Composting is a practice that allows “waste” from the yard and kitchen to be recycled. Plant debris, kitchen scraps and other organic materials are piled together to decompose. The nutrient-rich yield is then used to amend the soil and feed plants.

The benefits of compost are many. It improves the structure of soil, allowing it to retain more water while improving drainage. Compost has many of the macro- and micro-nutrients plants need to thrive, and the balanced array of nutrients it provides is available to plants over a long period of time.

Compost also helps balance soil pH and improves soil tilth and fertility. It loosens clay soils and prevents nutrient leaching by loosely binding nutrients into the soil and then, with the help of beneficial soil microbes, slowly releasing them over time.

One of the most important benefits of compost is the soil life that it supports. Beneficial bacteria, fungi, arthropods and other organisms thrive in compost-amended soils. In turn, these organisms help to process the nutrients contained in the compost and make them available for plant use, leading to healthier, more disease-resistant plants.

To top it off, composting is easy. All it takes is the right mixture of ingredients and a small amount of effort to have a productive, efficient compost pile.

First, find a place to build your pile. You can use a commercially made compost bin or find an empty corner of the yard in which to locate your pile. The site should receive full to partial sun. Piles in full shade may take longer to produce finished compost.

Next, gather your ingredients. It's important to understand that different materials provide different things. There are two basic classes of ingredients that constitute a well-balanced compost blend: the carbon suppliers and the nitrogen suppliers.

The carbon suppliers (called “browns”) are generally added to the pile in a non-living state. They're usually brown and have a low moisture content. Carbon suppliers are high in lignin and are slow to break down. Carbon suppliers include autumn leaves, straw, hay, shredded newspaper, bark chips, shredded cardboard and sawdust.

The nitrogen suppliers (called “greens”) are those items used in a fresh state. Nitrogen suppliers often are green (except for manures) and have a high moisture content. Because they contain many sugars, they are quick to decompose. Nitrogen suppliers include untreated grass clippings, plant trimmings, kitchen scraps, seaweed and animal manures (such as cow, horse, chicken or sheep).

The relative proportion of carbon supplying materials to those materials higher in nitrogen (the C:N ratio) is an important factor in determining how well the pile breaks down. Basically, as you build your pile, it should contain about 30 times more carbon than nitrogen (a C:N ratio of 30:1).

This ratio is accomplished by building a pile that contains two to three times more “brown” materials than “green” materials (by volume). So, for every five-gallon bucket of fresh green grass clippings, you should add three five-gallon buckets of straw or autumn leaves.

This ideal carbon-to-nitrogen ratio is important for fast decomposition because the microbes and other organisms that process the ingredients use carbon as a source of energy. They need a lot of it to work efficiently and quickly. If you have three times more “browns” than “greens” in your pile, as I recommend above, the finished compost happens a lot more quickly and the temperature of the pile gets high enough to kill most weed seeds and pathogens (160 degrees F). Piles with the wrong C:N ratio will seldom reach these temperatures and will take a long time to produce finished compost.

Unlike certified organic farmers, home gardeners don't necessarily need their C:N ratio to be exactly 30:1. However, if it is, you'll discover the pile finishes faster and the resulting compost is of exceptional quality.

Once the right ingredients have been used to create the pile, it's the job of billions of microbes and other organisms to break it down. The organisms needed for this decomposition process are already present in and on most compost ingredients. However, throwing some finished compost into a newly built pile may increase their populations more quickly.

These microbes use oxygen and exhale carbon dioxide while decomposing, which means composting is an aerobic process. To maintain aerobic conditions in your pile, oxygen must be provided by turning or otherwise aerating the pile on a regular basis (ideally, about once a week).

If the pile is not turned and no oxygen is present, decomposition happens through fermentation. Different organisms are at work here, and they release both methane and ammonia, and as a result, the pile may stink. Decomposition does not smell bad when adequate oxygen is present.

If you don't want to go through the effort of regularly turning your compost pile, know that “cold” or “slow” composting (otherwise known as pile-it-up-and-wait) is also a valid composting technique for home gardeners. But, “cold” compost piles take a long time to produce finished compost (sometimes years), and the resulting compost more than likely hasn't reached the 160 degrees required to kill most pathogens and weed seeds. Also, caution should be used when adding animal manures to “cold” compost piles as temperatures often don't get high enough to kill any pathogens possibly contained in them.

For record-fast compost production, begin with two to three times more “browns” than “greens,” finely shred or chop all ingredients, add a few shovelfuls of finished compost to the new pile, and aerate at least once a week.

Oh, and don't forget to thank your microbes!

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com.

Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.

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