How Aeroponics Works

­Simply put, aeroponics is a method of growing plants in a soilless environment with very little water. Basically, it's growing without earth. Despite this leap in advancement, aeroponics actually had a fairly slow start. Techniques for growing plants without soil were first developed in the 1920s by botanists who used primitive aeroponi­cs to study plant root structure [source: Barak, et al]. This absence of soil made study much easier: In aeroponics, plants' roots dangle in midair, with only the plants' stems held in place. However, the leap in logic that led to growing plants in this way for recreation rather than academic study didn't occur until the 1970s. Hydroponics, a similar technology where plants' roots are grown in nutrient-rich water rather than soil, emerged and overtook aeroponic development.

Hydroponics (growing roots in a nutrient rich, water-based medium instead of soil) came into popular use in the West in the 1970s. Research and use of aeroponic systems continued behind the scenes, however, and the technique made its big public debut when "The Land" pavilion at Disney's Epcot Center opened in 1982.

It would take the interest of NASA to push aeroponics further into the limelight. In the 1990s, study and refinement of these techniques took off after NASA funded a project by a small aeroponics operation. NASA's involvement would give the growing aeroponics movement a decidedly futuristic image.

Despite this image, the concept behind aeroponics system is actually fairly simple. Find out how simple it is on the next page.

­Imagine a board with holes drilled equidistantly apart and plugged with a stabilizer like foam rubber. After plants germinate from seed in a soilless medium like Rockwool, (a fibrous material woven from strands of lava) they're transplanted to the board. As the plant grows, the upper parts of the plant (the crown) grow above the board, while the roots are left to dangle below.

Beneath the board is an enclosed area known as the root chamber. This area's purpose is twofold: It protects the roots from light and it holds the nutrient/water solution that feeds them. A sump pump pushes the solution through a pipe and out of a series of nozzles that atomize the solution and spray a fine fog directly onto the roots. In an enclosed system, whatever doesn't get absorbed by the roots falls back down into the solution chamber and gets cycled through again. The pump is set to an automatic timer and delivers this high-powered nutrient solution at regular intervals.

A-frame aeroponic systems are also in wide use. Instead of horizontal boards, A-frame systems use tall cones made of PVC frames and enclosed with chicken wire and plastic. The interior serves as the root chamber. The plants' roots hang at a downward angle inside the cone, while the plants grow upward through the plastic on the side. (Think of a Chia Pet teepee.) A-frame systems have a decided advantage over horizontal systems in that they require less square footage for the same plant density, since the systems are arranged upward instead of outward.

This kind of thinking reflects the basic premise behind aeroponics -- using the minimum amount of input to gain the maximum output. The fact that it lacks soil is another important aspect. Soil provides plants with stability, warmth, and an easy way to distribute nutrients and water. But soil is also stingy, especially when it comes to allowing plants oxygen.

This may seem counterintuitive since the first thing you ever learned about plants is that they consume carbon dioxide and release oxygen. It's true that plants require carbon dioxide to convert sunlight into sugars through photosynthesis. But they also use oxygen to break those sugars down into useable forms of energy. More oxygen equals more plant growth, and plants receive more oxygen under aeroponic conditions, with their roots exposed to air and unencumbered by dense soil.

The way nutrients and water are delivered also demonstrates the efficiency of aeroponics. The nutrient solutions used on plants require only a little water. In enclosed systems, water use is even further diminished. Atomizing nozzles ensure the most effective delivery of nutrients, since they turn the water into a fine mist. Plants absorb nutrients through their roots by osmosis, a selective absorption of compounds through cell walls. Roots can absorb nutrients more easily as a result because they're delivered via the mist.

Aeroponics, you may have noticed by now, is plant growth on steroids. This is why it shouldn't surprise you that aeroponically grown plants tend to produce larger fruit crops and bigger roots. What's surprising is just how much more fruit a plant can yield.

There's an abundance of anecdotal evidence supporting the idea that aeroponic growing may be superior to growing in natural conditions. Online message boards among aeroponic devotees will tell you the same.

Academic research has also yielded a torrent of evidence to support this claim. A 1991-92 study conducted in Sardinia, Italy, found that certain hybrid tomato varieties produced abundant "fruit of excellent commercial quality" in a very short time, enough to make the process researchers used viable for commercial use [source: Leoni, et al]. What did they do? The Sardinian researchers used a high-density aeroponic system (HDAS), with plants grown close together. Since the plants' roots aren't competing for nutrients in the same soil, they can be grown in dense plantings aeroponically. Even better, the aeroponic tomatoes were ready to produce fruit four times in one year, rather than the one or two times observed in field conditions.

­In 2001, a University of Arizona study looked at the effects of aeroponics on plants prized for the medicinal properties of their roots. The researchers studied two plant varieties, echinacea and burdock, and found some startling results. While the echinacea crop suffered fungal and insect outbreaks, the yields were still comparable to those seen in natural field settings. The burdock greatly outperformed its outdoor counterparts: The root harvests from the burdock plants tested in the University of Arizona study yielded almost 1000 (yes, thousand) percent more than field-grown burdock crops do on average. Even better, the researchers pointed out that the absence of soil made the aeroponic crops easier to harvest.

NASA has come up with similar results: In 1997, the space agency sent a variety of aeroponically grown Asian bean seedlings to the Mir space station while simultaneously observing an aeroponically grown control group on Earth that used an identical growing system. The only variable separating the Mir and Earth crops was gravity. The space beans were grown at zero gravity, while the Earth crop was grown at normal atmospheric conditions. The Mir crops actually grew better than the beans grown on Earth.

The success of the test was of great value to NASA. It proved that food crops could not only grow, but thrive in zero gravity. It also showed that this aeroponics system would come in handy on long space flights and missions. It could also prove useful during for possible colonization of other planets.

So, good, humanity's saved. We have the agricultural technology available to sustain us. However, plenty of people are using aeroponics right now. Growers who use the technology aren't just on the cutting edge; their combined efforts may end up saving humanity from packing up to find another home.

Because aeroponic systems are so easy to use after they're built -- setting the grow lights and sump pump timers allows relatively hands-free growth -- the technology is coming into wider use.

­Small commercial outfits have found the technology useful for cutting costs and boosting profits. A Colorado basil farmer has the time to work his day job as an optometrist while still providing the herb to more than 100 area restaurants [source: Weaver]. Aeroponic systems cut costs like water, fertilizer and soil: Ultimately, all you need is the nutrient solution and the water required to mix it. It also reduces space requirements. Because of all these attributes of aeroponic growing, little guys can compete better with larger growers.

Aeroponics has become a favorite tool among serious growers of another variety of plant -- marijuana. Pot growers have taken to growing indoors in increasing numbers. Many are finding that the technology produces higher yields with less space requirement [source: Escondido]. The lack of water needed to grow aeroponically also makes this method attractive. A single mature marijuana plant can require as much as 15 gallons of water per day [source: Ecology Center]. Unusually high water bills can tip off law enforcement. Pot growers who move their operations inside, especially those who opt for city growing, will find they've got company. Urban gardeners have found that aeroponics suit their needs well. Soil is often scarce in cities, which makes using aeroponics a good growing option in town.

Growing food crops on rooftops and in apartments, to use another example, reveal some obvious advantages. Growing one's own food has become increasingly attractive as food prices have increased, but those same food prices are based around an environmental threat. Let us explain: Each food item has a transportation cost, the amount of money and resources dedicated to moving it from its area of origin to your dinner table. Many involved in the urban gardening movement believe that local food production cuts down on both prices and environmental impact. It takes a lot of carbon dioxide emissions to move a grapefruit from Florida to New York; growing food locally -- especially in a communal aeroponic system in an apartment building -- reduces those impacts dramatically.

Water has also become a point of contention among humans in the 21st century. About 70 percent of the water consumed by humans is used for agriculture, and about 45 percent of that is lost due to shoddy irrigation techniques [source: UNESCO, WAPA]. Aeroponics' use of water, in an enclosed system that recirculates it, drastically cuts down on water consumption by as much as 98 percent [source: NASA].

As more people are born into the world, land becomes scarcer. Arable land is often created by leveling forests and other ecosystems. So are cities, suburbs and exurbs. By combining the increased growth of human activity with food production inside those areas instead of reserving rural areas for food production, humans could drastically reduce their impact on the environment and allow some cropland to return to its natural state. Allowing these areas to naturalize should let forests return, arguably leading to more carbon dioxide scrubbed from the air, which is what helped humanity develop and flourish in the first place.