Fertilizer recommendations for olive based upon nutrients removed in crop and pruning

The above-ground part of fourteen, young (ten-year-old), rainfed olive trees were separated into trunk (wood and bark), main branches (wood and bark), secondary branches (wood and bark), twigs, leaves and fruits. Based on the dry matter and nutrient concentration in the different tissues, the total amounts of nutrients in each tree were estimated. A controlled scheme of pruning conducted annually allowed the quantification of the amount of nutrients removed in pruning. Olive yields and nutrient concentrations in the fruits (pulp and pit) were used to quantify the nutrients removed in the crop. The results showed that the amounts of nutrients annually removed were relatively low, suggesting that more conservative fertilizer applications could be made than those usually recommended by the laboratories of soil testing and plant analysis. In this orchard, with a yield goal of 2500 kg fruit ha−1, the nitrogen (N) rate to apply as fertilizer should not exceed 20 kg N ha−1 year−1. The transient nature of N in the soil/plant systems recommends that N be applied every year to increase the nutrient-use efficiency. The application of other nutrients as fertilizer should be diagnosed beforehand by soil testing and/or plant analysis. Nutrients removed by crop and pruning do not provide all the information on the need for supplemental fertilizer applications. Soil testing and plant analysis should be used routinely for a continuous adjustment of the fertilizer program.

► The nutrient concentrations in the different olive tree components are shown.
► The total amount of nutrients in a whole olive tree is shown.
► Nutrients removed in pruning wood and in crop are used to estimate fertilizer rates.
► Guidelines for fertilizers recommendations are provided.