A QUICK GUIDE TO
As operators in the Controlled Environment Agriculture are searching for new ways to improve yields while reducing costs, one area that deserves more attention than it receives is aeroponic irrigation.
Aeroponics can outperform all other forms of hydroponic and substrate-based irrigation systems in total yield, harvests per year, and product quality. Crops grown in aeroponics develop significantly more phenols, vitamins, anti-oxidants and have recently been observed to produce previously undiscovered secondary metabolites exhibiting anti-cancer activity.
However, if you ask a grower about aeroponics, 9 out of 10 will tell you that it is a complicated, niche approach reserved for researchers and extreme yield seekers. This used to be true because despite the benefits, aeroponic irrigation used to be extremely difficult to implement and operate at any scale due to high-pressure pumping, clogging nozzles, as well as upfront and operating cost.
Freya Cultivation Systems has developed an aeroponic irrigation technology that eliminates all the legacy issues of aeroponics – and advances the state of aeroponic technology to a level where we are buildng commercial-scale aeroponic platforms for greenhouses.
If you are interested in doubling your yield, forget any pre-conceptions and continue reading.
Aeroponic irrigation is a process of growing plants in air while intermittently spraying them with aerosolized nutrient solution. When done right, plants can be sprayed for 3 seconds every 10 minutes.
Different terms have been used to describe aeroponics - such as “high pressure aeroponics (HPA)”, “low pressure aeroponics (LPA)”, and “fogponics”. These terms loosely describe the particle size of irrigation water misted on the plant roots. HPA, which uses very high pressure pumps with pressure-nozzles is the most productive due to the droplet diameter that it produces (between 30-70 micrometers). This particular droplet diameter range effectively boosts plant metabolism, oxygenation, disease resistance – but achieving the required droplet diameter is very difficult operationally. Therefore, other “alternative” techniques have emerged, such as LPA or fogponics, that may look the same, but in reality, they do not produce the right spray and therefore do not induce the required plant response - and are therefore far from the actual potential of aeroponic irrigation."
Freya’s ultrasonic irrigators have the ability to produce aeroponic mist in adjustable droplet diameters without any pressure-pumping. The e-nozzle technology uses ultrasonic vibrations within a titanium nozzle body to efficiently disperse high flow-rates of nutrient solution – up to 50 Liters per hour per nozzle. Moreover, because the nozzles are uncloggable, labor is near-zero and full nutrient solution recirculation is possible without any filtration.
Root zone oxygenation is an underutilized value driver in most CEA operations.
It is well established that plant roots can absorb and utilize oxygen. The positive effect of oxygen was first observed in field agriculture, where compacted soil was observed to produce lower yields compared to loose, well-aerated soil. This has led to innovations in field agricultural practices and equipment, for example, aeration equipment, or tractor tires that reduce soil compaction. When it comes to CEA, proper root zone oxygenation is rarely achieved due to the limitations of oxygen solubility in water.
Increased oxygen availability to the roots enhances yield, crop health and product quality.
In typical CEA practice, careful consideration is given to avoid “overwatering”, which submerges the roots in water and displaces dissolved oxygen (DO) in the root zone creating hypoxic root conditions. In drip-fed hydroponics that utilize a fibrous media, e.g. rockwool or coco coir, a natural limit is reached relatively quickly for irrigation, a limit beyond which excess water will starve the plants of oxygen.
Most CEA facilities operate at a temperature range between 20° C and 25° C (68° F – 77° F), which limits the DO concentration in the nutrient liquid to approximately 20 ppm. Dissolved oxygen is rapidly taken up and needs to be replenished - popular DO management techniques include disk aerators in liquid reservoirs, high flow rate mixing (agitation), air stones, Venturi systems, plasma treatment, and chemical additives.
New oxygenation technologies are emerging – including a novel nanobubble technology promising to maintain DO at 25 ppm – but these numbers are still too low for maximized plant performance.
Aeroponic irrigation works in a different way. Instead of submerging plant roots or using drip-fed growing media, plant roots are suspended in air with the nutrient solution delivered to the roots as an aerosol. Ideally, for most indoor crops, aerosol droplet diameter will be between 10µm and 50µm, depending on the plant and desired outcome.
The natural limit of dissolved oxygen (DO) in hydroponics is lifted for aeroponics. Whereas hydroponics struggles to maintain DO of 20 ppm, the DO of air is over 210,000 ppm (21% oxygen). Roots grown in aeroponics therefore have access to all the oxygen they could need to develop to their full potential. Operationally this is even more significant, because it means no extra effort or expense is needed to oxygenate the nutrient liquid.
Because oxygen concentration in the ambient environment is always around 21%, plant roots are exposed to significantly more oxygen than in hydroponic systems, maximizing plant metabolic potential. The boosted plant metabolism results in higher total yields, increased number of harvests and improved produce quality when compared to hydroponic or substrate-based approaches. In addition, due to the nature of aerosol delivery, it is possible to introduce a precise volume of water and nutrients resulting in predictable and repeatable outcomes, including weight and biochemical profile, resulting in less water and nutrients waste, and greater efficiencies and cost savings.
Further, when comparing root development between hydroponics and aeroponics, aeroponic roots develop unencumbered by growing media. Utilizing small droplet diameters, aeroponics dramatically increase root surface area compared to DWC or drip-fed media systems. Increased root surface area increases the potential for nutrient and oxygen uptake, and therefore increased metabolic activity. Furthermore, high combined surface area of aerosol droplets enhances the mineral nutrition effectiveness resulting in increased accumulation of minerals.
Credit: Freya Cultivation Systems.
To master aeroponics, several key factors must be managed:
While aeroponics offers numerous advantages, it's important to acknowledge its limitations. These limitations can vary depending on the technology and methods used.
As we conclude our journey through Aeroponics 101, it's clear that aeroponics represents a compelling future for agriculture. Ongoing research, technological advancements, and the commitment of dedicated growers hold the promise of overcoming current limitations and unlocking even greater potential.
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