Introduction to Aquponics An Integrated Fish and Plant Production System
Aquaculture Aquaculture -- also known as fish or shellfish farming -- refers to the breeding, rearing, and harvesting of plants and animals in all types of water environments including ponds, rivers, lakes, and the ocean.
What is Hydroponics? • Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil.
What is Aquaponics? Aquaculture + Hydroponics = Aquaponics Combined production of fish and hydroponic plants in a recirculating aquaculture system
Why Aquaponics? • Advantages • Plants use nutrients from fish waste to produce a marketable product • Hydroponic plants act as biofilter • Integrated systems reuse nutrients and conserve water (up to 98% less water than conventional farming) • Disadvantages • Requires knowledge of fish and plant husbandry • Requires commercial fish diet and reliable energy source • Moderate initial capital costs for system construction
Stocking and Harvesting Drain and harvest tank 24 weeks later Average weight 700 – 750 grams/fish Survival greater than 95% Staggered production Allows a tilapia harvest every 6 weeks A total of 2 harvests from each tank/year Tilapia production
What do fish need? • Food-Feed a floating diet with 32% protein 3 times/day • Achieve daily feeding rate of 60 – 100 grams of diet/m2 of hydroponic growing area/day • This is optimal amount for plant production, balances the system, and minimizes water quality problems • Aeration-Fish are animals and need oxygen • Several airstones/tank • Pump to circulate water • Clean Water-Fish can’t be left to float in their wastes. • They emit ammonia from their gills and create solid and liquids waste filled with ammonia
Feeding a Fish Tank Marketable Nile tilapia Tilapia Production
Plant Requirements • Light • Oxygen • Temperature • Indoor production is climate controlled • Outdoor production is dependent on the season • Adequate Spacing • Crop Dependent • Protection • Wind protection • Control of pests
Plant Requirements • There are 16 essential macronutrients and micronutrients for plant growth • Macronutrients • N, P, K, • Micronutrients • Ca, S, Mg, B, Cl, Cu, Fe, Mo, Mn, Z • There are recommended ranges for aquaponic and hydroponic vegetable production • Typically aquaponic nutrient levels are lower than recommended hydroponic nutrient levels • Possible because fish are always creating effluent that passes through hydroponic raceways
Nitrogen Balance • The main nutrient that we monitor in our system is nitrogen. • There are 3 kinds of nitrogen that occur in aquatic environments: • Ammonia • Nitrite • Nitrate • We want to limit the amount of Ammonia (<1 ppm) and Nitrite (< 5 ppm) • Nitrates are not as harmful to fish and should be 100-150 ppm.
pH Balance • Must compromise pH for fish, plants and biofiltration • Fish prefer 7.5 – 8.5 • Plants prefer 6.0 – 6.5 • Nitrifying bacteria prefer 7.0 – 8.0 • Maintain aquaponic system pH at 7.0 • Calcium hydroxide [Ca(OH)2] and potassium hydroxide (KOH) increase pH when it falls below 7.0 • Calcium hydroxide and potassium hydroxide added on alternate basis until pH returns to 7.0
Why is Aquaponics Better Than Hydroponics? • In Hydroponics, humans have to recreate the nutrient environment needed to grow plants. • Nutrient concentrations decline over time and have to be re-added. • In Aquaponics, the nutrients are provided and recycled through the system (i.e. fish poop).
Nutrient Supplementation • Tilapia effluent provides adequate levels of macronutrients and micronutrients, but supplementation of calcium, potassium and iron required • Calcium supplemented with addition of calcium hydroxide • Potassium supplemented with addition of potassium hydroxide • Iron supplemented with the addition of chelated iron to maintain concentration of 2 mg/L
Plant Production Methods • Batch Culture • One planting and one harvest of aquaponic system during plant production period • Can quickly deplete nutrients as plants mature • Staggered Production • Multiple plantings and harvests on a rotational basis • Prevents quick nutrient depletion • Allows uniform nutrient uptake
Principles to Remember • Staggered fish and plant production maintains a balanced nutrient concentration in the system • Optimum fish feeding rates prevent nutrient accumulation or deficiency • Base addition maintains optimal pH and supplements nutrients • Be vigilant in preventing, recognizing and treating plant pests/disease