For more than 12 years, we have collaborated with the Polytechnic University of Madrid in agronomic trials in our olive groves, studying various aspects of crop management. During this time, many students and researchers from various backgrounds have passed through our farm, and have carried out end-of-career projects, master’s degree work and even doctoral theses. The latest one has been Antonio Hueso’s Doctoral Thesis, which has focused on irrigation management in hedgerow olive grove seeking the optimization of this fundamental resource.
The study covers five complete campaigns, in which they have established a method to know about the hydration status of olive trees according to different irrigation water inputs. To do this, they have worked with the measurement of the stem water potential, measuring it with a pressure chamber.
The thesis approach is very interesting, because the focus is on reducing the amount of water provided to the olive grove, avoiding a decrease of the production quantity and quality of the resulting oil. To this end, they have considered the different key moments throughout the olive tree cycle from a physiological point of view, analyzing separately two critical periods: spring (where sprouting, flowering and early stages of olive tree development take place) and autumn (when oil is formed inside the fruit).
The experimental part covered different groups of olive trees according to the amount of irrigation water they received, analyzing several olive groves. In this way, they sought to compare the effects on the olive grove by providing the entire established irrigation dose or different doses by reducing the doses percentage (as an example, for one of the spring trials they studied the differences between providing 100% of the irrigation dose, 50%, 25% and 0%). The parameters they analyzed were the water potential of the stem, growth, flowering, fruiting, water productivity, characteristics and production of olives and oil.
The results, widely described in the full document, are very revealing. We are clearly suggested to decrease irrigation during the hardening stage of the bone and also in the autumn, since the amount of oil in the olive (% fresh weight) was the least sensitive parameter.
In short, it is a magnificent work that manages to bring knowledge and tools to the sector to be more efficient in the use of water. This thesis demonstrates that deficit irrigation is the best way forward in rational and sustainable olive grove management.