Thursday, September 30, 2010


Composting is the decomposition of plant remains and other once-living materials to make an earthy, dark, crumbly substance that is excellent for enriching garden soil. It is one way to recycle your yard and kitchen wastes, reduce the volume of garbage you send to landfills and live a more sustainable life. When I lived in San Francisco, the city kindly collected food scraps (including meat and fat which really cannot be composted in your backyard) for composting. When I moved to the country in Virginia I had to rethink my approach to composting and recycling.

Your approach to composing to a large extent will be dictated by how large your yard is. If you live in a small lot suburban or urban environment that does not collect your kitchen scraps, then you will have to utilize a rodent proof and enclosed method of composting. There are basically three enclosed methods of composting which can be used for interior, garage or small yard/patio composting.

Bokashi is a method of intensive composting that can be used inside your home. Kitchen waste is placed into a container which can be sealed with an air tight lid to contain the smell. Kitchen scraps are layered with a Bokashi carrier which is usually wheat bran, rice hulls or saw dust that has been inoculated with composting micro-organisms. When using this method, it is best to have more than one container and to fill the second while the bacteria in the first are completing their work.

Vermiculture is the method of composting using worms. Worm composting typically uses a commercial worm bin (though you can always build your own shallow, sealed bin). Bedding material must be used, typically, shredded newspaper that has been moistened. A handful or two of soil, ground limestone, or well-crushed eggshells every couple of months is good for providing grit and calcium. You fill the bin with moistened bedding, toss in a few handfuls of soil, and add the worms and food scraps. Various species of worms can be used, but red worms are sold for the purpose (at least around here). They seem to survive well in these systems. Be sure to keep your worm composter at moderate temperatures, which basically requires keeping it in the garage.

The Sierra Club recommends a sealed drum composters if you have some outdoor space. These systems are rotating drums of various sizes. To achieve a good carbon to nitrogen ratio it is recommended that 50/50 balance of brown dry materials and green wet materials are added by weight. Brown materials include leaves, dry grass, shredded newspaper, and other natural products. Green materials include fruit and vegetable peels, egg shells, coffee grinds, and green plant trimmings. You simply rotate the drum three times a week during warm weather to ensure perfect mix and proper air circulation. When the weather is freezing do not turn the drum. You can watch the short composting video at this link.

Because I have acres of land and woods I have the luxury of utilizing the lazy girl’s methods of composting. The most basic and passive form of composting is backyard mulching. The largest amount of green waste generated at the suburban home is from the garden. Grass clippings should never be collected and sent to a landfill, your are just throwing away nutrients for your lawn. The first step in mulching is to take the grass clippings collector off of your lawnmower. By leaving the clippings on the ground, they will decompose and add nutrients to the soil, improving the quality of your yard. I combine mulching with not fertilizing my yard, since the grass clippings contain similar nutrients. This way I am being “green” and “sustainable” by doing less.

There are two ways to mulch leaves and this depends on the density of trees in your yard. You can either collect the leaves or spread them evenly on soil-exposed areas, to ultimately produce rich topsoil. If the layer of leaves is light, use the lawnmower to shred the leaves to help their decomposition and leave them. If leaves are collected and placed in a pile, make sure to moisten several layers of the pile to help them decompose more quickly.

Passive composting requires that you have both a carbon source and a nitrogen source and that bacteria develop. The bacteria develop naturally and the desired carbon to nitrogen ratio is about 30 to 1 that is approximated by a 50:50 mixture by weight according to some sources and 3 to 1 by weight according to the U.S. EPA. Composting is not an exact science and getting close enough will work. Good carbon sources are dried leaves, bark, shredded news paper or cardboard. Nitrogen sources are raw or cooked plant waste. The following is a list of compostable household waste; cardboard rolls, clean paper, coffee grounds and filters, cotton rags, dryer and vacuum cleaner lint (but only natural fibers), eggshells, fireplace ashes, fruits and vegetables, small amounts of grass clippings, hair and pet fur, hay and straw, houseplants, leaves, nut shells, sawdust, shredded newspaper, and tea bags (pull out the little staples and discard separately).

For your compost pile you need to layer carbon source with nitrogen source into a large pile. This pile can be left open or placed into a bin. It is then left to sit as the organic matter begins to rot. Over time (around 1 to 3 years depending on your carbon and nitrogen ratio, material size, temperature and aeration), the material will have decomposed into a rich compost material that is great for use as topsoil. Turning the pile is believed to speed up the decomposition, but certainly releases the stink. Modern composting guides suggest using smaller homogeneous sized bits of waste, shredded paper if enough dried leaves are not available to keep the carbon to nitrogen ratio (brown leaves, bark and paper to green moist waste) at 30 to 1 and monitoring the moisture level.

The vegetative waste management and yard waste composting regulations in Virginia allow composting of leaves, grass, brush and other collected material, but not composting of land-clearing debris. For an individual homeowner, Virginia pretty much leaves you alone unless you become a nuisance to your neighbors or a health hazard.

If you have a large enough yard you can either follow the traditional methods or the slightly more active approach of the early organic movement (the writings of Howard and Balfour are recommended if you are interested), suggesting that a layered pile in a temperate damp climate will do just fine with minimal effort and if you are willing to wait a couple of years and have lots of land to spare you can take my approach and build layered compost pile in edge of the woods each year and then leave it and start a new one. Time will ultimately take care of missing the ideal ratio, cold weather, failure to toss regularly with a pitch fork and most other failings.

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