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Aquaponics has been used successfully in a wide range of locations. Moreover, aquaponic techniques have been revised to meet diverse needs and goals of farmers beyond the common IBC or barrel methods (described throughout this publication). There are many examples, but these were chosen to highlight the adaptability and diversity of the aquaponic discipline.
A pilot-scale aquaponic system was built in Myanmar to promote micro-scale farming during the implementation of an e-Women project funded by the Italian Development Cooperation. The goal was to create a productive unit under low-tech and low-cost criteria by using locally available materials and stand-alone solar energy. The system hosted tilapia and a wide range of vegetables (Figure 9.17). The system was used for the development of a cost-benefit analysis, inclusive of depreciation, for household- scale systems with the objective to meet the daily income target of USD1.25 set by the Millennium Development Goal.
Using local prices, a 27 m2 aquaponic system placed within a bamboo net house and powered by solar panel costs USD25/m2. This system provides a net profit of USD1.6- 2.2/day from vegetables, and a daily ration of 400 g of tilapia for home consumption. The payback period is 8.5-12 months depending on the crops. The net house prevents any need for pest control and avoids seasonality by securing income against adverse climatic conditions (rain). Fry nursing, very common among farmers in Southeast Asia, could be another interesting option in aquaponics to further boost incomes in poor or landless households.
This pilot project showed that aquaponics could play an important role in securing food and livelihood in many areas across the world. The production of fish and plants with small plots allows vulnerable people to produce income, adds value to household work and empowers women at community level.
The integration of marine or brackish water aquaculture with agriculture provides new ways to produce food in coastal or saline-prone areas where traditional farming cannot be developed. The inland culturing of aquatic animals, beyond the environmental benefits derived from pollution or landscape restoration, is beneficial for the greater control of the production factors and the reduction of the risks related to contaminants or pathogens. Even though saltwater is not ideal for plants, as it creates osmotic shocks, limits growth and procures sodium toxicity, it is still possible to grow some useful plants in lower salinity.
A wide range of plants can benefit from the nutrient-rich water obtainable from aquaponics or closed recirculating systems. Halophytes (salt-tolerant species) can boost food output in arid and saline areas and raise farm productivity. Some species are highly-valued speciality crops, such as Salsola spp. (Figure 9.18), sea fennel, Atriplex spp. or Salicornia spp., while other are cropped for grains, such as pearl millet, quinoa and eelgrass, and still others can be grown for biodiesel. Ideal saline conditions for halophytes are in the salinity range of one-third to one-half of sea strength, but some plants are tolerant to hypersaline conditions.
Adapting horticultural plants to saline water is one of the greatest challenges of modern agriculture. However, it is possible to grow some horticultural species directly with brackish-water. Most of the plants belonging to the Chenopodiaceae family (beet, chard) can easily grow in a salinity of one-sixth to one-third of sea strength owing to their higher resistance to salt (Figure 9.19). Other common species such as tomato and basil can achieve substantial production up to one-tenth of sea strength (Figure 9.20) providing that tailored agronomic strategies are adopted: increased concentrations of nutrients, plant bio-conditioning, grafting with salt-tolerant rootstocks, improved climate control and higher planting densities. Nevertheless, the qualitative traits of saline crops are higher than freshwater, both for their organoleptic characteristics, taste and shelf-life.
There is an aquaponic technique from Indonesia that deserves special attention. In Bahasa Indonesia, this technique is called bumina and yumina, translated literally as "fruit-fish" and "vegetable-fish". This name demonstrates how intimately linked the plants and the fish are within an aquaponic system. Bumina and yumina are essentially a version of the media bed technique.
The fish are housed within an in-ground pond dug into the earth and lined with sandbags or hollow-form bricks. This pond is lined with a tarp, or better, a polyethylene liner. The liner is necessary to prevent unwanted biological and chemical reactions occurring within the sediments on the bottom and helps to keep the system clean. Alternately, the fish are housed within a raised concrete cistern. Water is pumped out of this pond into a header tank, usually constructed out of a large plastic barrel. This barrel can contain mechanical and biological filter material if the stocking density is high enough to require it. From this header barrel, the water is fed, by gravity, through a distribution pipe. The entire pond is lined with satellite pots, simple flower pots or other small containers that are full of organic growing media. The distribution pipe lays atop these satellite pots and water is delivered through small holes. The water irrigates and fertilizes the plants in these pots, and then exits the bottom of the pots back into the fish pond (Figure 9.21). The cascading water effect also helps to aerate the fish pond.
Bumina and yumina are used as an important component of homestead food security initiatives throughout Indonesia aimed at increasing home protein production. The initial investment of these systems is smaller than that of the IBC systems outlined in this publication, but they require an in-ground pond so are inapplicable for some urban, indoor or rooftop applications.
Source: Food and Agriculture Organization of the United Nations, 2014, Christopher Somerville, Moti Cohen, Edoardo Pantanella, Austin Stankus and Alessandro Lovatelli, Small-scale aquaponic food production, http://www.fao.org/3/a-i4021e.pdf. Reproduced with permission.