Composting
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A Little History
Compost Bins
Ingredients
Adding Materials to Your Compost Bin
Mixing and Turning
Using Your Compost
Troubleshooting
For More Information on Composting
Compost is organic materials (grass clippings, leaves and vegetable food wastes) that have decomposed into a rich soil conditioner. Composting is the process of combining the right ingredients and conditions that allow microorganisms to make compost. It's really just a way of "recycling" organic materials.
Compost provides many benefits
- Compost improves the drainage and aeration of clay soils, and reduces the likelihood of waterlogged plants.
- Compost increases the moisture and nutrient holding capacity of sandy soils, and reduces drought damage to plants.
- Compost helps keep nutrients in the soil near the plant's roots.
- Compost keeps soil from crusting on top, thus helping seeds to sprout and water to soak in more easily.
Many of your neighbors are already composting, and you can too! To make composting easier, this article covers the tools, containers and organic materials you will need; how compost happens; and how to become the envy of your neighbors after your compost is done.
A Little History...
Who composted first? It's hard to know, but the first recorded use of compost was by a Roman statesman, Marcus Cato, over 2,000 years ago! The Roman empire fell, but composting lives on!
In the 1800's, famed agricultural chemist and educator George Washington Carver helped many people understand the nutritional value and great taste of peanuts. But peanuts were not his only interest; he also taught people of his day that compost was important to gardens, and it saved money. He said, "make your own fertilizer...compost can be had with little labor and practically no cash outlay".
Compost Bins
You don't need a bunch of fancy tools to compost -- just a pitchfork or shovel to turn the compost, a bucket or hose to water the compost, and a compost bin.
City of Minneapolis Ordinance requires that compost piles be contained by some type of compost bin. Piles without bins can become unsightly and may not be able to generate enough heat to safely decompose organic material. Many local garden centers or hardware stores have compost bins, or you can make one.
- Woven wire bins
Bins made of woven wire or snow fence are popular because they are inexpensive, simple to build, and easy to move and store. Steel posts can be used for corner supports. - Turning bins
These bins make turning the compost easier because they give you something to turn the compost into. And, with a multi-bin composter, you can start new compost while the first batch is still cooking.
Whatever you use, your compost bin should be at least 3'x3'x3' to generate sufficient heat for composting. City Ordinance prohibits any compost bin larger than 5'x5'x5'.
The space you can have for compost bins is limited by the size of your property as follows:
- Lots less than 5,000 sq. ft. can have up to a total of 125 cubic feet of compost bins.
- Lots between 5,000 and 10,000 sq. ft. can have up to a total of 250 cubic feet of bins.
- Lots of more than 10,000 sq. ft. can have up to a total of 375 cubic feet of bins.
Where is a good place to put your compost bin? In your backyard!! Partial shading is ideal. This will keep your compost from drying out too quickly. Avoid placing the bin under the edge of a roof, where rainwater may run off and over-water the pile. City Ordinance requires that your bin be placed at least one foot from any property line, and 20 feet from any habitable building other than your own home.
Ingredients
Successful composting combines the materials below, in the right proportions, to give microorganisms such as bacteria and fungi an environment in which to thrive. Microorganisms are essential to the composting process and are naturally found on "greens" and "browns".
Greens -- Organic material like grass clippings and garden plants. Greens are high in nitrogen, and provide the building blocks for the protein that microorganisms need to reproduce.
Browns -- Organic material like leaves, straw, woody plants and woodchips. Browns are high in carbon and provide the carbon source for microorganisms.
Water -- The material in the compost bin should be like a damp sponge - wet to the touch, so that you get just a drop or so of water when you squeeze a handful of compost. If the compost gets too wet, air will not get to the organisms. Without enough water, the organisms will not thrive.
Oxygen -- Those little microorganisms need to breathe too! Without enough oxygen your pile may begin to smell badly. When you first make your pile there will be enough oxygen. Later, you will add more oxygen to the pile each time you turn it.
Other ingredients… the good and the bad
- Okay to add -- coffee grounds, crushed eggshells, fruit remains, tea bags, vegetable scraps. Vegetable and fruit scraps are high in nitrogen and moisture and tend to become compacted, so air cannot get to the microorganisms. Pay special attention if you are composting fruit and vegetables.
- Do NOT add -- bones, dairy products, fats and oils, grease, meat, pet feces, plastic or synthetic fibers. City of Minneapolis Ordinance prohibits these materials in home composting bins.
