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New Mexico State University

New Mexico State University

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Recycle Organic Wastes in the Home Garden as Compost

LAS CRUCES -- Fall finds most gardens a tangled mess of frost-bitten vines, dried corn plants and monster-sized zucchini. Fallen leaves collect near fences with each gust of wind. Rather than sending this trash to the landfill, gardeners should consider composting.

"Cleaning up organic garden trash during the fall is the first step to control insects and diseases in next year's garden," said George Dickerson, horticulture specialist with New Mexico State University's Cooperative Extension Service.

"It eliminates the hiding places used by overwintering insects and plant material that harbors disease organisms. Composting this garden trash kills insects and diseases and helps recycle nutrients when applied to the spring garden."

A properly constructed compost pile can reach temperatures as high as 150 degrees. A proper balance of various types of organic wastes, water and air is required for successful composting.

"Green wastes like food scraps and grass clippings should be mixed with dry or woody wastes to create an appropriate mixture of nitrogen and carbon," Dickerson said. "Microorganisms in the compost feed on carbon for energy and require nitrogen to build amino acids and proteins in their bodies."

Livestock manure or nitrogen fertilizer also can be added to piles with too much carbonous material. Thermophilic bacteria, which generate heat for the composting process, reproduce at an optimum rate when the carbon-nitrogen ratio is 30-to-1, he said.

Shred leaves and woody material before adding to the compost pile to increase their surface area, giving the microorganisms more places to feed. Keep the pile moist but not soaked. The compost should have the consistency of a damp sponge, Dickerson said.

"It's important that the pile have plenty of air," he said. "Overly wet compost will decompose anaerobically, or without air, causing it to stink. Piles with plenty of air will decompose aerobically resulting in a sweet, earthy smell."

The compost pile or bin should be at least 3 feet high and 3 feet wide to provide enough mass to insulate the pile and keep the composting process going. Turn piles with a garden fork when the inside temperature reaches 130 to 150 degrees, placing outside material toward the inside of the new pile for uniform composting.

"The pile will eventually cool off and shrink in size," Dickerson said. "Composting creates heat, water vapor and carbon dioxide. The end product is humus, which can be used in the spring garden as a soil conditioner, natural fungicide and low-analysis organic fertilizer."