Study of Nutrient Status in Olive Orchards of Qazvin Province using Nutritional Indices

Olive is one of the most important agricultural products in Qazvin Province, which has the second highest production in Iran. However, unbalanced fertilization is the main reason for disruption and disturbance in the nutritional balance and low yield in olive orchards. Increasing the yield is possible if there is a balance between the nutrients in the plant. In order to optimize the use of fertilizers and to diagnose nutritional disorders, the use of nutritional indices seems to be necessary. This study was conducted in 80 olive orchards in Tarom city in Qazvin province (Iran) for three years. Soil and leaf samples were taken and analyzed as the standard method. In September, harvesting was performed and yield was measured. Then, the nutrient indices for the orchards were determined by Compositional Nutrient Diagnosis (CND) and Deviation from Optimum Percentage (DOP) diagnosis methods. Based on the average calculated yields by both methods, the studied orchards were classified into two groups of high and low yields. The average optimum concentration of nutrients (reference numbers) for nitrogen, phosphorus, potassium, calcium, magnesium, manganese, zinc, copper, and boron was obtained by both methods and the results of the DOP and CND indices were compared. The DOP and CND indices showed a deficiency of Mg, N, and Ca in most of the studied orchards. Generally, according to the studied indices, all orchards with low relative yield were in unbalanced conditions in terms of nutritional elements.