Agricultural Ideas for Science Fair Projects (page 3)

— U.S. Department of Agriculture
Updated on May 2, 2014


It's easy to think of all microorganisms as bad things, as germs. But many microorganisms are very helpful, especially for agriculture, and some are even essential. Microorganisms are used to fight pest insects, diseases and weeds that make producing crops and raising livestock less efficient. Other microorganisms help make nutrients in the soil more available to plants.

What happens to the way plants grow if there are no microorganisms in the soil?

Take a sample of fertile soil from a field or garden and divide it into two portions. Bake one in an oven (to destroy the microorganisms). Leave the other portion alone as a control. Plant the same number of seeds in each soil sample. Remember to treat both samples the same while the plants are growing. Make sure all the plants receive the same amounts of water and light, and are kept at the same temperature. How do the plants differ as they grow?

Are different plants affected in different ways by specific microorganisms?

Some microorganisms and plants form mutually beneficial partnerships. For example, certain bacteria make a natural nitrogen fertilizer for plants in the family called legumes. Peas, alfalfa and soybeans are legumes. The nitrogen-fixing bacteria are available from garden supply stores and by mail order. Grow both legumes and non-legume plants with and without the bacteria. Are there differences in how well the plants grow?


Most schools have special rules about doing any experiments that involve live animals. Be sure and check with your teacher before you decide on such an experiment.

Can different colors and types of cloth attract or repel insects from plants?

Plant a number of groups of the same type of plant near each other, but far enough apart to surround each set with several feet of fabric. Or select several of the same kind of bush in one yard. You want to use the same type of plant in the same place, so all of the plants will have the same potential for insect damage.

Surround each group of plants with a different color fabric. Be sure water can penetrate the fabrics. At set intervals, record all the insects you can find on each plants and any signs of insect damage on the plant. It is a good idea to check reference sources for common insect problems of the type of plants you are using.

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