The Effect of Different Potassium Fertilizer on Yield and Oil Content of Olive (Olea europaea cv. Ayvalık)

Abstract

Olive, its fruits as well as its oil is an important crop / food in the agriculture of Turkey. It is very well known that the impact of a balanced fertilization on the quality of fruits is very great.Olive soils and leaves should be  analyzed at recommended times of the year for a proper fertilization. In this regard, the effect of potassium (K) fertilizer can not be denied. Therefore, the objective of this current study was to examine the effect of different K fertilizers/treatments (KNO_3,  K₂SO₄ ve KNO₃+K₂SO₄), on yield (kg/tree), NPK uptake by the fruits of Ayvalık olive variety and its oil %.  A field experiment was conducted in a 35 year old Ayvalık olive plantation of Olive Research Institute in Bornova-Izmir- Turkey during the years 2016 and 2017. The experiment was designed in randomized blocks with 4 replications and 3 trees per replication. After soil and leaf analysis, fertilizers were applied via fertigation from April to September. Following harvest, oil (%) and oil /tree (kg) were assessed. Results showed that the examined parameters significantly (5%) change with respect to different K fertilizers /treatments as well as with respect to years.  However, no significant relations were found between leaf K contents and the different K fertilizers. On the other hand, the available K in the soil under the trees  increased after a well organized fertilizer application / fertigation. In this regard, leaf and fruit K contents varied with respect to years. Yield per tree was always high in all of the treatments compared to the control parcel.  In the case of oil yield per tree and oil % , results indicated the significant effect of K₂SO₄ in the first year and KNO₃ in the second year. It can be concluded that olive yield and oil content increase after a balanced and well organized fertilization.