Making and Using Compost at Home

Compost is a mixture of soil and decayed organic matter or humus that is used to improve garden and potting soil. Properly prepared compost is free from weed seeds and offensive odors and rich in nutrients that plants need. It may be applied as a thin top dressing for lawns, as mulch around shrubs and young trees, or mixed into the soil in vegetable and flower gardens. Compost is produced in piles or pits from organic waste such as leaves, grass clippings, manures, straw, hay and garden refuse.

One of the greatest benefits of making compost is that it allows us to recycle garden and yard waste into a valuable, usable product, reducing the amount of solid waste going into landfills. Converting your garden, fruit, and vegetable wastes to compost is something you can do to improve the environment. Neighborhood composting facilities or shared family compost piles are options. Composting small prunings and twigs and encouraging municipalities to shred large prunings and downed limbs allows reuse of damaged or overgrown plants in the landscape.

Chemistry of Compost

The conversion of organic wastes to rich humus involves several types of bacteria and fungi. Fungi begin the process by breaking down cellulose and other complex molecules in the residue. Fungus populations increase rapidly in a new compost pile. The temperature inside the pile may rise to 150 to 160?F, inactivating weed seeds and harmful disease organisms. After several months, the temperature decreases, the fungi disappear, and millions of bacteria continue gradual breakdown of the organic materials into rich, dark, crumbly humus. In regions with acid soils, wood ashes or limestone may hasten decay and prevent excess acidity and sourness.

Getting started

Locate the compost heap in an area where water will not stand. Many gardeners use an out-of-the-way, accessible location near the garden or refuse disposal site for convenience.  The compost may be made using a below-ground pit or an above-ground method that does not require laborious digging.  Although it is possible to simply accumulate the compost in a loose pile, an enclosure of some type is desirable. Several materials can be used for this purpose.

• Woven wire or wood slat fence. Various types of woven wire are available, from reinforcing wire to fencing wire. Heavy gauge wire that is self supporting is preferable; however, finer wire supported by rods or posts could be used. Lining the fence with a layer of plastic will speed decomposition.
• Cement blocks or bricks. Mortar is not necessary because the weight of the blocks will hold the pile in place.
• Scrap lumber (see Figure 3). Don’t use good lumber because the damp compost may ruin the boards. If a permanent enclosure is desirable, use redwood or cypress. Old pallets frequently can be obtained free of charge, and strapping five of these together to form a cube makes an excellent compost bin.

The size of a compost pile varies, depending on the quantity of organic material available and the amount of compost needed. Rectangular or square shapes may be slightly easier to work with than round ones. Round enclosures made of wire bent into a cylinder have the least amount of surface area to dry out and work well. Either shape can be used successfully. For most households, a pile 5 feet wide by 5 feet long or a circular pile about 5 feet in diameter is sufficient. The height of the pile will fluctuate as organic material is added. A pile or bin could be divided into two parts, or use two identical bins, one for accumulating this year’s waste and one for compost made last year.

Several kinds of plant materials can be used in the compost pile. These include leaves, grass clippings, weeds or garden refuse, fine hedge clippings, straw, corncobs, cold wood ashes, sawdust, old unusable hay, and mulch raked from around flower or vegetable gardens. Avoid using severely diseased vegetable or flower plants.  Kitchen scraps such as egg shells, peelings or plant residues can be added to the pile if covered to prevent flies, but avoid using meat scraps or bones since this may attract dogs or other animals.

Making the Compost Pile

In slow composting, start with a layer of soil or sand 2 to 3 inches deep on the bottom. Then add a layer of organic materials. For fine materials such as thin grass clippings, use only a 2- to 3-inch layer; for coarser materials such as straw, use 6- to 8-inch layers. To hasten decomposition, add a small quantity of commercial garden fertilizer, 1 to 2 cups per square yard of area. You may substitute an inch or two of manure. The purpose of the fertilizer or manure is to provide a source of nutrients for microorganisms that must build up in the compost pile to ensure decomposition.

Repeat this sequence of soil or sand, organic materials, and fertilizer in layers as organic materials become available. Water each layer as it is added.
The top of the compost pile should be dish-shaped or slightly lower in the center than on the sides. This allows rainfall to soak into the pile rather than run off. Because of extremely high temperatures generated by the composting process, a dry compost pile oxidizes too rapidly and the overheated, feathery compost that results is of little value. In dry weather, a weekly soaking of the pile is desirable to keep it sufficiently moist.

The rate of decomposition can be hastened by turning the pile, slicing through the layers and turning them upside down. This action is similar to spading garden soil when it is turned over. This mixing should be followed by reforming the “dish” at the top of the pile and watering.

Compost should be ready to use 4 to 6 months after starting the pile, but most gardeners prefer to keep two piles or one pile divided into two sections. Materials can be accumulated in one while last year’s finished compost is available for use from the other.

As your compost pile progresses, these signs will indicate whether all is going well.

• In two to three weeks, the pile should shrink or sink. If it has not, loosen the pile with a shovel or fork to provide more aeration or add moisture if the compost is dry.
• Check for a strong ammonia or offensive odor. This may be caused by overwatering, or an imbalance of materials. Aerate as above. Ammonia odors often come from composting a lot of fresh, green plant material, especially grass clippings.
• After four to five weeks, or less than a week for quick composting, it should be hot deep within the pile.  Push a wire or stick deep into the pile, pull it out and touch it to check temperature.
• In three to four months, the pile should be about half its original height. The compost will be dark, moist and crumbly. It should have the odor of moldy leaves or a rich earthy odor.

Quick Composting

In recent years, the emphasis has been on quick composting. Materials are finely shredded, premixed with soil and/or fertilizer, moistened, and placed in an enclosed bag or bin. The resulting compost, in a month or so rather than four to six months, is comparable in quality to that of slow composting. It does, however, require slightly more effort.

Several commercial bins can be purchased for use in quick composting processes and each comes with operating instructions.

You can use containers such as plastic bags or garbage cans for the same purpose. Sheet plastic and a standard enclosure work as well. Begin by lining the enclosure with sheet plastic. Next, finely shred the organic material with a soil shredder, compost grinder, or coarse hammermill.  These devices are costly for most gardeners, but the serious gardener may find them useful. For those who do not wish to purchase a grinder or shredder, a rotary lawn
mower can be used to pulverize or shred leaves and coarse materials such as plant stems. For mowers with bagging attachments, collect the organic materials in the bag. With discharge mowers, blow shredded materials into a central pile by turning in a circle.  Then mix and add shredded organic materials, soil, and fertilizer or manure in proportions similar to those used for the slow composting method. It is not necessary to turn the pile. It should be ready for use in two to three weeks in warm weather or five to six weeks in cooler weather. The compost may be stored for longer periods if
not immediately needed.