Successful home composting involves providing the optimum conditions for microbial life to speed up this process. Compost is made by billions of microbes (fungi, bacteria, etc) that digest the yard and kitchen wastes (food) you provide them. Just like humans, these little guys need not only food, but also air and water to survive and eagerly gobble your garbage. The compost pile should be about as moist as a wrung-out sponge and it is nice to turn the materials in the pile weekly to evenly expose them to air.
RECIPE FOR GOOD COMPOST
Brown stuff 50-70% of volume
(leaves, hay, dry matter)
"Browns" are rich in carbon and carbohydrates, providing energy for the microorganisms. Most of the browns leave the pile as carbon dioxide breathed out by the bugs. Use a mulcher or shredder, if possible, to reduce the particle size. This will increase the surface area and accelerate the rate of composting. It is a good idea to moisten brown stuff as you place it in the pile, or if the pile is too wet, use dry brown stuff to absorb the excess moisture.
Green stuff 30-50%
(grass, vegetative food scraps, manure)
"Greens" are fresh, damp materials that quickly decompose on their own. They are high in not only water, but nitrogen, which is important to increasing the population of microorganisms in the pile.. "Greens" are also the source of most odors in the compost pile. They should be mixed completely or at least in layers with dryer brown materials (always cover food scraps with other materials). Too much green material can collapse in volume, lose its air, and putrefy.
Black stuff 0-5%
(Dirt, Old compost)
"Blacks" are the inoculants, like the yeast in bread, which starts the process. Dark soil or compost contains millions of soil organisms. These "bugs" provide a jump-start to a compost pile and can help reduce the time required for decomposition.
(Damp sponge consistency)
It is very important to have adequate moisture inside the compost pile. The vast majority of problem piles are too dry. Water the pile as you build it, not from the top at the end. Leaves are like shingles and should be stirred and sprayed to insure that they get wet. If you do NOTHING else, moisten the pile. You may still need to water the pile weekly. A tarp can also help regulate pile moisture by either trapping moisture in or keeping excess rain out.
(Open sided bin, turning pile)
The microorganisms that break down compost are aerobic, meaning they need air to survive. Without air, anaerobic organisms will begin to grow. These are usually bacterium that will eventually decompose the pile, but smell like putrefying garbage in the meantime! This happens most often when too much fresh green matter or garbage is added and not mixed well.
Mix browns, greens, and blacks.
Keep the bin full, moist, and stirred.
Give it time and see what happens!
CREATING YOUR COMPOST AREA
There are many different composting systems, but the most characteristic is the bin or pile method, the ingredients for which are listed above. Other ways to decompose organic wastes usefully include grasscycling, mulching, vermicomposting, sheet or trench composting, or tumbling systems. Sheet or trench composting is when organic wastes are applied directly to the garden. Kitchen wastes should be in a trench 8 inches deep, and left to rot a few months before planting over them. Autumn leaves can be applied directly by tilling them into the soil in late autumn, or at least 2 months in advance of planting in the area. A tumbling system is simply a horizontal barrel on legs that can be rotated easily. Due to the small capacity and lack of ventilation, these systems can also trap a lot of heat, which can aid the composting speed.
Locate the compost heap in an area where water will not stand. Many composters locate their piles near their gardens or the source of the wastes for convenience. You may also want to consider a two-bin system so you can access older compost easily while fresher materials are stored in the second bin.
Size of the compost pile
For fast, efficient composting, a compost pile must be large enough to hold heat and moisture, and small enough to admit air to the center. As a rule of thumb, compost piles need to be about 3 ft. by 3 ft. by 3 ft. (1 cubic yard). A smaller pile will dry out easily, and cannot retain the heat required for quick composting.
TOP (left to right): Movable holding units constructed from wire, snow fencing, and wood and wire.
BOTTOM (left to right): Stationary holding units constructed from cinder blocks, mortared bricks, and wood
If you choose to enclose your pile, many materials will do, from hay bales to an old garbage can with large holes drilled in it. Bins are also available commercially locally.
- Woven wire or wood slat fence -- Covering the compost pile with a layer of plastic will speed the compost decomposition.
- Cement blocks or bricks -- Mortar is not necessary since the weight of the cement blocks will hold the pile in place.
- Boards of scrap lumber -- Don't use good lumber since the damp compost may ruin the boards. A permanent enclosure of redwood or cypress is possible. Old wooden pallets are ideal for this type of bin.
- Not enough air.
- Pile too wet.
- Not enough water in pile.
- Too woody.
- Pile is too small
- Too dry.
- Lack of nitrogen in pile.
- Compost is done!
What can I put in my pile?
- Vegetable scraps
- Citrus rinds
- Grass clippings
- Bark, wood ashes
- Horse manure
- Small garden clippings
- Small stalks, stems, and vines
- Fat/Vegetable oils
- Dairy products
- Plastics or synthetic fibers
How do I use my compost?
Many people churn compost into their garden beds. If the compost is not totally finished, you will want to mix it in at least two months before planting new seedlings. Decomposer microbes may attack seedling roots if the roots contact unfinished compost.
Compost may also be used as "topdressing" on yards, bases of plants, and houseplants.
Houseplants also enjoy "compost tea" made by combining equal parts compost and water and letting it sit. Toss the dredges back into your compost pile when finished watering the plants with the tea.
Unfinished, woody compost is often used as mulch. All in all, compost will help your soil by adding organic matter, beneficial microbes, a spongy texture to retain moisture, nutrients, and more! The City of Lawrence uses its compost in many landscaping improvement projects.
When is my compost "finished"?
While there is no set time for compost to be done "cooking," it should be ready to use 4-6 months after starting the pile. Well shredded, maintained piles can finish in as little as 3 weeks in warmer weather. Signs your compost is ready include a loss of heat (microbes are slowing down), a rich "earthy" smell, and the inability to distinguish many of the original ingredients visually.
What are the health benefits of using compost in my garden?
Plants that grow in nutrient-rich soil will in turn contain more vitamins nutrients in their edible parts. Today, many commercial crops are grown using oil-based fertilizers instead of compost. This has caused commercial foods to decrease in nutritional value, including a decrease in selenium, a cancer-preventing mineral that used to be plentiful in corn.
Compost is also obviously made from 100% natural materials, meaning there are no harmful chemicals to store in your house or spray on your plants when you want to fertilize the soil.
Does my pile need to be hot in order to work?
Heat is not essential, but is a sign of healthy microbial growth and activity. Active piles can reach 150-160° F, inactivating weed seeds and harmful disease organisms. Hotter piles also decompose faster. If you desire a warmer pile, try "insulating" your pile with bags of leaves or bales of hay* (*beware that some haw/straw may be from a crop that was treated with an herbicide containing Clopyralid. This could negatively affect your compost).