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Drip irrigation increasing alfalfa yieldsDrip irrigation increasing alfalfa yields

May 18, 2009

5 Min Read

Drip or micro-irrigation is found in most every major crop in the West except on alfalfa, which is now the largest acreage field crop in California and Arizona.

THE WUERTZ family, from left, Greg, Howard, and David, grows alfalfa in Coolidge, Ariz. Sundance Farms includes 542 acres of alfalfa watered with subsurface drip irrigation which has reduced water use and increased yields by one-third each.

For almost four decades, the Wuertz family and its Sundance Farms in Coolidge, Ariz., have been pioneers in drip irrigation, but only recently started growing alfalfa with a drip system.

Not surprisingly, the 83-year-old head of the family, Howard, and sons Greg and David are making it work.

“We typically have grown cotton, wheat, and specialty crops, but not alfalfa due to low prices,” said Howard Wuertz. “When hay prices increased several years ago, we decided to plant alfalfa.”

Drip-irrigated alfalfa is conserving water and increasing yields.

“We’re using about one-third less water to grow alfalfa with subsurface drip irrigation (SSDI) compared to traditional flood irrigation,” Howard said.

“With SSDI we apply 7 to 8 inches directly to the root zone per alfalfa cutting (28 to 30 days) compared to about 12 inches that’s typically applied through one or two flood irrigations to the soil surface.”

The water savings are realized with drip lines installed 20 years ago and since used on primarily cotton and wheat. The drip lines are buried 8 to 10 inches deep and 40 inches apart.

“The 40-inch drip lines provide plenty of water to grow alfalfa. It makes excellent alfalfa hay,” Howard said.

The Netafim drip tape is either five-eighths or seven-eighths of an inch in diameter, depending on the length of the water run. Howard says the preferred SSDI installation is in four, 40-acre blocks across 160-acres.

The Wuertz family’s SSDI irrigation regime for alfalfa includes eight irrigations per cutting; 2 inches of water weekly, 1 inch early in the week and 1 inch later. The field remains about 85 percent saturated. “We irrigate at the consumptive use the crop needs,” said David Wuertz, the farm’s general manager.

The nine annual cuttings include an initial green chop for silage.

“Alfalfa is a summer crop that is difficult to cut, cure properly, and bale (in the early spring) so it’s green chopped instead,” Howard said. “The dairies love the green chop; they scream for it. The cows produce a lot more milk with the green feed.”

Drip irrigation produces one-third ton more alfalfa per acre per cutting for the Wuertz family.

“I have a neighbor who gets 1.3 tons of alfalfa per acre per cutting with flood irrigation,” Howard said. “Our production under SSDI averages 1.75 to 1.8 tons per acre/cutting. That’s one heck of a story.”

Phosphate, nitrogen, calcium, magnesium, and other nutrients are applied through the drip.

“My experience demonstrates that it’s about 30 percent to 40 percent more efficient to place nitrogen and phosphates in the root zone via SSDI than spraying on top of the ground and then watering it in,” Howard said.

An installed SSDI system, including filter station and injection system, for Arizona alfalfa production costs about $2,000 per acre.

“The system can pay for itself in three to five years,” Howard said. “A properly designed, installed, operated, and maintained SSDI is the cheapest irrigation system on the market today when amortized over the life of the system.”

Most of Sundance Farms’ 3,000-acres are watered by SSDI. In addition to the 542 alfalfa acres under SSDI this year, there are 1,500 acres of upland cotton (Stoneville and Deltapine varieties), 750 acres of durum wheat, and about 300 acres of watermelons.

The Wuertzs first grew alfalfa in the 1970s under flood irrigation and later switched to other crops. They re-entered the alfalfa business in fall 2007 planting 200 acres of the forage crop where drip was installed 20 years ago. Last fall, 342 additional acres were planted in alfalfa.

The Wuertzs acknowledge that available water supplies will tighten in Arizona, a state plagued by 13 consecutive years of drought. David Wuertz predicts that urban water users will gain more CAP water in the future, resulting in less Colorado River water delivered to Central Arizona for farmers.

The Wuertzs started AZ Drip Systems, Inc. in 1982, a company that holds five U.S. patents on drip and minimum tillage equipment. Wuertz’s tillage system, the Sundance system, is designed for tillage with buried drip.

The initial cost of SSDI for alfalfa can cause sticker shock, especially amid today’s lower hay prices. Another obstacle is the huge learning curve for irrigators; moving from a flood-irrigation mentality to a SSDI mindset.

“It’s difficult for an irrigator to move from applying 6 acre inches in a single irrigation to 1 acre inch of water and then three days later another inch,” Wuertz said. “People have a real hard time watering eight times between cuttings, versus once or twice.”

Drip-irrigated alfalfa creates no problems at harvest such as wet fields. The water is turned off two to three days before cutting.

Another drawback for SSDI in alfalfa is the damage to irrigation lines caused by pocket gophers which gnaw on irrigation lines. Gopher tunnels can also divert irrigation water and lead to soil erosion.

Wuertz applies the soil fumigant Telone before planting for root knot nematode and gopher control in the field. Traps are then placed on field edges to keep other gophers at bay from the drip systems.

For related stories, visit westernfarmpress.com/alfalfa/.

email: [email protected]

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