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		Nebraska's first digester produces energy, controls hog odor
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		Arizona sun powers sustainable farming experiment
		Western governors map out region's renewable energy future
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Arizona sun powers sustainable farming experiment

The irrigation system at Wolfberry Farm in Arizona's Chino Valley runs off the power generated by 32 40-watt solar panels. (Photo by Tim Crews)

Wolfberry Farm, an experimental agro-ecology facility, is combining the best of modern technology and ancient farming practices to revive agriculture in north central Arizona.

Prescott College acquired the 30-acre site in the Chino Valley in 1996, and it has served as a laboratory for ecologically and environmentally sustainable farming methods ever since. "We're here to test theories, not to read about them," explained Dr. Tim Crews, project coordinator.

Students conduct experiments in irrigation methods, native plants, drought tolerance, crop rotation, soil regeneration, organic farming and more. Crews readily admits that some experiments are more successful than others, like the farm's namesake crop, a small red fruit in the tomato family that has done well enough to consider marketing as a condiment.

The Tepary bean was less successful. The traditional dryland crop grows quickly in response to the region's average summer rainfall of about six inches. "The beans were planted in a drought year," Crews recalled. "They couldn't survive without the monsoons."

The failures help the students understand the frustrations farmers go through and why they rely on tried and true practices. The successes are helping Wolfberry Farm challenge conventional farming practices, like the use of electricity.

Renewable energy counts as success

Wolfberry Farm's irrigation system, greenhouse fan, straw bale farmhouse and open air classroom run on solar power. "The grid runs by the site so we had access, but we wanted to see if we could run a growing system within the farm's footprint," said Crews.

That meant finding an environmentally-friendly power source to run the irrigation system, one of the biggest energy loads on a conventional farm. Water pumping became Wolfberry Farm's first photovoltaic operation.

The system consists of two 2,500-gallon tanks supplying the water to the fields and the house, and pumps that run directly off of 32 40-watt panels. The farm recently switched from a gravity fed drip system to pressure pumping. "The tanks weren't high enough, so we were overwatering some of the lower fields to get all of them," said Crews.

The new system pumps directly into a closed-pipe network at 10 psi. "Presumably, it will use about the same amount of power, but it will use less water to irrigate the fields more evenly."

The 500-sq. ft., three-room farmhouse runs off 10 40-watt panels connected to an array of four 60-watt batteries. Super-insulated straw bale construction keeps the house cool in the summer and warm in the winter. "There's a back-up propane heating system on the house that we haven't used," Crews noted.

Although the resident must keep a close eye on electricity use, the house and the equipment in it were designed or selected for energy efficiency. For example, the farm chose a high-efficiency conventional refrigerator because, Crews said, "We wanted equipment that was readily available and easy to fix."

Instead, the refrigerator turned out to be the house's biggest energy user, especially in the summer. "It could be that we just got a bad unit. We switched out for a new model last spring and it ran much more efficiently even through the summer."

The classroom array is the most recent addition to the farm. Two 40-watt panels allow teachers and students to use microphones, give PowerPoint presentations and hook up laptop computers.

Finding use for excess power

Like the pumping system, the greenhouse fan runs directly off one 40-watt panel. The fan draws on its power supply about eight months of the year, while the irrigation system's energy needs usually peak around June, the hottest, driest part of the growing season. That has Crews and his students thinking about ways to use the excess power the irrigation array generates.

Up to now, selling power to Arizona Public Service, Prescott College's utility, has not been an option. "They didn't have a net-metering plan when Wolfberry Farm started up," said Crews.

The state adopted a renewable portfolio standard in 2001, and Crews thinks things may change. "Representatives from Wolfberry attended the ribbon-cutting of APS's big solar array," he said, adding that the utility has shown some interest in another eco-farm the college is planning.

Solar-powered farm implements may be another option for the Wolfberry group. "At first, we looked into using solar power to produce hydrogen fuel," said Crews, "but the technology still has too far to go."

Then our research turned up a group that has been developing a tractor that runs on a direct-charge solar battery. So now we are working on a prototype solar tractor."

The prototype might be plowing fields next spring or it could end up as another lesson learned. Either way, Wolfberry students will continue to ask the question that has dogged Arizona's long agricultural history: Can farming in the region be more ecologically and environmentally sustainable? History should prepare for some surprising new answers.