What you can expect from an iAVs.

The legacy of iAVs being the subject of properly constituted research trials is that we have so much validated information available on the method…something that’s not available for most other growing systems.

Remember, the numbers cited in this article are baseline benchmarks…dating back to the mid-1980s.

Imagine what they’d look like if they reflected modern cultivars and culture methods.  An even better idea would be to skip the imagination and build your own iAVs.  Seeing is believing!

Anyway, In the meantime…

Food

  • Yields attained in Raleigh, NC indicated that this automobile-sized space could produce 150 kg of fish and 1,100 kg of vegetables per year which assumes a periodic harvest as both the fish and vegetables reach an appropriate size…an average of 3 kg (7 lb) fish and 21 kg (46 lb) vegetables each week). 1
  • iAVs has the capacity to produce fish and fresh vegetables sufficient to provide a family with 200 kg of fish and 1,400 kg of vegetables (fruit) per year in a footprint equal to an automobile parking space. 1
  • Each 1.0 kg of fish weight gain provided sufficient quantities of all required plant nutrients to sustain 2 tomato plants yielding 5-7 kg of fruit per plant over 3 months.
  • Tomato yields exceeded 6.8 kg (15 lb) per plant.

Water Use

  • The rate of water input (replacement of evapotranspiration losses) in the IAVS technique ranges from 1 to 3% of system capacity per day.
  • The IAVS technique requires only 11 cubic meters of water per year for each 1.0 cubic meter of syste capacity (at a 3% per day rate of loss).
  • Depending upon the crop, season, and the biofilter to tank volume ratio, this technique permits from 120 to over 300 crop applications with each unit volume of water.
  • Each litre of water employed can produce, in fish and fruit, 0.7 grams of protein,7 kilo-calories food-energy, and most essential vitamins.
  • The water efficiency of iAVs is at least 13 times that of UVI raft (DWC) aquaponics – and that doesn’t even account for their failure to factor rainwater into their water use data.
  • Including annualized losses for evapotranspiration and incorporation into biomass (food) at 85% of total input and a seepage loss of 6%, each litre of water utilized by the IAVS technique can produce 6 g FW of fish and 17 g DW of vegetables.
  • Collectively, tilapia and tomato yields result in 0.7 g DW of protein and 7 Cal. (or 7,000 calories) per litre of water used.

Component Ratio

  • As the size of the biofilter per fish tank volume is increased, the yield of tomato (for example) decreases from 27 to 19 kg per square meter per crop, but the fish grow 20% faster. This results from a reduction in nutrient availability per plant but an increased filtration capacity (cleaner water) for return to the fish with increasing biofilter size (increasing plant number).

Energy Use

  • The sum of the water pumping intervals in the technique developed at NCSU is less than 2 hours per day. The energy demand of this technique is approximately one-twelfth the energy requirement of other recirculating aquaculture techniques.

Fish and Fish Feed

  • Each kilogram of feed input to the system will result in the production of approximately 0.75 kg of fish and 6.70 kg of fresh vegetables.
  • Fish yields ranged from 50 to 70 kg per cubic meter of water per year (0.41 to 0.57 lb/gal/yr).
  • Feed conversion ratios for fish of average market size (0.25 kg) ranged from 1:1.1 to 1: 1.3.

Notes:  

  1. Some numbers…for example, those relating to the ‘Carpark Model’…may seem at odds with each other.  The lower figures relate to low-tech applications…like those typically found in remote villages…where the higher figures apply to medium-tech situations.
  2. iAVs has never been optimised.  The research trials sought to achieve two goals…to prove the concept (the Proto ’86 trial)…and to establish the relationship between the fish tank and sand biofilter volumes (the Ratio 411 Trials).  These metrics are simply the outcome of those trials…and provide a performance baseline.  The production outcomes were exceeded by Boone Mora and Tim Garrett in the USDA-funded Commercial iAVs Trial…and, it’s reasonable to expect that they will be exceeded by other operators as more is learned about the method.

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