The Aero-hydroponic Method
Aero-hydroponics is not a simple method to understand. The equipment required is somewhat more complicated than other hydroponic methods, but there is a great advantage in that once an aero-hydroponic system is set up, it will run almost indefinitely without additional investment in such disposable components as growing media and non-recirculating nutrients.
What is most surprising about aero-hydroponics is not how it works, but why plants grow better. The key is dissolved oxygen at the root boundary zone
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The essence of Dr. Soffer's work at UCD was in quantifying root growth in proportion to dissolved oxygen. Only the green parts of the plant can form oxygen from carbon dioxide - roots require a supply of oxygen for metabolism and growth. Plant growth in oxygen deficient conditions, such as those found in many soils, is limited. Dr. Soffer found the enhanced oxygen at the root zone produced enhanced growth.
In aero-hydroponics, the nutrient solution is sprayed through the air in order to infuse the nutrient with dissolved oxygen. The method differs from classic aeroponics in that most of the plant's roots are not suspended in air and fed by a spray of nutrient solution; rather, the majority of the roots are submerged in oxygen-infused nutrient which is in constant motion in order to maintain high levels of dissolved oxygen at the root boundary zone where oxygen and nutrients are taken in by the plant.
The result is a propagating tool of unsurpassed performance
. Dr. Soffer was successful in propagating plant varieties at UCD that had never been propagated before
. He took particular delight in propagating varieties of conifers and even pistachio trees (pistachio cuttings required 90 days to generate roots). Moreover, he found that cuttings could be rooted aero-hydroponically in purified water without using rooting hormones such as IBA or NAA. This is because plant tissue already contains the natural rooting hormone IAA (Indole Acetic Acid).