Influence of different nitrogen sources on composting of Miscanthus in open and closed systems

Composting of Miscanthus straw was compared in two different, insulated sys tems, one constructed from four open boxes and one of four closed reactor v essels. Composting of Miscanthus supplemented with either ammonium sulfate, urea, liquid pig manure or brown sap from grass was studied. Hygienization of composts was evaluated by integrations of heat developments. Mixtures o f Miscanthus and ammonium sulfate or liquid pig manure lead to high heat de velopment in beginning of composting period while composting of mixtures of Miscanthus and brown sap or urea progressed later in composting period. Th e period of high microbial activity during composting may therefore be exte nded using mixtures of manure and brown sap or ammonium sulfate and urea as nitrogen source.