 78–81
GoalExplain why farmers test their soil and why testing river water helps protect fish and birds.
New words
soil test · a check of how acidic or alkaline soil iscrop · a plant grown for food, such as wheat or cottonwastewater · used water that is sent away after use
Explanation
Plants grow better in the right kind of soil. Some crops, such as cotton and wheat, grow best in soil that is not too acidic and not too alkaline. So farmers check their soil. A simple check mixes a spoonful of soil with clear water, lets it settle, and tests the clear liquid with an indicator. If the soil is not right, farmers can change it step by step with grown-up advice. Water is tested too. Factories use water and send it away as wastewater. Scientists and the factories themselves test this water so it is not strongly acidic or strongly alkaline, because very acidic or alkaline water would harm the fish and birds of the Nile. Testing is a way of caring for the river that gives Egypt its water.
soil in water→let it settle→test the clear liquid→read the colour
Worked examples
Karim’s aunt has a vegetable garden. She tests the soil and finds it is neutral, so most garden plants should grow well.
Field
Blue strip
Result
A
turns red
acidic
B
stays blue
not acidic: test with the red strip too
A farmer in the Delta tests two fields. Field A turns the blue strip red. Field B changes neither. Field A is acidic and Field B is neutral.
A scientist tests river water near a town every month and writes the result in a table.
Class activity
Garden soil test. With a grown-up, put a spoonful of garden soil in a clear jar of tap water, stir, and let it settle for an hour. Test the clear liquid on blue and red litmus paper. Is the soil acidic, neutral or alkaline? Wash your hands after touching soil.
Practice
1
Why do farmers test their soil?
Some crops grow better in one kind of soil than another.
2
Which liquid do we test: the soil, or the clear liquid above it?
The clear liquid above the settled soil.
3
Why is wastewater tested before it goes into the river?
So it is not strongly acidic or alkaline and does not harm the fish and birds.
