Aquaponics, the combination of hydroponics and aquaculture, is working its way on to the University’s campus as the greenhouse attempts to expand its newest program. As the University strives to become a more green and sustainable campus, aquaponics may be the next step toward this goal.
Hydroponics, the study of growing plants without soil, and aquaculture, the farming of fish or other aquatic organisms, are efficient methods of producing both plant and fish crops, according to a study conducted by Iowa State University professor D. Allen Pattillo.
The University greenhouse is home to different species and biomes, but its newest addition includes tanks of fish, pumps and crops. Kevin Neves, the University biology instructor, started this system in fall 2016 when he arrived on campus along with two other students. He has been working in aquaculture for 15 years, and in the three years before coming to the University, he was working on an integrated multi-trophic aquaculture setup in Maine.
“In a standard aquaculture operation, you’re growing fish and you’re feeding the fish. Fish produce waste, and we need to deal with that waste in one form or another,” Neves said.
The greenhouse aquaponics system currently has two tanks full of yellow perch, which are fed standard fish food. The perch grow to about 10 or 12 inches, the standard to sell them for consumption. Next, all the feces and uneaten food go into another tank filled with freshwater shrimp and an orange mesh that allows bacteria growth.
The shrimp then take the ammonia fish produce and convert it into nitrate, which is a type of plant fertilizer. The nitrates travel through pipes into floating beds in which plant roots grow into water. Most of the water then is drained out and pumped back into the yellow perch tank.
Plants being grown from this system include kale, spinach and a few experimental plants, such as tomatoes. Neves first tried to grow thyme and lettuce, which failed in the system.
“It’s environmentally friendly, it’s sustainable, everything looks good and it has so little impact on the environment,” Neves said.
This system is low maintenance, only requiring those who maintain it to feed the fish, and occasionally add a few gallons of water to the system as water evaporates in the greenhouse.
Frank Schemenauer, a horticulturist for the greenhouse, became involved with the project after he discussed the possibility of housing the aquaponics system with Neves. Schemenauer focuses on logistics and input during assembly, assisting students growing plants for and within the system and troubleshooting potential pest problems for the plants.