MORE IN COMPOST

Over time, anything that once was living – plant leaves and tree branches, fruits and vegetables, even animal bones and meat – will be broken down and digested by macro- and microorganisms, returning nutrients and organic matter to the earth.

By itself, the soil of our lawns, gardens and fields is essentially "dead," sterile dirt; the addition of organic material is what makes soil "live" and fertile and enables plants to grow. As plants and trees grow in the wild world, they take nutrition from the soil; decomposing leaves and other plant matter give it back. But as we rake our leaves and bag our clipped grass, we're removing the materials that give soil its life.

Meanwhile, 25 to 30 percent of the residential waste stream is food and yard waste – carrot tops, wilted lettuce, grass clippings, dead leaves and branches. Collection and dumping of such wastes uses up fossil fuels; when burned, these organic wastes create nitrogen oxides, causing harmful smog; when dumped in a landfill, they contribute methane gas. Home composting reduces these impacts, and offers up the benefits of free soil conditioners for a home's (or even neighborhood's) gardens, lawns and trees.

Adding compost to soil

• improves the soil's "tilth," the fluffiness of the soil, where roots can grow and water can rest;
• helps the soil retain moisture, meaning less watering is needed;
• increases soil's ability to hold nutrients;
• helps dissolve mineral nutrients;
• returns organic matter to the earth;
• and keeps waste out of landfills and waterways.

Composting generally refers to an active process (even though leaving a pile of grass on the ground for awhile would yield the same end product). Creating an active compost pile can be carried out with as much or as little intervention and attention as desired, so long as a few key elements are present: air, water, and adequate "food," or raw organic material, for the worms, bugs, fungi, bacteria and other decomposers that will come to call it home. Healthy compost piles have a varied but balanced diet of equal parts "browns" – woody, carbon-heavy materials like dead leaves, twigs, straw and chopped up branches that provide long-term energy to the decomposers – and "greens" nitrogen-heavy materials like freshly clipped grass, fruit and vegetable trimmings and coffee grounds that provide protein and short-term energy. Manually turning the pile gives those macro- and microorganisms an adequate air supply, and watering it occasionally keeps things hospitably moist. As the organic waste decomposes, a compost pile will heat to temperatures well over 100 degrees Fahrenheit. Meat, dairy and oily products have no place in residential piles, as even that heat isn't high enough to kill pathogens, though such products are often included in industrial composting programs, where compostables are often gathered into eight-foot-high triangular piles, called "windrows," that can stretch for hundreds of feet.

History

The natural process of composting, of course, is nothing new; the decomposition of organic material is pretty much how things on Earth have been from the get-go. Manipulation of that breakdown – the act of composting – and tilling it into soil is a slightly more modern approach, first practiced by prehistoric farmers who used animal manure and "muck," or nutrient-laden river-bottom soil, to encourage their crops; the first known reference to compost was found on a set of clay tablets over 4,000 years old. After a few recent decades of chemically enhanced agriculture, compost is now enjoying something of a resurgence lately, as renewed interest in organic farming has surged.

Context

With landfill space an ever-shrinking resource – and people's growing awareness of their own impact on the environment – municipal composting is increasingly being seen as a way to reduce waste streams in the United States. Cities such as San Francisco, California and Portland, Oregon, have instituted (so far voluntary) curbside compostables pickup.

External Links:

Wikipedia - Compost

Online Composting Center

Master Composting Guide

Gaiam - Composting

Composting supplies and equipment

Further Reading:

The all-time classic of the subject, J.J. Rodale's Complete Book of Composting, is updated every decade or so to include new techniques and information.

Smith & Hawken publish a small but in-depth primer on the subject, Hands On Gardener: Composting.