Page 9 - Poultry Mortality Composting

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Nutrient Balance (C:N)

The proper compost mix requires both carbon (C) and nitrogen (N) at the proper ratio near 30:1. This will result in a composting process that generates little odour yet offers an environment where microorganisms can flourish. Fresh poultry carcasses contain approximately 80% moisture, 12% C and 2.4% N, thus have a low C:N of 5:1 by weight. Plant materials such as dry poultry litter, wood chips, sawdust, chopped corn stover, shredded paper or straw have a high C:N for on-farm mortality composting.

Moisture

Like all living things, microorganisms need water. To encourage their growth and rapid composting, water content of the mixture should be 50 – 60% w.b. (wet basis). It is important to avoid excess water due to the potential for odour and excess liquids released by decomposing carcasses. When fresh poultry carcasses are used, there is usually no need to add extra moisture. If the carbon material is extremely dry (>85% dry matter) or the carcasses have dried out before composting, water may be needed.

Temperature

Temperature is a good indicator of the “health” of the compost process. A probe-type dial thermometer with a 1 m (39 in) stem is good for monitoring temperatures, Figure 1. Temperatures should be checked frequently throughout the pile. Normally, temperatures in the primary stage should rise to 55 – 65 °C (131 °F –149 °F ) in 1 or 2 days and peak at 60 – 70 °C (140 °F –158 °F ) within 7 to 10 days.

Temperatures above 55 °C (131 °F) over 3 days will kill parasites and fecal and plant pathogens within the pile. However, to maintain high temperatures, the pile must be adequately sized, 2.4 – 3.6 m (8 – 12 ft) wide at the base and 1.5 – 2.1 m (5 – 7 ft) tall. At temperatures above 66 °C (150 °F), microbial activity declines rapidly as compost temperature exceeds 71 °C (160 °F).

Although experience indicates that temperatures above 75 °C (167 °F) are rare, a remote possibility exists that temperatures could rise to spontaneous combustion levels. If temperatures appear to be rising towards 75 °C (167 °F), the compost should be spread on the ground to cool.

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