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

Plants uptake nutrients and “clean” water with the support of beneficial bacteria that convert metabolites toxic to fish

Solids are removed from the systems or further mineralized Fish are fed and release nutrients into water

Aquaponics

Is a closed production system that integrates aquaculture with soilless culture (hydroponics)

Solid removal

Water returns back to fish

Aquaponics vs hydroponics

Plant trough

water line

pump Floating system

Substrate system

Fish tank

clarifier

NFT

Net filter

degassing units

• Hydroponics is by far the most productive system in agriculture

• Fertilizers supplied from separated tanks and added into the system

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

CropSoil ton/ha

Soilless ton/ha

soya 0.7 1.8beans 12.5 52.5peas 2.5 22.5wheat 0.7 4.6oat 1.1 2.8beets 10 30potatoes 20 175cabbage 14.7 20.3lettuce 10.2 23.7tomatoes 12.5 to 25 150 to 750cucumber 7.9 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)

1-5 5-10 10-15 15-20 20-25 >25 Salinity (ppt)

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

Plants and saltwater

Use of HALOPHYTES for: •  Food •  Animal feed •  Oil/fuel

•  Production can be higher in saline conditions than freshwater

•  Market potentials

1-5 5-10 10-15 15-20 20-25 >25

Salsola spp

Salicornia

Salinity (ppt)

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)

Seawater at 30 – 35ppt

Osmotic pressure

Body fluids at 10 ppt

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 Stress inhibitors/plant hormon inducers

(4) Use of resistant plants Use of resistant species/varieties Use of salt resistant roots and adopt the

grafting technology (wild species or GMOs)

commercial variety

Join

resistant variety

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 Raw

processed

biofuel

raw feed seed meal

•  Production with aquaponics is 5kg/m2 (9ppt – 1/3 marine salinity) up to 7 kg/m2 (18ppt – 2/3 marine salinty), higher than chemically fertilized hydroponics

•  Higher crude protein levels than chemically fertilized hydroponics

•  Same oil content

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

edpantanella@gmail.com