ifoam'96 ifoam'96
Book of Abstracts
11th IFOAM Scientific Conference
11-15 August 1996, Copenhagen, Denmark
EcoWeb Denmark


Optimizing of N-transfer after Legume-Wintercrops. P2; 50

König, U. J.

Institut for Bio-Dynamic Research e.V., Brandschneise 5, D-64295 Darmstadt, Germany

In the last 10 years the Organic Agriculture has been comming into discussion in regard of the cultivation of legumes, criticizing the potential leaching of nitrate after following soil treatments. Even the legumes-wintercrops were not excepted.
On this background a three year examination was carried out by two project partners: the »Institut for Bio-Dynamic Research« in Darmstadt and the »Institut for Plantproduction« of the University of Bonn and was financed by the German government.
The aim of this project was to receive an overview to which degree the cultivation of legumes-wintercrops becomes dangerous to the drinking water by nitrate leaching and under which conditions the nitrate can be optimal conservated.
Therefore, from autumn '91 to autumn '94 monthly examinations of nitrate content of soil were carried out in 4 soil depths (each 25 cm) on 35 plots of 19 farm sites ecological treated and in two field experiments on a sandy soil, all in Germany located.
The results showed that under usual organic agricultural use no dangerous level of soil nitrate will be reached after cultivation of winter-legumes. The highest calculated amount of assimilated N by the legumes was 90 kg/ha under controlled experimental conditions. The average of all plots showed that only 28 kg/ha leaching of nitrate-N could be found (range: 3-75 kg/ha nitrate-N). The few plots with higher values were found on the one hand on fen soils (54-75 kg/ha nitrate-N), on the other hand on plots with false treatements, e.g. during winter untilled soils on rainy sites (57-75 kg/ha nitrate-N).
No correlations could be found between the values of nitrate content measured in november or december and the calculated leaching of nitrate during the whole winter period. Even the soil type and different crops showed no dependent relation to nitrate leaching.

König, U. J. (1996): Zwischenfruchtanbau von Leguminosen. Verfahren zur Minimierung der Nitratausträge und Optimierung des N-Transfers in die Folgefrüchte. Schriftenreihe des Instituts für biologisch-dynamische Forschung, Darmstadt 148 pp.