Week 12 - Increasing Yields, Selective Breeding, Controlling Pests and Environmental Management

Exercise 4.1

Lesson 4.1: Increasing Yields

ACTIVITY A: Increasing Yields

Required Readings

Science in Action 7
pages 151 to 155

Science Focus 7
pages 132 to142

Our population is steadily growing. Decreases in infant mortality and increases in life expectancy means that more people are living to become adults and those adults are living longer lives. Higher standards of health care across the world have made this a worldwide trend, not just in the developed nations. In short - the human population is EXPLODING!

To cope with this, farmers have had to develop new strategies for getting more food. All these people in our world need plants for food and fibre. It would be easy to say, "Just grow more crops." This is not really the case. We are limited by the amount of arable farm land available. Some of our land is not suitable for farming. It is too cold, forested, dry, or wet. 

However, we can change this. We have technology that can increase the yield of plants by modifying the environment.

If an area is too dry, we can irrigate the area. This provides water for plants to grow. Water can be pumped from a body of water or from underground. It then travels through pipes until it reaches the farmer's land. The farmer can build an irrigation system to deliver the water to the plants that need it.

If the area is too cold, we can use greenhouses. These greenhouses can be built to have a controlled temperature and light in all seasons, so we can have fresh vegetables even in the winter. Greenhouses also offer a way for us to have a high yield for the small area that they take up. A greenhouse can produce more food than an open field because the environment is controlled for the best growing conditions for the plants.

If the soil in an area is not suitable for growing, we can use a greenhouse with artificial soil. Hydroponic systems allow plants to grow in gravel or coarse sand. Water enriched with the right balance of nutrients is circulated around the roots of all the plants. Plants are monitored to ensure they are growing correctly. Most commercial greenhouses use hydroponic systems for growing their plants.