Compost Testing Yields Good Results

Since the start of this semester, it has been my goal to put some science behind the composting that goes on at Washington College, and yes, we do compost by the way. Mid-September, I met with Dr. Sherman, associate professor of chemistry at Washington College who specializes in soil chemistry. She agreed to guide me through the testing and soon I was on my way to determining the quality of our compost.


The procedures were taken from the manual Test Methods for the Examination of Composting and Compost (TMECC), developed by the U.S. Composting Council. The purpose of following these procedures rather than our own is to have the ability to analyze our compost according to widely used standards. Also, in the future we may want to market our compost to the public, and following the TMECC procedures will allow us to put a Seal of Testing Assurance on our compost.

So far, three tests have been performed on the compost from last year, which finished decomposing over the summer. It has been tested for pH, conductivity (soluble salt concentration), and moisture. It is still in the process of being tested for organic matter, which will tell us the percentage of carbon-based materials in the compost. This does not, however, tell us the carbon to nitrogen ratio which is most important during the process of composting, determining the ability for the pile to decompose aerobically and at the correct temperature. This test is quite complicated, so we must send samples to select labs with the proper equipment.

These are the results:

pH: 7.43
Conductivity: 10.83 dS/m
Percent Moisture: 42.8%

Analysis of the results:

A pH within the range of 6.0 and 7.5 is optimum for compost according to the TMECC. In this range, necessary nutrients are available for microbes and the compost can decompose readily. If the pH were below or above this range, necessary biological processes would not occur. A pH within this range indicates that nutrients necessary for plant growth are available. The presence of toxic metals is also an important factor in compost quality. Toxic metals are indicated by a pH less than 5, so we do not need to be concerned about toxic metals in our compost.

Electrical conductivity measures the soluble salt concentration in a sample. Salts are important factors in compost quality because high concentrations can damage seedlings, prevent or delay germination, and decrease nutrient availability. Low concentrations may indicate low fertility levels. Typical compost samples have a conductivity of 1.0 to 10.0 dS/m, and although our reading was slightly higher, it is not excessively high and will not likely damage plants when mixed in with soil.

The percent moisture measures the amount of water in the sample. Percent moisture does not really affect its quality, but rather its ease of handling and transportation. A preferred moisture range is 40-50%, so our compost should be easy to handle.

By the end of the semester we should have results for the organic matter tests as well as results from a sample being sent to a soil analysis lab to determine carbon/nitrogen ratio.

You may be wondering about the actual application of the compost on campus. Some of the compost from last year’s pile has just been applied in front of Daly Hall. Now with these data we can rest assured that the plants are growing in quality compost. Look for signs in front of Daly indicating the use of the compost and be on the lookout for more signs in other areas in the future!

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So what exactly is composting all about?

I spend my afternoons knee-deep in rotting fruits and vegetables. I’m quite friendly with maggots, worms, and other creepy-crawlies that you’ve probably never even heard of. I chase off swarms of flies reminiscent of the Amityville Horror. It’s not that bad; I’d even go so far as to say that I have fun doing it.

…No, really.

I’m half of Washington College’s formidable composting duo. Every weekday afternoon, Donna and I head out to Buildings and Grounds to work on the compost pile. When we get there, there are two or three trash cans waiting for us in front of the compost pile. The bins are filled with food waste from the dining hall. We drag them over and dump them on top of the heap. Then, we use our shovels to break the food into smaller pieces so it will decompose faster. Doing this also helps mix the new waste into the compost. When we’re finished, we cover the pile with dead leaves and woodchips and rinse out the trash cans.

I’ve heard that a lot of students on campus aren’t even aware of the composting program. I’m going to give you updates on our progress about once a week so you can stay informed about the environmental efforts on campus. But first of all, what is compost, and why is it important?



Compost, once it is complete, is an excellent natural fertilizer. It’s brown, crumbly, and doesn’t seem all that different from fertile soil. Compost is easy to make at home. It’s largely food waste, with dry materials, such as leaves, added to improve the chemical ratio. It needs moisture and air to decompose properly. All kinds of creatures find compost piles to be lovely places to live. If you were to dig into our pile here, you would find maggots, worms, and all kinds of other bugs that help decompose the food and make the compost more fertile. The process eventually concludes with mature compost- the familiar soil-like substance you might use to fertilize your houseplants.

But why compost in the first place? Why deal with all the rotting food and bugs? Is it really worth it? The answer is yes. First of all, compost saves space in landfills. America is quickly running out of space for landfills, and with the amount of trash we produce, this is a pretty serious problem. While food is biodegradable, landfills are terrible places for decomposition. The conditions aren’t survivable for all the friendly critters that live in a backyard compost pile. Oxygen can’t get to the trash that sits in landfills. The minimal decomposition that does take place in landfills actually creates explosive methane gas- something that is far more undesirable than a few maggots.

A compost pile has access to oxygen and water, making it an ideal environment for the bugs that aid in decomposition. Mature compost is nutrient-rich and chemically balanced, making it an excellent fertilizer. Some scientists even believe that the heat produced by a compost pile could even one day be used to heat homes!

While it is clear that a compost pile is far superior to a landfill, don’t just throw all trash into a compost pile. There are very specific guidelines about what belongs in a compost pile and what doesn’t. Of course, anything that is non-biodegradable is out. No matter how hard you try, you won’t be able to turn a plastic bag into compost. Food waste and paper, however, make excellent additions to a compost pile. Avoid composting animal products, such as meat, eggs, and dairy, because they will attract rats and smell really bad. Also avoid things that have been treated with pesticides because they will harm the bugs in the compost pile, and eventually the plants that receive the compost as fertilizer.

Now that you know the basics of composting, you might be interested to learn more about the program here at Washington College. Check back for weekly progress updates!

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