What do you think of when you think of trash? A smelly, yucky garbage bin? A weekly chore? Litter that ruins the beauty of the world around you?

All those things can be true. But did you realize that trash can also be useful? It’s true! When you gather together certain types of trash in a compost pile or bin, you can turn it into something that your garden will love!

Did you realize that about 30% of all garbage in the United States consists of food and yard waste? From coffee grounds and orange peels to grass clippings and egg shells, much of what we throw into the trash that ends up in landfills could actually be turned into something beneficial.

Composting is a fantastic way to recycle these types of waste. Composting is a process that takes advantage of the fact that microscopic organisms that live in the soil will break down organic materials, such as old plant and animal tissues, and turn them into new soil called compost.

You can think of composting as an example of the natural life cycle of organic things. They grow, die, decay and eventually return to the Earth as new soil that helps other things grow. In addition to tiny microorganisms, earthworms also help speed this process along by feeding on some of the organic materials in soil.

Although composting is a natural process, you can help it along by creating special compost piles — sometimes called heaps — in your yard or by using compost bins you can build or buy at the store. To create the ideal conditions for composting, you’ll need just a few things: organic waste, soil, water and air.

The soil provides the microorganisms that will eat the organic waste. The air provides oxygen and the water helps to speed the process along. Organic waste can take many forms, including leaves, newspaper, fruits, grass clippings, egg shells, vegetables, coffee grounds and woody materials.

When you start a compost pile, you need a mixture of both carbon and nitrogen. Carbon is found in organic materials like leaves, straw, newspaper and woody materials. Nitrogen is found in things like fruit and vegetable waste, grass clippings and coffee grounds. Healthy compost contains about one-quarter nitrogen and three-quarters carbon.

As microorganisms break down these materials, they release carbon dioxide and heat. A good compost pile will get quite warm (as high as 100-150° F!). To keep the process moving along as quickly as possible, it’s necessary to keep it active by turning it and watering it frequently. This allows needed oxygen to be circulated throughout the pile.

Although you can compost many things, there are certain things to avoid. Meat and dairy products contain a lot of fat, which can cause your compost pile to emit a very unpleasant odor if these items are added. You should also avoid human and animal waste, since they can contain diseases and parasites.

37 Join the Discussion

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    • WOHOO, great guess, Skye! Thanks for sharing your comment and using your imagination to Wonder about tomorrow…! It’s so much fun to be creative with our Wonder Friends– we hope to see you tomorrow! :)

  1. HA HA!! My momma tried to compost, and it stunk! I guess she wasn’t turning it! Today’s Wonder is SUPER!! Thanks!

    • YIKES, we sure are glad you learned why it’s important to turn your compost, Bryleigh! We bet your mom did a great job for a first-time composter! We Wonder if you’ll try it this time, after all the WONDERing you’ve been doing?! :)

    • HOORAY, we are so glad you enjoyed this article, Yadira T! We hope you give composting a try– we’d love to hear how it’s going! Thanks for sharing your SUPER comment today! :)

    • Hi there, Jaryn, we sure are glad you’re WONDERing with us today! Composting is a cool process, but it’s important to remember what can and cannot go into composting. In order to stay healthy, it is recommended that we do not put animal or human waste in our compost– this attracts insects and parasites that can harm us and potentially make us sick. We wouldn’t want that to happen! We are so proud of all the great WONDERing you’ve been doing, Jaryn! :)

  2. I loved the video! The bunny was sooo cute. I did not know that compost could be used for so much. I hope I can wonder again some time.

    • Thanks for sharing your comment, Gabriel! We are oh-so-glad you learned something new about composting today! It’s a pretty nifty idea to Wonder about! We certainly hope you come back soon– each day there is a new Wonder that will be waiting for you! :)

  3. Dear Wonderopolis,
    Today’s wonder was interesting and WONDERful. Me, and my class were right…sort of, we said recycleing.

    I think tomorrow’s wonder will be about how phones work.

