HO-63
YARD AND GARDEN
HORTICULTURE DEPARTMENT • COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA 47907
MAKING COMPOST
John A. Wott, Extension home environment horticulturist
Introduction
Compost improves soils and makes even the finest plants grow better. Adding organic matter not only returns needed nutrients to the soil, but also helps aerate it, which promotes plant growth. Composting also is an ecological means of disposing of leaves, garden trimmings, grass clippings, and the like. It is especially useful for improving soils which are low in natural organic matter. Using compost on gardens also decreases the need for application of chemical fertilizers.

What to Use
To begin your compost pile, you need raw organic matter, soil, and fertilizer. The decayed organic matter will form humus. The humus allows the soil to hold moisture, warmth, and air. Common organic matter materials are leaves, weeds, grass clippings, garden refuse, and manure. Fertilizer is used to speed up decomposition.

Building
Start the compost pile in an inconspicuous location of your yard. Locate it where any offensive odors which may develop can be avoided. A shady spot near a source of water is also desirable. The compost pile may be heaped on the ground or contained within a box. Figure 1 illustrates the use of a simple contained bin.
To make the compost pile, mix together raw organic material, fertilizer, and soil. To describe the formation of a compost heap, it is convenient to speak of layers. However, in actual gardening the layers might be less definite.
Normally the pile may be started directly on the ground. However, to provide aeration to the bottom of the pile and to improve drainage, a trench may be dug across the base of the area and covered with stiff wire mesh (hardware cloth) before the layers are begun.
Begin the pile by spreading a 6- to 8-inch layer of organic matter over the area. Place the coarsest material on the bottom. Shredded or chopped materials decompose fastest, so if a shredder is available, coarse organic matter should be run through it. Materials that tend to mat, such as grass clippings, should be placed in layers only 2 to 3 inches thick. Moisten, but do not soak, the layers of organic material.
Over the layer of plant material, sprinkle a complete garden fertilizer such as 12-12-12 or 10-6-4 or similar analysis fertilizer. About 1 cup for each 25 square feet of top surface area should be adequate. This speeds the decomposition of the organic matter by the beneficial decomposition organisms. An equal amount of ground limestone may also be added to the compost heap, unless the finished product is later to be used for acid-loving plants.
If fresh animal manure or poultry manure is available, a 1- to 2-inch layer may be substituted for the commercial fertilizer. Or a dried, bagged manure may also be substituted. If so, 10 cups of dry manure (2-2-2 or similar analysis) will equal 2 cups of 10-10-10 (or similar analysis fertilizer).