Olive fertilization under intensive cultivation management

Demand for olive oil has grown dramatically over the past decades. The accompanying increase in production has been largely due to improvement in horticultural practices by means of intensification. Modern intensive olive orchards are characterized by high yielding cultivars, high tree density, mechanization, and micro-irrigation enabling the application of fertilizers via the water distribution system (fertigation). Recent works have provided deeper insight in macronutrient fertilization and olives. Concerning productivity, P availability positively affects flower quality, fruit set and, consequently, oil production. In the case of nitrogen (N), there is an optimal level, since both low and high levels of N fertilization are associated with diminished productivity. Surprisingly, the effect of potassium (K) availability on productivity is relatively small, partially a result of K substitution by Na at low K levels. In modern olive cultivation, beside yield, oil quality also plays an important role. Increasing exposure to N negatively affects major quality parameters of olive oil, whilst P and K levels have minor effects. Increasing irrigation level augments the demand for nutrients on the one hand and their availability on the other. The elevated irrigation volume was found to enhance K and P uptake while N level was not affected. The quality of the irrigation water also plays a major role in olive nutrition. Recycled wastewater may provide a substantial amount of nutrients required by this crop. In a long-term study in a super-intensive olive orchard irrigated with recycled municipal wastewater without additional fertilization, no nutrient deficit or reduction in yield was found in comparison to trees irrigated with fresh water and standard fertilization (N and K). Furthermore, irrigation with recycled water without adjusting the fertilization regime, led to a substantial increase in environmental contamination with N. In conclusion, fertigation systems in intensive olive orchards allow precise control of the amount and timing of nutrient application. This supplies growers with a tool for obtaining high oil yields of high quality, while minimizing environmental contamination.