Study of the nutritional dynamic in olive leaves: periods of analytical stability
The aim of this study was to establish the evolution curves of macro- and micro-nutrients in olive leaves and the periods of time in which they are statistically stable and can be considered suitable for a nutritional diagnosis. The study was carried out in two farms of the province of Jaén (Andalucia, Southern Spain), with olive trees of the Picual variety, under an irrigation regime and no nutritional deficiencies over the entire year. The evolution curves of each nutrient had great similarities when comparing between farms and between periods. Only in some periods the farm “Poco Humo” had higher concentrations, probably due to the most favorable edaphic characteristics of this farm. Nitrogen and phosphorus showed minimum concentrations when the leaves were young and when they were one year old, and maximum concentrations during the winter. Potassium and boron showed higher concentrations when the leaves were young, and the concentrations decreased throughout the first year of life. Concentrations of calcium, magnesium and manganese had the opposite behavior: these accumulated in leaf until reaching maximum values in winter and then remained stable, with some oscillations but without statistically significant differences. No changes were observed in the zinc concentrations in the sampled periods. Periods of at least two consecutive months without statistically significant differences were found during the winter period for all elements except nitrogen. Analytical stability was observed from the second fortnight of May till the first fortnight of August for all elements except phosphorus and boron.