Tilapia Powered Aquaponics to Optimize Land and Water Use for Safe Food Production from the Rooftop
Abstract
Tilapia powered vertical aquaponics system (TPVAS) is an effective way to increase crop production in a food desert city per unit rooftop area by extending crop cultivation into the vertical dimension to feed the ever-increasing population of the world and keep the city-pollution free and cooler. Experiments conducted over the years to assess the viability of tilapia powered lettuce, strawberry, water spinach and mint production in the media-based vertical aquaponics system at the rooftop and lab of Bangladesh Agricultural University, Mymensingh, Bangladesh. The wastewater of the tilapia tank irrigated to the 4 feet height and 3-4-inch diameter vertical plastic pipes holding 15 to 18 saplings in each pipe which passing through the coco dust, coco coir, water hyacinth root, and brick chips media then return into the fish tank again. Fish growth performances, nutrients availability, and their use assessed. The mean length and weight gain of tilapia were 2.95 (±0.83) to 11.77 (±2.49) cm and 32.71 (± 9.43) to 170.38 (±78.7) g. The feed conversion ratio (FCR) were 2.5, 2.35, 2.33 and 1.5 and survival rates were 96, 78, 85 and 98.33% for lettuce, strawberry, water spinach and mint based tilapia aquaponics systems. The fish and vegetable production was 30.64 to 135.20 and 12.47 to 123.25 MT/ha/90 to 120 days respectively. Among the four media, coco coir produced the highest crop than the others.Therefore, it is concluded that the TPVAS is suitable and capable of producing fish and vegetables at the rooftop keeping the rooftop cooler and greener than nearby traditional roof gardening buildings.
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Introduction
The world population will reach 9.6 billion by 2050, 34 percent higher than the present population. Most of the population increase will occur in developing countries like Bangladesh (Kodmany, 2018) where agricultural land is shifting to other uses day by day. Global food production will face great challenges in the future as the rice-growing field has decreased by 18% from 1971 to 2015 (BBS, 2016; Christine and Gruda, 2015). Moreover, the natural calamities like cyclones, tornadoes, droughts, floods and river erosion destroys a significant amount of crops each year that threatened food security in the country. In addition, huge demand for seeds and fertilizers, higher transport costs, burning fossil fuel, and climate change impact are responsible for price hick of agricultural commodities in the country (Hugh, 2016) The scientists emphasized to grow food in the cities at the vicinity of the consumers to cut the transport costs and address climate change impact (Paxton, 1994; Wakeland, 2012).
Bangladesh is one of the world's leading fish producing countries with a total production of 4.134 million tons, where inland fisheries contributed 82.26% comprising 29.34% from capture fisheries and 52.92% from aquaculture (DoF, 2018). The fisheries sector plays an important role in lessening malnutrition, earning foreign exchange and improving the socioeconomic status of the rural small farmers of Bangladesh (Uddin and Farjana, 2012). Fish supply 60% animal protein to the countrymen and support the livelihoods of 11-12% fishermen (FAO, 2012). The country ranked 3rd place among the inland water fish producing countries and 5th in aquaculture (FAO, 2018). The farmers expanding aquaculture activities horizontally not addressing the environmental pollution and shortage of land (Marco and Kuenzer, 2016). In such a situation, environmental engineering and eco-friendly farming the “Tilapia Powered Vertical Aquaponics System” (TPVAS) can a substitute to resolve the problems (Katy, 2019). The TPVAS has been increasing popularity as a way to reduce the need for arable land and grow crops where they are to be consumed. When farming indoors, on rooftops and balcony in a closed or semi-closed environment, the plants are protected from the bad weather, insects, and pests (Liu et al., 2016). There are no losses of nutrients in closed systems and water use is less in comparison to traditional farming
Conclusion
Vertical aquaponics system proved highly successful in producing vegetables in a small area even from the rooftop. With the shortage of suitable farming land in urban sprawl, rooftops are progressively being seen as a reasonable place for producing food and make the building a sustainable food production unit in the future for cities. Like most of the cities in our country an abundance of fallow rooftop places are prevails. The present experiment used four different types of vegetable tilapia in vertical aquaponics system which performed well; nevertheless, water hyacinth root performed better thanthe coconut coir, coco fiber and brick chips. The system efficiently recycles the fish tank wastewater and uptake nutrients to grow crops compared to the conventional system, therefore, the vertical aquaponics system could potentially help to enhance food and nutrient security and reduce pressure on land resources. In this amazing food growing technology, the fish acts as the powerhouse of vegetable production. Aquaponics already proved as a green, sustainable and eco-friendly food growing technology, hence, vertical aquaponics will be able to feed the 21st century’s 8.3 to 9.0 billion people and safeguard the environment for the future generation.