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New Mexico State University

New Mexico State University

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Compost a hot prospect in preventing Chile disease

LAS CRUCES - Compost may deserve its own info-mercial on the Chile lovers channel to tout its success in preventing a seedling disease while enhancing soil and saving landfill space at the same time.

True, compost is anything but a glamorous product, with urban and agricultural waste as its main ingredients. But George Dickerson, horticulturist with New Mexico State University's Cooperative Extension Service, is enthusiastic about compost's potential to recycle waste and to protect New Mexico's signature Chile crop.

Currently, Dickerson is working with an earthy concoction made from shredded branches and stabilized bio-solid waste (sludge) from the City of Albuquerque. As compost heats up, microorganisms break down the waste. High temperatures pasteurize disease-causing bacteria, leaving finished compost that meets Environmental Protection Agency standards for food crops.

"We're trying to take wastes that normally go into the landfill and recycle these not only in the backyard but also areas," Dickerson said.

In southern New Mexico chile fields, doses of Dickerson's compost reduced losses to the "damping off" fungus that kills chile seedlings in cool weather.

"Bio-solid compost made from landscape wastes like old tree limbs tends to act like a natural fungicide," he said. "We found that when we apply 20, 30, or up to 50 tons per acre of this compost, it can reduce damping off by up to 37 percent."

Researchers believe the same fungi that help break down woody material in compost simply out-compete the fungi that cause the disease.

Some greenhouses already have found that replacing potting soil with compost made from woody material can reduce plant diseases and the need for fungicide use.

"What we're doing now is trying this idea in a field situation to see if we get the same kinds of effects from compost," Dickerson said. "One of the main reasons we've put it on chile is to see if we can fight chile wilt in the future."

Chile wilt, also called Phytophthera root rot, can devastate yields, claiming up to 25 percent of the year's crop. Compost will match up against the disease later this season as field trials continue, Dickerson said.

Whether or not it kills chile wilt, Dickerson thinks composting has untapped potential for New Mexico's rural and urban areas.

In Albuquerque, tree limbs, grass clippings and other yard waste make up about 34 percent of residential solid waste. The city also treats 50 million gallons of wastewater daily, which is converted into 22 dry tons of stabilized bio-solids.

Although it sounds unappealing, such raw material is the stuff of compost, which requires a mix of high-carbon waste like tree branches and nitrogen sources like animal waste or bio-solids.

"In agriculture, we're looking at using things like dairy waste that might normally be applied to agricultural land directly," Dickerson said. "But that waste may contain weed seed and attract flies, and it may be in large chunks that are hard to incorporate into the soil."

The composting process heats up the waste, killing weed seed and creating fertilizer that's less smelly and easier to spread.

Traditionally, composting has been a small-scale, backyard affair. For years, New Mexico gardeners have cherished compost for adding needed organic matter to the soil, improving its texture, or tilth, and enhancing soil's ability to hold water and nutrients. Compost also serves as a low-analysis fertilizer, slowly releasing small amounts of nutrients.

Although there's no info-mercial planned soon, Dickerson has written a bulletin extolling the benefits of compost. County Extension offices throughout the state can provide information on how to get a copy of guide H-159, "A Sustainable Approach to Recycling Urban and Agricultural organic Wastes."