Aeroponics

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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 hydroponics and in-vitro (Plant tissue culture) growing. Unlike hydroponics, which uses water as a growing medium and essential minerals to sustain plant growth, aeroponics is conducted without a growing medium.^[1]

Contents 1 History 2 Basic Principles of Aeroponics 2.1 Methods 2.2 Ecological advantages 2.3 Apparatus 2.4 How Aeroponics Works 2.5 Aeroponic propagation (cloning) 2.6 Air-rooted transplants 2.7 Aeroponic seed germination 2.8 True aeroponics 2.9 Benefits of air (oxygen) 2.10 Other benefits of air (CO2) 2.11 Natural disease-free cultivation 2.12 Water/Nutrient hydro-atomization 2.13 Advanced materials 2.14 Nutrient uptake 2.15 Terminology 3 Types of Aeroponics 3.1 Lo-pressure units 3.2 Hi-pressure devices 3.3 Commercial systems 4 History of aeroponics 4.1 Early lab research 4.2 Commercialization 4.3 Aeroponically grown food 5 NASA aeroponic history 5.1 Space plants 5.2 Biocontrols in space 5.3 Aeroponics for space & Earth 5.4 NASA inflatable aeroponics 5.5 Mission to Mars 6 Benefits of Aeroponics for Earth & Space 6.1 Less Nutrient Solution Throughput 6.2 More control of plant environment 6.3 Improved nutrient feeding 6.4 More user-friendly 6.5 More cost effective 6.6 Pathogen Control & Disease Prevention 6.7 Use of seed stocks 7 21st Century aeroponics 7.1 Contemporary aeroponics 7.2 Aeroponic bio-pharming 7.3 Large scale integration of aeroponics 7.4 NASA aeroponic links 8 In popular culture 9 See also 10 References 11 Technical links

[edit] History

The word aeroponic is derived from the Latin meanings of 'aero' (air) and 'ponic' (work). Aeroponic growth refers to growth achieved in an air culture. Such conditions occur in nature (see epiphyte). For example, in tropical climates orchids develop and grow freely in trees (Rains, 1941).^[2] Laboratory research on air culture growing utilizing vapors began in the mid-1940s. Today aeroponics is used in agriculture around the globe.^[3]

[edit] Basic Principles of Aeroponics

The basic principle of aeroponic growing is to grow plants in a closed or semi-closed environment by spraying the plant's roots with a nutrient rich solution. Ideally, the environment is kept free from pests and disease so that the plants may grow healthier and quicker than plants grown in a medium. However, since most aeroponic environments are not perfectly closed off to the outside, pests and disease may still cause a threat. These conditions advance plant development, health, growth, flowering and fruiting for any given plant species and cultivars. Carbon dioxide in the air is necessary for healthy plant growth. As aeroponics is conducted in air combined with micro-droplets of water, almost any plant can grow to maturity in air with a plentiful supply of carbon dioxide, water and nutrients.

Some growers favor aeroponic systems over other methods of hydroponics because the increased aeration of nutrient solution delivers more oxygen to plant roots, stimulating growth and helping to prevent pathogen formation.^[1]

[edit] Methods

Aeroponics refers to the method of growing crops with their roots suspended in a misted nutrient solution.

Aeroponics is a form of hydroponic technique. Water is the sole nutrient carrier and typically the method is not hybridized with geoponic technique; although due to the sensitivity of root systems aeroponics is often combined with conventional hydroponics which is used as an emergency 'crop saver' -backup nutrition and water supply- if the aeroponic apparatus fails.

In an aeroponic system the plant's rootzone is suspended into an environment where the roots protrude into an atomized nutrient solution; the leaves and crown, often called the "canopy", extending above. The roots of the plant are separated by the plant support structure. The lowest stem and root system are sprayed or misted for short durations with a hydro-atomized pure water/nutrient solution.^[1]

One of the more singular aspects of aeroponic growing is the frequent omission of media, whether organic or not, for anchoring the plant. Many times closed cell foam is compressed around the lower stem and inserted into an opening in the aeroponic chamber, which decreases labor and expense; for larger plants, trellising is used to suspend the weight of vegetation and fruit.

