Third-generation pecan grower Gary Arnold is downright stingy about water — efficiently and effectively irrigating his 327 acres of pecan trees in New Mexico’s Mesilla Valley.

Arnold is a partner in Arnold Brothers Partnership in Fairacres, near Las Cruces. The partnership with his brother Phillip produced about 500,000 pounds of pecans in 2008 (a 1,671 pound average) in the off-year for pecans.

The brothers grow mostly the Western Schley variety with a few Wichita in the mix.

Arnold, no stranger to water issues and conservation, is a former president of the Elephant Butte Irrigation District (EBID), a surface water source for the Arnold farm. EBID is the largest surface water supplier in New Mexico, serving 8,000 constituents in southern New Mexico.

“There’s a growing demand for water here,” Arnold said.

Arnold and other pecan growers are always searching for new methods to grow more pecans with fewer vital inputs, including water. Technology has contributed significant advances.

“Many pecan farmers in the Mesilla Valley utilize laser leveling to maintain level orchard floors to allow for even distribution of irrigation water that results in reduced use,” Arnold said. “I use laser leveling periodically to touch up my fields to make sure the (field) borders are irrigated properly.”

Some newer pecan orchards in the Valley use water-stingy subsurface drip irrigation and sprinklers. The vast majority of the trees in this pecan Mecca are mature trees grown for decades with flood irrigation. Only flood irrigation can provide water deep enough to saturate the critical feeder root zone created by this practice, Arnold says.

Arnold’s 18 leaseholds stretch across 30 miles from the town of Hatch south into the Mesilla Valley. Ordering water for so many locations is an enormous challenge. Trees are irrigated 12 to 14 times a year on average, less in the spring and more once temperatures top 100 degrees in the early summer.

Arnold says pecan trees in the valley require about 4 to 6 acre-feet of water annually to meet the tree’s physical requirements, produce a robust crop, and leach the accumulated salts.

“We used to irrigate every two weeks regardless and we’ve changed that,” Arnold said. “We only apply water when it’s needed. We gauge fertilizer the same way.”

Arnold inserts a tensiometer, a moisture measurement tool, into the soil 2 to 3 feet deep to gain an accurate reading of the crop water demand.

“Sometimes it’s moist at the top of the soil but 2 to 3 feet down the roots can be dry as a bone,” Arnold said.

To conserve water and place it more efficiently in orchards, Arnold has replaced numerous small turnout water ditch boxes (gates) on the farm ditch that release water into the orchard. One larger box now “shoots” water more quickly to the trees.

“Shooting water as quickly as possible allows us to use less water in the long run,” Arnold said. Most of the irrigations include 3 to 4 inches of water each.

The water requirements depend on the soil type, trees per acre, microclimate, and other factors. Arnold’s orchards, which are located in a flood plain, have soils stratified with clay and sand layers.

“It’s difficult to manage all the acreage with different soils and the same amount of water,” Arnold said. “I have three or four soil types on the main farm that I micromanage to use as little water as possible yet meet the trees’ requirements to grow the maximum crop.”

Arnold paid $80 each for the first 2 acre-feet of EBID water last year and then less for his later needs. Most EBID water is from snowmelt into the Rio Grande River.

Future water allotment

The importance of water conservation throughout the Mesilla Valley continues to increase. New Mexico State Engineer John D’Antonio released a draft of the proposed Lower Rio Grande Active Water Resource Management regulations in 2006. The plan proposed limiting surface water delivery for all crops grown in the Lower Rio Grande basin to 4 acre-feet per acre annually.

The New Mexico Pecan Growers Association (NMPGA) hired water attorney Tessa Davidson to pursue additional water for the pecan industry.

“The goal of the New Mexico Pecan Growers was to get recognition from the state of New Mexico that pecan trees need a certain amount of water at the head gate to survive,” said Davidson, owner, Davidson Law Firm, LLC, Corrales, N.M. The 4 acre-foot state plan was shallow.

Scientific information from New Mexico State University helped prove the point. Evapotranspiration studies supported the additional water requirements. Davidson says pecan trees in heavy soil require about 4.5 acre-feet/acre compared to about 7 acre-feet in sandy soil.

The state engineer, the NMPGA, and 275 pecan growers representing 25,000 acres in the Mesilla Valley struck an agreement of 5.5 acre-feet for mature pecan orchards, an amount the parties agreed was the average need. The accord was not a guarantee of 4 acre-feet annually as available surface water supplies vary from year-to-year.

“This agreement vindicates them (pecan industry) and provides growers with what they were entitled to,” Davidson said. “It was a win-win for the state of New Mexico and pecan growers. It allows pecan growers to have some certainty that in a full water year they will get what they need. Some folks will need to buy more to get what a particular orchard needs.”

Newer orchards planted during the negotiations can qualify for 5.5 acre-feet of water once the trees are mature, Davidson says. The agreement now moves to the comment phase, which could take about a year. The Lower Rio Grande Adjudication Court must approve a final agreement.

“It’s a good agreement,” said Arnold, who placed all his acreage into the agreement. He commended the NMPGA for its leadership through the negotiations.

Pecans contribute about $150 million to the Doña Ana County economy annually, Davidson added.

email: cblake@farmpress.com