One organic vs. inorganic science-fair project would explore the effectiveness of fertilizers, some of which use petroleum-based chemicals. To start, use fast-growing plant seeds, such as cucumbers or radishes, and sow them into the same exact soil in different pots. Experiment with two brands of organic and two types of inorganic fertilizer in different pots with the seeds. Photograph the growth in all the pots and graph the findings on a chart. A variation on this project would be to examine the difference between organic and inorganic soils on plant growth and vegetable yields.
Test organic chicken versus inorganic chicken for bacteria. In this sixth-grade science-fair project, two raw chickens are purchased from the grocery store. Swab each chicken and apply the swabs onto separate agar plates, used to grow any bacteria found on the chickens. One control agar plate should be used for the experiment. Observe and identify the bacteria colonies that grow from the chickens underneath a microscope, and determine which chicken contained more bacteria.
Students should experiment on whether organic or inorganic pesticides work better against pests like insects. Organic pesticides, such as orange oil and mint oil, should be tested against inorganic, or synthetic, ones. Using four different groups of the same kinds of insects, such as ants or crickets, two organic and two synthetic pesticides are sprayed onto the insects separately. Careful observation should be made on how many insects die immediately and if any die later on. Graph and document all the results.
Organic and inorganic milk is produced by different feeding and care to the dairy cows. One experiment with milk would be a taste test between organic milk and inorganic milk, in which cows are given hormones and feed from inorganic grain. Samples of cheese, yogurt and milk can be used for the experiment, and the same group of test takers should be used for the entire experiment. Record each test taker's response to the taste and texture of the dairy product.