Agricultural Ideas for Science Fair Projects (page 2)

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

Medicine and Health (Nutrition)...

Are all apples equally sweet? As apples ripen, the starch in the fruit changes to sugar, making the fruit sweet. What kind of sweet differences are there between apple varieties or individual apples of the same type?

Starch levels in apples can be measured by dipping a portion of the apple into an iodine solution. The starch reacts with the iodine solution to produce a blue-black color in a pattern that is characteristic for each variety of apple. For example, Red Delicious apples lose starch in a fairly even ring, while Golden Delicious apples have an uneven pattern.

You can find reference standards for starch iodine patterns for Macintosh, Red Delicious, Empire, Spartan, and Gala apple varieties on the Internet.

It is best to test fresh apples that have not been stored, so this experiment is best done in the fall. Another way to use this test is to track apple ripening from a single tree over the harvest season to pinpoint the best time to harvest that tree’s apples.

Environmental Science...

Is there chemical contamination in your streams and creeks? One way to test for such contamination is with a bioassay.

Of all the possible water-quality bioassay organisms, lettuce might be one of the last you would think of. Lettuce doesn't live in water, so why use it to test water quality? The reason is lettuce bioassays are inexpensive, easy to do, and the seeds are pretty sensitive to some types of contaminants in water, including heavy metals, pesticides and other organic toxins. Although any variety of lettuce may do, Lactuca sativa Buttercrunch is the standard variety recommended for bioassays by the U.S. Environmental Protection Agency, the Food and Drug Administration, and the Organization for Economic Cooperation and Development.

You might try taking a series of samples along one stream or compare streams near industry to water running though agricultural areas.

Directions for conducting experiments can be found at: Lettuce Bioassay

How does soil pH affect the pH of water that touches the soil?

A pH meter can be found at almost any garden shop or nursery.

Gather different types of soil. Put some of each type in a cup and check out the pH. Then add water to the cups, and mix. Wait for the soil to settle and measure the pH of the water. Be sure you use water from the same source for each soil. Find out more about soil.

Does soil type change how well crops grow?

Fill boxes with different types of soils and plant the same crop in all the boxes. What happens to the plants? You could measure height, width, number of leaves, how fast the plants grow, number of flowers, or yield of seeds or fruits.

How are different soil types affected by water running over them?

Farmers in many parts of the country have to irrigate--to water their crops rather than rely only on the rain. But water running over soil can cause it to wear away, or erode. A simple experiment in soil erosion .

Medicine and Health (Nutrition)

Do different varieties of the same fruit have the same level of vitamin C?

What about different brands of orange juice? Or fresh juice compared to juice from frozen concentrate? Does the way a fruit is stored or how long it is stored change the level of vitamin C? Here's how to test for vitamin C content.

Are there different amounts of iron in different breakfast cereals?

The iron in ready-to-eat breakfast cereals is in the form called elemental, not in combination with any other chemical compound. Iron is sprayed on the outside of cereal flakes. You can separate the iron with a strong magnet.

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