ISHS Acta Horticulturae 469: International Symposium on Composting & Use of Composted Material in Horticulture
INFLUENCE OF BIOWASTE COMPOSITION AND COMPOSTING PARAMETERS ON THE NITROGEN DYNAMICS DURING COMPOSTING AND ON NITROGEN CONTENTS IN COMPOSTS |
| Authors: | I. Körner, R. Stegmann |
| Keywords: | waste model, compost application, quality, process regulation, ammonification, nitrification, denitrification, aeration, N-balance, N-release |
| Abstract:
The investigations describe the N-dynamics during composting by means of nitrogen balances for the different composting experiments. Various models were used for laboratory composting experiments of biowastes each representing a season. The aeration rate as an important composting parameter was varied. Aeration and substrate composition affect the course of pH value, temperature and moisture content during the composting process. These composting parameters have a significant influence on N-turnovers from proteins in biowaste into inorganic (ammonia, nitrite, nitrate) and organic substances and on N-releases via exhaust air and leachate. Thus the ammonification rate is high if substrate is optimally aerated. Aeration, a porous substrate structure and an high pH value are basic requirements for a release of ammonia via exhaust air. A N-release via leachate only occurs under unfavourable composting conditions. Nitrification and denitrification processes are more likely when substrate contains a higher portion of green waste. The amount of total nitrogen and plant available nitrogen in compost is a consequence of biowaste composition and of composting conditions. Compost contains less inorganic N-forms than organic N-forms. The highest contents of ammonia were measured during the thermophilic phase. Nitrate may occur in matured compost. By regulating N-reactions during composting, composts with a more predictable fertilising effect could be produced. | |
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