Dangers Involved in Excessive Use of Chemicals

Back to: Agricultural Science Primary 4

 

Welcome to class! 

In today’s class, we will be talking about the dangers involved in the excessive use of chemicals. Enjoy the class!

Dangers involved in excessive use of chemicals

The fertility of our soil needs to be maintained and one of the ways to do so is to apply fertilizer which is a chemical. When our crops are planted, to ensure that they grow up healthy and yield great harvest they must be protected from pests and weeds. To do this pesticides and herbicides are used. These are also chemicals. It is important that they are used appropriately and in the right amount. Excess use of these chemicals has adverse effects on the soil, the crops, the water bodies around the farmland and also the entire environment.

Activity

The above is an effect of the excessive use of fertilizer. Can you describe what you are seeing in the picture?

Effects of excessive use of chemicals

1. Chemicals can kill crops
2. Chemicals can kill beneficial living things in the soil like earthworms.
3. Chemicals can be washed away by rain into streams and rivers thereby killing fishes and other living things in the water
4. Chemicals, when blown away by the wind contaminate the air.
5. Chemicals can contaminate various sources of water like well, stream and river.
6. When fishes and other living organisms inside water dies, they will give off an offensive odour.
7. When excess fertilizer is washed off into water bodies, they cause excess growth of some water plants called algae.

The picture shows excessive growth of algae which covers the surface of the water.

Activity

Looking at the picture above can you describe what can happen when this occurs?

Weekend assignment

1. List five effects of the excessive use of chemicals on crop plants.
2. State the importance of the following to crop plants.

• Pesticide
• Herbicide
• Fertilizer

 

In our next class, we will be talking about How to Raise Ornamental Plants (Flower Plant).  We hope you enjoyed the class.

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