[edit] Ecological advantages

Aeroponic growing is considered to be safe and ecologically friendly for producing natural, healthy plants and crops. The main ecological advantages of aeroponics are the conservation of water and energy. When compared to hydroponics, aeroponics offers lower water and energy inputs per sq meter of growing area.^{[citation needed]}

[edit] Apparatus

The first commercially available aeroponic apparatus was manufactured and marketed by GTi in 1983. It was known then as the Genesis Machine - taken from the movie Star Trek II: The Wrath of Khan. The Genesis Machine was marketed as the 'Genesis Rooting System'.

GTi's device incorporated an open-loop water driven apparatus, controlled by a microchip, and delivered a hi-psi, hydro-atomized nutrient spray inside an aeroponic chamber.

At the time, the achievement was revolutionary in terms of a developing (artificial air culture) technology. The Genesis Machine simply connected to a water faucet and an electrical outlet. ^[4]

[edit] How Aeroponics Works

[edit] Aeroponic propagation (cloning)

Aeroponic culturing revolutionized cloning (propagation from cutting) of plants. Firstly, aeroponics allowed the whole process to be carried out in a single, automated unit.

Numerous plants which were previously considered difficult, or impossible, to propagate from cuttings could now be replicated simply from a single stem cutting. This was a major boon to green houses attempting to propagate delicate hardwoods or cacti – plants normally propagated by seed due to the likeliness of bacterial infection in cuttings.

Aeroponics has now largely surpassed hydroponics and tissue culture as means for sterile propagation of plant species. With the Genesis Machine, or other comparable aeroponics setup, any grower could clone plants. Due to the automation of most parts of the process, plants could be cloned and grown by the hundreds or even thousands. In short, cloning became easier because the aeroponic apparatus initiated faster and cleaner root development through a sterile, nutrient rich, highly oxygenated, and moist environment (Hughes, 1983).^[1]

[edit] Air-rooted transplants

Aeroponics significantly advanced tissue culture technology. It cloned plants in less time and reduced numerous labor steps associated with tissue culture techniques. Aeroponics could eliminate stage I and stage II plantings into soil (the bane of all tissue culture growers).

Tissue culture plants must be planted in a sterile media (stage-I) and expanded out for eventual transfer into sterile soil (stage-II). After they're strong enough they are transplanted directly to field soil. Besides being labor intensive, the entire process of tissue culture is prone to disease, infection, and failure.

With the use of aeroponics growers cloned and transplanted air-rooted plants directly into field soil. Aeroponic roots were not susceptible to wilting and leaf loss, or loss due to transplant shock (something hydroponics can never overcome). Because of their healthiness, air-rooted plants were less likely to be infected with pathogens.^[1]

The efforts by GTi ushered in a new era of artificial life support for plants capable of growing naturally without the use of soil or hydroponics. GTi received a patent for an all-plastic aeroponic method and apparatus, controlled by a microprocessor in 1985.

Aeroponics became known as a time and cost saver. The economic factors of aeroponic’s contributions to agriculture were taking shape.

[edit] Aeroponic seed germination

By 1985, GTi introduced second generation aeroponics hardware, known as the 'Genesis Growing System'. This second generation aeroponic apparatus was a closed-loop system. It utilized recycled effluent precisely controlled by a microprocessor. Aeroponics graduated to the capability of supporting seed germination, thus making GTi's the world's first plant and harvest aeroponic system.

Many of these open-loop unit and closed-loop aeroponic systems are still in operation today.

In a true aeroponic apparatus the plant is totally suspended in air, giving the plant access to 100% of the available oxygen in the air. This maximizes the level of oxygen surrounding the stem and root system, accelerating and promoting root growth within the plant. While there is a constant available source of oxygen, the intermittent hydro-atomizing of a spray/mist of the water-nutrient solution provides the necessary moisture and essential minerals to keep plants turgid and alive.^[1]

[edit] True aeroponics

Air cultures optimize access to air for successful plant growth. Materials and devices which hold and support the aeroponic grown plants must be devoid of disease or pathogens . A distinction of a true aeroponic culture and apparatus is that it provides plant support features that are monomial. Monomial contact between a plant and support structure allows for 100% of the plant to be entirely in air. Long-term aeroponic cultivation requires the root systems to be free of constraints surrounding the stem and root systems. Physical contact is minimized so that it does not hinder natural growth and root expansion or access to pure water, air exchange and disease-free conditions.

