advantages of aeroponics

Aeroponics vs Passive Sub-Irrigation

Which one better, Aeroponics or Passive Sub-Irrigation? In this post, we will talk about aeroponics and passive sub irrigation pros and cons.

The hydroponics is a type of growing plants mainly for food, materials, comfort, and beauty.

The hydroponics is a method of growing plants, usually crops, without soil, by using mineral nutrient solutions in an aqueous solvent.

What are the techniques of hydroponics?

There are a lot of ways to grow plants hydroponically, each one uses specific nutrients. 

Techniques of hydroponics:

  • Static solution culture technique
  • Continuous-flow solution culture technique
  • Aeroponics technique
  • Fogponics technique
  • Passive sub-irrigation technique
  • Ebb and flow (flood and drain) sub-irrigation technique
  • Run-to-waste technique
  • Deepwater culture technique 
  • Rotary technique

What Is Aeroponics Technique?

Aeroponics is the process of growing plants in an air or mist environment without the use of soil or an aggregate medium.

Aeroponic culture differs from both conventional hydroponics, aquaponics, and in-vitro (plant tissue culture) growing.

Aeroponics is a great alternative for growing plants in small spaces, especially indoors.

The basic principle of aeroponic growing is to grow plants suspended in a closed or semi-closed environment by spraying the plant’s dangling roots and lower stem with an atomized or sprayed, nutrient-rich water solution.

Low-pressure units: In most low-pressure aeroponic gardens, the plant roots are suspended above a reservoir of nutrient solution or inside a channel connected to a reservoir.

A low-pressure pump delivers nutrient solution via jets or by ultrasonic transducers, which then drips or drains back into the reservoir.

High-pressure devices: High-pressure aeroponic techniques, where the mist is generated by a high-pressure pump(s), are typically used in the cultivation of high-value crops and plant specimens.

How Does It Work?

The plants can be started from vegetative cuttings by placing them in the openings on top of the growing chamber.

The stems are suspended in the growing chamber. Seeds are started by placing them on a special mesh holders in the growing chamber.

The microcomputer controller releases a pulsed hydro-atomized spray mixture of water, nutrients, and growth hormones into the enclosed air environment of the growing chamber.

The microcomputer supplies the timed spray intervals and duration for the plants.

The plants rapidly develop root systems and grow in a moist air-rich environment. Just lift the chamber top to see how they are developing.

The hydro-atomized spray provides just the right amount of moisture to stimulate the plants allowing it to be turgid as it develops.

Read also: Best Growing Support Materials for Hydroponics

Read also: How To Start Hydroponic Gardening

Aeroponics Technique In Hydroponics?

Aeroponic techniques have proven to be commercially successful for propagation, seed germination, seed potato production, tomato production, leaf crops, and micro-greens.

Since inventor Richard Stoner commercialized aeroponic technology in 1983, aeroponics has been implemented as an alternative to water-intensive hydroponic systems worldwide.

The limitation of hydroponics is the fact that 1 kilogram of water can only hold 8 milligrams of air, no matter whether aerators are utilized or not.

Another distinct advantage of aeroponics over hydroponics is that any species of plants can be grown in a true aeroponic system because the microenvironment of an aeroponic can be finely controlled.

The limitation of hydroponics is that certain species of plants can only survive for so long in water before they become waterlogged.

The advantage of aeroponics is that suspended aeroponic plants receive 100% of the available oxygen and carbon dioxide to the roots zone, stems, and leaves, thus accelerating biomass growth and reducing rooting times.

NASA research has shown that aeroponically grown plants have an 80% increase in dry weight biomass (essential minerals) compared to hydroponically grown plants.

Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponically grown plants require ¼ the nutrient input compared to hydroponics.

Unlike hydroponically grown plants, aeroponically grown plants will not suffer transplant shock when transplanted to soil, and offers growers the ability to reduce the spread of disease and pathogens.

Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology.

Aeroponic techniques have been given special attention from NASA since a mist is easier to handle than a liquid in a zero-gravity environment.

What Is Passive Sub-Irrigation Technique?