Adding Materials to Your Compost Bin
Layering the bin:
Step 1: Start with a 2"-3" layer of small sticks or wood chips or a 4"-8" layer of browns. This will help airflow up through the pile.
Step 2: Add a 4"-8" layer of greens and moisten.
Step 3: Add a 4"-8" layer of browns and moisten.
Tip: Break up sticks before you place them in the pile. Long sticks make turning the pile difficult, and smaller pieces will break down quicker.
Step 4: Sprinkle on a thin layer of soil or finished compost.
Step 5: Repeat steps two through four until the bin is full.
If you already have greens and browns mixed together, you can combine steps 2 and 3.
After a few days, your pile will begin to heat up as the microorganisms thrive and your pile begins to decompose. Ideally, your pile should heat to about 140-160 degrees to kill weed seeds or diseases in garden plants. (Your bin must be at least 3'x3'x3' and have the right mix of ingredients in order to heat up properly.)
Mixing and Turning
How often you mix the compost depends on how quickly you want a compost product. The more frequently the materials are mixed, the more air will get to the microorganisms, and the faster they will be able to decompose the materials.
When mixing the pile, be sure to:
- Turn the materials at the outside or the edges of the bin to the inside, so that all the material will be properly heated and composted.
- If your pile is not moist like a damp sponge, be sure to add water as you turn the pile.
After you turn the pile, the heat will increase, and peak after 4 to 7 days. To maintain a hot pile (one that is rapidly decomposing) turn the pile each time it begins to cool.
After being turned several times, the pile will no longer heat up -- the work of the microorganisms is done. Just let your compost pile sit as insects and earthworms complete the job.
How long will it take? That's up to you. Finished compost can be made in as fast as one month under ideal conditions, or as long as 12 to 24 months. The time it takes depends on how often you turn the compost, the balance of greens and browns, and the moisture level.
Using Your Compost
There are a variety of ways you can use your finished compost:
As Soil Enrichment in Vegetable and Flower Gardens
Add from 1"-3" of compost to your soil and work it in well. Adding compost will help soil keep nutrients near the plants roots.
As Mulch Around Trees, Shrubs, or Plants
Apply a 3"-6" layer of compost around the base at the plants. Compost makes an ideal mulch for annual and perennial gardens.
Compost used as a mulch will help suppress weeds, reduce soil erosion, moderate the soil temperature, and conserve soil moisture. Compost will also make a cozy home for earthworms, who help aerate the soil.
As a Substitute for Peat Moss
Mix one part compost and two parts potting soil.
Compost Tea
Compost can also help you get a nutrient-rich liquid fertilizer. Place some compost in a gunnysack or similar bag of loose woven fabric. Soak the bag in a barrel or bucket of rainwater for three days. Use this to water your plants. It will feed them and stimulate growth.
Troubleshooting
Composting is pretty low tech, but you may encounter a few problems at first. Here are some common problems and solutions:
The compost has a bad odor
Solution: There is not enough air, or your pile is too wet. Mix the pile, or add dry materials to the pile.
Pile is not composting quickly.
Solution: Pile may have dried out. Mix the pile and moisten as you turn the compost.
The compost is moist and sweet smelling but still won't heat up
Solution: Not enough greens. Add a nitrogen source like grass clippings, manure, or nitrogen fertilizer.
The compost is damp and warm only in the very center.
Solution: Pile is too small. Be sure your pile is at least 3'x3'x3'.
Unwanted pests are attracted to the pile
Solution: They smell food scraps. Stop adding food scraps.
Unwanted pests are nesting in the pile
Solution: Turn the pile.
Neighbors keep asking why your garden looks so great
Solution: They don't compost. Show them your compost bin, your compost and share this article with them.
For More Information on Composting
Here are a few of the many books about composting that are available:
"Backyard Composting: Your complete guide to recycling yard clippings" by Harmonious Technologies
"Let it rot! The Gardener's Guide to Composting" by Stu Campbell
"Rodale Guide to Composting" by Jerry Minnich and Marjorie Hunt
"Worms Eat My Garbage" by Mary Appelhof
For more information about composting, see www.hennepin.us keyword search "composting" or call Hennepin County Environmental Services at 612-348-3777.
Thanks
For inspiration and great information about composting, we thank the Seattle Solid Waste Utility, King County, Washington, the City of Plymouth, and the Minnesota Extension Service of Hennepin County.
Last updated Dec. 6, 2011