You learned previously that food gives us energy and the nutrients that are required to live and grow. As the population of Canada and the world increases, more and more food is needed. In this activity, you will learn how food production has been increased and the impact this has had on the environment.  

 As demand goes up, farmers try to increase how much food they grow each year. They have turned to technology to help them in this endeavour. There are, however, costs that go along with producing more food.

Two major types of chemicals have been developed to increase food production. These are:

• pesticides

• synthetic fertilizers

Pesticides are chemicals that control or kill organisms that people consider to be pests. Pesticides are grouped according to the kind of organisms they control or kill. For example, a herbicide is used to control or kill weeds and an insecticide is used on insects. Farmers use pesticides to kill organisms that compete with or eat the crops they plant. Homeowners may use pesticides on the grass for their lawns. Scientists have estimated that pests destroy about 30 percent of the world's food crops. Pesticides are used to help protect human food supplies.

Synthetic fertilizers that contain plant nutrients are used to increase the yields of food crops. This allows farmers to grow more food on the same amount of land. Fertilizers that contain nitrates, however, can affect the natural nitrogen cycle.

 Nitrogen is an important nutrient that all plants and animals need for growth. During the natural nitrogen cycle, nitrogen gas is converted to nitrates, which plants and animals can use. In the natural nitrogen cycle, all parts are balanced. Some of the nitrates are in the producers, some are in the consumers, and some are in the soil.

But the use of fertilizers can disrupt this natural cycle. You may see algae or other plants growing quickly and overtaking a stream or a pond. This is because the nitrates from fertilizers have been washed into these waterways from lawns or farms.

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 What happens then to organisms in the streams and ponds?

• The fast-growing plants block sunlight from reaching deeper water, causing the plants in this water to get no sunlight and therefore not able to carry out photosynthesis.

• When these plants die, they stop producing oxygen.

• Decomposers then have a lot of food from the dead plants, and their population increases rapidly. The decomposers use up oxygen during cellular respiration.

• This lack of oxygen causes fish and other aquatic animals to die.

The image below illustrates this process: