Bulletin of the University of Agricultural Sciences II. [antikvár]

EVALUATION OF THE IMPACT OF DIFFERENT INORGANIC NSOURCES ON THE N-TRANSFORMATION PROCESSES OF THE SOILPLANT-ATMOSPHERE SYSTEM USING THE 1SN-TRACER TECHNIQUE GY HELTAI1 - K. DEBRECZENI: - G BAKONYI3 - M. KECSKÉS4 Department of Chemistry and Biochemistry1. Department of Zoology3, Department of Microbiology4, University of Agricultural Sciences, H-2103 GÖDÖLLŐ. HUNGARY Institnte for Agricultural Chemistry cmd Soil Science2, Pannon University of Agncultural Science, H-8361 KESZTHELY, HUNGARY Received: 20.04.1995 KEYWORDS: soil/plant N-transformation. N'-traccr technique. microbial Ntransformation. mesofaunal N-transformation ABSTRACT The paper gives a survey on the investigation of N-cycling in soil/plant (mesofauna)/air relations using the 15N-tracer technique. An ecological approach was followed. i.e. a wide spectmm of dynamic and cumulative N-flows was detected simultaneously in mesocosmic and microcosmic experiments. The interaction of short tenn and long tenn N-transformation processes was evaluated using different inorganic fertilizer N-sources (ammónium and nitráté). Mathematical models for the description of kinetic changes are in the process of elaboration. INTRODUCTION The adequate management of nitrogén cycling in the soil/plant (animal)/atmosphere system is of global importance nowadays. Intensive agricultural and industrial activities interfere with the extremely fíne balance of overlapping natural cycles and may lead to environmental hazards such as the pollution of waters by nitráté leaching and the emission of nitrogén oxides and ammónia into the atmosphere (Dubgard, 1991; Seiler, 1981; Colburn, 1984). The nitrogén transformation processes and their interactions on very wide spatial and time scales so they must be described from the "microcosmsic" level (e.g. the rhizosphere) through the mesocosm (individuai plants), up to the field, régiónál and global system levels on a time scale ranging from a few seconds to several years. The crop models developed recently already consider a very complex interaction system at field level and on a long-term time scale. The essential components of these models are N-transformation models, which themselves are süli very complex. Crop models can be used succcssfully for the prediction of dry