Composting is controlling the natural decay of organic matter by providing the right conditions for

composting critters to convert yard trimmings into aproduct that can be returned to your landscape and

garden. Tiny organisms (mainly bacteria, fungi and protozoa) break down garden and landscape

trimmings in a moist, aerobic (oxygen-demanding) environment. The final product is a dark, crumbly

form of decomposed organic matter. Compost improves your soil. When added to soil,

compost breaks up heavy clay soils, helps sandy soils retain water and nutrients, and releases

essential nutrients. Compost also contains beneficial microscopic organisms that build up the soil and

make nutrients available to plants. Improving your soil is the first step towards growing healthy plants.

WHAT CAN I COMPOST?

Most plant material can be used for compost. Organic trimmings in your landscape, such as fallen

leaves, pine needles, grass clippings, flowers and the remains of garden plants make excellent compost.

Compost made from grass clippings treated with herbicides and pesticides is not recommended for

use in vegetable gardens. Kitchen scraps, such as fruit and vegetable peels and trimmings, crushed

eggshells, tea bags, and coffee grounds and filters can also be composted. Woody yard trimmings can

be run through a shredder before adding to the compost pile. Sawdust may be added in moderate

amounts if additional nitrogen is applied. Add a pound of actual nitrogen per 100 pounds of dry

sawdust.

WHAT MATERIALS SHOULD AVOID ADDING TO MY COMPOST PILE?

Organic materials that should not be added to your compost pile include meat, bones and fatty foods

(such as cheese, salad dressing and leftover cooking oil). Do not add pet or human wastes to a compost

pile. Weeds that have not gone to seed can be added to the compost pile. Weeds with large storage roots

like nutsedge, Florida betony or greenbriar should be left out and dried in the sun before composting to

reduce their chances of survival. The high levels of heat produced in the center of the

compost pile can kill many pests, such as weeds with seeds and diseased or insect-infested plants.

However, it is very difficult to mix the contents thoroughly enough to bring all the wastes to the

center, so some disease organisms may be returned to the garden with the compost.

“ESSENTIALS” OF COMPOSTING

Organic materials for composting all contain nutrients that provide energy and growth for

microorganisms. These organic materials each have their own ratio of carbon to nitrogen (C:N) in their

tissues. These C:N ratios are important because the tiny decomposers need about 1 part of

nitrogen for every 30 parts of carbon in the organic material. If the ratio is greater than 30:1, nitrogen

will be lacking and materials will decompose more slowly. Leaves, straw and sawdust are high in carbon, while

grass clippings, manure and vegetable scraps are higher in nitrogen. It helps to think of these

materials as greens and browns. Greens, such as grass clippings, are high in nitrogen. Browns, such

as leaves or sawdust, contain high amounts of carbon. Be aware that anything organic will decay (as long

as it is organic, the critters will eat it); however, it may take a long time to make compost when the

C:N ratio is too high. For example, a pile made solely of sawdust will take years to decay. Adding

more greens, such as grass clippings or vegetable scraps, will speed up decay and produce compost in

less time. Experiment to find the right combination of materials for your compost pile.

Average carbon to nitrogen ratios for organic materials.

Greens:

Pig manure 5-7:1

Coffee grounds 20:1

Vegetable scraps 12-20:1

Grass clippings 12-25:1

Cow manure 20:1

Poultry manure (fresh) 10:1

Horse manure 25:1

Alfalfa / sweet clover hay 12:1

Poultry manure w/litter 13-18:1

Horse manure w/ litter 30-60:1

Browns:

Leaves 30-80:1

Cornstalks 60:1

Straw 40-100:1

Bark 100-130:1

Paper 150-200:1

Sawdust 400:1

Wood chips 800:1

Surface Area and Size of the Compost Pile: The more surface area the microorganisms have to work

on, the faster the materials will decompose. You can increase the surface area of your yard trimmings

by chopping them up with a shovel or running them through a shredding machine or lawnmower.

A large compost pile will insulate itself and hold in the heat created by the tiny organisms. Piles smaller

than 3 feet x 3 feet x 3 feet have trouble holding this heat, while piles larger than 5 feet x 5 feet x 5 feet

prevent enough air from reaching the center of the pile and the microbes. In addition, turning a large

pile is a chore. If your pile is large, you will have to turn it more often. If the pile is small, you will get a

good batch of compost during warm months.

Moisture and Aeration: The microbes in your compost pile need a certain amount of water and air

to survive. Microbes function best when the materials are about as moist as a wrung-out sponge

and are provided with plenty of air. Too much moisture will force out the air and suffocate the

microorganisms. Too little moisture will slow down decay. Whenever you add water, be sure to mix the

material to distribute the moisture evenly. Turning the materials in your pile supplies oxygen to

the composting critters. A lack of oxygen in a compost pile can lead to an odor problem due to the

production of ammonia and methane gases. Decomposition without oxygen also causes the

production of chemical compounds that are toxic to plants. Organic matter that has been allowed to

decompose without oxygen (for example, “composting” in closed garbage bags) should be

exposed to air for several days to complete the composting process and to destroy any plant-toxic

compounds.

Temperature and Time: As a result of the decomposition process, the interior temperature of

the pile should peak between 90 and 140 °F or higher. A hotbed (or long-stemmed) thermometer

can be used to check the interior temperature of the pile at least 12 inches from the surface. The

intensity of the process depends on the amount of nitrogen in the materials. The time required to

produce compost depends on the kind and coarseness of the materials, volume of the pile, and

availability of moisture and air. It can take a month, a year or longer.

