Compost Fundamentals

Composter's Needs

(considerations before choosing a compost method)

time required

Organic matter can compost to safe, stable material in as little as three weeks, or as long as six months or more. The actual composting time is not particularly important, provided that is it sufficient for destruction of pathogens and parasites, and for nitrogen conservation. Composters need to determine how quickly they want finished compost.

The time required for satisfactory stabilization depends primarily upon:

  1. initial C:N ratio
  2. particle size
  3. maintenance of aerobic decomposition and
  4. moisture content.

The C:N ratio determines time required for stabilization, provided moisture content is in the optimum range, compost is kept aerobic, and particles of material are of such size as to be readily attacked by the organisms present - all factors that can be controlled in the composting operation. Low C:N ratio feedstocks decompose in the shortest time because the amount of carbon to be oxidized to reach a stabilized condition is small. Also, a larger part of the carbon is usually in a more readily available form, while in higher C:N ratio materials, more of the carbon is usually in the form of cellulose and lignin which are resistant to attack. The changing biological population in the environment attacks cellulose and lignin last. When the available C:N ratio is above 30, additional time is required for recycling nitrogen.

If material is not kept aerobic so that high temperatures can be maintained during the active decomposition period, or if the particle size is so large that the bacteria cannot readily attack the material, or that the interior of the particle becomes anaerobic, longer composting periods are required.

Under aerobic conditions at high temperatures and when the initial C:N ratio is in the optimum range or below, the material takes on the appearance and odor of humus after 2 to 5 days of active decomposition. However, active decomposition is not complete at this stage, and the C:N ratio may not have been lowered to the level desired for fertilizer.

destruction of pathogenic organisms

pesticides and herbicides

fly control

reclamation of nitrogen and other nutrients

time required

Why Compost | Biology & Chemistry | Compost Needs
Composter's Needs | Benefits & Uses | Conclusion

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