^[1]

[edit] Benefits of air (oxygen)

Clean air supplies oxygen which is an excellent purifier for plants and the aeroponic environment. For natural growth to occur the plant must have unrestricted access to air. Plants must be allowed to grow in a natural manner for successful physiological development. The more confining the plant support becomes, the greater incidence of increasing disease pressure of the plant and the aeroponic system.^[1]

Some researchers have used aeroponics to study the effects of root zone gas composition on plant performance. Soffer and Burger [Soffer et al., 1988] studied the effects of dissolved oxygen concentrations on the formation of adventitious roots in what they termed “aero-hydroponics.” They utilized a 3-tier hydro and aero system, in which three separate zones were formed within the root area. The ends of the roots were submerged in the nutrient reservoir, while the middle of the root section received nutrient mist and the upper portion was above the mist. Their results showed that dissolved O2 is essential to root formation, but went on to show that for the three O2 concentrations tested, the number of roots and root length were always greater in the central misted section than either the submersed section or the un-misted section. Even at the lowest concentration, the misted section rooted successfully.^[1]

[edit] Other benefits of air (CO₂)

Plants in a true aeroponic apparatus have 100% access to the CO2 concentrations ranging from 450 ppm to 780 ppm for photosynthesis. (At one mile above sea level the CO2 concentration in the air is 450 ppm during daylight. At night the CO2 level will rise to 780 ppm.) Lower elevations will have higher levels. In any case, the air culture apparatus offers ability for plants to have full access to all the available CO2 in the air for photosynthesis.

Growing under lights during the evening allows aeroponics to benefit from the natural occurrence.^[1]

[edit] Natural disease-free cultivation

Aeroponics can limit disease transmission since plant-to-plant contact is reduced and each spray pulse can be sterile. In the case of soil, aggregate, or other media, disease can spread throughout the growth media, infecting many plants. In most greenhouses these solid media require sterilization after each crop and, in many cases, they are simply discarded and replaced with fresh, certified sterile media.^[1]

A distinct advantage of aeroponic technology is that if a particular plant does become diseased, it can be quickly removed from the plant support structure without disrupting or infecting the other plants.

Due to the disease-free environment that is unique to aeroponics, many plants can grow at higher density (plants per sq meter) when compared to more traditional forms of cultivation (hydroponics, soil and NFT). Commercial aeroponic systems incorporate hardware features that accommodate the crops expanding root systems.

Researcher du Toit, L.J., H.W. Kirby and W.L. Pedersen (1997). “Evaluation of an Aeroponics System to Screen Maize Genotypes for Resistance to Fusarium graminearum Seedling Blight.” These researchers describe aeroponics as a "valuable, simple, and rapid method for preliminary screening of genotypes for resistance to specific seedling blight or root rot.” ^[5]

The isolating nature of the aeroponic system allowed them to avoid the complications encountered when studying these infections in soil culture.

[edit] Water/Nutrient hydro-atomization

Aeroponic equipment involves the use of sprayers, misters, foggers, or other devices to create a fine mist of solution to deliver nutrients to plant roots. Aeroponic systems are normally closed-looped systems providing macro and micro-environments suitable to sustain a reliable, constant air culture. Numerous inventions have been developed to facilitate aeroponic spraying and misting.

The key to root development in an aeroponic environment is the size of the water droplet. In commercial applications, a hydro-atomizing spray is employed to cover large areas of roots utilizing air pressure misting.

A variation of the mist technique employs the use of ultrasonic nebulizers or foggers to mist nutrient solutions in low-pressure aeroponic devices.

Water droplet size is crucial for sustaining aeroponic growth. Too large of a water droplet means less oxygen is available to the root system. Too fine of a water droplet, such as those generated by the ultra-sonic mister, produce excessive root hair without developing a lateral root system for sustained growth in an aeroponic system.^[1]

Mineralization of the ultra-sonic traducers requires maintenance and potential for component failure. This is also a shortcoming of metal spray jets and misters. Restricted access to the water causes the plant to lose turgidity and wilt.

[edit] Advanced materials

NASA has funded research and development of new advanced materials to improve aeroponic reliability and maintenance reduction. It also has determined that high pressure hydro-atomized mist of 5-50 microns micro-droplets is necessary for long-term aeroponic growing.

