Science fair projects that involve plants or soil chemistry are very popular. It's fun to work with living things and the environment that supports them. These projects are great from an educational standpoint because they integrate concepts from different areas of science. However, it isn't always easy to decide what to do with the plants and soil! Here are some science fair project ideas to help you define your project. Some relate botany and chemistry, some have an environmental science slant, and others are soil chemistry.
- How do different fertilizers affect the way plants grow? There are lots of different types of fertilizers, containing varying amounts of nitrogen, phosphorus, and potassium, in addition to other ingredients. You can test different fertilizers and see how they affect the height of a plant, the number or size of its leaves, the number of flowers, time until blooming, branching of stems, root development, or other factors.
- Does using colored mulch have an effect on a plant? You can look at its height, fruitfulness, number of flowers, overall plant size, rate of growth, or other factors.
- How do different factors affect seed germination? Factors that you could test include the intensity, duration, or type of light, the temperature, the amount of water, the presence/absence of certain chemicals, or the presence/absence of soil. You can look at the percentage of seeds that germinate or the rate at which seeds germinate.
- How are plants affected by the distance between them? Look into the concept of allelopathy. Sweet potatoes are plants that release chemicals (allelochemicals) that can inhibit the growth of plants near them. How close can another plant grow to a sweet potato? What effects does an allelochemical have on a plant?
- Is a seed affected by its size? Do different size seeds have different germination rates or percentages? Does seed size affect the growth rate or final size of a plant?
- How does cold storage affect the germination of seeds? Factors you can control include the type of seeds, length of storage, temperature of storage, and other variables, such as light and humidity.
- What conditions affect the ripening of fruit? Look at ethylene and enclosing a fruit in a sealed bag, temperature, light, or nearness to other pieces or fruit.
- How are different soils affected by erosion? You can make your own wind or water and evaluate the effects on soil. If you have access to a very cold freezer, you can look at the effects of freeze and thaw cycles.
- How does the pH of soil relate to the pH of the water around the soil? You can make your own pH paper, test the pH of the soil, add water, then test the pH of the water. Are the two values the same? If not, is there a relationship between them?
- How close does a plant have to be to a pesticide for it to work? What factors influence the effectiveness of a pesticide (rain? light? wind?)? How much can you dilute a pesticide while retaining its effectiveness? How effective are natural pest deterrents?
- What is the effect of a chemical on a plant? You can look at natural pollutants (e.g., motor oil, runoff from a busy street) or unusual substances (e.g., orange juice, baking soda). Factors that you can measure include rate of plant growth, leaf size, life/death of the plant, color of plant, and ability to flower/bear fruit.
Are you looking for more science fair project ideas? I have other project ideas listed in my Science Fair Project Ideas directory, along with advice on making posters, giving presentations, and working with the scientific method.