    • Hello, Alexis, thank you for sharing your comment with us today! We are very proud of you and your Wonder classmates– you guessed correctly! We hope you enjoyed learning a thing or two about composting and recycling… it’s fun to Wonder with great friends like you! We can’t wait to find out what tomorrow will bring– thanks for sharing your SUPER guess! :)

  4. I learned a lot.

    WOW!!!!! Garbage can be useful? Wow! Did you realize that about 30% of all garbage in the United States consists of food and yard waste for example coffee grounds and orange peels 2 and egg shells, much of what we throw into the trash that ends up in landfills could actually be turned into something beneficial as a compost which is very green.

    Composting is a fantastic way to recycle these types of waste. Composting is a process that takes advantage of the fact those microscopic organisms that live. It is very important to compost what you can.

    • Hi there, Jules, thanks for WONDERing about composting, recycling and reducing waste today! We are glad you’re here! We Wonder if you, your class or your family have ever composted? We hope you have a WONDERful day! :)

    • We hope you do, Dani S! We think composting is a great way to reduce waste in the world and help our plants grow, too! Thanks for sharing your comment today– we’re glad you are WONDERing with us! :)

  5. Cool. I learned about this last year in school but this time I understand it more. That’s why I love this website!

    • That’s great news, Josephine L.! Thanks for sharing your comment about composting– sometimes it takes us all a couple of times to really understand something, like composting! We are glad that you are learning and WONDERing today– we are oh-so-happy you’re here! :)

    • Great guessing, Abby! We Wonder if our Halloween-themed background helped you form your guess!? We are glad you’re WONDERing with us today! :)

  6. Hello! Today’s wonder was very interesting! I love coming to this website and learning all this cool stuff! I will certainly try composting. And I have a wonder: How did composting start? Did people leave trash outside and find out about it or were there tests about it?

    Oh, and I think the next wonder is about knock-knock jokes! Maybe how they started?

    Well, have a nice night!


    • Hi there, Isabelle! We are glad you have taken an interest in composting– it’s a great way to help the environment!! We think the WONDERing you’re doing on your own is SUPER, and we bet, with a bit of research, you can find out more information on composting and how it came to be! Thanks for sharing your SUPER comment and joining the fun at Wonderopolis today! :)

    • Good morning to you, Daniela S! We’re so glad that you’ve shared your comment and said hello to your Wonder Friends Yadira and Josephine– how thoughtful! :)

    • That’s SUPER great to hear, Wonder Friends in Ms. Kilpatrick’s class! We think you would be doing a great thing for the environment by composting– we hope to hear how it goes! We’d love to see some pictures, too! Your 5th grade classroom sounds like a very COOL place to be! :)

  7. Dear Wonderopolis,

    This wonder is perfect for us! Yesterday, in science, we made our own compost cups!

    You gave us great advice for making our composts better! Now we understand why it would gross and maybe even dangerous to put dairy products in our composts!

    Thanks for an awesome Wonder!

    Miss Thomasson’s Third Grade Class

    • Hello to our Wonder Friends in Miss Thomasson’s Class! We apologize that you are receiving such a delayed response! We were busy getting our compost together in the Wonderopolis garden and we didn’t mean to overlook your SUPER comment!

      Thanks for letting us know that you enjoyed our compost Wonder– we sure hope that your compost cups are working out well. It sounds like a WONDERful science project– way to go!

      Have a terrific day and keep up the WONDERing! :)

  8. this is very useful infomation and if everybody composted just imagine!
    i think i might tell my parents about this and we give it a shot!!!!!!!!!!

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Have you ever wondered…

  • What is compost?
  • What kinds of things can you compost?
  • How do you make a homemade compost bin?

Wonder Gallery

compost bin shutterstock_82289665Vimeo Video

Try It Out

Ready to give composting a try at home? First, you’ll need to get permission — and probably a lot of help — from an adult. If they’re unsure about composting, share today’s Wonder of the Day with them and let them know how environmentally-friendly composting is!

When you’re ready to do a little more research to learn what you’ll need to do to set up your own compost pile or bin, jump online and check out the links below:

Good luck with your composting efforts! We hope you’re able to reduce, reuse and recycle your compostable waste into something you can use in your garden.

Still Wondering

Watch National Geographic Education’s Putting Waste to Work video to see emerging explorer Sasha Kramer fight some of Haiti’s most pressing health, economic and environmental problems — one toilet at a time!

Wonder What’s Next?

Tomorrow’s Wonder of the Day will make quite a splash!

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