Making Compost


Photo courtesy Karim Nice
Where do you want your compost pile?
To make compost, you must do the following:
  • Choose a site for the compost pile.
  • Choose a structure.
  • Add the ingredients.
  • Care for and feed the compost pile.
  • Collect the finished compost for use.

Choose a Site
Where you want your compost pile is an important question. You want to be able to compost discretely away from your house, but not so far away that you may not want to go out and attend to it. Also, you do not want it so close to the boundaries of your property that your neighbors might complain. Part of the answer may be dictated by local housing ordinances or homeowner organization rules that may specify where a compost pile can be located. Other factors to consider include the following:

  • Downwind from your house - Even a well-managed compost pile may occasionally emit unpleasant odors.
  • Wind - Although wind provides air, too much wind can dry and/or scatter the material.
  • Sunlight - Sunlight can help warm the compost pile in the winter, but too much sunlight can dry it out. If the pile is located by a large deciduous tree, you will have cool shade in the summer and sunlight in the winter.
  • Drainage - You want good drainage so that water will not accumulate by the pile.
  • Surface - Bare earth is better than concrete. Make sure to give yourself a sufficient work area around the pile (6 to 8 ft, or about 2 m).

Choose a Structure
Compost structures can be as simple as a heap where you just pile all of the ingredients and let nature take its course -- this is passive composting. Passive composting is less efficient and slower than active composting, in which you manage the compost process on a daily basis.


Compost structures come in many shapes.


Photo courtesy Karim Nice
Commercial
home composting unit
You can also build more complicated compost bins out of chicken wire, wood or concrete blocks. They can be simple, one-compartment structures in which you add new materials to the top, turn the compost frequently and collect the finished compost from the bottom.

They can also be multi-compartment (three-bin) structures in which you add new material to one bin, transfer partially-completed compost to the middle bin and move finished compost to the final bin. There should be some covering on the top of the bin to minimize excess rainwater and reduce scattering from the wind. Many varieties of compost bins are available commercially.

The choice depends entirely on the effort and expense that you wish to devote to the project, as well as the amount of compost that you wish to make. Also, local ordinances may dictate what kind of bin you can use.

Add the Ingredients

Composting Meat & Dairy
Meat and dairy products are high in fat. They will cause an unpleasant odor if added to a passive pile or poorly-managed active compost pile. For a hot, well-turned compost pile, meat and dairy wastes are not a problem. However, it is better to run the wastes through a blender or food processor to reduce their size and speed their decomposition.
You can compost the following materials easily:

  • Kitchen waste - best to chop up or grind the wastes so that they can be broken down faster
    • Fruit and vegetable wastes - peels, skins, seeds, leaves
    • Egg shells
    • Coffee grounds (including paper filters), tea bags, used paper napkins
    • Corncobs - should be shredded to make them break down quickly
    • Meat/dairy products - see sidebar

     

  • Yard waste
    • Grass clippings - Some grass is okay, but too much will add excess nitrogen to the compost pile and make it smell bad. It may be best to use a mulching lawn mower for your grass.
    • Leaves
    • Pine needles
    • Weeds
    • Woody materials (branches, twigs)
    • Straw or hay

     

  • Newspaper

     

  • Seaweed, kelp or marsh grass hay - If you live by the ocean and it is legal to harvest these, they are excellent, nutrient-rich materials. Rinse or soak them thoroughly in fresh water to remove excess salt before adding them to your compost pile.

     

  • Sawdust - This is an excellent source of carbon.


Photo courtesy Karim Nice
Kitchen and yard waste in a compost bin

The following materials SHOULD NOT BE COMPOSTED:

  • Human waste or pet litter - They carry diseases and parasites, as well as cause an unpleasant odor.
  • Diseased garden plants - They can infect the compost pile and influence the finished product.
  • Invasive weeds - Spores and seeds of invasive weeds (buttercups, morning glory, quack grass) can survive the decomposition process and spread to your desired plants when you use the finished compost.
  • Charcoal ashes - They are toxic to the soil microorganisms.  
  • Pesticide-treated plant material - These are harmful to the compost foodweb organisms, and pesticides may survive into the finished compost.
Cover the composting materials with plenty of soil in the compost bin. Some sources say that it is best to arrange carbon-rich and nitrogen-rich materials in alternating layers. Add water to moisten the compost, but do not soak it. Turn the compost with a shovel or compost fork to mix it and provide plenty of air.

Care and Feeding
Add new layers of composting material to the top along with fresh soil. Water the compost bin regularly to keep the compost moist. Turn the compost everyday or every other day to ensure an adequate supply of oxygen. With some bins, you can avoid turning the compost by inserting perforated PVC pipes into the bins to introduce a regular air supply.

Worm Composting
Worms can reduce composting times by as much as 50 percent. You can seed your compost pile with earthworms or buy special composting worms. You can also set up a worm box outside the house to process kitchen waste and meat scraps. See the Lots More Information section for more on worm composting.
As you add new layers and turn the compost, you will be mixing new layers of intact trash with partially decomposed layers. The partially and nearly finished material will settle to the bottom because the particles are smaller. The finished compost will come out the bottom of the bin. In three-bin systems, you add intact trash to the first bin and actively transfer partially and finished compost to the second and third bins.

Here are some signs that your compost pile is working properly:

  • It does not smell bad. It should have a sweet, earthy smell, like peat moss.
  • It is warm. The microorganisms are "cooking away" and you may even see some steam rising from the pile, especially on a cool morning.
  • You may see some gas bubbles in the pile, because carbon dioxide is being released as the microorganisms do their work.

Collect the Finished Compost
The finished compost will collect at the bottom of the bin in a single bin system or at the third bin in a three-bin system. There is no strict definition of when the compost is done. Basically, if you think it's done, it's done. Here are some parameters that you can use to judge this:

  • Temperature - After you turn the pile, measure the temperature. If it is below 100 F (38 C), then it is probably done.
  • Appearance - Does the material look at least 50 percent decomposed? Can you recognize anything in it as the trash you put in?
  • Size - Has the volume of the compost reduced by 50 to 75 percent?
  • Color - Is it dark brown or black?
  • Texture - Is it smooth or crumbly?
  • Smell - Does it smell earthy like soil?
Once your compost is done, it is ready to use. Finished composts can do the following:
  • Improve the soil structure in your garden or yard
  • Increase the activity of soil microbes
  • Enhance the nutrients of your soil
  • Improve the chemistry of your soil, particularly the degree of acidity (pH)
  • Insulate the changes in soil temperature around plants and trees
  • Improve insect/disease resistance in your garden plants and trees
Most home composters use their finished product around their own home, in their trees or gardens. Some home composters sell their finished compost to local nurseries or other family gardeners.