I have been asked whether vegetables from aquaponics systems have the same nutritional content as from soil grown. I have found little information produced by scientific study and seen that iron may be a common deficiency. Can anyone point me to a scientific study(s) on the topic. Thank you.
I dont know, but we are currently working on a grant application that would do this
While most of this info I’m NDAed on I can say when done properly it meets or exceeds soil controls for the crops i have data on especially cannabis.
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I tried to do some research on this a few years back with simple internet search tools with a similar lack of success. I would love to see more formalized research on this question. I would hypothesize that the nutrition value of nutritious food grown in aquaponics would exceed that of soil grown food since the supply of nutrients is constant, whereas the very nature of soil is that the plant depletes the nutrients in the surrounding dirt and needs to be replenished through some outside source like fertilizer or decaying matter. I know my anecdotal evidence is that my tomatoes from aquaponics taste much better than any that I’ve grown in soil. But I’d love to see some real science behind this data.
It definitely increases flavor compounds in some cases over 300%. Flavor is trigged by microbes and the more you have the better the flavor its why for instance dual root zone crops taste better than non dual root zone crops the added layer can dramatically increase your flavor compounds such as terpenes and flavonoids.
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Hi Richard,
Chelated Iron is commonly added to Aquaponic systems. But I’ve not found any studies.
Colin
The only stable nutrients from fish waste are nitrogen, phosphorus (if the right microbes are present), and boron. The rest will eventually become imbalanced especially if you have heavy feeding or varied crops. Generally the first to be stripped out are Iron, then potassium, then molybdenum / Calcium, then manganese then other micros. Try and people might you cant get around adding nutrients no matter the design. Min nutrient levels simply are not replaceable with fish food alone as putting that amount of nutrient thru the fish causes unwanted side effects in fish growth and or death. The Aquaponic Source worked with ABC organics for years on this problem and its not chemically achievable. Sure you can grow lettuce for a short period of time with no supplements and you can pull off even a cannabis harvest with out adding nutrients but they come in at under 25% of the possible yield and are nutrient deficient in the plant tissue across the board. The misinformation about nutrients and nutrient levels is one of the biggest things holding back aquaponics. Its literally the reason I made a subscription service to fix that issue for people its hard and alot of people don’t have time / don’t want to learn they just want an answer they can buy and make it work like everything else in life. Until last year you couldn’t buy that any where.
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I have found similar results in my ongoing research.
I am willing to work with people interested in furthering this research.
Limiting factor here is high cost and test equipment scarcity to test for all the nutrients and minerals to be tested on a daily basis to plot Nutrient and mineral availability from the fish, after bacterial and microbial conversion and uptake from the plants in the aquaponic system.
Thank you for taking the time to respond. It seems like “early days” for this to have been identified as an area worth researching - something that and people rely on the taste test which is generally pretty good! I’m sure once more aquaponic produce is available this will be looked at. Cheers.
We are planning to do comparative lab tests with products found in the store. We’ll report back when we have done them. May take a bit. Working on the financing of that (and a lot more) at the moment.
Hi Richard,
Coincidentally we are about to release a publication in Frontiers in Plant Sciences on this exact issue (we will have a preprint out in the next couple weeks). We created a set up where a hydroponics nutrient solution lettuce treatment was grown in the same greenhouse as three types of aquaponic systems (biofilter transfer, solids remineralization effluent, and the two combined). We found out that the commercial hydroponic nutrient solution had 460x more soluble iron than the remineralized effluent (where we developed a system that promoted iron extraction from the fish solids). Surprisingly, plant sap analysis did not show a big difference across treatments, meaning that the excessive concentrations of the HNS were insufficient at delivering iron into the plants at greater rates than observed in the aquaponics treatments. Several other trace nutrients were apparently deficient in the HNS compared to aquaponic treatments, despite extremely high water column concentrations. Interesting as well was that the root development in the HNS was stunted compared to other treatments, leading me to believe that the extreme nutrient excesses are influencing rhizosphere-based uptake mechanisms (a known effect of N overfertilization, for example). This is a complicated topic, though. Hopefully, the manuscript will help establish a new thread for this discussion – it will be the first ever study to investigate trace minerals in aquaponics from a water column and plant sap analysis, as far as I know.
In fact, mentioning our research I should also add that if anyone is interested in doing a PhD or Post-doc on the topic of aquaponic systems to please contact our lab coordinator (Dr. Alyssa Joyce [email protected] ) as we are actively recruiting new staff!
Cheers,
Victor
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Would be great if you could notify us here once the paper becomes available.
Wondering how the nutrient uptake situation would be when the hydroponic solution contains nutrient concentrations in the same range as the typical aquaponic process water.
Oftentimes we saw that other researchers were running their aquaponic system at pretty low EC. Once I saw figures as low as 0.7. The published result was lower growth and yield than in hydroponic nutrient solution, and we were wondering why they simply did not feed their fishes more of reduced the amount of fresh water.
We were running our system at roundabout EC 2.3 and that worked fine.
I am fully aware that EC says nothing about the nutrient composition of the solution, but when comparing aquaponics with hydroponics, the solutions hsould at least be in the same ballpark, methinks.
Regarding nutritional value of crops I think the plants would take up nutrients roughly relating to their availability unless the is a lock out due to excess concentrations of some nutrients in the solution as described by Victor.
If I remember correctly there is a well documented situation like this for Phosphorus and Potassium (?). Is documented in the Howard Resh Hydroponics handbook.
You can run much lower EC and Total PPMs in Aquaponics because the microbes increase bio availability and delivery of nutrients as well as chelate many minerals on the roots themselves and in the substrates and water so its much more akin to soil than hydroponics. Aquatic soil is a much better analogy than hydro thats why it seems so strange.
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How can i learn more about this subject of flavor? Our “taste tests” of our spring peas were that soil grown wete more flavorful than our aquaponics grown. I do not know what you are referring to here about dual root zone crops. Thank you for any counsel 
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You can test flavanoids, terpenes, and other essential oil compounds thru lab testing. Cannabis testing labs can do many of them but there are ones for general ag that can also do it for various veggie crops as well. Its not often tested in aquaponic veggies but we have to test all samples of cannabis by law for those compounds to sell it.
An example of a flavonoid would be anthocyanin the red / purple pigment in your red sailis lettuce as an example.
Thank you for your response