Assess for the best

Build systems with high distribution uniformity to reach production goals.
By Inge Bisconer, CID, CLIA

In the world of irrigated production agriculture, farmers usually rely on irrigation dealers to provide irrigation systems and agronomic crop consultants to help grow the crop. As irrigation systems have become more sophisticated in applying not only water, but nutrients as well, the two disciplines are merging to maximize farm profitability and optimize resource use efficiency at the same time.

One example is Eryn Gray in Santa Maria, California, an agronomist of nearly 20 years who founded Agrosource Irrigation seven years ago after discovering his client’s drip-applied nutrition program was failing due to the poor performance of the drip irrigation system.

“I was baffled why we weren’t getting the expected production results, so, as a certified crop advisor who also owned an agricultural laboratory, we began collecting data from a variety of growers to find out why,” he says.

After studying the data, he found it wasn’t the irrigation timing, the rates or misapplication of fertilizer that was wrong. Rather, the irrigation system itself was in disrepair and had poor distribution uniformity.*

Gray teamed up with consulting ag engineer Jim Anshutz, founder and owner of AGH2O in Fresno, California, to learn more about irrigation system uniformity and how to correct poorly performing systems.

“Jim had spent years developing a simplified drip system assessment routine that estimates the system’s distribution uniformity, identifies which components need replacement or repair and then monetizes how much system disuniformity is costing the grower in excess water and energy costs, and even more importantly, foregone yield potential,” says Gray. “Once growers realize how much money they are wasting, the need to invest in system improvements becomes very clear.”

Gray and Anshutz were able to combine their agronomic knowledge with irrigation system product and engineering know-how to create solutions that focus on retrofitting existing irrigation systems to deliver both water and fertilizer correctly.

Building uniformity

Today, a three-step methodology is employed to get customers on the right track.

First, Gray’s team conducts a simplified DU and return on investment analysis on existing irrigation systems using average water and power costs and crop values. Upon meeting with the grower, more accurate, grower-provided data can be used if available. The resulting report estimates how much the grower can afford to invest in system repairs, upgrades and replacements to retrofit the system back into optimal operating condition.

Second, engineers determine if there is a need for additional field data to be collected using a detailed irrigation system evaluation procedure. They evaluate the system components including the mainline and submain pipe sizes, valves, pressure regulators, filters and emission devices to identify whether or not they are operating according to manufacturer specifications and whether they can achieve a DU of about 0.92. They also consider chemical shock treatment if the emission devices are plugged but recoverable. All of this data is consolidated into an ROI analysis which estimates how quickly the retrofit investment will likely be recovered due to water and energy savings and enhanced yields that will be realized upon system improvements. If the system is upgraded, a new DU analysis should be performed to confirm improvements, with a comparative follow-up DU analysis conducted a year later.

DU in action

One of Gray’s customers grows more than 1,000 acres of winegrapes in Paso Robles, California. After the DU and ROI estimator analysis was completed, he discovered the drip irrigation system DU was 0.75 instead of the ideal 0.92. He was spending nearly a million dollars a year in energy costs due to applying 30% more water and fertilizer than needed to overcome the poor system DU. Crop yield suffered too.

According to Anshutz, Charles Burt, PE, PhD, CID, CAIS, of the Irrigation Training and Research Center at Cal Poly San Luis Obispo estimated that for every percent degradation in irrigation system uniformity, there is about a half percent decrease in permanent crop yields, and that the percentage is even higher for fruit and vegetable crops.**

“When I ask my growers how much they could increase production if the irrigation and fertigation were optimized, most will say 10%-15%,” says Gray. “But to be conservative we use a smaller number in the program, usually about 5%. That amount of increased revenue typically supersedes the investment. In most cases, the ROI is less than 18 months.”

Sometimes irrigation system block layouts are redesigned by Gray’s team according to soil type as determined by satellite soil maps and NRCS soil survey data. This usually requires more block valves to be plumbed into the system, which increases system costs by about 15%. But the resulting precision irrigation saves money and increases yield, outweighing the additional expense.

