Carbon in Your Compost

Brown materials are anything that came from a tree that is no longer living. These carbon-rich materials are really important elements in your compost. Just like humans, the tiny microbes that live in your compost need to eat. They like a balanced diet of browns and green nitrogen-rich materials (food scraps, grass clippings, coffee grounds, and green leaves) to stay healthy. They include:

  • Mulch and wood chips
  • Untreated sawdust
  • Dried leaves
  • Small sticks
  • Untreated straw
  • White paper
  • Brown paper grocery bags
  • Paper-based take out containers and brown paper straws
  • Paper towels and napkins
  • Toilet paper and paper towel rolls

How to Use Browns in Your Compost

Brown materials can be considered the dry ingredients that balance the green “wet” materials. In my experience, lack of brown materials is the most common cause of stinky and failed compost piles. When you first start a new compost system, add a few inches of brown to the bottom, even in a tumbler or container. Then every time you add anything green, cover it completely with browns. Think of it like the layers of a lasagna. Keeping a layer of browns on the top of your compost and you’ll avoid a stinky pile which attracts critters. Ideally, you will use about 50% greens and 50% browns. When in doubt, add more browns. Using too many browns may cause your pile to break down more slowly or need more water, but it will help prevent it from getting stinky.

Just like the nutrients in different types of foods vary, so does the amount of carbon that each type of material contains. Generally, the items that are closer in form to a tree have more carbon, so you’ll need to use less mulch than shredded paper, for example. Paper is highly processed so the quantity of carbon it has changed from it’s original tree form. If you’re interested in learning more about carbon:nitrogen ratios and how using them can help you compost more effectively, this site will explain it in more detail.

Where Can We Find Browns?

Just like food scraps, the brown materials are considered by many to be waste – yard waste, tree service waste, packaging and recyclables. It’s great that we can re-purpose them into valuable compost!

Plan to gather up your brown materials and have them on site before you add your food scraps. Pinellas County has free mulch pick up sites located throughout the county. They are self-service so bring a shovel or pitchfork and a container. I have a car, so I usually bring a rubbermaid tote or two. Works great! If you’re filling a truck bed, cover it with a tarp so it doesn’t blow out. St Pete also offers low cost deliveries of mulch. Tree services will deliver mulch if you have space for a lot of mulch. Just ask them what kind of trees they have – you don’t want any invasive species. They pay to dispose of it, so they are usually happy to give it to you when they are near your neighborhood. Be prepared to wait awhile though. There is a waiting line!

Photo: This mulch came from a local tree service. They ran oak branches through a chipper, then dumped their truckload in my yard. It was several cubic yards; consider the size of your space before requesting a “chip drop”.

Another option is to rake your leaves and ask your neighbors to do the same, then save them in bags or a pile. I have a corner of my yard behind a tree where I’ve lined bags of leaves against the fence. I pull one out every week or two for my compost, or to use as mulch around plants.

Don’t forget about all of the paper products that we either recycle or toss out every day. Brown cardboard, paper grocery bags, newspaper and white paper are all compostable. Even some take out containers (the papery-looking ones) are able to be composted in your backyard, as can un-coated paper plates. Shred or rip them into small pieces, being careful to remove staples, tape, glossy or glittery sections and the plastic windows on envelopes.  Pro tip: Get the cardboard wet and it basically falls apart or you can use a powerful paper shredder.

A young man in one of our compost classes summarized it perfectly when he said, so basically, you just remember to always start and stop with browns. They should be on the top and the bottom of your greens every time.

Published by Pinellas Community Composting Alliance

Pinellas Community Composting Alliance was formed as an education and advocacy group to promote community composting in our Tampa Bay area. We do this by holding classes, helping to establish community compost drop off stations, and working with others to help create a more sustainable local food system.

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