If there’s one thing that aquaponics is short on, it’s verifiable data.
Unless, of course, you happen to be talking about iAVs.
Notwithstanding serial demonstrations of concept spanning 20(?) years, there isn’t even much available ‘data’ on the UVI raft system. (yet to see any two start-date claims that agree, ranges from 1987 to 2001. iAVs began July 1984, registered Sept. 1985).
Anyway, we thought it might be interesting to use what we could find to compare the UVI system with the iAVs.
Premise:
The graphic presented below compares the concluding UVI report with the 1980’s iAVs data in several key productivity metrics, each of which clearly differentiates (distinguishes) the efficacy of the iAVs approach from the UVI/DWC method.
The UVI ‘data’ (reported result of a trial) applied in the below comparison is, to our knowledge, the ‘best’ production result obtained at UVI in 25 years of repeated one-off trials.
The Lo-tech iAVs data (values below) were derived (reduced by 40%) from the mean productivity at four tank to filter volume ratios (16 ‘systems’; 4 ea. at 4 v:v ratios). These experiments were conducted in the late 1980’s at a relatively low stocking density with ‘male’ tilapia which benefited from forced aeration. The chosen 40% reduction is intended to suggest a reduced yield rate in the absence of electrical powered aeration. Alternatively, with forced aeration and/or at greater stocked densities, the Lo-tech iAVs results would be significantly greater than indicated in the bar graphs.
The Hi-tech iAVs yields (below) reflect a 10% reduction of yield resulting from the USDA-sponsored iAVs Commercial-scale Demonstration Project conducted in 1992-93 by Dr. Boone Mora and Tim Garrett (both novice growers/managers).
All calculations (from an Excel spreadsheet, not shown) were premised on (derived with) the fish grow-out tank(s) set at identical volume. Lighter color bar extensions to indicate the potential for further yield increases. (source citation below graphic).
Contrast:
(click image to enlarge)
Additional Note of Significance: UVI did NOT (ever) acknowledge/report any precipitation water volumes received in their data. Since the dominant fraction (±80%) of the UVI area was outdoors in the tropics, surely there were rain water additions to that system, which are NOT factored in these contrasts. If I were to have included the mean annual precipitation at St. Thomas, the UVI annual water volume result would be barely visible at the scalar used above. The annual mean rainfall in St. Thomas falling on the UVI raft area alone is a larger volume of water than the iAVs used in total in a North Carolina greenhouse when projected at identical scale.
Below is a numerical (factorial) comparison of Hi-tech iAVs to the aforementioned UVI/DWC result.
(click image to enlarge)
Merit:
In stark contrast to UVI/DWC, the iAVs is FAR simpler to create (establish), to operate (manage), with MUCH higher resource use efficiency and FAR greater productivity and thereby representing a highly significant potential for exceptional profitability.
Additionally, the iAVs excels in the production of high-value (in both nutritional and economic terms) fruit-bearing crops, such as Achenes, Brassica (cole spp.), Capsicums (peppers), Cucurbits (cucumber, melons, squashes), Legumes (beans, peas), Solanum (eggplant, tomatoes), and some root crops – in addition to all ‘greens’, culinary and medicinal herbs.
“With Lo-tech iAVs, each liter of water employed [‘system’ capacity plus (a high of) 2.5%/day ‘loss’ rate x 365] can produce, in fish and fruit, at least 0.7g DW protein [6g LW Tilapia, 2.8g FW flesh], 7+ kilo-calories of food-energy, and most essential minerals and vitamins. This level of productivity is two to three orders of magnitude [100 to 1000+ times] more efficient in the use of water than open-field production in the U.S. (i.e., corn, soy, … and catfish, poultry, …).” ~ H.D. Gross, 1988. [All emphasis and bracketed values added.]
Hi-tech iAVs (actually, moderate-tech) has already virtually doubled yields, with several ‘avenues’ available by which to provide further improvements.
Commercial Context:
With ‘wastes’ from low-density tilapia culture fertilizing Kewalo™ tomato, the 1989 iAVs crop at NCSU produced USDA Grade No 1 fruit at 61 kg/ m2/yr. (at 3 crops/year). Summer 2012 Atlanta-area mean “Certified Organic” No. 1 vine-ripe 6×6 (large) tomato producer price (‘farm gate’) was US$6.26/kg (US$2.84/lb). This equates to US$380 m2/yr. at the iAVs ’89 tomato yield. April 10,2015 Atlanta-area wholesale terminal price for ‘Organic’ vine-ripe light-red-red medium, Florida” tomato was $5.85/kg (for US$357 m2/yr.). May 1, 2015 Philadelphia terminal price for ‘Organic’ Vine-ripes 6×7 light-red, Ontario” tomato was $6.90/kg (in 5 kg flats) which translates to $421 m2/yr.
Unique local production factors and prevailing/seasonal market unit prices should be factored in at/for each location. In general, all food groups globally are and will continue to increase in value, especially for vegetable crops as water availability for traditional agriculture is impacted by persistent drought in primary production regions.
In a modern commercial greenhouse facility, tomato grown as an annual crop and with CO2 supplementation, iAVs fruit yield is projected at 80 kg/ m2/yr. or greater. This yield equates to US$552+ m2/yr at May 1, 2015 US East Coast price sold into the wholesale market (US$2.23 M/ac/yr, US$5.52 M/ha/yr, AU$7.18 M/ha/yr).
The above valuations are excluding any revenue from the sale of fresh fish, fish meal, any intercrops (numerous options), value-added processing or products, potential ‘branding’ premium, and/or direct marketing. Other plant species can be equally productive in terms of market value achieved per unit area/time, as can specific cropping combinations and/or scheduling to exploit seasonal markets and/or niches (e.g., restaurant chefs, commercial vendors, hospitals, shop online, ‘Organic’ dip, salsa, sauce, … processors, etc.).
Application:
Two principle applications of the iAVs technology are readily apparent. One is as a small-holder activity using local inputs, providing food self-sufficiency plus a surplus for the cash market. A second application is as large-scale, commercial enterprise(s) sited near population centers. Either approach could be combined with ongoing water conservation/harvesting, gardening, local-food or commercial greenhouse projects, planned or already in place. This technology was expressly developed for and is eminently applicable to the requirements of regions where water and/or land resource availability are dominantly limiting to food production.
We’d like to hear from anyone who has any documented production results to report. In fact, we’d like to issue a challenge to anyone who can produce data that demonstrates superior performance to iAVs.
Of course, conjecture, speculation and unsupported opinion are no substitute for verifiable data. Let’s keep it real!
-o0o-
I find you’re missing one significant factor when comparing these systems and that is labor. Labor is going to be your largest long term cost commercially, and you never mention it at all. The UVI raft system and the new mobile gutter NFT systems both operate with less labor than a media based system.
I don’t know of any commercial aquaponic operation using media beds of any kind, be they sand or gravel.
Kevin…..thanks for your interest in what we’re doing.
We’ve not spoken about labour for a couple of reasons. First, it’s a feature of all systems. Second, the amount of labour required to operate and maintain any system will be dependent on its size, the crop being grown and the production model in use.
Any backyard system, for example, will be more labour intensive than a commercial one.
Once you get into large scale systems, mechanisation and automation assume greater significance. I don’t agree that, at this scale, that there’s any real difference.
We don’t know of any commercial systems using sand or gravel either. We understand why they wouldn’t be using gravel but there’s no logical reason why sand shouldn’t be used….and we’re doing what we can to encourage the conduct of commercial trials.