Aquaponics is a relatively new cultivation technique that combines the practice of aquaculture (raising fish) with hydroponics (growing plants without soil using a nutrient solution). Aquaponics utilizes symbiotic relationships found in nature where microorganisms break down organic elements into forms that are easily assimilated by plants. Fish create ammonia as a waste product where a majority of it is excreted from the gills from the process of removing oxygen from the water. The rest is released through the fish’s urine and fecal waste. Ammonia is highly toxic to fish and high levels can lead to skin ulcers and death. In traditional Aquaculture, large amounts of fish are kept in relatively confined quarters and the water is exchanged regularly throughout the day to prevent buildup of toxins that can lead to fish mortality. In order to do this, Aquaculture facilities are located next to available sources of fresh water and sometimes even in the flow of water current. Some common problems that arise from this are the continual need for large amounts of fresh water to maintain water quality as well as downstream pollution from the waste generated from the high populations of fish. This can lead to Nitrate pollution and algae blooms which take up the available oxygen in the water and can lead to die off of downstream native fish or water life.
Hydroponics is an innovative growing technique that utilizes nutrient rich water delivered to the plants roots which are commonly supported in an inert (no nutritional value)media such as Coco, Peat, expanded clay pellets, lava rock, recycled glass, etc. The nutrient solution is prepared using chemical fertilizers and is typically recycled over the course of a week as the plants remove the nutrients they need for growth from the solution. During this time, the plants may take more of some nutrients and less of others which can lead to an imbalance of ratios that are ideal for plant growth. After a week, it is common for the nutrients to be disposed of and a new solution of properly balanced formula prepared and used. This can seem wasteful and with the cost of petroleum based chemical fertilizers on the increase, unsustainable.
Aquaponics is unique in that it addresses and solves the issue of waste produced by the fish and the amount of water needed to maintain quality as well as the wasting of nutrients and chemical dependence in hydroponics. Aquaponics utilizes nitrifying bacteria (Nitrosomonas, Nitrospira sp., and Nitrobacter) to convert the ammonia created by the fish first into Nitrite, which is still highly toxic to fish, and then into Nitrate, which is only toxic to fish at high levels. This process of biological conversion produces Nitrogen, one of the primary nutrients required by plants for growth. The feed used in aquaculture is also a source of other nutrients such as Phosphorous and Potassium as well as trace elements such as Calcium, magnesium, boron, etc. The nutrient rich water is then passed through the roots of the plants, where the elements are removed by them for growth, and the filtered water is then returned to the fish to repeat the process, creating a recirculating organic system. In this environment, there can be no use of chemicals or pesticides to treat the fish or the plants as they would have adverse effects on the other. This promotes the potential for a totally organic system, which is highly desirable in today’s market. Additionally, due to the recirculating properties of Aquaponics, there is a minimal amount of water loss, primarily from plant transpiration and evaporation. Due to this, the amount of water used for cultivation is greatly reduced and only and 1/8th of the water used for soil grown crops is needed. This makes the viability of Aquaponics in arid regions and areas with little fresh water resources greater and both vegetables and fish as a protein source can be used to feed the community. So, with water conservation, multiple crops and organic production, Aquaponics is quickly gaining attention as a solution to the world’s current food availability problems.
The concept of Aquaponics can be traced back to the ancient Hanging Gardens of Babylon, built by King Nebuchadnezzar II for his wife who was from a fertile mountainous region to help assuage her feelings of homesickness. Water from the Euphrates River was delivered to the top of the gardens where it was allowed to flow through irrigation canals to water the plants and trees of the garden. 1000 years later, the Aztec Indians in the Valley of Mexico used floating rafts on shallow lake beds to grow crops for food. Called ‘Chinampas’, the rafts were layered with soil and designed to absorb the water from the lake to irrigate the plants. In Asia, rice paddies were commonly grown with fish to help fertilize the crops. Both the Hanging Gardens of Babylon and the Chinampas of the Aztecs were cultivation techniques that used fertile water to grow plants in ways different from conventional soil grown practices. The Aquaponics of today was rediscovered and developed in the mid 80’s at the University of the Virgin Islands in St. Croix by Dr. James Rackocy as a way to treat the effluent produced from intensive fish culture. Due to the unavailability of fresh water, methods were devised to treat the water from the fish by using plants as a bio filter, and it was discovered that the plants responded quite well, so well in fact, that the plants proved to be a better source of income than the fish and the concept of current Aquaponics was born. While still in its infancy, Aquaponics is steadily gaining ground as the cutting edge in water conservative organic cultivation techniques and is being embraced by people around the world as a viable aid in the ever growing food crisis.