Peel thickness requirements vary depending on the citrus type and market needs. Thicker peels provide higher levels of oil extraction and offer a greater resistance against pests and better shelf life. In the fresh fruit market a thicker peel is regarded as being easier to peel, however, excessively thick peel is undesirable. For juice production a thicker peel gives lower relative juice content resulting in lower juice extraction levels. Tailoring your crop nutrition plan will help to manage a desired citrus peel thickness.
Nitrogen and potassium increase peel thickness while phosphorus reduces it. A correct balance of these three major nutrients is essential.
Nitrogen
Increasing amounts of nitrogen can significantly increase peel thickness. These trials show examples of this in both Valencia oranges and Satsumas.
These thicker peeled fruits will have reduced risk of damage in transport and handling and will be at lower risk of disease ingress.
Phosphorus
High rates of phosphorus - as in these trials - can reduce peel thickness. It is important to correctly balance the amount of phosphorus and nitrogen.
Potassium
In similar fashion to nitrogen, high rates of potassium will increase skin thickness - as shown in this trial with mandarins.