Management of nitrogen fertilization of winter wheat and potato crops using the chlorophyll meter for crop nitrogen status assessment

This paper presents experimental results from a new field-scale N management strategy for winter wheat and potato crops in Belgium. At the beginning of the season, a global N recommendation is given using the balance-sheet method. The crop development and related N needs are strongly influenced by unexpected factors during the growing season. Therefore, the N predictive recommendation needs to be adapted to the crop N status. For this assessment, the chlorophyll meter was preferred over several plant diagnostic tools. In order to eradicate environmental influences, the measurement procedure was defined. The proposed procedure was based on the establishment of chlorophyll meter relative values. In winter wheat, the procedure allowed the third N dressing amount to be modulated using an over-fertilized plot. The same approach was tested on potato crop to introduce N split-application. The results showed, however, that an over-fertilized plot as reference is not suitable for determining the supplemental N required.