For long-term growing, the mist system must have significant pressure to force the mist into the dense root system(s). Repeatability is the key to aeroponics and includes the hydro-atomized droplet size. Degradation of the spray due to mineralization of mist heads inhibits the delivery of the water nutrient solution, leading to an environmental imbalance in the air culture environment.

Special low-mass polymer materials were developed and are used to eliminate mineralization in next generation hydro-atomizing misting and spray jets.

[edit] Nutrient uptake

The discrete nature of interval and duration aeroponics allows the measurement of nutrient uptake over time under varying conditions. Barak et al. used an aeroponic system for non-destructive measurement of water and ion uptake rates for cranberries (Barak, Smith et al. 1996).

^[6]

In their study, these researchers found that by measuring the concentrations and volumes of input and efflux solutions, they could accurately calculate the nutrient uptake rate (which was verified by comparing the results with N-isotope measurements). After verification of their analytical method, Barak et al. went on to generate additional data specific to the cranberry, such as diurnal variation in nutrient uptake, correlation between ammonium uptake and proton efflux, and the relationship between ion concentration and uptake. Work such as this not only shows the promise of aeroponics as a research tool for nutrient uptake, but also opens up possibilities for the monitoring of plant health and optimization of crops grown in closed environments.^[7]

[edit] Terminology

Aeroponic growing refers to plants grown in an air culture that can develop and grow in a normal and natural manner.^[1]

Aeroponic growth refers to growth achieved in an air culture.

Aeroponic system refers to hardware and system components assembled to sustain plants in an air culture.

Aeroponic greenhouse refers to a climate controlled glass or plastic structure comprised of equipment to grow plants in air/mist environment.

Aeroponic conditions refers to air culture environmental parameters for sustaining plant growth for a plant species.

Aeroponic roots refers to a root system grown in an air culture.

[edit] Types of Aeroponics

[edit] Lo-pressure units

In most lo-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 sprayer nozzles or by ultrasonic transducers, which then drips or drains back into the reservoir. As plants grow to maturity in these units they tend to suffer from dry sections of the root systems, which prevent adequate nutrient uptake. These units, because of cost, lack features to purify the nutrient solution, and adequately remove incontinuities, debris, and unwanted pathogens. Such units are usually suitable for bench top growing and demonstrating the principles of aeroponics.

[edit] Hi-pressure devices

Hi-pressure aeroponic techniques, where the mist is generated by high-pressure pump(s), are typically used in the cultivation of high value crops and plant specimens that can offset the high setup costs associated with this method of horticulture.

Hi-pressure aeroponics systems include technologies for air and water purification, nutrient sterilization, low-mass polymers and pressurized nutrient delivery systems.

[edit] Commercial systems

Commercial aeroponic systems comprise hi-pressure device hardware and biological systems. The biological systems matrix includes enhancements for extended plant life and crop maturation.

Biological subsystems and hardware components include effluent controls systems, disease prevention, pathogen resistance features, precision timing and nutrient solution pressurization, heating and cooling sensors, thermal control of solutions, efficient photon-flux light arrays, spectrum filtration spanning, fail-safe sensors and protection, reduced maintenance & labor saving features, and ergonomics and long-term reliability features.

Commercial aeroponic systems, like the hi-pressure devices, are used for the cultivation of high value crops where multiple crop rotations are achieved on an ongoing commercial basis 24/7.

Advanced commercial systems include data gathering, monitoring, analytical feedback and Internet mode connections to various subsystems.^[8]

[edit] History of aeroponics

It was W. Carter in 1942 who first researched air culture growing and described a method of growing plants in water vapor to facilitate examination of roots.^[9]

In 1944, L.J. Klotz was the first to discover vapor misted citrus plants in a facilitated research of his studies of diseases of citrus and avocado roots. In 1952, G.F. Trowel grew apple trees in a spray culture.^[2]

It was F. W. Went in 1957 who first coined the air-growing process as “aeroponics”, growing coffee plants and tomatoes with air-suspended roots and applying a nutrient mist to the root section.^[2]

[edit] Early lab research

Soon after its development, aeroponics took hold as a valuable research tool. Aeroponics offered researchers a noninvasive way to examine roots under development. This new technology also allowed researchers a larger number and a wider range of experimental parameters to use in their work.^[2]

