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New Mexico scientist says drought puts alfalfa at risk

As a strangling drought grips the Southwest, a New Mexico State University scientist says alfalfa growers should take steps to save their stands of the state's No. 1 cash crop.

“Especially on dryland farms, now is the time to consider production methods aimed at preserving future stands,” said Denise McWilliams, an agronomist with NMSU's Cooperative Extension Service. Alfalfa, valued at $161 million annually, easily supersedes other more high-profile crops like chile, pecans and cotton, and can have a life span upwards of 15 years.

Alfalfa has the ability to go dormant during extended dry periods and is one of the few crops that can then recover with adequate rain or irrigation, McWilliams said. That's only as long as plant roots remain white, moist and pliable, though.

Key production strategies to consider are cutting and irrigation management, along with insect control and fertilizer reduction.

Prudent and careful cutting is a producer's main tool in boosting alfalfa survival during drought spells. In some areas of New Mexico, a single crop can easily produce six or more annual cuttings in one year.

Harvesting frequency not only determines alfalfa's ability to survive, but also hay quality. Another factor is plant genetics, which can help or hurt alfalfa's ability to withstand dry conditions.

“It's difficult to make standard recommendations across crops in various regions,” McWilliams said. As a result, her survival guidelines are based on the plant's maturity, as well as cutting height.

Consider maintaining at least 6 to 8 inches of top growth if cutting during drought periods, she said. This not only allows the plant to maintain itself, but also allows for more of the stand to survive through the drought and possibly into the fall and winter.

Some producers with limited irrigation are already seeing signs of trouble in their alfalfa fields. “It's going to get bad here in the next two weeks,” said Woods Houghton, agricultural agent with the Eddy County Extension office in Carlsbad. “Hopefully, if we can get one watering in the fall before it goes into winter dormancy, we can preserve the stand.”

Sandra Barraza, Colfax County Extension program director in Raton, said the lack of snow pack and rain has severely limited irrigation allotments.

“We have farmers who aren't even going to cut at all. They're just hoping it comes back next year.”

Alfalfa is New Mexico's leading cash crop largely because of its ability to grow in just about all of the state's widely different climate zones. More than half of the state's 270,000 acres are planted in just four counties - Chaves, Doña Ana, Eddy and San Juan — but a mix of farming communities across the state contribute to the total.

According to the New Mexico Agricultural Statistics Service, the state's growers produced 1.35 million tons of alfalfa last year. One reason for the plant's versatility lies in its ability to find water. It has very deep roots, usually more than four to five feet in depth, so it can scavenge for water, McWilliams said.

Alfalfa can require 8 to 10 acre-inches of water for each ton of hay produced. But that number depends on evaporation, soil type, texture, drainage and other climatic conditions. Irrigation needs are also affected by the quality of the water, especially if it is saline.

McWilliams added that insect control is another consideration during drought. Leafhoppers, plant bugs and aphids all stress the crop and should be controlled. “Keep a close watch on recently cut fields,” she said.

“New regrowth is easily damaged by increasing populations of these insects.”

Finally, McWilliams warned producers that applying fertilizer now could significantly stress plants, especially if drought persists into fall and winter. “Don't apply additional fertilizer unless soil tests show low fertility,” she said.

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