Nitrogen Turnover in the Soil-Crop System


Book Description

In the Netherlands the Institute for Soil Fertility Research plays a major role in soil biological, soil physical and plant nutritional research on the availability of nitrogen to crops. Main subjects of research are nitrogen turnover in the crop-soil ecosystem through biological transformations, nitrogen transport through the soil and nitrogen losses by leaching, denitrification and volatilization, and nitrogen use efficiency of various crops and cropping systems. The current knowledge in the different fields of research is integrated in simulation models. Simulation models not only make it possible to summarize and structure knowledge, but also, after verification, to extra- late the knowledge to situations different from the situations that have actually been studied. Such research is also carried out in other European and non-European countries. To compare the various simulation models currently in use, a workshop was organized by the Institute for Soil Fertility Research on 5-6 June 1990 on the occasion of its centennial. The title of the workshop was 'Nitrogen turnover in the soil-crop ::cosystem: modelling of biological transformations, transport of nitrogen and nitrogen use efficiency'. The 40 Jarticipants, who came from Canada and various European countries, were requested to run their model with data Jrovided by the Institute prior to the workshop. Data from 18 cases were made available to the participants: three ocations, three treatments, and two seasons.




EPA-600/2


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CRREL Technical Publications


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Distributed Hydrological Modelling


Book Description

It is the task of the engineer, as of any other professional person, to do everything that is reasonably possible to analyse the difficulties with which his or her client is confronted, and on this basis to design solutions and implement these in practice. The distributed hydrological model is, correspondingly, the means for doing everything that is reasonably possible - of mobilising as much data and testing it with as much knowledge as is economically feasible - for the purpose of analysing problems and of designing and implementing remedial measures in the case of difficulties arising within the hydrological cycle. Thus the aim of distributed hydrologic modelling is to make the fullest use of cartographic data, of geological data, of satellite data, of stream discharge measurements, of borehole data, of observations of crops and other vegetation, of historical records of floods and droughts, and indeed of everything else that has ever been recorded or remembered, and then to apply to this everything that is known about meteorology, plant physiology, soil physics, hydrogeology, sediment transport and everything else that is relevant within this context. Of course, no matter how much data we have and no matter how much we know, it will never be enough to treat some problems and some situations, but still we can aim in this way to do the best that we possibly can.