Cut Water Costs and Boost Yields With Drag Hose System
As a dealer for Raaft tracks (an aftermarket product to keep irrigation pivot tires from creating ruts in the field), Bob Gruner could have mixed feelings about the PMDI system he installed on a ½-mile pivot nearly two years ago. Officially known as Precision Mobile Drip Irrigation, the T-L Irrigation system consists of in-line drip hoses in place of nozzles or sprinkler heads, which are dragged by the center pivot or lateral-move system.
In effect, PMDI technology combines the lower cost of pivot irrigation with the proven efficiency of drip irrigation for total water efficiency that approaches 95%.
As the hoses are pulled through the field, emitters deliver an even water pattern across the full length of the unit. That, of course, means the wheel tracks stay dry, since the hoses are being dragged along behind the unit. That also means fewer Raaft track sales for the Amarillo, Texas, farmer if the PMDI system catches on.
Cuts Irrigation Cost, Boosts Yields
Yet, even Gruner can’t discount the fact that PMDI has reduced his irrigation expenses by 30% or more, while increasing yields by at least 20%. That windfall came at a cost of $100 to $200 per acre, depending on the design and hose spacing.
“I put the T-L PMDI system on a 270-acre pivot that I would typically divide between 90 acres of wheat, 90 acres of corn, and 90 acres of fallow,” Gruner explains, noting that he installed the system, which consists of drip hoses on 40-inch centers, in June 2015. “However, after I installed the PMDI system, I split the circle evenly between wheat and corn.
“Where my average on wheat is normally 50 to 55 bushels per acre, I saw a 68-bushel average under the PMDI,” he continues. “The corn did equally well. My normal average on late corn is 175 to 180 bushels per acre. Under the PMDI circle, I averaged 210 to 220 bushels over the past two years, for an average 35-bushel increase.”
At the same time, Gruner says he was able to stop irrigation a month early on the PMDI field due to the amount of water in the soil profile, even though the farm only received 5½ inches of rain during the year.
“In my part of the country, it can take four hours for water to seep into the soil. So if I have sprinkler heads that pool water on the surface, I’m going to have some runoff. With the PMDI hoses, the water spreads out and seeps into the soil before it has a chance to run off, evaporate, or blow away in a mist,” Gruner continues. “I’m on limited water in this area, and the well on the whole 270-acre pivot only puts out 500 gallons per minute. So I have to conserve as much water as I can. That’s why I can see this system paying for itself in two years or less.”
Other PMDI Systems
T-L Irrigation isn’t the only company to offer a PMDI system. Dragon-Line of Ulysses, Kansas, sells its own aftermarket version. Like the T-L system, it utilizes emitter hoses that are dragged behind the pivot at optional spacing. Both brands use drip hoses manufactured by Netafim, a firm that makes hose for drip-irrigation systems.
While both PDMI systems can be installed on any brand of pivot, the primary difference between the two brands is the length of the hoses and the spacing of the emitter holes. In all installations, the hoses generally increase in length from the pivot point to the end of the pivot. Both systems may require filtration or chemical treatment to remove and to neutralize contaminants from the water to prevent clogging. It’s generally best to tie up the hoses over the winter to prevent any damage from rodents, deer, or livestock.
Still, Gruner and some of his neighbors who have adopted the system insist any extra maintenance is worth the time and effort in terms of yield and savings.