Isaac Zipori

Uri Yermiyahu

Arnon Dag

Ran Erel

Alon Ben-Gal

Liu Quan

Zohar Kerem

Background: Intensive olive (Olea europaea L.) orchards are fertilized, mostly with the macronutrients nitrogen (N), phosphorus (P) and potassium (K). The effect of different application levels of these nutrients on olive oil composition and quality was studied over 6 years in a commercial intensively cultivated 'Barnea' olive orchard in Israel.

Results: Oil quality and composition were affected by N, but not P or K availability. Elevated N levels increased free fatty acid content and reduced polyphenol level in the oil. Peroxide value was not affected by N, P or K levels. The relative concentrations of palmitoleic, linoleic and linolenic fatty acids increased with increasing levels of N application, whereas that of oleic acid, the monounsaturated-to-polyunsaturated fatty acid ratio and the oleic-to-linoleic ratio decreased.

Conclusions: These results indicate that intensive olive orchard fertilization should be carried out carefully, especially where N application is concerned, to avoid a decrease in oil quality due to over fertilization. Informed application of macronutrients requires leaf and fruit analyses to establish good agricultural practices, especially in view of the expansion of olive cultivation to new agricultural regions and soils. This article is protected by copyright. All rights reserved.