Composting is the process where organic wastes (grasses, leaves, kitchen scraps and garden debris) are converted into a highly desirable, organic, soil-like material. Gardeners have used compost for centuries to increase organic matter in the soil, improve soil physical properties, and supply some of the essential nutrients for plant growth.
"Bugs" in the form of natural bacteria, worms, fungi, and a variety of invertebrates help turn food and yard waste into compost. The larger bugs process organic wastes physically by tearing or breaking it apart. The smaller bugs process material chemically, by eating it. It is the small bugs that release nutrients in a form that plants can absorb. The bugs work together, feeding in your pile (and on each other), to break down materials. These bugs need a moist environment to thrive. Some of these bugs feed directly on the waste, while others feed on the bacteria in the pile. As they feed on the compost pile, they generate a lot of heat, which also helps the material decompose. The internal temperature is dependent upon the microbial activity, not heat from the sun.
Before starting a compost pile in your yard, contact your city recycling coordinator for composting requirements.
Buy or make your own compost bin. You can compost in a simple pile, but using a container or bin helps your compost pile retain heat and moisture and look neat and some cities require that you use a container to compost.
Place your bin in a convenient location for easy access. Pick a spot in your yard that's at least partially shaded. Other considerations:
- Convenient for you to add materials
- Access to water
- Good drainage - place on bare ground
- Away from large trees - their roots steal nutrients and can grow into the compost
- Not against a building where the compost can rot siding and other structural materials.
A pile that is 1 cubic yard (3 feet high, 3 feet wide, 3 feet long) is big enough to retain heat and moisture, but small enough to be easily turned. Home compost piles shouldn't be larger than 5' x 5' x 5'.
A Recipe for Good Clean Dirt
Like a simple recipe, your compost pile needs the right mix of ingredients in order to produce the best results. A successful compost pile requires three things:
Microbes require air, otherwise the anaerobic microbes will take over, and they are stinky! Air can be incorporated into the pile by turning the pile with a shovel or hoe, or adding bulky, oddly shaped material to make little spaces.
Microbes "tiny microscopic bugs" also require moisture. The microbes live in the thin sheath of water that coats the organic material in the compost pile. If there is no water, the microbes will dehydrate and die. But too much water will displace all of the air space causing anaerobic conditions.
In general, the mixture should feel about as damp as a wrung-out sponge. Pick up a handful of the mixture and squeeze: if water drips out - that's too much; if the material falls to pieces as soon as you open your hand - that's too dry; if the mixture stays in a clump for a few seconds before breaking apart - that's just right.
The Right Ingredients
As a general rule, add three parts of dry ingredients - leaves or dry grass - to one part of wet food waste.Add food and yard waste including:
- Vegetable and fruit scraps, rinds and peels
- Coffee grounds and filters
- Tea leaves and tea bags
- Egg shells
- Nut shells
- Plant trimmings
- Grass and leaves
Do Not Add the Following
- Butter, cheese, or dairy products
- Meat or bones
- Gravies or sauces
- Pet waste
- Diseased plants
- Weeds gone to seed
- Ash from charcoal or coal
- Branches and wood chunks
How to Use Finished Compost
Once you have some nice clean compost you can use it in the following ways to improve your yard and garden:
- Mix compost in with your soil to improve quality.
- Use it to fill in low spots in your yard.
- Use it as mulch for landscaping and garden plants.
- Mix compost in the soil for potted plants.
- Top dress your lawn to retain moisture.
For more yard and garden information, visit www.extension.umn.edu/gardeninfo.
Troubleshooting Common Backyard Composting Problems
Does your compost pile stink? (It should smell like dirt, not rotten eggs!) Not sure if it's working? Is your pile attracting critters?
Composting effectively can be a delicate balance. If you're having trouble with your compost pile, you should check out the Minnesota Pollution Control Agency's Fact Sheet "Diagnosing common backyard composting problems" for assistance.