Drip Irrigation Study Shows WUE Improvement

Study evaluated drip system distribution uniformity in key produce regions of California California_Drip_Irrigation

Author: Hank Giclas, Western Grower & Shipper

Water use efficiency has long been a priority for produce growers in the United States, but with diminishing water resources there has been a renewed urgency to improve efficiency in drip irrigation systems.

Western Growers, in concert with JR Simplot Water Services and The Toro Company, recently concluded a study to evaluate distribution uniformity in drip irrigation systems in key produce regions in California, including both the Oxnard Plain and the Coachella Valley.  This study was done in cooperation with Western Growers members who were interested in water efficiency and will be published soon to provide useful information to those operating drip systems.

An irrigation system’s uniformity of water distribution or distribution uniformity (DU) is a key measurement of a system’s water use efficiency.  If water is not distributed evenly or uniformly on a field, areas receiving less acre-feet of water may have poorer plant health and reduced crop yields.  Conversely, to compensate for unequal distribution and avoid reduced yields, the system must over-irrigate.

DU, expressed as a percentage, is considered outstanding when above 90 percent, as good between 70-90 percent, and poor when it is below 70 percent.  Operating with a DU above 90 percent makes good economic sense in that DU correlates closely to crop yield and reduces costs related to increased water use, which includes the water itself, energy to power the system, and often fertilizers and other chemicals run through drip systems.

These increased costs can be significant.  For example, an irrigation system operating at 75 percent DU versus 85 percent DU can use more than twice the water, three times the fertilizer and increase energy cost by three times.  In addition to increased costs, poor DU also impacts yield revenue.  A study in 2014 (J Anshutz, “Retrofitting your irrigation system for success and profitability”) assumed an average yield of 2,500 pounds per acre and a crop value of $3 per pound.  In a field with 85 percent DU, the author estimated a per-acre revenue loss of $188 due to DU degradation, while in a field with 75 percent DU, the loss grew dramatically to $563 per acre.  These numbers increase substantially as DU further degrades below 70 percent, demonstrating a real impact on the bottom line for growers using poorly designed and maintained irrigation systems.

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Full article shared from Toro DripTips website.