Réglette azote colza®: a decision support tool for rapeseed N management adapted for Switzerland

The Réglette azote colza® is a decision support tool for rapeseed nitrogen fertilization, developed by the French institute Terres Inovia. This tool was designed to determine the nitrogen dose the most adapted to the needs of the crop, based on the rapeseed status at the beginning and at the end of the winter. The parameters were evaluated from field experiments carried out by Agroscope. The tool was then tested on technical, economic and environmental criteria and compared to the corrected norms. On our dataset, the Réglette azote colza® gave better estimation of the crop’s nitrogen needs than the corrected norms. The improvement of the estimation results in a reduction of the number of situation with nitrogen excess or deficiency, and therefore, an optimization of nitrogen use. This study, with first positive results, needs further assessment in various environments, to represent the diversity of the conditions of rapeseed production in Switzerland.