Getting More with Less Key to Water Management

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Using a pump-up pressure chamber to determine when to start irrigating can save on irrigation costs as well as help preserve tree health (photo courtesy L. Milliron.)

California’s shrinking water availability and increasing energy costs have put a premium on proper irrigation management, according to a certified crop consultant and water-use expert.

Cory Broad, territory sales manager for Jain Irrigation, said the days of going out and turning on the pump whenever you so desire are over. And with the uncertainties surrounding the future availability of surface water and groundwater, stresses on water use are only expected to increase.

Full implementation of the Sustainable Groundwater Management Act and other impending regulatory actions will affect water users across the state, Broad said, “and, unfortunately, it is going to disproportionately impact agriculture.”

Approximately 600,000 acres of farmland in California will be idle this year due to water shortages, he said, and pumping caps of between 0.6 acre-feet and 1.3 acre-feet per acre will be common. “And it is going to impact 1 to 1.1 million acres permanently across the state.”

Broad noted that water use of 3.5 to 4 acre-feet per acre is common in tree crops. “So, there are some really challenging decisions that are already starting to be made by growers,” he said. “This is a kind of deer-in-the-headlight moment for everyone.”

Against this backdrop in a webinar this past fall, Broad said it is important for growers to prepare for the future by answering some basic questions, including how to grow a crop economically with good agronomic principles but with less water.

“These are things we are going to have to become comfortable with,” he said.

Partner with a Pro
First off, Broad said, it is important for growers to partner with an irrigation professional. “Find a certified crop advisor with water management expertise,” he said.

“Water proficiency is a must-have for growers and their advisors,” he said.

Also, invest in high-quality, energy-efficient equipment. Drip, microsprinkler, flood and furrow irrigation all have their places, he said, but the products that support the system have to be high-quality.

“One question to ask [when purchasing equipment] is whether it is energy-efficient,” he said. “Energy rates in ag have basically doubled in the last 15 years in California. And I don’t see that changing anytime soon, especially as the 2045 Energy Initiative isn’t that far off.”

With fertigation common, maximizing investment in crop nutrients also should be a consideration when investing in irrigation equipment.

“By investing and spending money on calcium and nitrogen and then putting it on ununiformly because you didn’t invest in an irrigation system, you are hurting your initial investment and you are hurting your long-term investment,” Broad said. “So, it is important to invest in good equipment.

“Also, investing in technology is important,” he said.

Soil moisture sensors can be invaluable, he said. “You can get moisture, you can get EC, you can kind of track fertigation. They are reliable and inexpensive.”

Growers also should consider going with an automated irrigation system, he said. “Our automation requests [at Jain Irrigation] have tripled this year because of labor challenges and the opportunity to use water more efficiently,” he said.

Also, software can be a critical addition to good irrigation management, he said. “It is something I interact with every day,” he said. “Good software that uses satellite imagery is low-cost, fits all economic models and allows a grower to do more with less.

“From our end, it gives us that opportunity to build confidence when we are doing water budgeting because we are using this imagery in conjunction with weather data and crop functions,” he added. “And it gives you a field-specific management view of what is going on. Each week, you are getting a calculation and an image, and it shows you literally how much water your field is using and giving you the health of your crop.”

First Irrigation
Another step growers can take to reduce water use and maintain crop health is to consider delaying their first irrigation in the spring, Broad said. And a key to that is knowing your soil water holding capacity.
“I think if you can start to understand your soils, their texture and structure, you can expand this budget and focus on saving water, because you kind of know the water is there, and then you know how much you are going to use, and then you can say, ‘On this day is when I am going to start irrigating,’” Broad said.

“Knowing the rooting depth of your crop also is important to help calculate water availability,” he added.

Growers should consider measuring tree stress with a pressure chamber to determine when to start their spring irrigation, according to Luke Milliron, UCCE farm advisor for Butte, Glenn and Tehama counties.

“Not only do you save on water, which has become expensive all of a sudden and the availability of which is uncertain, but you also can avoid damaging the tree, which you can do in the spring if the roots are saturated for too long,” Milliron said.

Milliron noted that research has shown that even in drought years like 2021 and 2022, walnut growers using the pressure chamber found they didn’t need to irrigate until May.
“The ability for water savings is tremendous in walnuts,” Milliron said.

“A lot of folks just intuitively start irrigating in late March or certainly during April based on the ground drying out and early heat waves,” Milliron said. “They are concerned that they are losing deep soil moisture, so they are trying to keep the bank full, so to speak.

“What we have shown is that folks can wait, use the pressure chamber, and even though the top of the soil is dry, the tree roots are tapping into water that is potentially as deep as 10 feet,” he said. “Let the trees tell us when to irrigate.

“Waiting for when the trees are actually experiencing just a modest level of stress according to the pressure chamber is a good trigger,” he said.

“You’ll get nervous because you probably are going to be irrigating later than all of your neighbors, and that is a nerve-wracking thing to do,” he added. “They might be on their second, third or fourth irrigation, and you haven’t started.

“In almonds, the soil dries out much sooner and they obviously leaf out sooner,” Milliron said. “Still, I think the pressure chamber is a tool you could use. The ability for water savings in almonds, at least in our research studies, is very modest, though. It might be one, or at the most two, irrigations.”

Information on the pressure chamber, including operating instructions, are available at sacvalleyorchards.com/manuals/.

Proper Maintenance
Properly maintaining irrigation equipment also is important, Broad said, with flushing hoses a key component of any maintenance program.

“Every field requires different flushing protocols, but they all require care,” he said. Particularly if using surface water, growers should flush their hoses monthly at a minimum, he said.

In summary, Broad said it is important for growers to partner with the right people, invest in a good irrigation system, create a water budget for each field so they know what the crop is going to use and understand their soil types.

“And then, improve your irrigation maintenance scheduling,” he said.

With more water-use restrictions on the horizon, energy costs tripling over the last decade-and-a-half and crop input costs soaring, understanding how to grow healthy crops with less water and less energy is more important than ever, Broad said.