What is iAVs Sandgardening?

Its name is what it does…it’s a gardening method that uses sand – instead of soil – to grow plants. 

Sandgardening is a revolutionary ‘old’ way to grow plants. It’s revolutionary in terms of its ability to rapidly change things for the better for a lot of people….and it’s a fresh look at a very old gardening media…one that worked for a long time but then fell victim to convenience and fashion.

Sandgardening puts productive, resilient and sustainable food gardening within reach of everyone.

What is a Sandgarden?

Picture two buckets…one located above the other – so that the upper bucket can drain into the lower one. 

Fill the upper tub with sand and the lower one with water. Use a timer-operated pump to raise a predetermined amount of water from the lower bucket to the upper one. The water percolates down through the sand and drains back into the lower bucket. Set the timer so that this irrigation is repeated at scheduled intervals.

These are the practical elements – the hardware – of a sandgarden. This is scalable from a single bucket to a 1000 square metre controlled environment cropping greenhouse.

How does a Sandgarden work?

In effect, a sandgarden is a plant support system that provides a measured quantity of water and plant food – at predetermined intervals.

In so doing, this apparently simple structure addresses the main reason that aspiring gardeners fail…the failure to provide sufficient water and plant nutrients – at the time that the plants need them.

But that’s just the beginning at this stage, we could slip along to our local hydroponics shop and buy a carefully formulated mix of inorganic chemicals and add that to the water tank. That’s the basis of sand hydroponics…a food production method that enjoyed its heyday from the 1940s on into the 1970s.

It worked well but it relied for its productivity on carefully formulated inorganic nutrient mixes that were drip-fed – or sprinkled – into the sand alongside the plants.

But there’s a further distinction between a sand hydroponics unit and a sandgarden. A sandgarden is organic by virtue of its design.

While being organic underpins sandgardening’s sustainability…it’s not the sole reason for its incorporation into the method.

It’s what happens in the sand – when you add organic matter – that separates it from other media.

What does a typical Sandgarden look like?

There’s no such thing as a typical sandgarden. They can range in size from a 10-litre bucket to a commercial CEA greenhouse complex.

Why sand?

Sand is among the most commonly available substances on the planet…far more common than any soil type much less good organic soil suitable for food production.

Sand is 100% recyclable…it can be washed and sieved and re-used…forever!

Some soils are good, some are sad (depleted and lifeless)…and some are bad (toxic)…or non-existent. It’s much easier to provide a consistent growing environment using sand. Good soil is a rapidly-diminishing resource…and soil-building is an ongoing process. The nature of good soils is such that they require regular replenishment.

Building and maintaining fertile soils requires knowledge and skills…and hard-won experience…to be consistently successful.

Fortunately, creating the sand equivalent of soil is very easy.

Sand + organics + oygen + water + microbes = soil.

Sand…and the microbial life that it supports…is the secret to the mechanical and biological filtration efficacy of a sandgarden. Sand can even be customised to provide the ideal growing environment for specific plants.

What is the best sand for Sandgardening?

It should be inert…producing no chemical reaction when in contact with water. It should be free of silt and clay. It has to drain effectively.

For practical purposes, silica quartz sand in the range of 0.5mm to 1.5mm has been found to be very suitable. We’re fortunate that silica quartz is the most common substance on the surface of the earth.

The best way to ensure that available sand is suitable for sandgardening is to test it…using a few simple tests.

Doesn’t sand clog?

No.  iAVs-suitable sand…used in accordance with iAVs guidelines will not clog.

Is Sandgardening easy to do?

If you are someone who has the ability to follow directions, sandgardening is arguably among the easiest of all ways to grow plants. 

Once you have the nutrient tank and the sandbed…and the pump and timer…and some suitable sand…the intermittent watering system will take over the day-to-day (and life and death) matter of ensuring that the plants get food and water.

While sandgardening is premised on some very complex microbiology, its actual operation is disarmingly simple…and its most important functions can be fully automated. In short, it doesn’t get any simpler.

What plants can I grow in a Sandgarden?

The better question might be “what can I not grow in a sandgarden?” The answer is…not much! The list of plants that can be cultivated in sand grows almost daily.

You are not limited to the usual fruit and vegetables either. You can grow root crops, melons and vine crops, fruit trees, ornamentals, grapes and flowers…and even potatoes.

You can also use a sandgarden to propagate plant and tree seedlings.

What fish can I grow in an iAVs Sandgarden?

The original research trials were based on tilapia – a fish of legendary robustness – able to tolerate poor water quality for extended periods. iAVs has been shown to work just as well with rainbow trout…and they require clean cool water and high levels of dissolved oxygen. iAVs would also be suited to many other species that fall within these extremes.

Where can I build an iAVs Sandgarden?

  • On pavement and sealed surfaces
  • On rocky atolls.
  • In hot arid environments…including deserts.
  • Inside a controlled-environment greenhouse or an indoor grow room
  • Any balcony or rooftop that is well enough engineered to support the weight of the sand.
  • …and anywhere else where the soil is either non-existent or otherwise unsuitable for growing plants.

How efficient is iAVs in its use of water?

During its research phase, iAVs demonstrated that a each litre of water could be recirculated through the sand biofilter 120 – 300 times before being lost to evapotranspiration and incorporated into plant biomass.

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 6g FW of fish and 17 g DW of vegetables.

Collectively, tilapia and tomato yields result in 0.7g DW of protein and 7 Cal. (or 7,000 calories) per litre of water used.

Collectively, tilapia and tomato yields result in 0.7g DW of protein and 7 Cal. (or 7,000 calories) per litre of water used.

We have never seen any other gardening method provide these metrics… much less come close to them. We are confident in our claim that iAVs is among the most water-efficient food production systems ever devised.

Is Sandgardening organic?

Sandgardening is ‘organic’ in the sense of its inputs being plant and/or animal-based.

Sandgardening is ‘organic’ in that it produces clean fresh food…without the need for synthetic fertilisers, herbicides or pesticides.

Whether Sandgardening is able to be ‘certified organic’ would depend on the specific circumstances of the proposed operation.

How big is a Sandgarden?

The sandgarden is infinitely scalable.

We use 20-litre buckets as demonstration systems and depending on the particular variant, a sandgarden could be even smaller still. It can be a single plant …or a backyard vegetable garden…or a commercial farm.

Who can build and operate a Sandgarden?

Virtually anyone. Sandgardening can be designed to suit special needs through the use of raised beds that permit wheelchair access…and other adaptations.

Sandgardening is a great learning aid for ‘kids’ of all ages.

If iAVs is so good, why isn’t it better known?

The precise reasons for why iAVs lapsed into obscurity around 2000 may never be known but, in the articles titled…”Aquaponics’ Biggest Mistake“…and…“Why iAVs lapsed into Obscurity”…we attempt to provide prospective reasons.