The ability to precisely control the root zone moisture levels and the amount of water delivered makes aeroponics ideally suited for the study of water stress. K. Hubick [Hubick et al., 1982] evaluated aeroponics as a means to produce consistent, minimally water-stressed plants for use in drought or flood physiology experiments.^[10]

Aeroponics is the ideal tool for the study of root morphology. The absence of aggregates offers researchers easy access to the entire, intact root structure without the damage that can be caused by removal of roots from soils or aggregates. It’s been noted that aeroponics produces more normal root systems than hydroponics.^[11]

[edit] Commercialization

Aeroponics eventually left the laboratories and entered into the commercial cultivation arena. In 1966, commercial aeroponic pioneer, B. Briggs, succeeded in inducing roots on hardwood cuttings by air-rooting. Briggs discovered that air-rooted cuttings were tougher and more hardened than those formed in soil and concluded that the basic principle of air-rooting is sound. He discovered air-rooted trees could be transplanted to soil without suffering from transplant shock or setback to normal growth. Transplant shock is normally observed in hydroponic transplants.^[12]

In Israel in 1982, L. Nir, developed a patent for an aeroponic apparatus using comprised low pressure air to deliver a nutrient solution to suspended plants, held by styrofoam, inside large metal containers.^[13]

In 1983, R. Stoner filed a patent for the first microprocessor interface to deliver tap water and nutrients into an enclosed aeroponic chamber made of plastic. Stoner has gone on to develop numerous companies researching and advancing aeroponic hardware, interfaces, biocontrols and components for commercial aeroponic crop production.^[2]

In 1985, Stoner's company, GTi, was the first company to manufacture, market and apply large scale closed-loop aeroponic systems into greenhouses for commercial crop production.

^[14]

[edit] Aeroponically grown food

In 1986 Stoner was the first person ever to market fresh aeroponically grown food to a national grocery chain. He was interviewed on NPR and discussed the importance of the water conservation features of aeroponics for both modern agriculture and space.^[3]

Stoner is considered the father of commercial aeroponics. Stoner's aeroponic systems are in major developed countries around the world. His aeroponic designs, technology and equipment are widely used at leading agricultural universities worldwide and by commercial growers.^[1]

(The Genesis Machine had come a long way fast. Sometime later, the Star-Trek TV series sustained the starship’s crew with food grown in its aeroponics-bay.)

[edit] NASA aeroponic history

[edit] Space plants

Plants were first taken into Earth's orbit in 1960 on two separate missions, Sputnik 4 and Discover 17 (for a review of the first 30 years of plant growth in space, see Halstead and Scott 1990.^[15]

On the former mission, wheat, pea, maize, spring onion, and Nigella damascena seeds were carried into space, and on the latter mission Chlorella pyrenoidosa cells were brought into orbit.^[16][3]

Plant experiments were later performed on a variety of Soviet, American, and joint Soviet-American missions, including Biosatellite II, Skylab 3 and 4, Apollo-Soyuz, Sputnik, Vostok, and Zond. Some of the earliest research results showed the effect of low gravity on the orientation of roots and shoots (Halstead and Scott 1990).^[3]

Subsequent research went on to investigate the effect of low gravity on plants at the organismic, cellular, and subcellular levels. At the organismic level, for example, a variety of species, including pine, oat, mung bean, lettuce, cress, and Arabidopsis, showed decreased seedling, root, and shoot growth in low gravity, whereas lettuce grown on Cosmos showed the opposite effect of growth in space (Halstead and Scott 1990). Mineral uptake seems also to be affected in plants grown in space. For example, peas grown in space exhibited increased levels of phosphorus and potassium and decreased levels of the divalent cations calcium, magnesium, manganese, zinc, and iron (Halstead and Scott 1990).^[17]

[edit] Biocontrols in space

In 1996, NASA sponsored Stoner’s research for a natural liquid biocontrol, known then as ODC (organic disease control), that activates plants to grow without the need for pesticides as a means to control pathogens in a closed-loop culture system. ODC is derived from natural aquatic materials.^[18]

