Best Management Practice of Nutrient of Olive Orchards in Rainfed and Irrigated Areas of Morocco

This experiment started in 2014 with the objective to assess the effect of improved methods for nutrient recommendations for olive orchards in Morocco. Two on-farm experimental sites were selected, with olive orchards in irrigated and rain-fed areas of Marrakech and Essaouira provinces. The planting density was 204 and 25 trees/ha at irrigated and rain-fed sites, respectively. At each site, four treatments were used: without additional fertilization (control), farmer's fertilizer practice (FFP), fertilization based on nutrient removal, and fertilization based on foliar analysis. In the irrigated area, 0.66 kg N/tree was applied in the FFP, 0.46 kg N + 0.15 kg P₂O₅ + 0.36 kg K₂O/tree applied in the foliar analysis treatment, and 0.51 kg N + 0.20 kg P₂O₅ + 0.43 kg K₂O/tree applied in the nutrient removal treatment for the two olive varieties, Haouzia and Menara. In the rain-fed area, the applied fertilizers were: FFP, where no additional fertilizers were applied by the farmer, 0.23 kg N + 0.23 kg P₂O₅ + 0.50 K₂O kg/tree in the foliar analysis treatment, and 0.33 kg N + 0.22 kg P₂O₅ + 0.45 kg K₂O/tree in the nutrient removal treatment.

In 2016, the olive yields were very low due to the alternate bearing of olive orchards. In the irrigated area, there was no significant difference in the olive yield between foliar analysis and nutrient removal treatments. The average olive yield for both treatments was 10.6 kg/tree for the Menara variety and 4.3 kg/tree for the Haouzia variety. The yield was significantly higher by 3 kg/tree and 1 kg/tree than FFP for Menara and Haouzia varieties, respectively, and 4 kg/tree and 1.5 kg/tree higher than the control for the Menara and Haouzia varieties, respectively. In the rain-fed areas, the highest olive yields per tree were obtained when the fertilization program was based on the foliar analysis method. The average olive yield of 8.9 kg/tree, achieved through fertilization based on foliar analysis, was significantly higher by 1.7 kg/tree, 4.8 kg/tree, and 4.5 kg/tree than the olive yields obtained with fertilization based on nutrient removal method, FFP and the control, respectively. In terms of olive oil content, no significant difference was observed between foliar analysis and nutrient removal method of fertilization in the irrigated olive orchards (average of 9.3% industrial olive oil yield), but was significantly higher compared to olive oil yield obtained by FFP (7%) and the control (6.8%). However, the average industrial olive oil content (8%) in the rain-fed area was similar for all treatments.