Sam Freeman notes that; Irrigation is much more important than nutrition for Olive trees. Olive trees are not big feeders. Nitrogen (N) and (K) Potassium deficiency are the only common issues. Other nutritional issues occured very rarely.
Pre Harvest - Oil Accumulation.
As we head through this period, from late March into April, Olives accumulate oil and ripen.
Oil olives are just beginning to change colour.
During this phase it is important to maintain adequate calcium levels within the fruit. Calcium is important for cell development and skin strength. Much of the McLaren Vale region has subsoils high in calicum (eg. Limestone) however orchards on heavy, black soil or the light sands of Mt Compass are likely to be low in Calcium.
The use of Calcium Nitrate at this stage will greatly improve fruit set and development, as cell expansion rates increase within the fruit.
Post Harvest - Building up carbohydrate.
After harvest, applications of nitrogen are important to assist in the uptake of carbohydrates, which are used in spring to push early seasons growth.
Carbohydrate accumulation is vital to Olives. Generally post-harvest applications of nitrogen in the form of soluble urea (Liquifert N) (20-50 Kg/Ha), or liquid urea (Easy N) (20-40 L/Ha), can be applied.
On heavy black soil, or light sand where higher amounts of calcium are still required, then further additions of Calcium Nitrate can be applied (60-90 Kg/Ha).
Many growers also opt to use Potassium Nitrate (60-90 Kg/Ha) as a form of post harvest Nitrogen.