Another common upgrade is irrigation system automation to remove human error and ensure the right amount of water is applied. In one case, soil moisture sensor data revealed that irrigation instructions weren’t being followed.

In another case, the irrigator ran the system for 12 to 15 hours, or eight hours, instead of 10 as instructed. What happened? The irrigation system ran for only eight hours due to one of two reasons: either the irrigator had to visit another ranch and forgot to adjust it, or the pump was down. With automation, telemetry communicates whether the pump is on, flow and pressures are right, and block valves activated properly. If anything is wrong, alerts are sent to let the farmer know the pump isn’t on, the flow or pressure is wrong, or the valve isn’t activated. With this knowledge a solution can be executed through technology and control.

“Typically, there is about a 25% labor cost savings when automation is employed,” says Gray. “The State of California’s State Water Efficiency and Enhancement Program has funded much of the automation to date, which has been helpful, but more is needed.”

Following a standard system retrofit, the water and energy use efficiency alone can usually result in an ROI of less than 18 months.

“One customer was constantly fighting for adequate water on three well water systems covering 580 acres of grapes,” Gray says. “Our analysis discovered that the filtration systems were defunct and consuming excessive pressure. After retrofitting the system, well production was increased by 100% and the grapes began receiving enough water. Another customer was struggling to properly trigger veraison (transitioning from grape growth to grape ripening), which is highly influenced by irrigation. After the system was upgraded and automated, veraison was much more easily manipulated.”

It takes time and money to make changes and improvements, and sometimes there is a lack of a capital budget vs. an operational budget. There are also challenges in communicating the value of improvements between irrigation staff and the owners that write the checks.

“Thousands of acres have been fallowed due to lack of water, and more and more acres of 20-year-old almonds and pistachios and grapes are being pushed out due to ‘poor production,’” he says. “I truly believe that if growers use the DU and ROI Estimator methodology to trigger investment in upgrades, the loss of significant acreage will be avoided.”

Gray hopes for more cooperation between organizations like the Irrigation Association, crop consultants, commodity groups and agencies.

“The industry is fragmented and needs to come together to ensure that a sustainable, nutritious food supply continues to be grown on American soil,” he says. “It’s a matter of national security to improve our irrigation practices, which will in turn improve agriculture’s profitability and sustainability. Optimized irrigation is a win-win for the consumer, the producer and the country.”

Get connected

This routine has now been formalized into the Irrigation System DU and ROI Estimator program that is available for free via a website link that downloads onto the user’s Windows-based computer. It provides all the methodology, instructions, forms, data entry screens, reports, background calculations and interpretive information necessary for a field technician with nominal training to

  • conduct a drip/micro irrigation system distribution uniformity analysis by gathering flow and pressure data from specifically located emission devices in a representative block of the irrigation system.
  • identify specific irrigation system deficiencies by interviewing farm personnel regarding the operation of the system and physically observing the status of irrigation system equipment components.
  •  translate the evaluation findings into the economic value of improving the existing DU performance and equipment component deficiencies discovered, including the cost of pumping unnecessary applications of water, the value of forgone yield potential and the cost of less-than-optimal pumping plant efficiency.
  • provide an ROI analysis, in $/acre and $/field, based on the grower’s preferred ROI timeframe, in years, to encourage funding of corrective actions.

Funding for the Irrigation System DU and ROI Estimator program has been provided by the California Department of Food and Agriculture’s 2022 Water Efficiency Technical Assistance Program; grant administration has been provided by the Coalition for Urban and Rural Environmental Stewardship; program development and documentation has been provided by California contractors AGH2O and Surf N’ Earth Enterprises.

Inge Bisconer, CID, CLIA, is managing member of Surf ‘N Earth Enterprises in Cardiff, California, who has over 40 years of experience in California irrigated agriculture. She is a sales and marketing consultant who is passionate about helping farmers become better irrigators and more profitable and sustainable through improved water and resource use efficiency. She is currently president of the Irrigation Association.
*See article from Irrigation Today, January 2019, “Why drip system uniformity matters.
**See Irrigation System DU and ROI Estimator User Manual dated Oct. 27, 2023.
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