CONICET | Buscador de Institutos y Recursos Humanos

The diagnosis of tree nutritional status in fruit trees by leaf-nutrient analysis allows for fertilization scheduling by fertirrigation. In olive, a specific equilibrium in leaf nutrient concentration occurs that depends on the dominant edaphic and climatic conditions as well as the time of year. Therefore, the objective of this study was to determine leaf-nutrient reference values in olive in an arid region of Central-western Argentina at two different times of the year. Leaf samples were taken during the winter rest period (July) and summer (January; a month after pit hardening) over three consecutive years in 100 commercial olive orchards (i.e., lots) of various cultivars in the Tulum Valley of San Juan. Leaf nutrient contents were analyzed and the obtained values were compared with those reported for the Mediterranean Basin. Mean values of nitrogen (N), phosphorus (P) and potassium (K) in the winter were 1.78%, 0.15%, and 0.95%; respectively, while summer values were 1.63% (N), 0.17% (P), and 1.20% (K). The average N values were somewhat lower than those reported for the Mediterranean Basin with P and K values in contrast being similar or greater. Average values of the remaining nutrients (Ca, Mg, Mn, Na, Cu, Zn, B and Fe) were generally similar to those reported for the Mediterranean. However, boron levels were exceptionally high in the winter (25.38 ppm), and magnesium (0.13%) and manganese (33.04 ppm) were notably low in the summer. Considering that in the centre-west of Argentine leaf N and K are limiting nutrients and that reference values obtained in the winter rest period presented greater analytic stability, it is possible to suggest that use of regional reference values taken in rest period is adequate for scheduling fertirrigation programs in intensively-managed olive orchards.

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