By 1997, Stoner’s biocontrol experiments were conducted by NASA. BioServe Space Technologies’s GAP technology (miniature growth chambers) delivered the ODC solution unto bean seeds. Triplicate ODC experiments were conducted in GAP’s flown to the MIR by the space shuttle; at the Kennedy Space Center; and at Colorado State University (J. Linden). All GAPS were housed in total darkness to eliminate light as an experiment variable. The NASA experiment was to study only the benefits of the biocontrol.^[19]

NASA's experiments aboard the MIR space station and shuttle confirmed that ODC elicited increased germination rate, better sprouting, increased growth and natural plant disease mechanisms when applied to beans in an enclosed environment. ODC is now a standard for pesticide-free aeroponic growing and organic farming. Soil and hydroponics growers can benefit by incorporating ODC into their planting techniques. ODC meets USDA NOP standards for organic farms.^[20]

[edit] Aeroponics for space & Earth

In 1998, Stoner received NASA funding to develop a high performance aeroponic system for earth and space. Stoner demonstrated that a dry bio-mass of lettuce can be significantly increased with aeroponics. NASA made history by utilizing numerous aeroponic advancements developed by Stoner.

Abstract: The purpose of the research conducted was to identify and demonstrate technologies for high-performance plant growth in a variety of gravitational environments. A low-gravity environment, for example, poses the problems of effectively bringing water and other nutrients to the plants and effecting recovery of effluents. Food production in the low-gravity environment of space provides further challenges, such as minimization of water use, water handling, and system weight. Food production on planetary bodies such as the Moon or Mars also requires dealing with a hypogravity environment. Because of the impacts to fluid dynamics in these various gravity environments, the nutrient delivery system has been a major focus in plant growth system optimization.

There are a number of methods currently utilized (both in low gravity and on Earth) to deliver nutrients to plants. Substrate dependent methods include traditional soil cultivation, zeoponics, agar, and nutrient-loaded ion exchange resins. In addition to substrate dependent cultivation, many soilless methods have been developed such as nutrient film technique, ebb and flow, aeroponics, and many other variants. Many hydroponic systems can provide high plant performance but nutrient solution throughput is high, necessitating large water volumes and substantial recycling of solutions, and the control of the solution in hypogravity conditions is difficult at best.

Aeroponics, with its use of a hydro-atomized spray to deliver nutrients, minimizes water use, increases oxygenation of roots, and offers excellent plant growth, while at the same time approaching or bettering the low nutrient solution throughput of other systems developed to operate in low gravity. Aeroponics’ elimination of substrates and the need for large nutrient stockpiles reduces the amount of waste materials to be processed by other life support systems. Furthermore, the absence of substrates simplifies planting and harvesting (providing opportunities for automation), decreases the volume and weight of expendable materials, and eliminates a pathway for pathogen transmission. These many advantages combined with the results of this research that prove the viability of aeroponics in microgravity makes aeroponics a logical choice for efficient food production in space.^[1]

[edit] NASA inflatable aeroponics

In 1999, Stoner, funded by NASA, developed an inflatable low-mass aeroponic system (AIS) for space and earth for high performance food production.

Abstract: Aeroponics International’s (AI’s) innovation is a self-contained, self-supporting, inflatable aeroponic crop production unit with integral environmental systems for the control and delivery of a nutrient/mist to the roots. This inflatable aeroponic system addresses the needs of subtopic 08.03 Spacecraft Life Support Infrastructure and, in particular, water and nutrient delivery systems technologies for food production. The inflatable nature of our innovation makes it lightweight, allowing it to be deflated so it takes up less volume during transportation and storage. It improves on AI’s current aeroponic system design that uses rigid structures, which use more expensive materials, manufacture processes, and transportation. As a stationary aeroponic system, these existing high-mass units perform very well, but transporting and storing them can be problematic.^[14]

On Earth, these problems may hinder the economic feasibility of aeroponics for commercial growers. However, such problems become insurmountable obstacles for using these systems on long-duration space missions because of the high cost of payload volume and mass during launch and transit.^[14]

The NASA efforts lead to developments of numerous advanced materials for aeroponics for earth and space.^[14]

[edit] Mission to Mars

NASA's long range plans indicate that man's visit to Mars will utilize inflatable structures to house the spaceship crew on the Mars surface. Planning is under way to incorporate inflatable greenhouse facilities for food production.

