How iAVs became Sandgardening.

In early 2020, as a global pandemic passed across the world, I embarked on a quest to understand more about the most commonly available substance on the surface of the planet…sand!

My sand story actually began in 2014 when I commenced what was to become a six-year apprenticeship…and an almost daily collaboration…with Dr Mark R McMurtry…the inventor of the Integrated Aqua-Vegeculture System (iAVs).

Simply put, iAVs is a gardening method that utilises the metabolic wastes of fish to grow fruit and vegetables…using sand as the growing medium.

McMurtry’s motivation was to find a means whereby impoverished villagers could derive their nutrition without harming the planet. iAVs was the result.

Following its investigation at North Carolina State University, iAVs was judged to be a big deal by some of America’s leading horticulturists and, for a time its fortunes seemed assured.

Long story short, fate conspired to see iAVs relegated to obscurity…and that was how I found it in 2014. when I committed to helping Mark McMurtry bring about an iAVs renaissance.

In early 2020, we sought to reconcile our efforts to bring iAVs to a broader audience with what we’d achieved and it wasn’t stacking up.

We had made modest inroads – and many mistakes – in our efforts to draw attention to the method. A small band of backyarders had expanded to include farmers in countries like India and Egypt who had taken up the method…and their results confirmed the claims made for iAVs.

But, when I looked at the effort that was required to continue…and I considered what still had to be done…in the face of increasing years and declining energy levels…I realised that I either had to get a better return on the investment of my life energy or find something else to do.

I was tired of the struggle and I could easily have left it at that – but for three things…Dr Mark R McMurtry, the Integrated Aqua-Vegeculture system and a couple of questions.

I’ll talk more about Mark a bit later…but just so we’re clear, I regard the iAVs method as the jewel in the integrated aquaculture crown. It is a ‘living machine’ and a great example of waste transformation farming – indeed it’s the logical starting point for practical purposes. It is technically elegant and arguably one of the fastest ways to put clean fresh food on your table.

I think that it’s a contender for the most productive, resilient and sustainable food production system ever devised.

Suffice to say, I love iAVs.

But I did have some questions.

Question 1…”After six years of strident advocacy for the iAVs method I never actually built one. Why?”

It’s a good question and one that I have yet to satisfactorily answer for myself – much less anyone else. For a long time, I used the excuse that I had no suitable sand…and then I got suitable sand…and I had no time. Then I got time and I built two 8′ x 4′ sand biofilters and a sump tank. I recirculated water through the system and offered more excuses for my failure to add fish.

There was something that was making me decidedly uncomfortable about actually starting up my own iAVs but I couldn’t quite put my finger on it.

And then the penny dropped.

It was the fish.

After 16 years of building and operating small-scale recirculating aquaculture systems, I came face to face with the realisation that I really no longer wanted to keep fish. In a sense it was the quest for a better way of integrating fish and plant production that led me to iAVs…but I had learned most what I wanted to about rearing freshwater fish…and I finally admitted to myself that, when it came to eating them, I much preferred marine species anyway.

But, at the same time, I was still fascinated by iAVs.

I guess it was inevitable, therefore, that Question 2 would arise.

Question 2…”What if we just wanted to grow plants – in the sand – in a recirculating arrangement – just like iAVs – but without fish?

If the fish in an iAVs are the organic nutrient source for the plants, what if we built an iAVs with a different nutrient source?

I understood that iAVs without the fish wasn’t iAVs…but iAVs was always more about plants than fish anyway.

Was there a place for an organic plant production system – based on sand – that did what iAVs did – without the need to grow fish?

In the ensuing weeks and months, I set out to learn more about the history of sand use in horticulture.

I dragged out my old hydroponics books and read about the sand hydroponics installations that had existed – dating back to the 1940’s.

That confirmed for me that growing plants in sand had a history…a proud and diverse one…ranging from the Bengal system described by J. Sholto Douglas to the large WW2 US Army installations on Pacific atolls. Not only was I struck by the diversity of sand hydroponics systems but also their size.

In recent years, sand hydroponics had given way to lighter media like Rockwool and coco coir – and different methods like deep water culture and the nutrient film technique.

But the fact remained, that sand hydroponics worked very well until it was displaced by the convenience of other methods and media…that convenience made possible by cheap energy.

The cheap energy also provided most of the inorganic salts that are used to manufacture plant nutrients.

Even sand hydroponics suffered from the need to use inorganic salts.

I wanted an organic plant production system that used sand as media and evidenced the same capabilities of iAVs – but without the fish.

I recalled seeing allegedly organic bat guano preparations in hydroponics retail outlets…but the price and the source didn’t fit in with my emerging vision of a fish-free iAVs.

As I pondered the organic alternatives to the metabolic wastes of fish, I turned my mind to a name for a garden that used sand instead of soil…one that functioned like hydroponics but used organic nutrients in place of the inorganic salts.

And it had to demonstrate similar productivity, resilience and sustainability to iAVs…without the fish.

I wanted people to be able to embrace iAVs where practicable but to be able to access something different if, for whatever reason, they were unable to use fish.

The key feature of iAVs is sand…and its inventor affirms that (although fish provide the nutrients) he regards iAVs as a horticultural method…gardening…where the fish are the means to the end.

Question 3…So, if an iAVs can’t be an iAVs without the fish…what are we left with?

Sand + gardening = Sandgardening.

Sandgardening…the production of fresh organic food using sand as a growing media.

The idea that gave rise to sandgardening came from iAVs…and sandgardening is evidence of my belief that the iAVs method offers even greater scope in other organic iterations.

So, iAVs is a variant of sandgardening…indeed ‘the state of the art’…it’s our north star…the framework – and the benchmark.

Sandgardening is broader in its approach…and offers other variants for those who cannot – or will not – keep fish…but want to be able to grow their own clean fresh organic food.


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