San Diego avocado growers turn to experts at Cooperative Extension to manage water costs

San Diego County was once home to nearly 10,000 acres of avocado trees, but today there are about 14,000. lawyers, namely the cost of water.

On September 28, avocado growers gathered at the offices of the San Diego County Agricultural Bureau for an avocado irrigation workshop led by Irrigation and Water Management Consultant Ali Montazar. University of California water supply for Imperial, Riverside and San Diego counties.

“All the information we are developing right now is focused on [irrigation] efficiency. Growers want to know how much water they need and what tools they need to use to be more efficient,” Montazar explained.

Ground view of a surface renewal and eddy covariance evapotranspiration station in an experimental avocado orchard in Escondido. Photo by Ali Montazar.

Workshop participant John Burr, who has grown avocado trees for 15 years, confirmed that irrigation accounts for more than half of his annual production costs and meeting the needs of his trees is a constant challenge.

“The sophisticated avocado irrigation research conducted by Dr. Ali Montazar is the first of its kind that the University of California has conducted specifically on avocados. learn more about the technology it uses - from soil moisture sensors to the California Irrigation Management Information System level equipped station.

Burr hopes Montazar's research will help avocado growers accurately determine evapotranspiration in an avocado plantation or water use specific to avocados, critical components of how growers select tools to determine irrigation times.

“His presentation which showed the results of his research on the Kc (harvest coefficient) of avocado, although very early in his project, was really interesting. This indicates the possibility that we need to vary the Kc at different times of the growing season, but it is just beginning a two to three year project that will hopefully provide solid data on what is the Kc for lawyers,” Burr said.

The uncertainty of the Colorado River hovers

San Diego's avocado production is mostly handled by small farms. According to Montazar, this adds a level of complexity to water management, as there is more emphasis on user-friendliness and cost-effectiveness of irrigation tools and strategies.

"We don't know the future," Montazar said. “But we have to be prepared for all the consequences. The Colorado River is experiencing a significant water shortage, which could impact San Diego County's water supply source from the transfer of the Imperial Irrigation District in the future. It is wise to consider improving irrigation efficiency as the most viable tool for managing limited water supplies in Southern California. »

Water has always been a problem. In the 1970s, California's water program paved the way for an additional 98,000 acres of farmland.

According to a 1970 study analyzing the cost of producing avocados in San Diego County, water costs "averaged 3.5 acre-feet per acre at $60 per acre. acre-foot", which was based on the assumption that water costs would remain relatively low and affordable for a long time.

Unfortunately, this is no longer the case. San Diego County gets the majority of its water from the Colorado River, which is concerning given five-year projections that the river will reach extremely low reservoir levels by 2027.

In fact, starting in 2023, the San Diego County Water Authority will increase water rates, encouraging growers to invest in more efficient irrigation practices (Table 1).

Table 1. Cost of raw and treated water in San Diego County in 2022 and 2023.