Treehugger

Compost (and the act of creating it -- composting) is one of those things that TreeHuggers bandy about when talking about "going green" or "saving the planet", and the concept is fairly easy to understand: organic waste breaks down and decomposes to create a nutrient-rich fertilizer/soil additive. But, as it turns out, there's a bit more to it than that. Here's an introduction.



According to Wikipedia [en.wikipedia.org], Compost is the "aerobically derived remnants of organic materials," which, in plain English, is what you get when you combine the leftovers of plant and animal-based stuff, add a little air, water and nitrogen. The decomposition is performed primarily by aerobes -- organisms with oxygen-based metabolism -- although larger creatures such as ants, nematodes, and worms (in a process is also known as vermiculture) can also contribute. This decomposition occurs naturally except for in extreme anaerobic conditions, like in landfills, very arid deserts or cold weather such as boreal winters or polar regions, which prevent the microbes and other decomposers from thriving. Decomposition happens even in the absence of some of these ingredients, but not as quickly or as pleasantly.



Given enough time, all biodegradable material will compost. The goal in a composting system is to provide a healthy environment and nutrition for the rapid decomposers, the bacteria. Not all biodegradable materials are appropriate for backyard or at-home composting, though. Most backyard systems will not reach temperatures high enough to kill pathogens and deter vermin, so pet droppings, non-vegetarian animal manure, meat scraps, and dairy products are best left in the trash.

The most rapid composting occurs with the ideal carbon to nitrogen ratio of between 25 and 30 to 1 by dry chemical weight. In other words, the ingredients placed in the pile should contain 25 to 30 times as much carbon as nitrogen. For example, grass clippings average about 19 to 1 and dry autumn leaves average about 55 to 1, so mixing equal parts by volume nets approximately the correct range.



Compost is used most often at the consumer level in gardening and agriculture as a fertilizer-type soil additive, and can also often replace commercial fertilizers, but there are numerous other benefits. Using compost improves soil structure, texture, and aeration and increases the soil's water-holding capacity. Compost also loosens clay soils and helps sandy soils retain water. Adding compost improves soil fertility and stimulates healthy root development in plants. The organic matter provided in compost provides food for microorganisms, which keeps the soil in a healthy, balanced condition. Nitrogen, potassium, and phosphorus will be produced naturally by the feeding of microorganisms, so few, if any, other soil additives will be needed.

Anyone with a few extra square feet (even inside your kitchen or out on a deck or balcony) can produce compost (stay tuned for a few of our favorites later this week). Though a common misconception, properly aerated compost does not smell like rotten food, which makes it possible for apartment and other small home-dwellers to create their own without making a big mess or raising a stink. Check Wikipedia's compost article [en.wikipedia.org], the How to Make Compost's Guide [www.compostguide.com], the US EPA's composting site [www.epa.gov] and the USDA's Natural Resource Conservation Service compost site [www.nrcs.usda.gov] for more information, and stay tuned for more tips throughout the week.