Berks County Cooperative Extension -

COMPOST

What is compost?

Compost is a dark, sweet-smelling, soil-enriching substance that results from the decomposition of leaves, grass clippings, plant materials, certain forms of kitchen waste and miscellaneous other materials. Compost is so valuable to the home gardener that it is referred to as "black gold."

Why should one consider making compost?

Removing grass clippings, leaves and similar materials from the waste stream holds benefits for the environment and the soil. Composting, a form of recycling, reduces the volume of waste entering landfills. Sources suggest that the amount of yard waste generated annually per person in this country approximates 230 pounds. Food wastes add another 100 pounds per person. With solid waste disposal costs increasing and landfill space decreasing, composting is a relatively simple way to make a contribution to environmental preservation. A second reason to consider composting also involves the environment - the garden environment. Most soils in Berks County contain insufficient amounts of organic matter. Adding compost to the heavy clay soil typically found in the county loosens the soil, thereby facilitating movement of water and roots through the soil, and otherwise improves overall soil quality.

Getting started.

It will be necessary to construct some type of enclosure to contain the compost pile which must be not less than three feet high and three feet wide. Fencing, bricks, cement blocks or wood slats are typically used to construct the enclosure. If cement blocks or bricks are used, the design must allow for aeration. One side of the enclosure should be left open for turning and removing compost.

Gardeners with sufficient space and large quantities of suitable material frequently construct a series of composting bins. The first bin holds actively working compost; the second contains compost that is nearing completion; and the third bin is used to store finished compost.

What goes on the pile?

A variety of plant materials, kitchen waste and other materials constitute the ingredients. These materials include:

Grass clippings.
Leaves, which should be shredded. An ordinary lawn mower makes an excellent shredder.
Hedge clippings.
Shredded newspaper and cardboard.
Wood ashes.
Most kitchen wastes (see exceptions listed below) which should be incorporated into the pile, rather than being placed on the surface.
Garden refuse that does not display evidence of disease.

Particle size.

The size of material is important. The organisms responsible for composting work best when the surface area of materials is increased. Shred or chop ingredients before placing them on the compost pile.

Materials that shouldnot go on the pile.

The following items should not be placed in the compost bin:

Woody material (decomposes too slowly).
Dog and cat feces.
Kitchen wastes such as grease, fat, meat scraps and bones. These wastes create unpleasant odors and attract wildlife to the pile.
Glossy or otherwise treated paper.
Noxious weeds such as quackgrass.

If organic matter that has been treated with a herbicide or pesticide is added to the compost pile, it may be safely used if the composting process has been ongoing for at least one year.

Making compost.

While there are several methods of making compost, the standard method, which produces a finished product in eight to ten weeks in spring and summer (longer during cool or cold weather periods), is the procedure most home gardeners use. The ideal ratio of ingredients is 30 parts of carbon ("dead" material such as shredded leaves) to one part or nitrogen ("green" material such as grass clippings). The steps:

A four to six inch layer of dead material to start the pile.
A layer of the same size of green material. If green material is in short supply, add 2.5 ounces of actual nitrogen (supplied, for example, by adding 20 ounces of dried blood) for each bushel of shredded leaves.
Mix the layers. Test for proper moisture content. Squeeze the mixture. If several drops of water result, the moisture level is sufficient.
Continue to add layers of dead and green material, mixing each layer as it is added, until the desired height is reached.
After one week, turn the pile and check the moisture level. Thereafter, turn the pile on a weekly basis.
The composting process is complete when the pile's contents are brown and crumbly with an earthy odor. After the compost is finished, it should be aged an additional two weeks before being used around plants.

Preventing nitrogen depletion.

When compost is added to the garden, it "robs" the soil of nitrogen. To prevent this theft of nitrogen, add approximately one cup of 10% nitrogen (10-10-10 analysis) to each three bushels of compost.

Source: The Penn State Master Gardener Manual
Document created: 15 December 1999; Revised: 3 March 2001