This investigation was carried out on fifteen years old Sorani and Kaissy olive cultivars (Oleaeuropaea L.) trees grown in Basaltic soil that was poor in organic matter and potassium. The aim of the present investigation is to study the effect of different amount of organic and potassium fertilization on yield, fruit weight, oil percentage, and oil acidity. Results obtained showed that the highest value of fruit weight, yield, and oil precentage exhibited statistically the highest values by trees fertilized with the treatments (Organic + Potassium). Acidity increased in (Organic + Potassium) treatments but it was less than 2% oleic acid , while it was less than 1% oleic acid in Potassium treatments and in Organic treatments (Extra vergin oil).