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The plant waste we generate, from food scraps to yard clippings, makes up nearly a quarter of the material dumped in landfills. Most of it can be composted instead, which both keeps biodegradable material out of the waste stream and generates valuable soil for use in lawns and gardens. Even if it didn’t bring other benefits as well, those two things would make it worthwhile.
Composting is mostly passive. When you leave plant matter in a pile, it rots. Trouble is, it smells bad and isn’t very useful. With just a few deliberate actions, though, you can turn this natural process into a productive one. Keep a balance of ingredients and stir up the pile
every once in a while. There’s more to it, but this chapter can help you get started.
The Composition of Decomposition
It starts as a heap of recognizable materials—apple cores, grass cuttings, melon rinds, nut shells, and so on—and ends up a stable source full of nutrients, ready to help another cycle of plant life grow. In between those two states, compost is a combination of life and death.
In nature, when dying plants fall to the ground, they begin to decay. The nutrients in the plant become food for other plants, animals, and microorganisms. Those not absorbed by decomposition return to the soil.
Intentional composting follows the same path, but with some important differences. First, the plant material is contained, so it can
be moved once it is finished decomposing. And because it’s confined in a limited space, it becomes very hot—which kills organisms that might survive natural decomposition. The result is clean compost, free from weed seeds and pathogens that could affect the plants growing in it.
Compost can include any biodegradable material from food scraps to yard waste to manure. The speed with which it breaks down depends on the ratio of those ingredients, and on the presence of other materials that provide additional mass. Once this combination has finished decomposing, stabilizing, and curing, it is considered mature compost. The main ingredient in mature compost is humus, a dark and earthy substance that feels and smells like soil.
Ingredients for Success
The following biodegradable materials are suitable for use in compost, according to recommendation from the U.S. Environmental Protection Agency (EPA):
• Animal manure • Clean paper • Coffee grounds and filters
• Cardboard rolls • Grass clippings • Sawdust
• Cotton rags • Hair and fur • Shredded newspaper
• Dryer and vacuum • Hay and straw • Tea bags cleaner lint
• Eggshells • Houseplants • Wood chips
• Fireplace ashes • Leaves • Wool rags
• Fruits and vegetables • Nut shells • Yard trimmings
Items to Avoid
Some materials may seem appropriate for composting, but experience has shown that they do not help produce usable mature compost. Some release substances that can harm plants grown in the resulting compost, while others can impede the process of decomposition.
Others create unpleasant odors, attract unwanted animals, or just plain don’t break down very well. They include:
• Black walnut leaves or twigs • Fats, grease, lard, or oils
• Coal or charcoal ash • Meat or fish bones and scraps
• Dairy products • Pet wastes
• Diseased or infested plants • Yard clippings with pesticides
How Composting Works: Five Parts
Nutrients
Successful composting requires two kinds of ingredients: green and brown. That doesn’t refer to their actual colors, but to the two complementary purposes they serve. Green materials include food scraps, yard waste, and manure, which are full of nitrogen; brown materials include dry leaves and wood chips, which have little nitrogen but lots of carbon. The biodegradable material you add to a compost pile will vary according to your circumstances, but you will quickly learn what mixture works best if you pay attention.
Particles
The same way your stomach digests food more easily after you chew it, a compost pile will break down organic matter into its component parts more quickly if they are chopped, shredded, ground, or otherwise reduced in size. It translates to more surface area on which the natural processes of decomposition can take place. Smaller particles can also help keep the temperature of the compost pile consistent. The only drawback to finely broken down material is that it might prevent air flow that brings oxygen, another important ingredient.
Water
The microorganisms that break down biodegradable material need water. It serves as a medium for the nutrients, helping them get from source to destination in every step of the process. If the ingredients in your compost pile already contain large amounts of moisture, you will probably not need to add any. Closed composting containers retain moisture better than those that sit in the open air.
Oxygen
Decomposition can be both aerobic and anaerobic. Most plant matter, though, breaks down more quickly and completely when oxygen is present. The challenge is to aerate the pile without letting it get too dry. Methods include turning over the pile with a shovel or pitchfork, turning a barrel on a central axis, and adding shredded newsprint to create air spaces within the compost.
Temperature
Most of the work in composting is done by microorganisms, so the idea is to create the conditions under which they work best. One critical ingredient is temperature, which can slow or stop the progress of these microorganisms if it’s either too high or too low. At lower temperatures, the components do not break down fully, and simply rot. At higher temperatures, the microorganisms themselves may die.
While the surrounding air will affect the overall temperature of any compost pile, the best way to manage it is by ensuring the right mix of nutrients, particle size, water, and oxygen. To save yourself the frustration of unsuccessful compost, get advice from a friend or neighbor who has practiced composting for at least a few years.
Benefits of Using Compost
You can use compost as mulch, to amend poor soil, or in place of prepared fertilizer. Added to soil, compost improves texture and aeration. It helps sandy soils retain water, and loosens the structure of soils with high concentrations of clay. Compost increases the fertility
of soil and encourages healthy root growth. The nutrients that remain in compost after it has cured will add nitrogen, potassium, and phosphorus to the soil.
Compost also provides these benefits:
• Helps remediate • Helps reduce the risks of contaminated soil plant diseases and pests
• Reduces or eliminates organic • Reduces methane that would and nonorganic contaminants be generated by landfill • Treats semivolatile and volatile • Prevents erosion and silting organic compounds on sloped ground • Helps keep heavy metals out • Reduces the need for water, of groundwater fertilizers, and pesticides
Composting Methods
The methods and tools required for composting vary as widely as the ingredients that go into it. Some of the most common include heaps, holding units, turning units, pit trenching, and sheet composting. Here is a very brief description of each:
Heaps are just static mounds of biodegradable material, usually about three feet high by five feet around. The shape naturally retains water, but the only way to aerate this kind of compost is to turn it over using hand tools.
Holding units are simply bins that hold compostable material from start to finish. They can even be used indoors, because the right balance of ingredients will not smell bad. These work slowly, but may be the best choice for people with limited space.
Turning units allow the user to tip or roll the container to improve aeration. This helps speed up the process of decomposition, and raises the temperature to help destroy weed seeds and disease organisms. They generally take up more room than holding units.
Pit trenching is just what it sounds like—a hole in the ground, filled with composting material and covered with a thick layer of soil. This method requires the least maintenance of all, but takes anywhere from a month to a year to complete.
Sheet composting uses a similarly passive means of encouraging materials to decompose. The difference is that instead of burying them in a single hole, you spread them out over a large area, usually a garden, and turn them under. This method offers the least control over nutrient balance.
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