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Emergency Livestock Disposal Home
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Mortality Composting
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PRELIMINARY RESULTS
Oxygen
Oxygen concentration measurements, at 40-cm increments along a transect from the core of the test units to their outer edge, show distinct differences between the three cover materials used in trial # 5 (begun November 11, 2003).
Figure 1. Oxygen concentrations at week # 10 (January 23, 2004), in cornstalk (blue), silage (violet), and hay/manure (green) test units in trial #5.
As shown in the example above, cornstalk test units can exhibit oxygen concentrations near their core that are as high as the 21% typical in normal atmospheric conditions at their outer surface. Contrasting with this, silage and hay/manure test units typically exhibit oxygen deficient (but not anaerobic) conditions near their core.
The differences between the oxygen profiles in silage and cornstalks are probably caused by two factors. The cornstalks, which have higher permeability than silage, allow oxygen to migrate through the stalks much more easily than the silage. At the same time, the much warmer environment within the silage may reflect higher aerobic microbial activity and a higher demand for O2. In light of the similar carcass decomposition rates observed in silage and cornstalk test units, however, the differences in O2 profiles are thought to be due primarily to differences in cover material permeability.
The cause of the sag in the middle of the O2 concentration profile for the hay/manure test unit is uncertain. This may reflect increased activity and/or lower gas permeability at the interface between the straw and manure. The slight rebound in O2 near the core may reflect an area affected by cracking of the manure layer.
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In Brief
1. O2 concentrations are higher and more uniform in cornstalks than in silage or hay/manure test units.
2. High O2 concentrations throughout the cornstalk test units appear consistent with their surprisingly good ability to decompose carcasses and relatively low internal temperatures (high heat loss).
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