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Olive fertilizer: Multi-K increased by 10% the oil content of olives

Olive fertilizer: Multi-K increased by 10% the oil content of olives

| English

The trial, conducted in Turkey, resulted in increased quality of the olives, as well as more pulp and higher oil content

Foliar application of potassium nitrate fertilizer is a well-known and recommended procedure in olive orchards in Turkey, due to low potassium contents in many local soils. In a study carried out by Dikmelik, Puskulku & Altug of the Olive Research Institute at Ege University, Turkey, in 1998, with the important cultivar "Memecik", four foliar sprays were done at 4%.


Two foliar feeding treatments (20 days apart) were done after fruit-set (May); two additional sprays (20 days apart) were done after pit hardening (August). The sprays were done as 4% potassium nitrate at 1,000 L / ha, sometimes combined with urea. These foliar treatments were compared with the local commercial habit of the growers of side dressing with potassium-sulfate (SOP).


Side dressing with SOP

Foliar feeding with potassium nitrate

K contents in the leaves (% in D.M.) in December


0.81 (+ 33%)

K contents in the fruit pulp (% in D. M.) at maturity


1.65 (+6%)

Mean mass of 100 fruit units (g)


278.7 (+28%)

Pulp/pit weight ratio


3.54 (+22%)

Oil content in D. M.


52.9 (+11%)


Olive / Memecik
(widely used for fresh consumption and oil extraction)
Country / location Turkey / Izmir / Olive research institute, Kemalpasa
Objectives Enhance quality of olives, compare K application methods: foliar by Multi-K vs. S.D. by SOP
Haifa product tested Multi-K
Application method Foliar nutrition
Tested treatment 4 x foliar spray @ 4%. Twice (20 days apart) after fruit-set (May) + twice (20 days apart) after pit hardening (August).
1000 lit. /ha
Control treatment results 100 fruit units’ weight: 217.5 g.
Pulp/pit weight ratio: 2.90
Oil content: 47.8% in D.M.
Total yield: 2.47 m3
K content in December (fruit maturity): leaves – 0.61 B; fruit pulp – 1.56
Best treatment results 100 fruit units’ weight: 278.7 g.
Pulp/pit weight ratio: 3.54
Oil content: 52.9% in D.M.
Total yield: 2.14 m3
K content in December (fruit maturity): leaves – 0.81 A; fruit pulp – 1.65
Characteristics of best treatment 28% increase in mean size of fruit.
22% increase in pulp/pit weight ratio.
10% increase in oil content.
All these parameters are closely correlated to K content of the leaves and fruit.
There was a 13% reduction in yield
Conclusions This treatment should be adopted in all olive-growing areas with low soil-K content, in Turkey and elsewhere. Treatments should be continued also during the 2nd expansion period of the fruit, until maturity , in order to increase its oil content.
Reference Dikmelik, Puskulku & Altug. Olive Research Institute, Ege University, Turkey. A presentation made in a Fruit Quality scientific meeting.

Treatments positively affected the fruit size, 100-fruit weight, fresh weight and pulp: pit ratio when compared with the SOP treatment. The oil percentage increase and the quality of the treated olives was highly improved due to increase in size, higher pulp / pit ratio and higher oil content.


Want to learn more about fertilization of olive trees? download our complete guide - "Nutritional recommnedations for olives"

Need more information about growing olives? You can always return to the olive fertilizer & olive crop guide table of contents