Caso 2 - Growing Deeper

Students who are interested can explore the science of hydroponics. Growing plants without soil can be demonstrated very easily in the classroom and can lead to discussions of whether we really need soil.

Explore the idea of making your own soil "recipe" and then testing it to see if it will support plant growth.

Explore further the answers to these questions.

• How does soil become compacted? What happens when soil becomes compacted?

• Do you think soil found in the desert could ever be changed to have the ability to grow plants? What do you think would have to be done to get these soils to support plant growth?

• Name three important elements that plants need to grow. Name two sources of vitamins, minerals, and nutrients for people.

• Where does compost get its nutrients from?

• Do you think that insects, worms, and other things living in the soil are affected by the change in soil composition.

• What helps keep the soil on the earth from washing away during a heavy rainstorm?

Optional Activity: An Exercise in Soil Appreciation

We depend on soil for your food. As the world's population grows, the amount of soil capable of supporting each person is reduced, making it essential that we use the diminishing per capita soil supply wisely. How much soil do we have to work with?

Use an apple to represent the earth. Begin by cutting it into quarters. Take away three quarters, which represent the oceans. This leaves one quarter as land.

Cut the land in two and take away one of the parts, representing areas that are unsuitable for human habitation. Cut the remaining eighth of the apple into four equal parts. Three of theses pieces represent areas unsuitable for growing crops, either because of poor weather or soils, or because of development for other uses. Remove them, leaving 1/32nd of the apple.

Peel the remaining piece. The tiny section of peel represents the soil upon which we depend for all of our food. Now return to your garden or farm and practice soil conservation with the smallness of that piece of peel in mind.