• Deborah Orieta

Composting like a Fourth/Fifth Grader

As part of our sanctuary gardens project at North Shore Montessori School, our permaculture consultant Deborah Orieta is working with the fourth and fifth grade students to construct a usable composting system for the school. Through the project, the students are learning about waste management, reusing materials, and their own environmental impact.


Fourth and fifth graders discuss next steps in compost structure.

The unit on composting started with a discussion about national waste. If you’ve read our previous post (linked here) you know that the average American tosses out 4.4lbs of waste a day, which adds up to almost 300 million tons of solid waste per year (EPA, 2017). Of this waste, 22 percent is made up of food. One way to lower this number is through composting. Students are learning what materials can and cannot be composted, and at what scales (things like cheese, which can be composted in bigger facilities, are harder to compost in a home system). They are learning about the mechanics of the compost, about how bacteria and fungi work together to break down food, and about how essential air flow is to the preservation of the process.



Here are some things we’ve learned along the way:


1. Hot versus cold

  • Generally speaking, there are two types of compost. Cold compost refers to a compost pile where organic material is deposited in a pile and left to decompose naturally with little to no human intervention. Hot compost, on the other hand, is assembled more methodically, with the ingredients or waste broken up into smaller pieces and moistened. The mix of brown and green ingredients (see below) heat up due to microbial activity, reaching temperatures of up to 160 degrees Fahrenheit. The heat allows the process to happen faster and ‘sterilizes’ the compost, killing off any potential seeds that could sprout in the future. However, the high temperature also requires the compost to be turned to prevent the killing off of bacterial activity and ensure that all the material gets a change to heat up. Turning the compost can be hard work if done manually, but thankfully there are tools and different composting bins that make it easier if this is a concern for any compost initiates.

2. Bacteria (and fungi) are our friends

  • The world is full of bacteria, yeasts and fungi, but that doesn’t mean that every microbe is out to get us. Specialized bacteria and fungi are essential in breaking down our food waste and turning it into compost. These microorganisms are able to break down large pieces of organic material into itsi constituent parts, freeing up nutrients and minerals so that they are more easily taken up by plants. Their presence also improves soil texture, lending the finished compost more structure as it is better able to clump and hold onto water.

3. Airflow is essential

  • It’s easy to throw a lot of organic material in a corner and forget about it. However, building a structure that allows for all-around airflow can be highly beneficial. It will allow the compost to aerate, and prevent it from going “anaerobic” a process wherein lack of oxygen causes beneficial bacteria to die off, creating space for more unsightly varieties of microbes to find a home in the compost pile. To avoid this, the use of pvc tubes with holes, or pellets to lift the compost off the ground is encouraged.

4. Balance is key

  • We briefly mentioned brown and green materials, but what does that even mean? Brown materials can be dry leaves, old grass clippings, cardboard or paper. They are materials that are comparatively high in carbon, and not in an active state of decomposition (they aren’t rotting, and don’t smell). Green materials, on the other hand, are nitrogen heavy. They include kitchen waste as well as different kinds of manure and cover crops. Leguminous plants like peas or beans are a great example of green materials, because they are good at fixing nitrogen. These green materials can and often are in a state of active decomposition, and as they break down will provide the heat the compost needs to break everything else down.

  • It’s important that the compost has a good balance of green and brown materials. Usually a 1:2 ratio of green:brown works well, and an easy way to ensure that is by using buckets to build the pile. Two buckets full of brown materials for every bucket of green.

5. Recycling is the way of nature

  • Compost is our way of making soil. It is managed and controlled, but is merely an imitation of nature’s natural way of recycling organic waste. The soil under our feet is made up of hundreds of years of erosion and fallen leaves, mixed in with whatever else happened to find its ends in any given place. By composting, we are honoring the processes of nature, and closing the cycle of waste, shifting away from a linear economy of waste (where a product is made, used and thrown away) to one that is more circular (where a product is made, used, and transformed into something new).

Both Deb and the students are itching to get this compost started, and are delighted to share in the process with you. Stay tuned to learn more about compost and to follow along with the adventures of North Shore Montessori School and our other sites as they discover small and meaningful ways to make a difference and work towards the future.

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