SOME COMPOSTING METHODS

“Fast” Compost Recipe: This method can produce compost in a couple of months or less but is labor

intensive and requires frequent turning. Start your pile with a layer of browns, and then add a layer of

greens. If the greens are not fresh, sprinkle in some blood meal or cottonseed meal, poultry manure, or

other nitrogen source. Mix well and add water if necessary to moisten. Adding a layer of garden soil,

old compost or manure to each brown-green layer will introduce more critters to speed up the process.

Continue adding and mixing layers of greens and browns until you either fill the bin or run out of

materials. Slant the top of the pile to the center to catch rainfall. You may want to cover the pile with

a plastic covering or tarp to regulate the amount of moisture entering your pile. The cover should not

rest on the pile because it may cut off oxygen. Periodically, check the moisture content of your pile.

The compost should feel damp. Check the interior temperature of your pile and when the temperature

reaches 140 °F or begins to fall, it is time to turn the pile. You will need to turn your pile every three to

five days. Once your turning causes no rise in temperature, and the material appears dark and

crumbly, your compost is ready.

“Slow” Compost Recipe: Slow composting is the least labor-and time-consuming way to compost; it is

ideal for people who do not have a large amount of yard trimmings to compost all at once. This method

can take from six months to two years or longer to produce compost, so be patient.

The ingredients are the same as those for a “fast” compost. Add greens and browns to your pile

whenever they become available. Turn the pile occasionally to mix the materials together to prevent

the materials from clumping together and to avoid anaerobic decomposition. You will know that your

materials are decaying without oxygen by the foul odor: a telltale sign for you to turn the pile. Look

for ready-to-use compost near the bottom of the pile.

COMPOST STRUCTURES

Composting structures can be made from a wide variety of materials or purchased through local

garden centers or mail order catalogues. There are no set rules when building a compost bin. The sides

should be loose enough to provide some air movement and one side should open for easy

turning and compost removal. If you choose not to use a container, cover the heap with a layer of yard

trimmings or soil to prevent moisture loss.

Circular Bins: A circular bin is very useful for composting larger quantities of organic materials,

and can be easily made from a length of closely spaced woven wire fencing held together with chain

snaps. The bin should be 3 to 5 feet in diameter and at least 4 feet high. It is easiest to turn the

composting material by simply unsnapping the wire, moving the cylinder a few feet, and turning the

compost back into it. Simple bins can be made of old wooden pallets

stood on their ends in a square or open square and nailed or tied together. A chicken wire cage

supported by three or four wooden stakes will also work well. A standard-sized garbage can with eight

or more slots in the sides of the can for ventilation and five in the bottom for drainage can also be used.

Three-Chambered Unit: A three-chambered bin works on the assembly line principle, and is an

efficient structure for “fast” composting. Three batches of compost are in various stages of

decomposition at all times. The composting process is started in the first bin for three to five days. This

material is then turned into the middle bin for another four to seven days and a new batch is

started in the first bin. Next, the middle bin is turned into the third bin as nearly finished compost. Each

bin should be at least three to five feet in each dimension and should be made with rot-resistant

wood (redwood) or wood treated with an environmentally safe preservative.

Barrel or Drum: The barrel or drum composter is an excellent choice if you have limited space in your

yard. A barrel of at least 55-gallon capacity with a secure lid is required. To provide good air

circulation and drainage, drill six to nine rows of half-inch holes over the length of the barrel, and

place the barrel upright on blocks. Fill the barrel three-quarters full with organic wastes and add

water to lightly moisten. Mix the compost every few days by turning the drum on its side and rolling

it around the yard. The compost should be ready in two to four months.

USING COMPOST

Think of compost as a soil amendment and not as a fertilizer, since the nutrient level of compost is low

and released over time. Mix compost with soil to enrich the flower and vegetable garden. It can be

used to improve the soil around trees and shrubs, as a top-dressing for lawns, or as a mulch. Screen

compost by separating the larger particles and any uncomposted materials from the finer ones and add

it to the potting mix for houseplants. No more than one-quarter to one-third by volume of the potting

mix should be compost. Soaking compost in a burlap or cheesecloth sack steeped in water can

make compost “tea.” The weak nutrient solution can be given to young plants.

Troubleshooting guide for efficient composting.

Symptoms Problems Solutions

Rotten odor – Not enough air; pile too wet Turn pile; add coarse, dry materials (straw, corn stalks, etc.)

Ammonia odor – Too many greens (excessive nitrogen/lack of carbon) Add browns (straw, paper or sawdust)

Low pile temperature -Too small; not enough air or moisture; few greens; or cold weather Make pile larger;

add water while turning the pile; mix in nitrogen sources (grass clippings, manure, or a synthetic fertilizer, such as

10-10-10); or insulate the pile with a layer of straw or plastic

High pile temperature – Too large; not enough air Reduce pile size; turn pile Pests, such as rats, raccoons or

insects Meat or fatty food scraps in pile Remove meat and fatty foods from pile; cover with a layer of

soil or sawdust; build an animal proof compost bin.

All recommendations are for South Carolina conditions and may not apply to other areas. Use

pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at

the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies.

Follow all directions, precautions and restrictions that are listed.

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