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

Abstract

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. nitrogen / fertilization / winter wheat / potato / chlorophyll meter / diagnostic tool Résumé-Gestion de la fertilisation azotée des cultures de froment d'hiver et de pommes de terre à l'aide du chlorophyllomètre, outil rapide de diagnostic du statut azoté des cultures. L'objectif de cet article est de présenter de nouvelles stratégies de fertilisation azotée, à l'échelle de la parcelle, en blé d'hiver et pommes de terre en Belgique. En début de saison, un conseil global de fumure azotée est établi selon la méthode du bilan. Mais le développement de la culture et les besoins azotés correspondants sont fortement influencés par des facteurs imprévisibles. Ainsi le conseil de fumure doit être modulé par le statut azoté de la culture estimé grâce au chlorophyllomètre. Afin d'éliminer l'influence de facteurs extérieurs, un protocole d'utilisation a été défini. Cette procédure est basée sur l'établissement de valeurs relatives. En blé d'hiver, elle permet de moduler la quantité d'azote à apporter en troisième fraction grâce à une référence sur-fertilisée. La même approche a été testée en culture de pommes de terre en vue d'introduire le fractionnement dans la fertilisation azotée, mais les résultats ont montré qu'une placette surfertilisée ne permet pas de déterminer le besoin supplémentaire en azote. azote / fertilisation / blé d'hiver / pomme de terre / chlorophyllomètre / outil de diagnostic

Rate and time of fertilizer nitrogen application on yield, protein and apparent efficiency of fertilizer nitrogen use of spring wheat

“…Crop N status could reliably be measured at ZGS 32 in this study. Previous studies have also found leaf chlorophyll index measured using a SPAD-502 meter to be effective in assessing crop N status for wheat at late tillering and at more mature growth stages (Follett and Follett 1992;Fox et al 1994;Peltonen et al 1995;Denuit et al 2002). However, fertilizer N applied at ZGS 32 in this study primarily influenced grain protein, and was of limited value in optimizing grain yield.…”

“…Such a system includes application of some fertilizer N in spring, followed by additional fertilizer applied later in the growing season as required based on crop N status (Denuit et al 2002). Leaf chlorophyll index, as measured using a SPAD-502 meter, has been found to be effective in measuring wheat N status (Fox et al 1994;Peltonen et al 1995).…”

Opportunities for improved fertilizer nitrogen management in production of arable crops in eastern Canada: A review

“…Use of SPAD measurements to guide in-season fertilizer N management was demonstrated to reduce N losses without loss of corn yield . SPAD meter readings are sensitive to the leaf chosen and the measurement location on the leaf (Hoel 1998) and therefore well-defined sampling protocols are required (Denuit et al 2002). Disadvantages of the SPAD meter include the need for cultivar specific critical values (Minotti et al 1994) and the requirement for considerable manual leaf sampling in order to produce reliable average values.…”

“…Additional applications of fertilizer N are made during the growing season based on crop monitoring results, usually using an optical measurement of crop N status. Such decision support systems have been developed for potatoes and wheat using the SPAD-502 meter (Denuit et al 2002;Olivier et al 2006) and for wheat using basal stem tissue sap nitrate concentration (Justes et al 1997).…”

Using a chlorophyll meter to estimate tea leaf chlorophyll and nitrogen contents

“…Photosynthetic proteins account for more than half of the N in a crop leaf, and crop foliar Chl content is significantly correlated with foliar N content (Evans, 1989). Therefore, the SPAD-502 chlorophyll meter (SPAD) reading should reflect foliar N status (Denuit et al, 2002;Le Bail et al, 2005). The relationship between SPAD readings and foliar Chl or N for other crops has been intensively studied and is known to be affected by plant variety (Hoel, 2002), growing conditions (Campbell et al, 1990), sampling point (Chapman and Barreto, 1997), leaf age (Jinwen et al, 2009), and other factors.…”