Compost Creativity: Try Various Methods and Test Soil Fertility *

Areas of Science Geology
Time Required Very Long (1+ months)
*Note: This is an abbreviated Project Idea, without notes to start your background research, a specific list of materials, or a procedure for how to do the experiment. You can identify abbreviated Project Ideas by the asterisk at the end of the title. If you want a Project Idea with full instructions, please pick one without an asterisk.


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?
Worm manure versus soil from a compost pile.
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.

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Sabine De Brabandere, PhD, Science Buddies

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De Brabandere, Sabine. "Compost Creativity: Try Various Methods and Test Soil Fertility." Science Buddies, 28 July 2017, Accessed 22 Oct. 2019.

APA Style

De Brabandere, S. (2017, July 28). Compost Creativity: Try Various Methods and Test Soil Fertility. Retrieved from

Last edit date: 2017-07-28

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