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| Native plant species and amphibians exist symbiotically in a pond system. Photo By: Kaz Thomas |
By: Kaz Thomas
Aquaponics, a system of using fish or other aquatic species to grow alongside plants, has numerous potential benefits for agriculture in Georgia.
The practice combines aquaculture, which is raising fish in tanks, with hydroponics, raising plants in water. This system of agriculture has existed for a long time, with some examples being East Asian rice paddies benefitting from wild fish, and Aztec floating plant islands.
The process reduces water loss and nutrient runoff by creating a semi-closed ecosystem modeled from wild pond environments, which often have fish and aquatic plants living symbiotically. Symbiosis is a relationship between two species that benefits both.
Researchers at Georgia Southern University’s Sustainable Aquaponics Research Center are streamlining the process to discover efficient and sustainable ways to raise both plant and animal products.
“You feed the fish…it can be done with crustaceans as well. And then their waste goes directly into the water, and you have plants that have their roots suspended in the water,” said Brigette Brinton, the curator of SARC. “They absorb the nutrients and then of course grow really well because they have ready access to the nutrients and are well taken care of.”
The fish benefit as well, with contaminated water being naturally filtered by the growing plants. “That of course removes anything that would generally harm the fish, like the excess nutrients or ammonia from their waste, and so the water can cycle right back to the fish”, Brinton said.
SARC uses a 4,000-square-foot greenhouse to set up systems of both aquaponics and hydroponics.
There are several types of aquaponic systems, with three being Media Bed, Deep Water Culture (DWC) and Nutrient Film Technique (NFT).
Media Bed prioritizes a layer of rocks or soil for plants to root into, using embedded PVC pipes to provide nutrient-rich water flowing through the media. The technique is relatively simple and can be used by backyard gardeners.
Deep Water Culture uses a large water tank and floating rafts which plants grow on, with their roots suspended in nutrient rich water. SARC implements this technique with fish to aid nutrient production.
Nutrient Film Technique is similar to Deep Water Culture, with plant roots suspended in water. However, these plants are arranged in a vertical shelf with PVC pipe pumping through smaller, water-filled platforms.
Many edible plants such as lettuce, cucumbers and tomatoes can be grown using aquaponics. SARC partners with the Armstrong Southern Café to provide fresh vegetables for salads and sandwiches.
The long-term goal of SARC is to provide sustainability on the Armstrong campus and to act as a place of interdisciplinary research for students and faculty members.
The center also partners with nearby schools to educate students about aquaponics and more efficient methods of growing crops.
Dave Davies, the owner of Georgia Aquaponics Produce LLC. has a commercial use for the agriculture system. The business grows and sells aquaponic produce from DWC tanks, which Davies described as “A premium product. It's organic, and it tastes amazing, but it is twice as expensive.”
Aquaponics for commercial use have noticeable differences from research settings, primarily in costs. “Water is a minor cost because you only use 5% of the water that you would normally grow a crop with,” Davies said. The type of crop being grown is important, since it may require additional nutrients that the local water source cannot provide.
The largest cost is labor, which according to Davies, is “stopping it from taking off” in Georgia. “Most commercial growing operations now are mechanized, you put a tractor in and you plant 100 acres in a day. Aquaponics is very labor intensive,” Davies said.
Each system can be used efficiently, but the species within them are important. Smaller plants tend to do better in smaller systems, such as NFTs and Media Beds, while larger plants are best used in DWCs.
Improper PVC filtration can result in clogging from plant roots, underpowered water cycling and temperature fluctuations resulting in the loss of crops.
The balance of species and space is crucial in aquaponic systems, and too many of one or the other can result in failure.
“They grow too many fish and they don't have a big enough area to grow plants. What happens is that ammonia builds up in the tank because it's not being used,” said Davies. “It goes from ammonia, to nitrite to nitrate and there's not enough area for the plants to use all the ammonia that has been produced by the fish. Then the fish die, and the plants die.
Aquaponics has the potential to make gardening and farming in Georgia more efficient and sustainable. Further education, partnerships with schools, and workshops are the key to making the system more widespread.
“We need to start making people aware and start getting it sorted out because it is the future,” Davies said.
Extended research can result in higher yields of crops, efficient management of environmental challenges and deeper understanding of water ecology.