Nitrogen Fertilization of Olive Orchards under Rainfed Mediterranean Conditions

Aims: This work has the objective of studying the effect of nitrogen fertilization on olive yield, oil content and quality.

Study Design: Randomized complete block design with four nitrogen fertilizer treatments and eight replications. Each individual plot consisted of four trees.

Place and Duration of Study: The experiment was conducted during 2011 in farmers’ fields at three sites: Taza (S1), Taounate (S2) and Taoujdat (S3) in Morocco.

Methodology: Four nitrogen rates (0.00, 0.25, 0.50 and 1.00 kg N per tree) were applied to the varieties Moroccan Picholine (S1 and S2) and Arbequina (S3). Nitrogen was split into two contributions: half in March and half in May. Phosphorus (0.50 kg P2O5 per tree) and potassium (2.00 kg K2O per tree) were applied in March.

Result and Discussion: At S2 (35 years old trees), nitrogen fertilizer improved yield, yield efficiency and olive oil content. At S1 (9 years old trees) and S3 (7 years old trees), nitrogen applications had no effect on the olive yield and negatively affected the olive oil quality in particular in S3.

Conclusion: The effect of nitrogen fertilization on olive yield was dependent of the olive orchard, some trees responded to applied N and others did not. It should be noted that these results are preliminary due to the short duration of the experiment.