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Care to compost?

While I might be considered the gardener in the family, my husband is the king of compost. So he was a happy guy when Santa delivered a compost tumbler this year. With so many affordable and trouble-free composters available, almost anyone can convert yard debris into precious compost.

While composting occurs naturally, human intervention can accelerate it. The quality of the compost and the production speed depend upon several factors that human composters can manipulate. To improve the composting process, we can monitor the air, the moisture and the ratio of “brown” material to “green material.”

Aeration

Composting is an aerobic or oxygen-requiring process. The microorganisms and other biological decomposers responsible for composting consume oxygen along with the organic materials and produce primarily compost, carbon dioxide, water vapor, and heat.

The oxygen consumed during the process must continually be replaced by air movement through the materials. Because the penetration of air may be inadequate or inconsistent, some decomposition inevitably occurs under anaerobic conditions (without oxygen). Anaerobic conditions are undesirable in a compost pile because the decomposition products are often odorous.

In addition, as composting proceeds and the materials decompose, they shrink in size and begin to settle. Settling reduces the pile’s air spaces and restricts aeration. Regular mixing of the pile, referred to as turning, reverses the effects of settling.

Although turning recharges the pile with fresh air, its main effect is to fluff up the material. This increases the pile’s porosity and improves natural air circulation. Turning also blends the composting materials and breaks apart clumps of materials. Because of these benefits, turning speeds the composting process

Moisture

Microorganisms need moisture. Water serves as a medium for chemical reactions and provides a means for movement of nutrients to the microorganisms. On the other hand, too much water makes the materials soggy and heavy, hindering aeration.

The “squeeze” test is an easy way to gauge the moisture level of composting materials. The material should feel damp to the touch, but not dripping wet. Water should drip from the material only when you squeeze it tightly in your hand. If you can’t squeeze water out, the pile is too dry.

A compost pile’s heat will rise as long as it is providing a favorable environment for the microorganisms. Once the air and moisture become depleted, the bacteria population will diminish and the pile’s temperatures will decrease. A compost thermometer is a great monitoring tool.

Carbon-to-nitrogen ratio (browns and greens)

Microbial decomposers obtain many nutrients from the composting materials but carbon (C) and nitrogen (N) are the nutrients that most affect the process. Microorganisms primarily use carbon compounds as an energy source and ingest nitrogen for protein.

Because they require a balance of both nutrients, the proportion of carbon to nitrogen is important when combining organic materials to make compost. The ideal ratio (C:N) of these two elements is about 30 parts carbon to 1 part nitrogen by weight.

In a backyard or home composting situation, it is impractical for you to be precise. An easier approach is to develop recipes by thinking of carbon sources as “browns” and nitrogen sources as “greens” and then combining brown and green materials in rough proportions.

Examples of “browns” include dry leaves and shredded newspaper. “Greens” include grass clipping and kitchen scraps.

For more information, read the University of Florida/IFAS Compost Tips for the Home Gardener. It’s available online at http://edis.ifas.ufl.edu/ep323 0r by contacting your local Extension Office.

Permanent link to this article: http://santarosa.ifas.ufl.edu/blog/2012/01/18/care-to-compost/