McIntyre: Make your own 'black gold' from food and yard waste

University of Idaho Master GardenerJune 13, 2013 

The Environmental Protection Agency estimates about 23 percent of U.S. waste is garden debris, leaves, grass clippings, shrubs, and branches. Instead of dumping this organic waste in our landfills, turn it into nutrient rich organic fertilizer, compost.

Compost is a mixture of decayed organic matter that is used as a soil amendment. Creating a perfect environment for the breakdown of organic matter into compost depends on the right combinations of ingredients.

With a balanced ratio of nitrogen-rich "green" matter, carbon-rich "brown" matter, oxygen, water, heat from the sun and organisms - such as bacteria, fungi, worms and beneficial insects - the breakdown of organic matter accelerates and becomes compost or "black gold" to avid gardeners.

Compost increases the ground's ability to retain moisture. It is porous and loose with air pockets that harbor soil microbes. It soaks up water like a sponge and slowly releases water as the plant needs it.

Amending the soil with compost will help plants grow deeper, stronger roots over a wider area in this loose soil environment.It also increases drought-resistance, protects the ground from erosion, helps to suppress plant diseases and pests, and can promote higher yields of vegetative crops.

Compost is also an inexpensive alternative to chemical fertilizers and is less likely to harm sensitive roots.Chemical fertilizers can be extremely harsh on plants and can even leave heavy metals like lead, cadmium and arsenic in the soil. Most are made from petroleum and other non-sustainable sources and can kill the very microbes that make soil fertile.

Surprisingly, compost can also decontaminate soil. According the EPA, "The composting process has been shown to absorb odors and treat semi-volatile and volatile organic compounds (VOCs), including heating fuels, polyaromatic hydrocarbons (PAHs) and explosives.It has also been shown to bind heavy metals and prevent them from migrating to water resources or being absorbed by plants. The compost process degrades and, in some cases, completely eliminates wood preservatives, pesticides and both chlorinated and non-chlorinated hydrocarbons in contaminated soils".

The types of nitrogen-rich "green" organic matter you can use in composting are grass clippings, vegetable and fruit trimmings (table scraps), egg shells, vegetable culls, flowers, and chicken, cattle and horse stable manure.

Carbon-rich or "brown" organic matter refers to hay, straw, pine needles, leaves, sawdust, wood chips, corn stalks & trimmings from trees & shrubs.

Keep in mind there are some things that should NEVER be composted:

• Meat, oils, fried food, bones, dairy products, cat or dog waste, hair, and weeds, grass clippings.

• Plants, shrubs and flowers that have been treated with herbicide and/or insecticides.

• Diseased or insect-infested vegetation.

It is important, when you are creating a compost pile, have at least two piles or bins to contain the organic matter.Fill one bin to create a composting pile. Spray water water on it and turn it over with a pitchfork or similar garden tool. Continue to do this every day but do not add any more organic matter to the pile. Allowing the organic matter to break down, without disturbing the decaying process by adding new waste, will reduce the time it will take to have rich compost ready to mix into your garden soil.

Now you can start your second compost pile and repeat the process all over again. Quality compost can take as little as several weeks.A friend once told me to water and turn my compost everyday for a continuous cycle of rich compost every month.

So what are you waiting for? Get out and start composting now. Not only will you help by being a good steward of the Earth, by reducing massive amounts of waste in our landfills, but you can turn it into nutrient- rich organic fertilizer to amend your soil and promote growth and high yields of vegetables, fruits and flowers.

For organic matter ratios, examples of compost bin methods and more check out the University of Idaho's Compost publication.

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