Watching a pile of food scraps, leaves, and wood chips break down into a dark, rich, material may seem like magic, but it’s not. Rather, it’s a scientific process that provides a tangible lesson in biology, chemistry, and ecology. If you’re interested in learning about composting for kids, you’re in the right place.
We’re going to cover some of the basics about composting as well as composting activities you can do with kids.
The Science Behind Composting
We all know that kids have endless curiosity, so we’re going to equip you with the information you need to answer some of the most common questions about composting.
What is Composting?
Composting is the controlled decomposition of organic materials.
So, what’s decomposition, you ask? It’s the breakdown of organic materials into smaller components.
A great example of decomposition occurs on the forest floor. Although leaves fall from the trees each year, you don’t see giant leaf piles in the forest. This is because decomposers such as worms, beetles, fungi, and bacteria break down the leaves.
What Controls the Breakdown of Materials?
Thousands of organisms, including macroorganisms such as earthworms and millipedes as well as microorganisms such as bacteria and fungi, work to break down organic materials.
When you’re composting, your goal is to create a perfect habitat for these organisms.
Even if you can’t see these organisms, they are hard at work.
How Do We Provide a Proper Environment for Microbes?
Now that you know the importance of organisms, let’s see how you keep them happy, especially the microorganisms responsible for the final stages of decomposition. The success of microbes depends on three main factors: materials, water, and oxygen
When you’re building a compost pile, you want to have a proper ratio of carbon to nitrogen – the C:N ratio. You can control this ratio by incorporating specific amounts of brown materials (carbon-rich) and green materials (nitrogen-rich).
You want your pile to have a C:N ratio of 30:1. To do this, add two to three parts of brown materials for every part of green materials.
Brown materials include:
- Dead leaves
Green materials include:
- Food scraps
- Grass clippings
- Coffee grounds
You want your compost pile to be moist, rather than wet or dry. The materials should feel wet, but they should not be dripping water.
Microbes need water to live, yet too much moisture can limit the amount of oxygen they receive.
The fastest form of composting is done by aerobic organisms, those that live in the presence of oxygen. If a compost pile lacks oxygen and goes anaerobic, the composting process slows and you’ll likely smell unpleasant odors.
To keep oxygen levels at an adequate level (above 5%), users often turn their piles.
How Do the Microbes Break Down Materials?
Microorganisms such as bacteria and fungi release different types of enzymes. These enzymes, compounds that activate or speed up reactions, break down larger molecules into smaller molecules.
These smaller molecules are then taken up by microbes or circulated throughout the ecosystem.
7 Composting for Kids Activities
There are lots of activities available to help teach kids about composting.
Build a Soil-Arium
Similar to terrariums, soil-ariums act as small-scale replicas of larger systems. However, soil-ariums don’t contain live plants. Rather, they contain compost inputs.
To build a soil-ariuim, all you have to do is layer a mix of organic materials into a wide mouth glass jar and water. Place a piece of cloth over the mouth of the jar to let air in but keep bugs out.
Watch over the materials break down over the next few months.
This method of composting involves digging a trench in the soil and filling it with food scraps. Once the trench is full, you cover it back up with soil.
There’s no mixing up browns and greens or turning a pile, and it’s easy for kids to participate in. This method often draws in earthworms, which provide a jumping point for a lesson on larger decomposers.
Pocket composting is similar to trench composting. However, instead of digging a trench, you dig a small hole and fill this “pocket” with food scraps.
After a few months, you can plant on top of the pocket. It’s fun to compare plants located on top of a pocket with those planted into the natural soil.
Learn to Identify Carbon-Rich vs. Nitrogen-Rich Materials
This is one of the easiest ways to get kids involved in learning about the chemistry of composting. Remember, green materials are nitrogen-rich and brown materials are carbon-rich.
After explaining the basics of nitrogen-rich vs carbon-rich materials, have the kids gather some organic materials, or provide a selection of materials. Next, see if they can determine whether the materials are considered nitrogen-rich or carbon-rich.
Vermicomposting with a Worm Bin
With visible slimy, squirmy bodies that many kids can’t resist, worms can provide a great introduction to the basics of composting.
Vermicomposting doesn’t rely on microorganisms as much as it does the worms. Therefore, it offers a more visible look at the process of decomposition.
You can build your own worm bin or buy one of many kits available.
Soda Bottle Composting
Soda bottles are the perfect vessel for small-scale composting experiments. Their clear walls allow kids to examine how altering different factors impacts the composting process.
For example, one bottle can contain one part brown material to four parts green material, and another bottle can contain two parts brown material to one part green material.
Ah, the leaf pile. A joy to jump in, yet also a great lesson in composting!
By watching a leaf pile over the course of a few months, kids can observe changes in the leaves and the size of the pile. These changes provide teachable moments about decomposition and composting.
Adding Compost to Your Garden
Once you’ve made some compost, it’s time to add it to your garden! You can do so in a number of ways.
- Mix compost in with existing soil to enrich soil prior to planting
- Place some compost in holes before planting
- Create a seed starting mix by blending compost with coco coir and perlite
- Soak your compost in water to create a nutrient-rich compost tea
It’s Not Waste…It’s a Learning Opportunity
Composting can teach kids about chemistry, biology, and ecology. Not to mention, it provides a great opportunity to talk about reducing food waste!