Gardening Guide

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How to Make Compost

HOW TO MAKE COMPOST

COMPOSTING

Composting is a technique used to accelerate the natural decay process. The technique converts organic wastes to a mulch which is used to fertilize and condition soil. Leaf waste decomposes naturally in about two years. Composting can take as long as a year or as little as 14 days.

COMPOSTABLE MATERIALS

Most yard wastes can be composted, including leaves, grass clippings, plant stalks, vines, weeds, twigs and branches. Compostable food wastes include fruit and vegetable scraps, coffee grounds, eggshells and nutshells. Other compostable materials are hair clippings, feathers, straw, livestock manure, bonemeal and bloodmeal.
Materials should NOT be composted if they promote disease, cause odors, attract pests, or create other nuisances. These include meat, fish, poultry, and dairy products, foods containing animal fats, human/pet feces, and weeds with developed seed heads.

COMPOSTING REQUIREMENTS

1. SHREDDED ORGANIC WASTES. Shredding, chopping or even bruising organic materials hastens decay. One way to shred leaves is to mow the lawn before raking, collecting the shredded leaves in the mower bag. It takes at least a cubic yard of shredded material to form a compost pile.

2. GOOD LOCATION. The compost pile should be located in a warm area and protected from overexposure to wind and too much direct sunlight. While heat and air facilitate composting, overexposure dries the materials. The location should not offend neighbors.

3. NITROGEN. Nitrogen accelerates composting. Good sources include fresh grass clippings, manure and bloodmeal.

4. AIR. The compost pile and its enclosure should be well ventilated. Some decay will occur without oxygen, but the process is slow and causes odors.

5. WATER. Materials in the compost pile should be kept as moist as a squeezed sponge. Too little or too much water retards decomposition. Overwatering causes odors and loss of nutrients.

BUILDING AN ENCLOSURE

Enclosing the compost pile saves space and prevents litter. The enclosure should provide an entry large enough to permit the pile to be turned. It should measure at least 4’X4’X4′, but no taller than 6′ (too much weight causes compaction and loss of oxygen). The enclosure can be built of wood, pallets, hay bales, cinder blocks or stakes and chicken wire. Prefabricated compost bins are also available.

BUILDING THE PILE

Aside from the basic requirements for decomposition and preventing odors and other nuisances, there is no set method for building a compost pile. A variety of methods work well. Piles can be built in layers to ensure the proper proportion of carbon (e.g., leaves, woody materials) to nitrogen (grass, animal manure), but the layers should be thoroughly intermixed after the pile is built.

COMPOST STARTER

While layering, add a shovelful of native garden soil to each layer. This serves to inoculate the pile with decomposer organisms, naturally present in the soil.

MAINTENANCE

Turning and mixing the pile with a pitchfork or shovel, or shifting it into another bin, provides the oxygen necessary for decomposition and compensates for excess moisture. A pile that is not mixed may take much longer to decompose. Recommendations for mixing the pile vary from every 3 days to every 6 weeks. More frequent turning results in faster composting. Odors indicate that the pile is too damp or lacks oxygen, and that more frequent turning is necessary.

Occasional watering may be necessary to keep the pile damp, especially in dry weather. Covering the pile with black plastic reduces the need for watering; it also prevents rainwater from leaching out the nutrients.
A pile that is decomposing properly should generate temperatures of 140°-160°F at its center. The heat kills most weed seeds, insect eggs and diseases. The pile should be turned when the center begins to cool. Turning the pile maintains the temperature and ensures that all material is exposed to the center heat. When the compost is finished, the pile will no longer heat up.

Small amounts of fresh materials may be added but should be buried inside the pile to avoid pests and speed composting. It is better to add fresh materials to a new pile.

FINISHED COMPOST

Finished compost is dark brown, crumbly, and has an earthy odor. Depending upon seasonal temperatures, a well-built, well-tended pile generally yields finished compost in 2 weeks to 4 months. An unattended pile made with unshredded material may take longer than a year to decompose.

For piles that are not heating and composting too slowly, add dry molasses, green plant material or organic fertilizer.

If space allows, having two piles will ensure a steady supply of compost. One pile may be used to produce fast compost.

SAMPLE INSTRUCTIONS FOR FAST COMPOSTING

• Shredded leaves (about 2/3 by volume)
• Fresh grass clippings (about 1/3 by volume, or slightly more for faster decomposition)
• Kitchen scraps (grind in blender)
• 1 lb. of dried molasses

Begin the pile with a 4″ layer of leaves. Add a 2″ layer of grass clippings. Add a shovelful of native garden soil to each layer. Repeat the layers until the pile is about 4′ high, then add the kitchen scraps and dried molasses.
Chop vertically through the pile with the tines of a pitchfork to thoroughly bruise and mix the materials. Add just enough water to moisten the pile, and then cover it with a black plastic garbage bag. Using the same chopping technique, turn the pile on the second day after the pile is built, again on the fourth day, then every three days until the compost is finished. Except in dry weather, no further watering should be necessary.
The compost should be finished in about two weeks.