NASA planning scenarios also reveal the Mars surface crew will spend 60% of their time on Mars farming to sustain themselves. Aeroponics is considered the agricultural system of choice because of its low water and power inputs and high volume of food output per sq meter.

[edit] Benefits of Aeroponics for Earth & Space

Aeroponics possesses many characteristics that make it an effective and efficient means of growing plants.

[edit] Less Nutrient Solution Throughput

Plants grown using aeroponics spend 99.98% of their time in air and 0.02% in direct contact with hydro-atomized nutrient solution. The time spent without water allows the roots to capture oxygen more efficiently. Furthermore, the hydro-atomized mist also significantly contributes to the effective oxygenation of the roots. For example, NFT has a nutrient throughput of 1 L/minute compared to aeroponics’ throughput of 1.5 ml/minute.

The reduced volume of nutrient throughput results in reduced amounts of nutrients required for plant development.

Another benefit of the reduced throughput, of major significance for space-based use, is the reduction in water volume used. This reduction in water volume throughput corresponds with a reduced buffer volume, both of which significantly lighten the weight needed to maintain plant growth. In addition, the volume of effluent from the plants is also reduced with aeroponics, reducing the amount of water that needs to be treated before reuse.

The relatively low solution volumes used in aeroponics, coupled with the minimal amount of time that the roots are exposed to the hydro-atomized mist, minimizes root-to-root contact and spread of pathogens between plants.

[edit] More control of plant environment

Aeroponics allows more control of the environment around the root zone, as, unlike other plant growth systems, the plant roots are not constantly surrounded by some medium (as, for example, with hydroponics, where the roots are constantly immersed in water).

[edit] Improved nutrient feeding

A variety of different nutrient solutions, for example, can be administered to the root zone using aeroponics without needing to flush out any solution or matrix in which the roots had previously been immersed. This elevated level of control would be useful when researching the effect of a varied regimen of nutrient application to the roots of a plant species of interest. In a similar manner, aeroponics allows a greater range of growth conditions than other nutrient delivery systems. The interval and duration of the nutrient spray, for example, can be very finely attuned to the needs of a specific plant species. The aerial tissue can be subjected to a completely different environment from that of the roots.

[edit] More user-friendly

The design of an aeroponic system allows ease of working with the plants. This results from the separation of the plants from each other, and the fact that the plants are suspended in air and the roots are not entrapped in any kind of matrix. Consequently, the harvesting of individual plants is quite simple and straightforward. Likewise, removal of any plant that may be infected with some type of pathogen is easily accomplished without risk of uprooting or contaminating nearby plants.

[edit] More cost effective

Aeroponic systems are more cost effective than other systems. Because of the reduced volume of solution throughput (discussed above), less water and less nutrients are needed in the system at any given time compared to other nutrient delivery systems. The need for substrates is also eliminated, as is the need for many moving parts, resulting in lowered manufacturing cost and reduced maintenance costs.

[edit] Pathogen Control & Disease Prevention

Plants are most susceptible to loss from pathogens during the first 21 days of their life cycle. The aeroponic technology developed by the PI utilizes a patented plant support structure that separates the plants from one another. In a hydroponic or aggregate-based system, pathogen infections can easily spread throughout the entire system due to the plants’ common source of water or medium. In the ideal aeroponic system pathogens can be reduced and controlled by:

• separating the plants - thus preventing the pathogen from spreading infection from one plant to another.
• applying disinfectants and fungicides to the aerial and root zones individually,
• applying the water/nutrient at intervals that are best suited for plant development and growth,
• allowing the plant to expand without interference of restricting physical barriers,
• reducing the per plant exposure to surfaces where pathogens can linger or proliferate.

[edit] Use of seed stocks

With aeroponics, the deleterious effects of seed stocks that are infected with pathogens can be minimized. As discussed above, this is due to the separation of the plants and the lack of shared growth matrix. In addition, due to the enclosed, controlled environment, aeroponics can be an ideal growth system in which to grow seed stocks that are pathogen-free. The enclosing of the growth chamber, in addition to the isolation of the plants from each other discussed above, helps to both prevent initial contamination from pathogens introduced from the external environment and minimize the spread from one plant to others of any pathogens that may exist.

