Washington State University
Dr. Universe: How do I make compost without a compost maker? – Miracle, 15, Nigeria
My office is just down the road from the Washington State University composting facility. It processes more than 10,000 pounds of organic waste every month. That’s a lot of compost!
I talked about compost with my friend Jim Kropf. He works for WSU Extension. Extension programs connect universities with local communities. They offer classes and trustworthy, science-based resources that anyone can use online.
Kropf told me that composting is how nature recycles. “In the forest, leaves fall on the ground and come in contact with soil,” he said. “Worms, centipedes, microorganisms and fungi all work on those leaves to break them down into organic matter.”
Making compost is copying nature to make fertilizer for healthier gardens. It’s also a way to help our planet.
You don’t need anything fancy like a compost maker to make compost at home. Some people compost in a pile on the ground. Others compost in a container to keep pests out. The container should be at least 3 feet wide, 3 feet high and 3 feet deep and can be made from scrap materials. The container should let air in and drain excess water.
The basic compost recipe is half wet, nitrogen-rich “greens” and half dry, carbon-rich “browns.”
Fresh leaves and plant matter
Fruit and vegetable scraps
Coffee grounds and tea bags
NO meat, fat or dairy food scraps!
Dry leaves and grass
Hay and straw
Cardboard (unwaxed, no labels)
To get started, layer greens and browns in your compost pile. Chop or shred larger things because small pieces break down better.
Check the moisture level of the compost by grabbing a handful from the pile. If you can barely squeeze out a drop of water, it’s perfect. If it’s too wet, add more browns. If it’s too dry, add water. Cover the pile to protect it from rain.
You can make compost slowly by adding greens and browns to the pile for a year. Then, mix the compost with a shovel and leave it alone for another year. Eventually, you’ll have compost.
The fast process is more hands-on. Layer greens and browns as before, but this time use a shovel to turn the compost at least once a week. The center of the pile will get hot – between 150° F and 170° F (65° C to 76° C). The heat comes from the microbes breaking things down.
“When the temperature starts to fall, turn the compost,” Kropf said. “You’re going to bring the outside materials, that still look the same as the day you put them in, to the center. Then push the middle materials to the outside and do a good mix. That will spike the temperature again.”
Once the pile looks uniformly broken-down, let it sit. This is called curing. The compost is ready when it looks dark and crumbly. It no longer gets hot when you turn it.
There are lots of variations on making compost. One of my favorites is vermicomposting, or making compost with the help of red worms.
No matter which method you use, compost is a great way to care for your garden – and our Earth.
Adults can help kids submit a question at askdruniverse.wsu.edu/ask.
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