METHANE EMISSIONS FROM TYPICAL MANURE MANAGEMENT-SYSTEMS

Methane is the most abundant organic chemical in the earth's atmospher e, and its abundance is increasing with time and has reached levels no t seen in recent geological history. Methane is produced both naturall y and anthropogenically. One of the sources of anthropogenic methane i s manure from domesticated animals. A methodology has previously been developed to estimate the amount of methane generated from this source . This was done by estimating the methane conversion factor (MCF) typi cally achieved by various waste management systems. The present study was conducted to evaluate these MCF assumptions using dairy manure as the representative livestock manure. The MCFs for the most dominant of disposal methods, range/and/pasture disposal, were much lower than th e earlier estimates. Other waste management systems, such as solid sto rage and liquid slurry storage had much higher MCFs, at 20 and 30 degr ees C. However, these waste management methods are more prevalent in p arts of the world where the average annual temperature is closer to 10 degrees C. At that temperature, the MCF is negligible in all waste ma nagement systems. This study showed that the previously reported estim ates of MCF for some waste management systems were higher than was act ually the case. Consequently earlier estimates of the amount of methan e generated globally from manures were higher than those found in this study.