SALINE AQUAPONICS new pathways for food production E. Pantanella*, R.C. Bhujel Asian Institute of Technology (AIT) - Bangkok, Thailand
Presentation outline • Aquaponics and integrated aquaculture systems • Saline aquaponics/saline agriculture – Potentials for fish and plant integration – Management strategies – Potentials for business
• Conclusions
Aquaponics
Is a closed production system that integrates aquaculture with soilless culture (hydroponics) Fish are fed and release nutrients into water Solids are removed from the systems or further mineralized Plants uptake nutrients and “clean” water with the support of beneficial bacteria that convert metabolites toxic to fish
Water returns back to fish Solid removal
Aquaponics vs hydroponics • Hydroponics is by far the most productive system in agriculture • Fertilizers supplied from separated tanks and added into the system degassing units
NFT
Net filter
Fish tank clarifier Plant trough
water line
Substrate system
Floating system
pump
Aquaponics/soilless agriculture: advantages • 2-10 times more productive than soil • No use of external nitrogen fertilization • Complete reuse of water • Water use up to 10 times lower than soil • Organic crop management It is possible to grow plants in areas where traditional agriculture is impossible
Crop soya beans peas wheat oat beets potatoes cabbage lettuce tomatoes cucumber
Soil ton/ha 0.7 12.5 2.5 0.7 1.1 10 20 14.7 10.2 12.5 to 25 7.9
Soilless ton/ha 1.8 52.5 22.5 4.6 2.8 30 175 20.3 23.7 150 to 750 31.6
Aquaponics - Advantages • Contained systems from outer environment à lower pathogen risks à lower residues in fish • Optimal climatic control for fish than outer waters • Higher system resiliency due to presence of beneficial micro-organisms • Lower nutrients concentrations than chemical hydroponics, up to 10 times
• Up to date aquaponics has been mostly developed with freshwater
Potentials for Fish and Plant Integration
Aquaculture in the sea Cage aquaculture management is apparently easy … • No aeration like pond/tank • Environmental/sea conditions – Moorings/streams/tides /waves – Ruptures
• Pollution is not properly accounted • Competition with other water uses (tourism, navigation) • Fouling/manintenance • Parasites/health management/polluted water • Escapees
Integrated aquaculture in the sea Multitrophic aquaculture Use of fish, algae and molluscs • Management in open water • Pollution/evironmental risks (fishàenv, envàfish, escapees) • Partial reuse of nutrients • Easy management • Conflicts with other coastal uses
Integrated aquaculture on land Open systems
• Low nutrient levels (below 5-10 ppm) • Fish water and fish wastes integrate but not substitute common crop fertilization practices • Extensive/semi-intensive management – Horticulture, crops – Wetlands (land demanding) – Coastal restoration mangroves
Integrated recirculating aquaculture Partially closed systems • • • • • •
Full reuse of inputs and water Higher nutrient levels Higher environmental control Intensive management (higher productivity per acreage) Higher quality of productions (no residues) Lower health risks than open water (parasites, chemicals, pollutants)
Plants and saltwater HORTICULTURE / CROPS • Production of higher quality, but lower yields than freshwater • Tailored agronomic strategies are needed (follows…)
Cherry Tomato (pachino)
Cherry tomato production Increase of salinity in irrigation water at fruiting enhances: shelflife (thicker skin), higher dry matter, higher taste (sugar and acidity) Use of salt resistant varieties allows better growth 1-5
5-10
10-15
15-20
Salinity (ppt)
20-25
>25
Plants and saltwater Use of HALOPHYTES for: • Food • Animal feed • Oil/fuel
Salsola spp
• Production can be higher in saline conditions than freshwater • Market potentials Salicornia 1-5
5-10
10-15
15-20
Salinity (ppt)
20-25
>25
