Posts Tagged: water management

San Diego avocado growers look to Cooperative Extension experts to manage water costs

San Diego County used to be home to nearly 25,000 acres of avocado trees but today there are about 14,000. The drastic decrease is largely due to rising costs associated with avocado production, namely the cost of water.

On September 28, avocado growers gathered at the San Diego County Farm Bureau offices for an Avocado Irrigation Workshop facilitated by Ali Montazar, University of California Cooperative Extension irrigation and water management advisor for Imperial, Riverside and San Diego counties.

“All of our information being developed right now is focused on [irrigation] efficiency. Growers want to know how much water they need and what tools they should use to be more efficient,” explained Montazar.

Workshop attendee John Burr, who has been growing avocados for 15 years, confirmed that irrigation represents over half of his annual production costs and that meeting the needs of his trees is a constant challenge. 

“The sophisticated research in avocado irrigation that Dr. Ali Montazar is conducting is the first of its kind that the University of California has carried out specifically in avocados. His presentation allowed us attendees the opportunity to see and learn about the technology he is employing – from soil moisture sensors to the California Irrigation Management Information System level equipped station.”

Burr is hopeful that Montazar's research will help avocado growers accurately determine the evapotranspiration in an avocado grove or water use specific to avocados, critical parts of how growers select tools to determine irrigation runtimes.

“His presentation that showed his research finding of the avocado Kc (crop coefficient), while very early into his project, was really interesting. It indicates the possibility that we may need to vary the Kc for different times in the growing season, but he is just beginning a two-to-three-year project that will hopefully deliver solid data on what the Kc for avocados is,” said Burr.

Colorado River uncertainty looms

San Diego's avocado production is primarily managed by small farms. According to Montazar, this adds a level of complexity to water management because there is a greater emphasis on irrigation tools and strategies being user-friendly and cost-efficient.

“We don't know the future,” said Montazar. “But we need to be prepared for all consequences. The Colorado River is experiencing a significant water shortage, and this could impact the water supply source for San Diego County from the Imperial Irrigation District Transfer in the future. It is wise to consider enhancing irrigation efficiency as the most viable tool to manage limited water supplies in Southern California.”

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

According to a 1970 study analyzing the cost of avocado production in San Diego County, water costs “averaged 3½ acre feet per acre at $60 an acre foot,” which came with the assumption that water costs would remain relatively low and affordable for a long time.

Unfortunately, that is no longer the case. The county of San Diego gets the majority of its water from the Colorado River, which is concerning given five-year projections of the river reaching critically low reservoir levels by 2027.

In fact, beginning in 2023, the San Diego County Water Authority will be raising the rates for water, prompting growers to invest in more efficient irrigation practices (Table 1).

Table 1. Cost for untreated and treated water in San Diego County in 2022 and 2023.

NOTE: An acre-foot is about 325,900 gallons of water.

Training growers on irrigation a top priority

There are no loopholes or short cuts when it comes to irrigation because irrigation is the key to tree health. Ben Faber, Cooperative Extension subtropical crops advisor for Ventura and Santa Barbara counties, points out that tree health is how growers stay in business.

“You can mess up your fertilization program, and you can mess up your pesticide program, but if you mess up your irrigation program, you're out of business,” he said.

According to Faber, efficient irrigation requires a strong grasp on salt management.

 “We import water that has a lot of salt in it. So, you've got to figure out how to put the right amount of water on the root zone without causing root health problems,” said Faber.

This process requires meticulous care, as anything that gets below the root zone can cause groundwater contamination – something growers do not want to be responsible for.

While the latest irrigation technology, such as smart controllers, could help growers, Faber said that training and educating farm managers should be the priority. 

As Faber puts it, managing irrigation should be “like brushing your teeth” – something that growers do naturally and competently. Many growers are over-irrigating or wasting time trying to resuscitate dying trees. It's important to learn the needs of the tree and, in some cases, it might be best to stop watering all together.

The first step to water efficiency is acquiring knowledge and identifying needs. Because an over-irrigated tree looks just like an under-irrigated tree, it's crucial that growers learn to recognize the difference and plan accordingly.

This is where Cooperative Extension advisors and researchers come in. Opportunities like the Avocado Irrigation Workshop are ideal for growers looking for answers or support.

For more information and to learn about future workshops in San Diego County, visit https://cesandiego.ucanr.edu/.

 

Drip-irrigation study sees ‘huge’ reduction in water, fertilizer use for sweet corn

Study by UCCE advisor in Imperial County also shows 5% increase in yield

A new study suggests that drip irrigation for sweet corn can significantly conserve water, reduce fertilizer use and boost crop yield in the low desert of California – and likely in other areas of California with similar conditions.

