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Microsprinklers Can Help Growers Weather Drought

ALCALDE - Walter Lea, an apple and peach grower in Lyden, spent nearly $12,000 this spring to install a new, under tree microsprinkler system to irrigate his two-acre orchard.

NMSU fruit specialist Ron Walser supervises a new experimental orchard featuring a microsprinkler system at the Sustainable Agriculture Science Center at Alcalde. Microsprinklers have the potential to cut water use nearly in half, improve productivity and protect orchards from late spring frost. (06/07/2002) NMSU Agricultural Communications Photo by Norman Martin)

But Lea expects to rapidly recoup his investment thanks to the system's potential to cut his water use nearly in half, improve his trees' productivity and protect his orchard from late-spring frost.

Microsprinklers are installed underneath trees and vines in orchards and vineyards, where they gently spray a mist of water. The moisture softly sinks into soil, avoiding runoff. And because the microsprinklers soak the lower trunks and shaded soil rather than the sun beaten-foliage above, evaporation is substantially reduced.

"Microsprinklers are much more water efficient than flood irrigation, and they help produce healthier trees by eliminating or reducing diseases like root rot," Lea said. "Then there's the huge advantage of frost control. If this system works the way it's designed to, it will basically pay for itself."

Used widely in Washington State and other fruit-growing areas, microsprinklers are under study at New Mexico State University's Sustainable Agriculture Science Center at Alcalde.

"It's entirely new to New Mexico, but I expect many growers will adopt the system once they see all the benefits," said Ron Walser, an NMSU fruit specialist who is supervising the research.

Most New Mexico fruit growers use flood irrigation, which is only about 50 to 60 percent efficient, Walser said. Microsprinklers are generally 80 to 85 percent efficient, so growers can irrigate the same area with 30 to 40 percent less water.

Microsprinklers eliminate the flooding and drying cycles that damage tree roots and deprive them of oxygen, Walser said. That helps reduce root rot and other diseases.

In addition, because moisture from sprinklers spreads out along the entire orchard floor, tree roots will expand beyond planting rows, using the whole orchard. The extra moisture permits cover crops, like peas, to grow along the orchard floor, which can improve soil fertility by adding organic matter and nitrogen to soil.

Cover crops also increase the frost control of microsprinkler systems. "The system moistens the whole orchard area under trees so that when temperatures drop close to freezing, growers turn on the microsprinklers to allow frost or ice to form on the orchard floor," Walser said. "As the water freezes, it gives off heat and warms up the whole environment. I've seen up to five degrees protection from these systems, especially if there's a good cover crop to capture more water along the orchard floor."

Frost control may prove to be one of the system's most appealing qualities, especially for northern New Mexico growers who frequently lose part, and sometimes all, of their fruit to late spring frost.

Walser will test the system's varied benefits during the next three growing seasons on a five-acre plot at the science center, where organic fruit trials are just beginning. Microsprinklers are already irrigating a half-acre vineyard on the plot, as well as newly planted rows of fruit trees.

Walser is now comparing water usage at the center's vineyard with two private vineyards in Dixon and Abiquiu that use flood and drip irrigation systems, respectively. Moisture monitoring devices have been installed to measure surface and subsurface moisture levels at all three vineyards.

In future trials, Walser will measure water usage for fruit trees, comparing microsprinkler irrigation at the center with flood systems at private orchards. He'll also measure the microsprinklers' effect on temperatures in the center's vineyard and orchard, as well as soil fertility and fruit health.

As one of the first growers to adopt the system, Lea will participate in the research once his microsprinklers are fully functional this summer.

"I have high hopes for this system," said Lea, who plans to irrigate two acres of newly planted high-density peach and apple trees with microsprinklers. Lee expects to recoup about 50 percent of the system's cost from the U.S. Department of Agriculture's Natural Resources Conservation Service, which pays half the cost of the more efficient irrigation system.

"I expect those trees to produce a total of $25,000 per year in about three years," Lea said. "Apart from all the other benefits, if the microsprinklers protect the trees against frost and save just one crop, I'll have recouped the entire investment."