Seeking strategies to face climate change, the Ministry of Agriculture, through the Institute of Agricultural Research INIA La Cruz, is evaluating different strategies to address water scarcity through the reduction of evaporation or evapotranspiration in avocado plantations.
A field day was recently organised at Agrícola Pililén, in the heart of the Province of Petorca, and the objective was to learn about techniques in development for the reduction of evaporation and evapotranspiration in avocado trees. These include the use of plastic covers, of mulch plastic on raised beds (Waru Waru) and of subsurface or buried irrigation.
Technical team in charge of the project's execution
This information was shared by Raúl Ferreyra and Alejandro Antúnez, agronomists and specialists in irrigation at the INIA.
The event brought together producers, technicians and professionals from the avocado sector, as well as extension agents of Prodesal del Indap and Technical Assistance Services (SAT).
The action is part of the project "Strategies to reduce the demand for irrigation water for avocado trees as a way to address water scarcity in the province of Petorca", funded by the Agrarian Innovation Fund (FIA) and executed by INIA. It also has the collaboration of Exportadora Cabilfrut and the Association of Farmers of Quillota.
Avocado plantations in Petorca
The techniques that are being studied are the use of plastic covers, of plastic mulch on raised beds (Waru waru) and of subsurface or buried irrigation.
The plastic covers are plastic materials that are raised over the canopy of the trees. The objective of this strategy is to reduce water demand and increase yields. "These covers are intended to change the micrometeorological conditions that affect the crop, with a reduction in the amount of radiation and wind and an increase in minimum temperatures and relative humidity," explained INIA researcher Raúl Ferreyra.
Avocado production under plastic covers
Inside the greenhouse, the temperature increases by between 1 and 2 °C, the relative humidity also increases and the vapour pressure deficit falls.
As for the second technique, covering raised beds with plastic mulch directly protects the area irrigated by the dripper. Raúl Ferreyra explains that this "prevents the direct evaporation of the water, which helps in preserving soil moisture and improving the availability of water for the plant." Furthermore, the use of mulch facilitates the control of weeds and the growth of superficial roots.
Use of plastic mulch on raised bed
The use of subsurface or buried irrigation consists in the installation of an irrigation line, with the dripper discharging directly into the soil. This allows the soil surface to remain dry, with the water moving by capillarity directly below it. This has advantages over traditional or superficial dripping. "With this strategy, we are studying the extent to which evaporation is reduced, while also monitoring the moisture deep in the soil and the plant's water potential." Its impact on the commercial yield and the orchard's phenology, as well as on the development of diseases and the fruit's post-harvest conditions are also subjects of study.
In Chile, there are about 28 thousand hectares devoted to avocados. It is the most important fruit, with about 58% of the acreage nationwide.
The incorporation of these technologies is intended to respond to the challenges that Chilean producers face in order to tackle the impact of climate change.
Avocado trees are perennial. They consume water all year round and require a volume that fluctuates between 7,000 and 16,000 cubic metres per hectare per year.