Less water efficient farm acreage good fit for sub-surface drip

A winter snowcap adorned the massive peak of Mt. Graham near Safford, Ariz. in early April as a dozen agricultural folks excitedly scampered at ground level on a 40-acre parcel of land below.

“I’m a bit of a risk taker. I like to do what others are afraid to,” said farmer Rick Motes as he walked to the freshly dug retention pond next to the field. He surveyed the empty pit, turned around, and watched as workers installed sub-surface irrigation tape in the field.

Sub-surface drip irrigation is an increasingly popular conservation practice across the West. The benefits are substantial – conserving water and soil while directly spoon-feeding water and nutrients directly to the plant roots.

Though in this part of the Gila Valley near Safford, not a single sub-surface irrigation system exist. The reasons might vary from initial costs to heavily silt-laden surface water that left untreated can clog drip emitters. A sub-surface system was tried in the mid-90s but why it was abandoned is unknown.

Rick, and his wife, Rachel, operate Rick Motes Farms, a 1,000-acre farm including 100 acres of alfalfa and where 900 acres of upland cotton will be planted this spring. Of the acreage, the couple rent 650 to 700 acres from the mining company Phelps-Dodge.

The 40-acre parcel, the Motes experimental area for sub-surface drip, is marginal land in water efficiency with a steep slope. Over the past five years a green manure crop was grown to keep the water decreed. Cotton was grown before but with poor yields.

“The ground slopes about 4 to 6 inches every 100 feet. It’s a very steep field,” explained Eddie Foster, who has worked closely with Motes on conserving precious natural resources on the farm. Foster is a soil conservationist with the Natural Resources Conservation Service (NRCS) in Safford, Ariz. “Furrow irrigation on the field is horrible,” he said.

Rare floodwaters last year covered the field ruining the irrigation ditches. Replacing the conventional irrigation system would have cost almost as much as the drip. So Motes opted to pursue the sub-surface system, expand his profit potential, and practice conservation.

“I expect the sub-surface drip system will reduce my water needs by about one-third, and increase yields hopefully next year,” Motes said.

On this mid-90 degree day, Arizona Drip Systems, Inc. of Coolidge, Ariz. installed the system.

Another reason Motes pursued the sub-surface drip system was because of current and potential future water limitations. Normally he draws a six acre-foot allotment from the nearby Gila River for his farm ground. About 75 percent of his water for agriculture is from surface water while the remaining 25 percent is well water.

The problem with the Gila water is its flow is unreliable. Simply put the river sometimes dries up. Motes’ crops have been at a critical growth stage and surface water was unavailable.

“How can you economically farm without water?” he asked. “You can’t. With water, you need to have an ace in the hole that works.”

Federal legislation called the Gila River Water Settlement is also on Motes’ mind. The agreement if finalized by years-end could by law give the rights of nearly 50 percent of the Central Arizona Project’s water supply to Native Americans. For farmers like Motes and others the agreement could reduce available surface water, possibly groundwater, and jack up water prices.

Sub-surface drip is Motes’ ace in the whole, a method to provide him with a better water guarantee to remain farming the parcel.

Conservation funding

The sub-surface drip system cost about $1,200 to $1,500 per acre or $48,000 to $60,000 for the 40-acre tract.

Motes’ qualified for a beginning farmer contract (under 10 years of farming) under the NRCS’ environmental quality incentives program (EQIP). The nationally available program addresses locally identified natural resource problems such as water conservation, erosion control, animal waste management, and other conservation practices and has various financial benefits for many growers.

Under the NRCS/Motes’ contract, NRCS will cost-share 90 percent of the costs. Motes picks up 10 percent of the tab, not the landowner Phelps-Dodge.

Sub-surface drip details

As he eagle-eyed the drip tape installation, Howard Wuertz, an owner of Arizona Drip Systems, walked the fields providing input to the crew.

Wuertz explained that the 7/8-inch drip tape manufactured by Netafim of Fresno, Calif. was buried 10 to 12 inches under the bed and equivalent to the row bottom. The emitters, located every 12 inches, would release .24 gallons per hour each. Spacing was 16 inches. Four, 10-acre systems were planned.

Surface and well water would collect in the collection pond where most sediment would settle within 24-hours, he said. The water would then flow into the filtration system featuring 48-inch Netafim sand medium barrels for further cleaning.

Added chlorine would flush the system at 3 to 5 parts per million. The goal was a PH value of 7 (neutral), Wuertz said. Once pressurized, the water mix would be sent to the filed tape.

“The idea of sub-surface irrigation is to meet the needs of the plant when it needs it,” Wuertz said. “This (particular) system will run every two to three days.”

While Motes and Foster hope the system will cut water use by a third, Wuertz’s loftier opinion is an estimated 50 percent reduction in water savings and a 25 to 30 percent yield increase.

“The neighbors (around the farm) are watching us install the system today,” Wuertz noted.

Wuertz’ also farms 3,200 acres on Sundance Farms in Coolidge, Ariz. including watermelons, Durum wheat, and cotton. Sub-surface drip was installed on all but 250 acres. He said sub-surface drip doubled watermelon production from 20 to 40 tons per acre while using half the water.

Arizona Drip Systems has installed sub-surface drip in Arizona, California, and Nevada.

Management changes

One of the hardest changes for farmers in sub-surface drip versus conventional irrigation systems is changing the required management.

“With sub-surface drip, management changes include how often the crop is watered, for what duration, and how nutrients are applied,” Foster said. In addition, tillage changes drastically from conventional till to minimum till including the need for new equipment. But with the changes comes savings on fuel and labor, he added.

“The less you are in the field then the more you can improve the soil,” Foster said.

Arizona Drip Systems, Foster, and University of Arizona regional extension specialist Randy Norton will offer management input to Motes.

Rented ground

Jerry Sako, Phelps-Dodge’s farm manager, said the mining company owns farm land in southeastern Arizona for water rights for mitigation. The company owns 6,000-acres of farm land including 4,000 with decreed water rights.

About 75 percent of the land is in the Gila Valley between Geronimo and Solomon, Ariz. About 25 percent is owned in the Duncan, Ariz. area.

Phelps-Dodge has 13 farm leasees, soon to increase to 15. Motes’ lease is the company’s second largest, Sako said.

Motes, Foster, and Sako speak highly of each other. Each complements the other for working to the sub-surface installation experiment to fruition.

If for some reason Phelps-Dodge cancelled the lease with Motes on the 40-acre parcel, Foster said Motes would be responsible to payback the 10-percent of the NRCS contract since the dollars are public funds.

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