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

This study was initiated in 2013 in the Tensift-Al-Haouz region of Morocco. The objective is to assess the effect of improved methods for nutrients recommendations in olive orchards. Two on-farm experimental sites were selected with olive orchards in irrigated and rainfed areas of the provinces of Marrakech and Essaouira, respectively. The planting density was 204 and 25 trees/ha at irrigated and rainfed sites, respectively. At each site, four treatments included: a zero fertilizer control, farmer practice (FP), fertilization based on nutrient removal, and fertilization based on foliar analysis. In the irrigated area, applied fertilizers under FP were 0.66 kg N/tree, foliar analysis (0.7 kg N+0.3 kg P₂O₅ + 0.7 kg K₂O)/tree, and nutrient removal (0.80 kg N + 0.40 kg P₂O₅ + 0.85 kg K₂O)/tree. In the rainfed area, no additional fertilizers are applied by farmer, foliar analysis recommended (0.48 kg N + 0.40 kg P₂O₅ + 0.50 K₂O kg)/tree, and the nutrient removal-based treatment was (0.70 kg N + 0.40 kg P₂O₅ + 0.90 kg K₂O)/tree.

Under irrigation, fertilization based on NPK increased fruit yields and olive oil content compared to the zero fertilizer control. The highest fruit yields were obtained by the nutrient removal and foliar analysis treatments, respectively, which were 8.4 t/ha and 6.8 t/ha - slightly higher than yield under FP (6.5 t/ha). Yield without fertilization, averaged 3.0 t/ha, which is 50% less than the highest fruit yield obtained. In terms of oil content, no significant difference was observed between the foliar analysis and removal nutrient treatments; however, fertilization based on the two methods significantly increased olive oil content compared to FP and the control. Hence the average olive oil content based on dry matter was 42%, 40%, 38%, and 36% under the nutrient removal method, foliar analysis method, control, and FP treatments, respectively. The rainfed site showed the same trends, as the application of fertilization significantly increased fruit yield. No significant difference was observed between the control and FP, which had an average fruit yield of 1.2 t/ha. Application of NPK fertilization more than doubled fruit yield, reaching an average yield of 2.6 and 2.9 t/ha under the foliar analysis and removal methods, respectively. The olive oil content analysis for fruit obtained from the rainfed site is still in progress.