[edit] 21st Century aeroponics

Aeroponics is an improvement in artificial life support for non-damaging plant support, seed germination, environmental control and rapid unrestricted growth when compared with hydroponics and drip irrigation techniques that have been used for decades by traditional agriculturalists.

[edit] Contemporary aeroponics

Contemporary aeroponic techniques have been researched at NASA's research and commercialization center BioServe Space Technologieslocated on the campus of the University of Colorado in Boulder, Colorado. Other research includes enclosed loop system research at Ames Research Center, where scientists were studying methods of growing food crops in low gravity situations for future space colonization.

In 2000, Stoner was granted a patent for an organic disease control biocontrol technology that allows for pesticide-free natural growing in an aeroponic systems.

Stoner received a patent in 2001 for a novel aeroponic method and apparatus utilizing a low pressure mist generated by centrifugal force utilizing a rotating cylinder device. The rotating cylinder device distributes liquid nutrient solution to the roots of plants by use of centrifugal force, thereby eliminating the need for a high pressure and low pressure pump and nozzles, including ultra-sonic misters. The geometrical shape of the enclosed root growth chamber is such that it allows for fractionated droplets to ricochet in multiple random directions thus completely surrounding the plant roots in 360.degree, in any plane.^[3]

[edit] Aeroponic bio-pharming

Aeroponic bio-pharming is used to grow pharmaceutical medicine inside of plants. The technology allows for completed containment of allow effluents and by-products of biopharma crops to remain inside a closed-loop facility.

As recently as 2005, GMO research at South Dakota State University by Dr. Neil Reese applied aeroponics to grow genetically modified corn.

According to Reese it is a historical feat to grow corn in an aeroponic apparatus for bio-massing. The university’s past attempts to grow all types of corn using hydroponics ended in failure.

Using advanced aeroponics techniques to grow genetically modified corn Reese harvested full ears of corn. All the while containing the corn pollen and spent effluent water and preventing them from entering the environment. Containment of these ecologically harmful by-products ensures the environment remains safe from GMO contamination.

Reese says, aeroponics offers the ability to make bio-pharming economically practical.^[3]

[edit] Large scale integration of aeroponics

In 2006, the Ag University of Hanoi Vietnam in joint efforts with Stoner established the postgraduate doctoral program in aeroponics.

The university's Agrobiotech Research Center, under the direction of Dr. N. Thach, is using aeroponic laboratories to advance Vietnam's minituber potato production for certified seed potato production.

The historical significants for aeroponics - it's the first time a nation has specifically called out for aeroponics to further an agricultural sector, stimulate farm economic goals, meet increased demands, improve food quality and increase production.

Potatoes are one of the world's top foods containing a high level of protein. "We have shown that aeroponics, more than any other form of agricultural technology, will significantly improve Vietnam's potato production. We have very little tillable land, aeroponics makes complete economic sense to us”, attested Thach.

Vietnam joined the World Trade Organization (WTO) in January 2007. The impact of aeroponics in Vietnam will be felt at the farm level.

Aeroponic integration in Vietnam agriculture will begin by producing a low cost certified disease-free organic minitubers. Which in turn will be supplied to local farmers for their field plantings of seed potatoes and commercial potatoes. Potato farmers will benefit from aeroponics because their seed potatoes will be disease-free and grown without pesticides. Most importantly for the Vietnamese farmer, it will lower their cost of operation and increase their yields, says Thach.^[3]

[edit] NASA aeroponic links

• "A High Performance, Gravity Insensitive, Enclosed Aeroponic System for Food Production in Space"
• NASA Spinoff 2006
• "Re-examining Aeroponics for Spaceflight Plant Growth"

[edit] In popular culture

On the television series Star Trek: Voyager, the starship Voyager is fitted with an aeroponics laboratory by the character Kes for growing herbs and vegetables; the laboratory is occasionally featured as a setting in a number of episodes. On the show, however, the process is referred to as "airponics". [1]

[edit] See also

• Hydroponics

[edit] References

[edit] Technical links

• Aeroponics and Bio-pharming Research
• NASA Official Web Site
• NASA Web Site: Aeroponic Plants
• NASA Web Site: Aeroponic High Performance Food Production
• NASA Web Site: Low Mass Aeroponics
• NASA Web Site: Success Stories