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Compost Creativity: Try Various Methods and Test Soil Fertility

81 reviews


Areas of Science
Time Required
Very Long (1+ months)
Sabine De Brabandere, PhD, Science Buddies
*Note: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

If you want a Project Idea with full instructions, please pick one without an asterisk (*) at the end of the title.


Make your own fertile soil using kitchen scraps, manure, leaves, grass clippings, and other compostable materials. Which materials make the best compost? How does the amount of nitrogen change the rate at which the compost forms? How does a 'hot' compost pile compare to a 'cold' compost pile, or how does traditional composting compare to worm composting, or vermiculture?
Two types of composted soil are compared side by side
Figure 1. Different composting methods yield different soils. In this picture, the soil on the left is vermicompost (the result of organic material composted by worms), while the soil on the right is harvested from a compost pile.

Research will allow you to limit the scope of your project and select variables that quantify soil fertility. Note that potassium and potash refer to the same nutrient. Potassium refers to the chemical element with atomic number 19 (listed in the periodic table); potash refers to salts that contain potassium in water-soluble form.

Next, you need to set up a controlled experiment. Ideas can be found in the following projects:

Once you have your samples of compost or soil, you will want to quantify their fertility. A soil test kit that provides quantitative results for the pH, nitrogen, phosphorus, and potassium can help quantify nutrient content. These kits can be purchased from an online supplier, such as Carolina Biological Supply Company, item #665404 or at a well-stocked gardening store. Running water through a sample of dry soil, as shown in this video showing how to experimentally compare water retention abilities of different soil types, can help you quantify water retention of the soil. Can you find other measurable quantitative parameters that describe your soils?

The resource page Data Analysis & Graphs can help you analyze your data. If you need help summarizing your results or drawing conclusions based on your data, check out the resource page Conclusions.

As a last step, make an attractive Display Board and share your results.

icon scientific method

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Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.


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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

De Brabandere, Sabine. "Compost Creativity: Try Various Methods and Test Soil Fertility." Science Buddies, 12 Jan. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Geo_p036/geology/compost-soil-fertile. Accessed 30 Nov. 2023.

APA Style

De Brabandere, S. (2020, January 12). Compost Creativity: Try Various Methods and Test Soil Fertility. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Geo_p036/geology/compost-soil-fertile

Last edit date: 2020-01-12
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