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System at SFCC combines raising fish, growing plants

SANTA FE, N.M. — Ancient agriculture of the past may point the way for the future of feeding the world.

Or at least that’s the way Eric Highfield sees it.

Program coordinator for greenhouse technologies at Santa Fe Community College, Highfield is laying the groundwork for an aquaponics program at the school. In a mostly closed system, fish will be raised in tanks that will circulate their waste to provide nutrition for plants growing in floating rafts in other tanks.

The idea is hardly new – and it uses a lot less water than growing crops in open fields, said Highfield, who received his training with a master’s degree at the University of Arizona.

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“It’s theoried that the Hanging Gardens of Babylon used aquaponics,” he said. The Aztecs’ flowing gardens also probably used the approach, a variation of which still is seen in rice paddies in Asia, where fish fertilize the rice in flooded fields, he said.

Even Egyptians in ancient times grew plants without soil, he added. “It’s a way to feed people with less soil and space,” he said.

Eric Highfield handles a plant he is growing in water at Santa Fe Community College.

Eric Highfield handles a plant he is growing in water at Santa Fe Community College.

Aquaponics is a marriage of hydroponics (growing plants in water without soil) and aquaculture (raising fish).

Highfield has what he calls a hobbyist’s version in his classroom.

Water circulates through a cylindrical tank where goldfish flit, then flows through trays filled with small clay stones anchoring an array of young plants growing under fluorescent lights.

With the high amount of nitrogen produced by the fish waste, greens do the best in the system – especially at a commercial scale. Nitrogen fuels growth of leaves, so herbs, lettuce, bok choy, cabbage and leafy greens like kale thrive, according to Highfield.

But small-scale growers can probably grow almost anything, except for crops that need an extreme pH, such as blueberries or some chrysanthemums, he said.

Once the system is set up, the only additional inputs are chelated iron and fish food, plus occasional replacement of water lost to evaporation, according to Highfield.

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Outside the classroom building, in what used to be a parking lot, is a geodesic dome greenhouse, built by about a dozen students during the fall semester from a kit produced by a company in Pagosa Springs, Colo.

“What you see didn’t exist four months ago,” said Highfield.

Come spring, the project, again with the help of 12-15 students who have already enrolled in his class, will be expanded to the 550 square feet of that building, with crops floating in tanks or vining through the air. His first set of students, Highfield said, came from all around New Mexico, as well as from Texas and Indiana.

The greenhouse’s design includes beeswax that responds to temperature, liquefying and solidifying, expanding and contracting, to adjust vents as needed to warm or cool the greenhouse. Its energy requirements are essentially for a pump to circulate the water and move oxygen through the tanks, he said.

And this is where Highfield gets really enthusiastic about the opportunities at SFCC – and he confesses he initially looked down his nose a bit when approached about working at a community college.

“This is an amazing place,” he said, noting that he can collaborate with faculty members involved with green building technologies, solar energy, biofuels and more to fine-tune his project. “When I saw and heard what was going on here, I was just blown away. I’ve attended universities that don’t have the programs you have here.”

He’s working with the people at SFCC growing algae, for example, to see if they can develop a fish food that relies on that nutrient, instead of grain, to help put more omega-3 fatty acids in the fish diet – and therefore boosting that nutrient in the fish themselves for later consumption by humans.

He’s aiming to raise tilapia, but he still faces a stumbling block. Highfield said he’s trying to work his way through the requirements of the Department of Game and Fish for permission to import a non-native species.

While tilapia are ideal fish to farm, because of their quick rate of growth and efficient conversion of their diet to flesh on their bones, Highfield said he can still launch the program with some other type of fish that is not restricted.

And he has plans, eventually, to build and move into an even larger greenhouse on the campus, he said.

“The field is really dynamic, with a lot of changes going on,” Highfield said of aquaponics. “There’s a lot of growth and a lot of interest right now.”

He found his own way to the field through a life-changing event. “I broke my leg terribly while snowboarding. I couldn’t walk for a year and had a quarter-million dollars in medical bills,” he said.

Long interested in aquariums, he looked around for what to do with the rest of his life and discovered aquaponics.

“I found my love,” he said.

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