Aeroponics - Can plants grow without soil?

Plants can grow without soil.
The earliest historical records show a hydroponic like cultivation in MExico during period 1150 – 1350 CE.
Morehart, C. (2016). CHINAMPA AGRICULTURE, SURPLUS PRODUCTION, AND POLITICAL CHANGE AT XALTOCAN, MEXICO. Ancient Mesoamerica, 27 (1), 183-196. doi:10.1017/S0956536116000109

More recently V.M.Artsikhovski published in the journal “Experienced Agronomy” an article “On Air Plant Cultures”, in 1911, about his method of physiological studies of root systems by spraying various substances in the surrounding air - the aeroponics method. He designed the first practical aeroponics system.

Soil less plant growth is of much interest for cultivation in space, where every resource transportation involves exorbitant cost.

Soiless plant growth are generally classified as hydroponic, aquaponic and aeroponic.
Hydroponics involves immersion of the rhizosphere in a nutrient rich water solution.
Aquaponics is hydroponics with nutriente being generated by marine life, usually fish, but also arthropods.

Aeroponics uses a spray of nutrient rich water droplets between 5 and 50um directly on to the plant roots.

The advantages of soiless growth include very low waste of water and fertilizer, prevention of soil based infection, increased growth area in vertical systems, cultivation in resource constrained areas, ability to increase photosynthesis by artifical lighting.
Disadvantages are extreme dependency on un interrupted power, plant death if humidity levels are not mainatined for periods as low as 20 minutes, external nutrient supply and the need for good electronic control systems.

An aeroponic system can be setup in a lab for highily controlled plant growth experiments and growing of exotic species.

There are multiple variations on the above methods.

WE will construct two types
Vertical Driponics.
Vertical Aeroponics.

We will use commonly available materials. The goal is to encourage urban farming and experiments, at low cost.
Here is a photo of first prototype:

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I am interested in this, but can think of several practical modifications for my purposes.

Right off the bat… cool roots. Black tower will cook my collection. But I suspect we could make it out of clay and use only plants that will tolerate clay (several species will flat out die if there is any major root nutrient). Also plants that grow naturally on vertical cliff faces.

What clay… I’d been thinking earthen baked clay, but now I’m thinking “shadu” clay - the stuff they make ganesh idols out of. It holds water brilliantly without losing structure for quite a bit (a DRIP on it will kill it fast, but mist should only make it deliciously cool. Alternatively, a more durable option may be plaster of paris. If we make a design, we could probably make a silicone mould of whatever works and have the ability to churn out new towers in the time it takes for plastic to set.

Then the structure could be made out of a plastic mosquito screening (like they install on windows with velcro) or the bird screening, for some spine, coated on both sides with the clay and appropriate holes made.

This will inevitably result in some roots also gripping the clay or growing into it if it gets softened enough (it will - roots are determined things) and have the added bonus of a “buffer” in case of power failures. Both the evaporation from the clay as well as roots having some ability to absorb from it (like from soil).

For my “cool roots needs”, a modification could be to have a small “channel” of water around the top rim of the structure, which absorbs some of the water from the fogging chamber itself (no separate irrigation needed). This will result in some gravity fed wetting of the whole system, resulting in natural evaporative cooling + said “buffer” against power failures.

Drawback: This limits the plants I can grow in it to those growing on limestone cliffs or I’ll have to do a coat of regular clay on the inside (this may not be feasible - adhesion issues between dried PoP and wet clay - don’t ask how I know…).

What is the media used, or is there no media?

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Personally, I’d be wary of using this thing on expensive plants without a failsafe that doesn’t depend on electricity. One eposode of “Vasai-Virar under water, no power for a week” would FINISH them even with limited inverter backup.

Easy failsafe I can think of is an overhead tank that periodically gets filled by water collected below. If the PoP wicks water down the sides of the gadget, even in a power failure, the plants would have some humidity at the roots. And whether water is lost by fogging or wicking off by the container, if levels drop, the overhead tank would automatically replenish them. In a power cut, even with fogger not working, a person could at least refill the overhead tank manually to help the plants.

This is also not perfect, but better than nothing. A minor battery backup for just the fogger would be efficient on the battery (as opposed to battery AND pump) and an overhead tank would also allow that extended time backup.

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But this will defeat the objective of a cheap system… :confused:

Maybe I could just experiment with it as it is and see what happens and modify on the fly to meet growing conditions. Or try first with regular vegetable plants.

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