NITROGEN LOSSES FROM MANURE HEAPS

During storage and decomposition of solid manure, gaseous and leaching nitrogen losses occur which contribute strongly to the debit side of nitrogen balance-sheets of ecologically managed farms. Gaseous as well as leaching losses are highest at the beginning of the decomposition and decrease with time. Both are affected by temperature, straw:faeces-ratio, pH, initial N-content and heap rotation. Gaseous losses are always higher than leaching losses. During a 177 day experiment with cattle manure, only 2.5 to 3.4% of the initial nitrogen content leached with liquids, but 24.8 to 44.4% of it was lost by ammonia emission. However, leaching losses are of predominant interest, because of their ecological relevance in relation to water pollution. The protection of manure heaps against precipitation with plastic sheet, which is the most popular strategy to avoid leakage, did not markedly reduce nitrogen leakage but enhanced the ammonia emission as a consequence of changes in the physical and microbiological state of the compost.