Halophytes – grain Quinoa Grain production up to 65% of plant weight. 2x proteins than wheat 2.5 MT/ha, very rich in Essential Amino acids Eelgrass (Zostera marina) comparable to wheat (starch 50%, protein 13%, fat 1%) • Palmer saltgrass (Distichlis palmeri) grow with hypersaline water (38– 42 PPT - above marine salinity).Flour similar to wheat but 8.7% protein vs 13.7%.- Proteins well balanced in ammino acids
Halophytes - grain • Pearl millet (Pennistum typhoides) tolerates irrigation of EC of 27-37 dS/m. (up 20 PPT – 2/3 of marine salinity) It can provide 1.6 MT/ha and 6.5 MT/ ha as fodder • Seashore mallow (Kosteletzkya virginica) can reach 1.5 MT/ha with water at 2.5% salt (25 PPT – 4/5 of marine salinity). It is high in protein (32%) and oil (22%)
Halophytes – leaf/fodder Kochia scoparia Seeds are eaten as a food garnish called tonburi. It is called "field caviar" and "mountain caviar" • used in traditional Chinese medicine. • useful forage for livestock Sea fennel Has a number of uses in the culinary field. Asparagus flavour. Contain about thirty essential oils, such as gamma terpins Atriplex triangularis (similar to spinach) Common purslane (Portulaca oleracea)
Algae for food May need a different management (ex. hybrid systems + sterilization) - Spirulina – rich vegetable protein (60~ 63 % 3~4 times higher than meat ) – multi Vitamins – Wide range of minerals – 5x more Vit A than carrots
- Clorella - other seaweeds for salads Sterile productions to comply with food safety regulations
Management strategies
Fish and salt water Some marine fish perform better at low salinity due to the lower energy energy needs to balance the osmotic pressure • European seabass can grow with low salinity (5-7 ppt – 1/6 of marine salinity) • Barramundi can grow with freshwater • Seabream can grow at 10 ppt (1/3 of marine salinity)
Body fluids at 10 ppt Osmotic pressure
Seawater at 30 – 35ppt
Strategies in horticultural plant management (1) modulate the environmental conditions Climatic control to reduce evapotranspiration Flushing (2) Improved delivery of nutrients Higher nutrient concentration Different ion settings (3) Uses of anti-stress factors Vitamins/Antioxidants commercial Stress inhibitors/plant hormon inducers variety (4) Use of resistant plants Join Use of resistant species/varieties Use of salt resistant roots and adopt the resistant variety grafting technology (wild species or GMOs)
Business potentials
Salsola Salsola spp is widespread in the world – In Italy and Japan is a high-value salad – In the Middle East is a native plant that can be used as fodder • In Italy it is worth 2.4 $/kg at wholesale markets up to 5.8 $/kg for off-season retail markets • Production with aquaponics is 2 kg/m2 (20ppt – 2/3 marine salinity) up to 5 kg/m2 (10ppt – 1/3 marine salinity) every 28 days • Production is higher than chemical hydroponics
Salicornia • Production with aquaponics is 5kg/m2 Raw 2 (9ppt – 1/3 marine salinity) up to 7 kg/m (18ppt – 2/3 marine salinty), higher than chemically fertilized hydroponics • Higher crude protein levels than processed chemically fertilized hydroponics biofuel • Same oil content
raw feed
seed meal
Seabeet (chard) Saltwater enhances plant taste • At 10 ppt (1/3 marine salinity) yields are 50% lower than those under optimal conditions such as freshwater hydroponics (FH). • But plants can be planted at higher density to get closer production to FH • At 3.5 or 7 ppt yields are almost similar to FH
Sweet basil • Tailored growth strategies must be adopted for salinity (climatic control, double planting density, conditioning) • 20-35% lower yields than freshwater hydroponics (2.1-2.5 vs 3.2 kg/m2 every 28 days) • But plants give 30% more leaves (leaves are the commercial part of basil)
Conclusions/remarks • Saline aquaponics is a viable production system in arid or salt affected zones • Horticultural plants can be cropped in saline conditions providing that appropriate agronomic strategies are used • Aquaponics may need to be adapted to different design • Lower production but quality is enhanced
thank you for your attention
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