*3.2.2 Phosphorus*

Phosphorus did not have a significant impact on the Olive tree productivity and quality at the three test sites (**Tables 10** and **11**). These results confirm previous research that suggested that regular phosphorus intakes may not be necessary [13, 26, 27] and that phosphorus is not generally recommended in rain-fed olive orchards [23].


**Table 10.** *Phosphorus effect on olive yield.*


#### **Table 11.**

*Phosphorus effect on olive oil content and quality.*

## *3.2.3 Potassium*

The effect of potassium on yield and yield efficiency appears only at S3 (**Table 12**), but it did not affect either olive oil content or quality (**Table 13**). The non-response of olive trees to potassium input at S1 and S2 could be due to soil potassium richness in these orchards. This response of the olive tree to potassium supply at S3 may be due to the relatively low soil potassium content in comparison with S1 and S2 if we refer to the soil clay content which made potassium unavailable for the crop. An input of 0.5 Kg K2O.tree−1.year−1 was, therefore, necessary and sufficient to improve olive yield at this site. While in Spain, Garcia [11] recommended 1 to 2 Kg K2O.tree−1 based on olive tree's exports of potassium.


#### **Table 12.**

*Potassium effect on olive yield.*


#### **Table 13.**

*Potassium effect on olive oil content and quality.*

*Management of Olive Tree Fertilization in Morocco DOI: http://dx.doi.org/10.5772/intechopen.104644*
