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New Mexico State University

New Mexico State University

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Fall Is Great Time To Start Backyard Compost Project

LAS CRUCES -- Yard wastes comprise 20 to 30 percent of the solid wastes collected in landfills throughout the United States. Food wastes make up another 8 to 9 percent. These organic wastes not only take up space, they also can become environmental problems due to the methane gas and liquid drainage they produce.

"Backyard composting is one of the easiest ways to divert these organic wastes from landfills," said George Dickerson, horticulture specialist with New Mexico State University's Cooperative Extension Service . "With all the leaves and leftover plant debris in the garden, fall is a great time to begin a composting project."

Compost is a valuable, natural resource that can be applied to the garden or home landscape as a soil conditioner and low-analysis organic fertilizer. "Making compost is an accelerated way of imitating nature's cycle of life and death," Dickerson said.

The end product is a dark, loose, partially decomposed amorphous form of organic matter that reveals no hint of its origin. "The only difference between finished compost and forest humus created by nature is time," he said.

To begin composting, layer fall yard wastes and small amounts of soil in piles or bins. Microorganisms in the soil will begin the composting process. Shredding leaves and branches help them break down faster by increasing surface area. "The microorganisms in the compost material can digest these smaller pieces easier," Dickerson said.

Composting microorganisms function best when the piles are aerated. Construct bins with hardware cloth, chicken wire or stacked bricks with open spaces between them to allow free flow of air into the piles.

The microorganisms require both carbon and nitrogen to grow. Organic wastes like leaves, sawdust and shredded limbs have high concentrations of carbon. To counteract this, adequate amounts of nitrogen should be added to the pile. Grass clippings, livestock manure and food wastes are good sources of nitrogen. "A nitrogen fertilizer also can be added, as long as it doesn't contain an herbicide," he said.

The microorganisms also require water. When preparing a compost pile, spray each layer of waste with water until it reaches the consistency of a damp sponge.

Construct compost piles or bins at least 3 feet high and 3 feet wide to provide enough bulk to insulate the microorganisms and allow them to start multiplying.

Under ideal conditions, bacteria in the pile will produce heat. "The pile can heat up to as much as 150 degrees Fahrenheit," Dickerson said. Such high temperatures will kill most undesirable weed seed or plant diseases in the pile.

Turn the piles regularly with a garden fork, placing outside material toward the inside of the new pile for uniform composting.

The piles will eventually cool and have an earthy smell, he said. The finished compost can be used in the garden next spring as a soil conditioner, helping increase water-holding capacity in sandy soils or aerating heavier clay soils.

"Compost supplies nutrients like nitrogen, phosphorous, potassium, iron and zinc to plants in an organic form," Dickerson said. "This makes the nutrients more available to the plants over a longer period of time."