Although Imperial County is California's top sweet corn-producing county, with about 8,000 acres planted on average each year, irrigation methods for this crop have been rarely studied in this region (or anywhere else in the state), according to Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial, Riverside and San Diego counties.

Montazar conducted a study in the Imperial Valley over two crop seasons, 2020-21 and 2021-22, to demonstrate and quantify the potential benefits of switching to drip irrigation from the more common furrow irrigation method. The study, available in a recent issue of UC Agriculture and Natural Resources' Agricultural Briefs, will be published in a future issue of Vegetables West.

“I'm hoping with this project we can encourage growers to adopt it, because it seems very promising,” said Montazar, noting that drip irrigation is a “new practice” for sweet corn in California.

Among the 11 commercial sweet corn fields in the study over the 2021-22 season, the six that were under drip irrigation used, on average, 37% less water than the five under furrow irrigation. In absolute terms, the drip-irrigated fields saw an average water savings of 2.2 acre-feet per acre; for Montazar, who has studied drip for a variety of crops in the Imperial Valley, that was an astonishing result.

“I've worked with drip on processed onions, lettuce, alfalfa, spinach … we've never seen a figure like 2.2 acre-feet per acre, that's huge,” he said, attributing the dramatic drop-off to the high volume of water required to furrow-irrigate the sandy soil in the Imperial Valley.

More efficient irrigation also means less fertilizer is needed – a boon to the environment and Salton Sea water quality, as well as growers' bottom line. With fertilizer prices continuing to rise, sweet corn growers using drip could see a substantial 25% cost savings on fertilizer expenses – about $150 per acre less – compared to furrow irrigation, according to Montazar's study.

And by relieving plants of the stress from over- and under-irrigated conditions, drip irrigation helps keep soil moisture at its “sweet spot” – resulting in a 5% increase in marketable crop yield for sweet corn in the study.

“When we have a better, more efficient irrigation system, we can maintain soil moisture at a desired level, over time and space,” Montazar explained.

Because the benefits of drip appear to be linked to soil conditions (sandy loam, and other light soils), Montazar believes that this irrigation practice could deliver relatively similar water and fertilizer savings and improved crop yield in other regions across California, regardless of climactic differences.

“If you use drip in any part of the state, you have the benefits of drip – more uniform water application, more uniform fertilizer – that's not related to the desert,” he said. “That's part of the system's potential.”

Montazar plans to follow up on his preliminary study with additional research on sweet corn and drip irrigation during the 2022-23 crop season.

Avocado growers to get irrigation tools, strategies from UC ANR’s Montazar

CDFA grant supports research to optimize water use for iconic California crop

California growers, who account for more than 90% of avocado production in the U.S., will soon be getting some help in weathering the extreme fluctuations of climate change.

Ali Montazar, a University of California Cooperative Extension irrigation and water management advisor, recently received a grant to develop tools and strategies that optimize growers' irrigation practices across Southern California – the state's avocado belt. California avocados are valued at more than $411 million, according to the National Agricultural Statistics Service.

“This region faces uncertain water supplies, mandatory reductions of water use, and the rising cost of water – while efficient use of irrigation water is one of the highest conservation priorities,” Montazar said. “Water is the most critically important input to avocado production.”

Montazar will be conducting field experiments in six commercial fields of Hass avocados, located in San Diego, Riverside and Orange counties, in collaboration with the California Avocado Commission and supported by a California Department of Food and Agriculture Specialty Crop Block Grant.

At the California Avocado Commission's suggestion, Orange County was added to the study to better capture the range of climates and cropping systems across the region, Montazar said.

He hopes to develop “crop coefficients” that avocado growers can use to determine the optimal irrigation for their crop based on a host of factors: soil type and salinity, canopy features, row orientation, slopes, soil and water management practices, and more.

“Growers are unclear on how much water the crop actually needs under those conditions,” Montazar said.

He will incorporate data from the actual water use in the experimental orchards – including information from the newest soil moisture and canopy temperature sensors – to help ensure growers do not under- or overwater their crops. Overirrigating contributes to a devastating disease, avocado root rot, caused by the plant pathogen Phytophthora cinnamomi.

Another component of the grant supports outreach in disseminating these resources and best practices to the broader agricultural community.

“Developing and adopting these tools and information may have a significant impact on water quality and quantity issues and bolster the economic sustainability of avocado production not only in the well-established production region of Southern California, but also in Kern and Tulare counties where new avocado plantings are growing,” Montazar said.

Preliminary findings and recommendations are expected at the end of 2022.

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