Passive hydroponics, semi-hydroponics, or passive sub-irrigation is a method of growing plants without soil, peat moss, or bark.

Instead, an inert porous medium transports water and fertilizer to the roots by capillary action.

Water and fertilizer are held in a reservoir and conducted to the roots as necessary, reducing labor and providing a constant supply of water to the roots.

In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution.

Since routine maintenance is much simplified, passive hydroponics can reduce the labor required to maintain a large collection of plants.

The Kratky Method is a specialized passive hydroponic technique that involves plants suspended in net pots above non-circulating water and nutrient reservoir.

The various hydroponic media available contain more air space than more traditional potting mixes, delivering increased oxygen to the roots.

Allowing air to reach the roots is particularly important in preventing root rot in epiphytic plants such as orchids and bromeliads, whose roots are exposed to the air in nature.

Passive hydroponics also may add additional ambient humidity through evaporation.

It is important in passive sub-irrigation to wash out the system from time to time to remove the salt accumulation.

Plants that require drying between waterings or a dry dormant period may fail to thrive under the constant moisture of passive hydroponics.

Plants are developed in a medium known as inert porous that transports fertilizer and water towards the roots of the crop with the help of capillary action.

This is done from an individual container that is necessary, reduces labor, and supplies constant water towards the roots.

To be said in simple terms, a pot is placed inside a liquid of fertilizers combined with water or with the help of a capillary mat which is filled with the nutrient liquid.

The diverse hydroponic media obtainable are coconut husk and expanded clay which contains more airspace than the traditional pots and this brings augmented oxygen towards the plant roots.

This is a very important method in epiphytic crops such as bromeliads and orchids, as they have their roots uncovered to the atmosphere in nature.

The biggest advantage of passive sub-irrigation is that it avoids a lot of root decay in plants and evaporations bring in the additional benefit of humidity.

This will feed your plants automatically using no pumps or timers.

By using a float connected to a reservoir the nutrient solution can be adjusted to maintain an inch or two inches in the growing chamber automatically.  

This is very simple to build your own sub-irrigation system using as many grow containers as you want for a custom system.

The autopot system makes hydroponic growing easy. No pumps or timers needed.


Read: 10 Best Hydroponic Gardens and Kits

The Disadvantages of Passive Sub-Irrigation Technique

aeroponics pros and cons

So as we mentioned above passive sub-irrigation is a type of hydroponic growing system where the soil is replaced with water and nutrients suspended in solution.

Plants growing in hydroponic systems either grow with their roots directly in water or, as in the case of passive sub-irrigation, in moisture-retaining materials such as fiberglass, clay pebbles, coconut husk, or perlite.

In passive sub-irrigation, the inert medium acts as a wick to carry water from a reservoir below the planting up to the plant’s roots.

Like conventional hydroponic growing, the water contains all the nutrients the plants need.

In passive sub-irrigation, plants are grown in porous media that transport water and nutrients to roots.

Sub-irrigation systems usually exist in controlled environments, because the rate at which nutrients are mixed into the solution is very important.

Therefore using sub-irrigation systems outdoors is often difficult, so if you do not have a good indoor space for setting up a sub-irrigation system.

Expensive Equipment

Another drawback to passive sub-irrigation is that it requires special equipment, the cost of which can be prohibitive when you are first starting up.

Although costs vary considerably depending on the type of equipment you buy and how large a setup you desire, it is certainly more expensive than simply planting in the ground.

Fertilizer Frequency

A disadvantage of all hydroponics systems, including passive sub-irrigation, compared to traditional growing techniques, is the frequency with which you must supply the plants with nutrients.

Because they do not have access to soil, which contains many of the minerals and nutrients lacking in water-based growing systems, you must supply it to them in the water.

Disease Development

Because passive sub-irrigation waters plants from below, relying on the roots’ capillary action to draw liquid up into the plant, most plants grown in this way are significantly less prone to foliage diseases.

However, when insects or disease problems do take root, it is often more difficult to manage them because you cannot simply apply drenches the way you would in the garden.

Read also on Guide to Solutions:

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