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Since the days of von Liegib (1855) and Lawdor, who both, more or less independently discovered that, in addition to organic compounds, plants need inorganic nutrients for optimum functioning, nitrogen has occupied a special role in plant nutrition. This is, because nitrogen is needed in relatively large quantities by plants, the agro-ecosystem is open for nitrogen, i.e. large quantities of the element move through the system annually, and recently because of nitrogenous compounds play a major role in the environmental impact of agro-ecosystems.

The term efficiency has been used for a very long time by different disciplines, and the result is that it is not defined very well. In this contribution, efficiency of nitrogen use in crop production is considered from various angles.

Agricultural production can be defined as the formation of useful material with the sun as the source of energy. For this transformation process, nitrogenous compounds are indispensable and the efficiency of nitrogen use can then be expressed as the quantity of carbon dioxide that can be reduced by the green plant area per unit of nitrogen in the plant (photosynthetic nitrogen use efficiency).

In agricultural management application of nitrogen to the growing crop is an important management instrument, and fertilizer application therefore has been a subject of intensive study in agricultural sciences. The results have been presented in many different ways, and that has given rise to a highly confusing terminology with respect to nitrogen use. A systematic analysis shows that two processes can be distinguished: (i) the nitrogen applied to the soil has to be taken up by the vegetation to be effective, to what extent this happens can be expressed as nitrogen uptake efficiency; (ii) to be effective, the nitrogen taken up must be utilized by the vegetation to produce the required plant components; that can be expressed as physiological nitrogen use efficiency. If the two previous processes esses

Additional information

Authors: CARLIER L, DFE CLO-GHENT, Merelbeke (BE);VAN WAES J, DFE CLO-GHENT, Merelbeke (BE);DE VLIEGHER A, DFE CLO-GHENT, Merelbeke (BE);GEVAERT L, DFE CLO-GHENT, Merelbeke (BE);PITHAN K (EDITORS), Commission of the European Communities, DGXII/B/1, Brussels (BE)
Bibliographic Reference: EUR 19236 EN (2000) 359 pp., EUR 53.50
Availability: Available from EUR-OP sales agents
ISBN: ISBN 92-828-8670-0
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