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Beyond Drip Irrigation: Meeting Demands for Water Efficiency

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Between 1980 and 2014, California growers increased production by 38 percent while simultaneously decreasing their water consumption by 14 percent. But as drought patterns worsen, policymakers are again looking to agriculture to reduce its water use. Where might additional savings come from?

Drip irrigation and its limitations

The transition from flood irrigation to drip systems and similar technology has driven significant improvements in efficiency over the past two decades. California growers have collectively spent billions of dollars to adopt micro-irrigation, says Ryan Jacobsen, CEO of the Fresno County Farm Bureau and a wine grape grower himself. In high-production areas like the Coachella Valley and western Fresno County, more than 60 percent of farmland is now irrigated with low-volume drip, micro-sprinkler, or subsurface irrigation. Statewide, it’s more than half.

But even had the majority of specialty growers not already made the switch to micro-irrigation, this technology alone would likely not be enough to meet the industry’s needs for conservation. First, there is the increasing severity of water scarcity in the state. Most recently, California farmers entered the 2022 growing season on the heels of the driest January-through-April period since 1895 —this following the second driest water year on record.

Secondly, as Jacobsen points out, the efficiency savings of drip irrigation over flood irrigation don’t always translate to a net reduction in water consumption. “A lot of times, water technology does not mean less water use. Better delivery increases yield—but as yield increases, crops need more water,” he says.

Thirdly, California’s move toward drip irrigation has had unintended effects on soil salinity and groundwater recharge. Over time, and especially in years when rain is insufficient to flush soils, salts in drip-irrigated fields can build up peripheral to the wetting area. And, while drip irrigation does reduce the total amount of agricultural water applied, it also reduces the amount filtering down to replenish aquifers.

Variable rate on the rise

There are limits to how much more drip irrigation can be adopted in specialty agriculture. Could better drip irrigation be the answer, instead?

Variable-rate drip irrigation (VRDI) is in the early adoption stage, but indications are the technology has potential to contribute to water savings. A study conducted in California vineyards over three seasons found that growers using a VRDI system increased their yield by 10% while gaining 17% in water-use efficiency. “As these technologies become more affordable and applicable to a wider audience, we’re seeing greater adoption in the field, Jacobsen says.

Dr. Dan Howes is a professor and project manager with the Irrigation Training and Research Center at California Polytechnic State University. While VRDI may have applications for growers dealing with spatial variability in their fields and soil types, Howes cautions growers to make sure they’re treating the problem, not the symptom, before installing a VRDI system. A plant that isn’t using as much water as its neighbors could be a sign of a health issue that should be addressed—and not necessarily with more water.

“If [you’re] in the California Central Valley with fairly flat, uniform fields, why would you want to put more water on in one location and less in another?” Howes says. He reminds growers to first ask themselves, “Why aren’t the plants all using the same?”

Irrigation data and analytics

Regardless of the specific irrigation infrastructure in place, more data, better data, and more effectively deployed data about crop health can help growers optimize water use.

In general, Howes sees California farmers trending toward more automation of their irrigation management activities—which in turn demands better data collection to identify problem spots. This is especially true for larger companies and conglomerates that may not have historical experience with the fields under their management. “From a farm management standpoint, when you have so many acres to cover, a lot more data collection, like imagery, can help. You can’t be out there all the time,” Howes says.

In addition to moisture probes, Howes sees potential in increasing automation of plant-based crop health indicators. Existing methods, such as pressure bombs, are extremely time-consuming and labor-intensive. By contrast, new technologies such as sensors that continuously monitor trunk diameter shrinkage and swell on wine grape trunks and cordons could one day enable real-time data. But their reliability is yet to be determined, Howes says.

In the meantime, crop health assessments generated from aerial data provide an efficient route to visualizing change and variability. Ceres Imaging, a precision agriculture data provider, assists growers in optimizing irrigation by improving uniformity and identifying issues that contribute to waste.

In an annual report, Ceres Imaging analyzed more than 1 million acres of specialty crops across California and released findings from the 2021 growing season. For the first time, the report includes regional irrigation uniformity metrics, as well as new insights on common questions, such as:

  • Where are irrigation issues most common?
  • How do irrigation issues impact farm profits?
  • How does the impact of drip irrigation issues vary by crop type?

Download the free report here.

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