Chile’s Sustainable Avocados: Managing Salinity While Saving Water

Despite solid growth in consumption, in recent years the humble avocado got plenty of bad press. In many ways it became the go-to example for those pointing fingers at agricultural production. Chilean growers in particular have seen this issue up close, leading them to promote greater efficiency with innovative water treatment solutions like AQUA4D®.

In landmark projects overseen by scientists and supervisors from Santiago’s INACAP, these deployments of this water saving & salinity management technology have now shown the way forward for sustainable avocado cultivation.

Combatting drought and salts – simultaneously

Over the years, repeated application of water with high salt content leads to a dangerous build-up in the soil. However, it’s often difficult for growers to switch to another source, or prohibitively costly to remove the salts (for example, with reverse osmosis). On top of this, the solution has previously been to “wash” the soils – using even more water.

Therein lies the ingenuity of AQUA4D®: it enables continued irrigation with poor quality water, avoids intensive soil washing, and means growers do not need to find alternative water sources or use precious potable water. At the same time, this transformed water penetrates better into the soil – meaning less water needs to be applied while maintaining production.

Given the track record of this clean technology around the world, expectations were high for its impact on avocado crops; the results surpassed even the most optimistic projections.

Measurements and water management

AQUA4D® systems were installed at 9 locations in various regions. All possible variables were monitored, including measuring electroconductivity, soil moisture, sap flow, and leaf water potential, as well as NDVI data via drone.

The combined measurements all pointed to stunning increases in water efficiency and salinity management, with huge payoffs for plant health, fruit quality and much more.

Result: Increased soil moisture -> reduced water use

Soil probes at the project sites allowed research teams to track progress and compare side-by-side plots in real time. At a large grower in Santo Domingo (Valparaíso Region), the difference was clear – especially in the crucial warmer months.

“With the same water, same soil, the water was behaving differently and having a different effect when it reached the soil,” said Constanza Osorio, AQUA4D agronomist overseeing the projects. “But it’s all about managing these changes: measuring and changing.”  This is an illustration of the AQUA4D ‘Technology as a Service’ (TaaS) approach, where monitoring and consultation leads to tangible changes in irrigation cycles.

At Agricola Ríos in Quillota, for example, such water management alterations have led to significant savings: 25% less water was applied for each irrigation, equating to 384 m3/ha, or 1.5 months of irrigation.“We were obliged to implement changes in the irrigation frequency and amount, as the soils were still moist,” noted Enrique Rebaza, who oversaw the project.  A decision was made to reduce irrigation times from 8 hours to 6 hours. Considering the size of the site and the water normally required, this represents significant weekly, monthly, and seasonal water savings.

The grower, Alfonso Ríos, has since expanded the implementation of AQUA4D®. “With AQUA4D® we have been able to see, through different measuring instruments, that we can retain moisture longer in the soil and reach deeper with each irrigation,” explained Ríos. “Even with very tight irrigation for the industry (no more than 6,000 m3/ha/year), we can now reduce irrigation times significantly, with respective savings in operational costs and business sustainability.”

Result: Movement of salts below the rhizosphere

Various past AQUA4D projects in Peru, Palestine, California, and more proved the technology’s ability to allow continued irrigation with saline water. This means growers can continue using the same – often poor-quality – water supply, as the treatment reduces the salinity and EC levels to acceptable amounts.

This has now been the case in Chile, where a grower in Coquimbo has been able to continue irrigating without causing the build-up of salts in the soil – they are leached further down out of harm’s way.

Soil probes detected a displacement of salts, with soil electroconductivity increasing at each depth – consistent with leaching of salts. At the same time, soil moisture was hugely improved, resulting in a decision to reduce irrigation times by 33%.

This data was backed up by laboratory analysis of foliar samples from the Santo Domingo site, comparing the quantities of chlorine and sodium in the leaves of untreated vs treated trees. Between April and May, chlorine levels showed a reduction of 21% with sodium dropping by 50% over the same period:

Marco Vicencio, avocado advisor from GVCAgro, is excited at the possibilities this technology can offer growers in Chile. “With AQUA4D we’ve been able to use brackish water (EC > 4 dS/m) to irrigate avocado trees here (Pan de Azucar, La Serena). No one imagined this could be possible with not much water and healthy trees,” he said. “We can now see how with this technology it’s possible to produce avocados despite the very adverse conditions. The trees are growing really well, something that in the past wasn’t possible. The region is looking for more diversification and profitable crops, something that now with technology is possible to do.”

Result: Less stressed trees and improved health

The effect on overall tree health referred to by Vicencio was noted across the projects. Foliar analysis, plant sensor readings, and satellite imagery backed up what the growers were seeing with the naked eye – the AQUA4D® trees were healthier and more abundant.

The trees were less stressed and more stable, with better recovery between irrigations. This can be partly explained by the increased water availability – the roots are no longer fighting for water, so are less stressed.

“The sap flow sensors showed how in the sector treated with AQUA4D® there is less stress and more tree growth,” verified 2Grow’s Olivier Begerem, who was closely following the project. “Overall, it is very obvious that the treated plants are less stressed compared to the untreated plants due to more availability of water. This should certainly be a big advantage in very dry and sunny climates.”

This plant-level analysis was backed up by NDVI satellite imagery, comparing untreated “NT”) to treated (“TT”). As is clear from the image above, the treated trees showed both more moisture and more vigor.

Ultimately, this would all have clear effects on the fruits when harvest time arrived: “It seems the non-treated trees had more issues carrying their fruits and maintaining themselves,” added Begerem. “We expect the treated trees to have more fruits as they are more able to grow.”

Conclusion: Doing more with less

Ultimately, AQUA4D® water treatment has allowed these avocado growers to achieve the seemingly impossible: better output from less input. What’s more, with poor quality water able to be used for irrigation, the better-quality potable water is available instead for human consumption.

With salts now causing no more damage, water saved, and healthier trees, the first AQUA4D® avocado projects in Chile have been a resounding success. As increasing numbers of growers start using this innovative Precision Irrigation, the sustainability and profitability of this important Chilean industry is assured – along with boosts to food security and a more regenerative approach to agriculture.

-> For detailed agronomical reports on these projects, contact jose.gillet@istgroup.cl, and check the latest news at www.aqua4d.com

AQUA4D installation at Agrícola Ríos, Quillota (Chile) 

Measurement of avocados by AQUA4D agronomists