With an aeroponic set up, the plants are grown in air instead of using soil or any other aggregate medium. The aeroponic set up differs from both geoponics, aquaponics, and conventional hydroponics. Still, it is sometimes considered a type of hydroponics since a water solution is used to bring nutrients to the plants.
In an aeroponic system, the roots are either continously or discountinously kept in an enviroment saturated with fine drops of nutrient solution. In essence, they grow in a nutrient rich mist or aerosol.
Tomatoes, leaf crops and micro-greens are all examples of foods known to grow well in aeroponic systems.
In experiments conducted by NASA, aeroponically grown plants displayed an 80% increase in dry weight biomass (essential minerals) compared to hydroponically grown plants. Also, the aeroponic system needed 65% less water than the hydroponic one, and just ¼ of the nutrient input.
One of the reasons why NASA is so interested in aeroponics is that a mist is easier to handle in zero gravity than ordinary watering or hydroponics.
The basics of aeroponics
- The plants are typically grown in a closed or semi-closed environment that can help contain the nutritous mist.
- The spray / mist is directed to the dangling roots and the lower stem.
- In many set ups, closed-cell foam is compressed around the lower stem to keep the plant in place. For larger plants, trellsing can be necessary to suspend the weight of the plant, especially if it is also producing heavy fruits.
Advantages of aeroponics
Here are a few examples:
- Advantage: It is possible to strictly control and fine-tune the microenvironment for the plant.
- Advantage: Unlike conventional hydroponics, there is no risk of waterlogging. Plants that are sensitive to waterlogging often do better in aeroponics.
- Advantage: The roots always have access to plenty of oxygen.
- Advantage: Aeroponics makes it fairly easy to control the spread of pathogens.
- Advantage: Aeroponically grown plants will usually not suffer from transplant shock if they are planted in soil.
Low pressure and high pressure set ups
In low pressure systems, a low pressure pump is used to spray nutrient solution on the plant roots, either through jets or through ultrasonic transducers.
The plant roots are typically suspended above a reservoir of nutrien solution. Another option is to make a channel and connect it to a reservoir. In both types of set up, the spray will hit the plant roots and then drip down into the reservoir or channel.
A problem with low pressure systems is their inclination to cause dry sections on the root systems as the plants reach maturity. These dry sections will not absorb nutrients or water well.
In high pressure systems, one or more high pressure pumps are used to spray nutrient solution on the plant roots. This type of set up tend to be more expensive than the lowe pressure set up, and normally only used for high value plants or scientific research. These expensive set ups typically also feature various components that will help purify the nutrient solution and other components of the system.
Air exposure in aeroponics
In any type of culture, the root zone (rhizosphere) must have access to oxygen for the plant to survive. One of the advantages of aeroponics is that the plant has unrestricted access to air, and this to the availble oxygen in the air. The necessary support structure will typically be minimalistic and with very little contact between the structure and the plant, since the grower doesn’t want to block air access more than absolutely nessesary.
Diseases and pests
Many types of pathogens can spread through the growth media, which is one of the reasons why not having any medium is beneficial for the plant. If a plant in the system does get sick, it can be removed without disturbing the other plants, and the cause of the disease will not linger in any medium.
The lower risk of disease and pests make it possible to grow plants denser than normally in aeroponics.