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Hot or cold? Expert gives advice for composting during winter

Date: 02/05/2015

A compost operation near Gerald Thomas Hall at NMSU
Whether you?re creating compost using hot or cold methods, there are steps you can take during the winter to get the most out of your operation. (NMSU photo by Jay A. Rodman)


Winter in the desert Southwest is different from any other part of the country, and to have the perfect compost this time of year requires a little knowledge.

?Not all composting operations get hot. Not all composting operations need to be turned,? advises John Zarola, outreach coordinator at New Mexico State University's Bernalillo County Extension office. ?Composting in the winter is a fine thing to do ? cold or hot method.?

Zarola said in general, cold-composting operations will slow down, while hot operations will do what they normally do ? but the decomposition formula remains the same for each.

?Maintaining 50 percent moisture in any operation is a bit easier, as there is less evaporation at lower ambient air temperatures,? he said.

Zarola provided some tips to have the best cold or hot compost during winter:

Cold composting

Tip 1: In a cold method, there is no intention to create heat in the operation. Use bins, piles, pit, trench, sheet, worms and Bokashi.

Tip 2: Cold composting operations approach equilibration with the ambient air temperature. Once the temperature drops below 50 degrees Fahrenheit, the microbial action slows, prolonging the decomposition process, but the whole system will balance out as temperatures rise in the spring.

Tip 2: 50 percent moisture should be maintained throughout the process. When ambient air temperatures are lower, there is less evaporation in the process. Cold piles may remain static (not turned) as long as coarse bulking material is regularly added, especially to piles. Or, they may be churned and turned as the homeowner wishes.

Hot composting

Tip 1: In a hot composting method, there is an intention to create and maintain heat in the operation.

Tip 2: The batch method requires a minimum of a cubic yard of organics with a mixture of two parts carbon with one part nitrogen and 50 percent moisture. Heat is generated as the microorganisms secrete enzymes, which break the bonds of the carbohydrates. The heat being generated internally is not affected by the ambient air temperature.

Tip 3: Hot piles are a high-energy process, which require oxygen, so they need to be churned and turned every 7 to 14 days to maintain heat in the operation.

Written by Angela Simental



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