Aquaponics. ‘Aqua what?’ would be a reasonable response but you may well be hearing this word a lot more. One short answer is ‘promise’: the promise of cultivating delicious, organic fish and vegetables with minimal space and effort; the promise of helping humanity take the next great step in agriculture (forwards this time) in which we use our technology to make the most of nature’s intelligence rather than to ride roughshod over it; the promise of future fish’n’chips.
That’s a lot to live up to, yet we need some big answers to the big questions we face: how do we feed ourselves as we approach 7 billion and likely scarcity of oil and gas? How do we save our precious topsoil and leave some fish in the sea? Where will the water come from?
Could aquaponics grow into one of these big answers?
Fish have been cultivated in captivity for millennia but this ‘aquaculture’ has often struggled with the sludgey problem of poop: fish defecate in their water which needs changed before it kills them – that can mean a LOT of water.
And since the early twentieth century vegetables have been grown in a liquid solution rather than in soil, and while this ‘hydroponics’ can be wonderfully productive it can suffer from high disease vulnerability.
In a lovely example of the much sought ‘win-win’ you can combine these two into aquaponics to cancel out their respective flaws: by growing fish in a tank and cycling their water through plant-filled grow beds you create ideal growing conditions for the plants, which then clean and oxygenate the water ready for its return to the fish.
The result, according to the aquaponics evangelists, is an incredibly productive system. Joel Malcolm, founder of Backyard Aquaponics, reports a six month crop of “50kg of fish and hundreds of kilograms of vegetables” in an 8m by 4m space in his backyard. To put this yield in perspective the U.S corn industry, pushing nature to the limits with fossil energy subsidies (fertilizer) manages around 1kg per square meter. Joel Malcolm is reporting roughly 3kg of fish and 6kg plus of vegetables.
In fact beyond solving the waste issues, growing fish and vegetables together may be more productive for both than growing them separately. Aquaponics practitioners report lower incidences of disease in their fish and higher growth rates in their plants than would be expected in separate aquaculture and hydroponics systems. More research is needed, but these early reports suggest a symbiotic relationship with great promise.
So why have you not heard of aquaponics before? Perhaps it’s potential has languished unexplored for the same reason as many other smart green solutions: cheap oil has made us lazy and foolish. The chorus of voices from climate scientists to oil geologists grows loader by the day: we need to wise up, fast.
I hadn’t heard the term until March when I arrived at the Maya Mountain Research Farm to study permaculture – a design system for sustainable living – full of the big questions and desperate for some answers. Permaculture is about applying ecological principles to human life, so that we can meet our needs without killing ourselves, and although aquaponics wasn’t on the syllabus it perfectly embodies this.
One night MMRF’s director, Christopher Nesbitt, sat the group down in front of a laptop to watch ‘the aquaponics DVD’, a charming home production from Joel Malcolm. Chris’s enthusiasm was palpable. This was ‘really cool’ he assured us, and through the shaky handycam walk arounds and strangely ‘oscar moment’ piano music, it became clear that it was. There was something to this.
The amateur roots of the system seem fascinating. There is some history of academic research in the field and a few businesses, but it appears that the driving force is now a global community of ‘hobbyists’. A few pioneers, notably Joel Malcolm in Australia (producer of the DVD), have experimented on a shoestring and shared their successes and failures with others around the world. Aquaponics is growing up from the grassroots.
That’s how Chris became hooked: “When I discovered the website I was up until sunrise” he told me. “What Joel Malcolm has achieved is fantastic”. So Chris has been researching and preparing for a demonstration system at his agroforestry farm and teaching center.
I decided to return for my fourth visit to help to design and build it.
The elements of an aquaponics system are pretty simple: fish tank; fish; grow beds; gravel; plants; water; water pump; piping; roof. The final, crucial, component brings itself: the bacteria that convert fish poop into plant food in the water (ammonia to nitrites, nitrites to nitrates). Ongoing inputs are fish-food, top-up water and electricity for the pump.
Crucially we are building a system – every part affects every other. We have to think systematically, in the true sense of the word, balancing the sizes of grow beds to fish tanks to available energy from the solar pump, etc. Systems thinking will be even more important once it is up and running, tweaking the elements until the ecology ‘snaps’ into place.
In the model we have chosen the water gravity-feeds from an overflow in the fish tank, down through the grow-beds, and then drains into a sump tank, from where it is pumped back at intervals to the fish tank, causing the process to start again. Instead of pumping constantly the system will cycle on and off – an important energy-saver as we will be relying on solar PV for the pump.
I arrived in late August to find ground prepared by James and Herminio, long time MMRF employees and the real construction experts. It is impressive what these two achieve in a day. The roofing, to protect the system from tropical downpours, went up quickly, a solid wooden frame bolted to concrete. With a history of hurricanes and no shortage of wood, triangulation is the name of the game at MMRF and the buildings have a solid, chunky elegance.
With the frame completed we spent a day in the blistering sun painting it in burnt oil (courtesy of the local car mechanic) to help ward off hungry termites, blackening like derrick workers in a big strike.
Now we await delivery of our custom made tanks. We had ordered them in Spanish Lookout, a Menonite town four hours drive north – Iowa with palm trees as Chris describes it. It is Belize’s hub for agricultural supply and we were confident we could find what we needed. Having looked at premolded plastic feeding troughs it was as cheap – and far more satisfying – to order bespoke tanks from Mr Penner, of Penner Metalworks Ltd. They will be sexy, shiney and crafted by hand.
So we are getting there. Three weeks into the project we are almost roofed and ready to wire and plumb. This will be the really fun part, piping the tanks together and installing the solar system. Watch this space to see how we get on.
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