Improving Olive Tree Fertilization in Morocco

Between 2014 and 2015, IPNI participated in a study that evaluated the fertilization of 36 olive orchards in Morocco, in the Marrakesh and the Essaouira provinces. Analysis of tree leaf tissue showed that approximately 70% of the trees were deficient in N (Nitrogen), 90% of irrigated trees and all rainfed trees were deficient in K (Potassium), and all trees were deficient in P (Phosphorus).

In each orchard, IPNI compared local farming practices with two fertilization practices: replacing the N, P and K removed by the harvested crop each year; and fertilization based on analysing the leaf nutrient concentration.

The application of both methods led to a large increase in olive fruit yield, over any farmer practice: in rainfed orchards, olive fruit yields were improved by 58% through the crop removal method, and by 36% through the leaf analysis-based method. In irrigated orchards, fruit yields were increased by 22% in 2014 and 30% through the leaf-analysis method.

In addition, the olive oil content of the orchards was increased by 16% for irrigated orchards and 6% for rainfed orchards by following best fertilizer management practices.


Olive Fruit Yields from irrigated (left chart) and rainfed (right chart) orchards receiving fertilizer based on current farmer practice or improved nutrient recommendations. The large yield increase measured in rainfed orchards in 2015 was due to additional rainfall and the alternate year-bearing nature of olive trees.

This evaluation demonstrated how improved fertilization practices can enhance the production of olive fruit and oil. Simple fertilizer practices, such as applying fertilizer based on how much fruit was harvested in the previous year, can significantly boost yields and farmers’ incomes in Morocco.

Read more about the project here.