We measured nitrogen components during composting process of feces in a batch test in which sawdust was used as a matrix. Further decomposition rates of fecal nitrogen and carbon were obtained in the batch tests of different feces loading. In composting material that was a mixture of sawdust and fresh feces, fecal organic matter decomposed to CO2 and fecal nitrogen mineralized to ammonia during the composting process. The biological response of organic matter and nitrogen in the composting material was evaluated by oxygen consumption (OUR) and ammonia production that was a sum of volatilized ammonia gas and ammonia remaining in the composting material. Since composting material contains two different sources of organic matter from feces and sawdust, the OUR by using the sawdust matrix only was evaluated in preliminary tests. The fecal contribution to the OUR in the composting material was therefore calculated by subtraction of the result in the preliminary tests from the one in the composting material. The ammonia production from the fecal nitrogen was obtained by the same procedure. The decomposition rates of input organic matter in feces were approximately 83 and 70% respectively, whereas ammonia production rates were approximately 73 and 58% of input fecal nitrogen. There was an interesting time lag of the peak time between volatilisation rates of ammonia and CO2 during the composting process while fecal carbon and nitrogen simultaneously decomposed to ammonia and CO2 in the composting material.

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