By 2050, the world population will reach nearly 9.5 billion, which effectively means that we have to produce 70% more food for over two billion additional mouths. Hence, the food and agriculture systems need to adapt fast to the changing climate and become more resilient, productive and sustainable.
A plant consumes more water to produce food compared to us to survive in a day. As a matter of fact 15,000 litres of water is needed to produce one kilo of meat. This is why, with a growing population increasingly changing its diet towards 'water-hungry' products, all efforts must be made to improve the way we use water in agriculture to make the best out of the limited water resources. Aquaculture is one of the important source of protein production and accounts for almost one-half of the fish eaten globally. Aquaculture has the potential to decrease the pressure on the world’s fisheries and to significantly reduce the footprint of less-sustainable terrestrial animal farming systems in supplying humans with animal protein. However, two aspects of aquaculture may be addressed to improve the sustainability of this agricultural technique. One major problem for the sustainability of aquaculture is the treatment of nutrient-rich wastewater, which is a by-product of all the aquaculture methods mentioned above. Depending on the environmental regulations set by each country, farmers must either treat or dispose of the effluent, which can be both expensive and environmentally harmful. Without treatment, the release of nutrient-rich water can lead to eutrophication and hypoxia in the watershed and localized coastal areas, as well as macroalgae overgrowth of coral reefs and other ecological and economical disturbances. Growing plants within the effluent stream is one method of preventing its release into the environment and of obtaining additional economic benefits from crops growing with costless by-products through irrigation, artificial wetlands, and other techniques. Therefore, as a catalyst of crisis and food insecurity; an aquaponics system will serve the purpose of producing food for a sustainable future.
What?
Aquaponics is the integration of aquaculture and hydroponics, a soilless culture of growing crop. Aquaculture is the traditional way of culture of aquatic organisms. As soil provides nutrients to the crops grown. A plant can be nourished If nutrients for its growth can be provided through water. Thus, the concept of aquaponics came into the picture. In an aquaponic system, nutrient-rich fish culture water from fish tanks is used to provide plant food to vegetables and herbs grown in soilless system. Nitrifying bacteria in the soilless system converts ammonia and other toxic pollutants to an usable form of nutrients to be taken up by the plants. There are three general types of aquaponics systems: raft or deep water culture system, nutrient film system, and a system based on media-filled bed system. Raft culture typically is preferred for commercial operations, while the nutrient film systems are restricted to light weight leafy green vegetables. Media-filled beds are commonly used for home-based aquaponics gardening and require lower stocking rates than those used in raft systems.
Why?
Increasing population, shrinkage of land and scarcity of water approaches us to justifiable use of ever decreasing land and water resources. Therefore, an aquaponics system will be an effective method to fulfill our food and nutrition requirement.
Benefits:
In an aquaponics system no fertilizers, pesticides and herbisides are required as in a traditional way of culture of aquatic plants, animals and normal plants grown in the soil. Thus, it is a sustainable and intensive food production system having one nitrogen source and create less waste compared to traditional system of culture. In this system fish and plants can be grown almost anywhere, including warehouses, roof tops and basements.
Do it yourself- facts:
If we are planning to start a small scale aquaponics system at home, following are the points to consider:
1. Selection of tank: A tank is a crucial component in an aquaponic system. A round tank with flat or conical bottom is recommended as they are easy to clean. Durability and inertness of tanks is also a parameter to be considered.
2. Aeartion and water circulation: Optimum level of dissolved oxygen concentration (5-6 mg/L). Proper water circulation from the fish culture tank to plant culture bed and plant culture bed to fish culture tank keep animals, bacteria and plants healthy.
3. Water quality: Proper maintenance of key water quality parameters, viz; dissolved oxygen, pH, temperature, total ammonia nitrogen and alkalinity are essential in any aquaponic system.
4. Stocking density: An aquaponic system will be easier to manage and will be insulated against shocks and collapse if the stocking density is kept at optimum level. The recommended stocking density is 20 kg/1,000 litres, which will still allow for substantial plant growing area.
5. No overfeeding and removal of uneaten food: Feeding everyday to fish is essential for its good health and proper growth. But overfeeding can be avoided. Wastes and uneaten food are very harmful for aquatic animals because they can rot inside the system. Rotting food can cause disease and can use up all of the dissolved oxygen.
6. Selection of plant: Generally light weight leafy green plants viz; coriander, pepper etc. are extremely good to be grown in an aquaponic system.
7. Balance between plants and animals: Using a batch cropping system can help keep a steady harvest of both aquatic animals and vegetables to keep a consistent production level and maintain a constant balance between fish and plants.
Construction:
Some of the accessories required for a simple roof top small scale aquaponics system are:
1) Small plastic tank (cap:50 l) for fish culture, 2) Small plastic tank (cap:50 l) for plant bed filled with media (e.g., scrubber used for washing utensils) to support plant and substrate for nitrifying bacteria, 3) water pump 4) PVC pipe (dia: 12 cm and length as required), 5) PVC tubes (dia: 12-75 cm and length as required), 6) wooden table or platform made up of bricks to keep plant culture tank over it for gravity flow of water to fish culture tank and 7) electrical connections. The approximate cost of the above items may work out to be INR 5,000.