All About Composting
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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?
SHOULD I AVOID ADDING TO MY 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.
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.
Table 1. Average carbon to nitrogen ratios for organic materials.
Surface Area and
Size of the Compost Pile
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.
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.
SOME COMPOSTING METHODS
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.
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.
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.
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.
Barrel or Drum
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.
Table 2. Troubleshooting guide for efficient composting.
Prepared by Bob Polomski, Extension Consumer Horticulturist, and Nancy
Doubrava, HGIC Information Specialist, Clemson University.
Reprinted and published with permission by Savvygardener.com.
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