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66-508: A Hydroponicum is a farm, garden, or building devoted to soilless cultivation or hydroponics . This article about a building or structure type is a stub . You can help Misplaced Pages by expanding it . Hydroponics Despite inert media, roots can cause changes of the rhizosphere pH and root exudates can affect rhizosphere biology and physiological balance of the nutrient solution when secondary metabolites are produced in plants. Transgenic plants grown hydroponically allow

132-423: A biofilm of green algae on the glass, through photosynthesis . Clear containers can also be covered with aluminium foil, butcher paper, black plastic, or other material to eliminate the effects of negative phototropism . The nutrient solution is changed either on a schedule, such as once per week, or when the concentration drops below a certain level as determined with an electrical conductivity meter . Whenever

198-714: A bioregenerative life support system . As of 2017, Canada had hundreds of acres of large-scale commercial hydroponic greenhouses, producing tomatoes, peppers and cucumbers. Due to technological advancements within the industry and numerous economic factors , the global hydroponics market is forecast to grow from US$ 226.45 million in 2016 to US$ 724.87 million by 2023. There are two main variations for each medium: sub-irrigation and top irrigation . For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used, including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae and fungal growth in

264-432: A greenhouse or contained environment on inert media, adapted to the controlled-environment agriculture (CEA) process. Plants commonly grown hydroponically include tomatoes , peppers , cucumbers , strawberries , lettuces , and cannabis , usually for commercial use, as well as Arabidopsis thaliana , which serves as a model organism in plant science and genetics . Hydroponics offers many advantages, notably

330-451: A commercial setting, watering frequency is multi-factorial and governed by computers or PLCs . Commercial hydroponics production of large plants like tomatoes, cucumber, and peppers uses one form or another of run-to-waste hydroponics. The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Traditional methods favor the use of plastic buckets and large containers with

396-469: 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. The various hydroponic media available, such as expanded clay and coconut husk , contain more air space than more traditional potting mixes, delivering increased oxygen to the roots, which is important in epiphytic plants such as orchids and bromeliads , whose roots are exposed to

462-439: A constantly recirculating system. As with deep water culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir. The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day. The biggest advantage of top-fed deep water culture over standard deep water culture is increased growth during the first few weeks. With deep water culture, there

528-405: A container of inert growing media, such as rockwool, perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery frequency that is governed by the key parameters of plant size, plant growing stage, climate, substrate, and substrate conductivity, pH, and water content. In

594-504: A decrease in water usage in agriculture. To grow 1 kilogram (2.2 lb) of tomatoes using Hydroponic cultures lead to highest biomass and protein production compared to other growth substrates , of plants cultivated in the same environmental conditions and supplied with equal amounts of nutrients. Hydroponics is not only used on earth, but has also proven itself in plant production experiments in earth orbit . The earliest published work on growing terrestrial plants without soil

660-544: A deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients . Excellent aeration is the main advantage of aeroponics. 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. A major limitation of hydroponics

726-704: A hydroponic growth solution to provide all nutrients necessary for robust growth. Due to the plants continuous fight against gravity, plants typically mature much more quickly than when grown in soil or other traditional hydroponic growing systems. Because rotary hydroponic systems have a small size, they allow for more plant material to be grown per area of floor space than other traditional hydroponic systems. Rotary hydroponic systems should be avoided in most circumstances, mainly because of their experimental nature and their high costs for finding, buying, operating, and maintaining them. Different media are appropriate for different growing techniques. Rock wool ( mineral wool )

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792-497: A major in the United States Army and used his prior expertise with plant nutrition to feed troops stationed on barren Ponape Island in the western Pacific by growing crops in gravel and nutrient-rich water because there was no arable land available. In the 1960s, Allen Cooper of England developed the nutrient film technique . The Land Pavilion at Walt Disney World's EPCOT Center opened in 1982 and prominently features

858-419: A mist is easier to handle than a liquid in a zero-gravity environment. Fogponics is a derivation of aeroponics wherein the nutrient solution is aerosolized by a diaphragm vibrating at ultrasonic frequencies . Solution droplets produced by this method tend to be 5–10 μm in diameter, smaller than those produced by forcing a nutrient solution through pressurized nozzles, as in aeroponics. The smaller size of

924-671: A single causal organism; however, some plant diseases have been shown to be interactions between multiple pathogens. To colonize a plant, pathogens have specific pathogenicity factors , of five main types: uses of cell wall–degrading enzymes, toxins , effector proteins, phytohormones , and exopolysaccharides . Some abiotic disorders can be confused with pathogen-induced disorders. Abiotic causes include natural processes such as drought , frost , snow and hail ; flooding and poor drainage; nutrient deficiency ; deposition of mineral salts such as sodium chloride and gypsum ; windburn and breakage by storms; and wildfires . Epidemiology

990-411: A single solution there are limits. Bertolini et al. 2001, Ito et al. 2002, and Ragozzino et al. 2004 developed PCR methods for multiplexing six or seven plant pathogen molecular products and Persson et al. 2005 for multiplexing four with RT-PCR. More extensive molecular diagnosis requires PCR arrays . The primary detection method used worldwide is enzyme linked immunosorbent assay . Crop rotation

1056-937: A standard 5.1 kg bag of Growstones that corresponds to 25.8 to 258 grams of calcium carbonate . The remainder is soda-lime glass. Plant pathology Plant pathology or phytopathology is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Plant pathology involves the study of pathogen identification, disease etiology , disease cycles, economic impact, plant disease epidemiology , plant disease resistance , how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases. Plant pathogens, organisms that cause infectious plant diseases , include fungi , oomycetes , bacteria , viruses , viroids , virus -like organisms, phytoplasmas , protozoa , nematodes and parasitic plants . In most plant pathosystems , virulence depends on hydrolases and enzymes that degrade

1122-702: A standard research and teaching technique in the 19th and 20th centuries and is still widely used in plant nutrition science. Around the 1930s plant nutritionists investigated diseases of certain plants, and thereby, observed symptoms related to existing soil conditions such as salinity . In this context, water culture experiments were undertaken with the hope of delivering similar symptoms under controlled laboratory conditions. This approach forced by Dennis Robert Hoagland led to innovative model systems (e.g., green algae Nitella ) and standardized nutrient recipes playing an increasingly important role in modern plant physiology . In 1929, William Frederick Gericke of

1188-450: A variety of hydroponic techniques. In recent decades, NASA has done extensive hydroponic research for its Controlled Ecological Life Support System (CELSS). Hydroponics research mimicking a Martian environment uses LED lighting to grow in a different color spectrum with much less heat. Ray Wheeler , a plant physiologist at Kennedy Space Center's Space Life Science Lab, believes that hydroponics will create advances within space travel, as

1254-443: A view held by Hoagland. Because of these irreconcilable conflicts, Gericke left his academic position in 1937 in a climate that was politically unfavorable and continued his research independently in his greenhouse. In 1940, Gericke, whose work is considered to be the basis for all forms of hydroponic growing, published the book, Complete Guide to Soilless Gardening . Therein, for the first time, he published his basic formulas involving

1320-414: A wool with an appropriate, stable pH. Baked clay pellets are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellets are inert, pH -neutral, and do not contain any nutrient value. The clay is formed into round pellets and fired in rotary kilns at 1,200 °C (2,190 °F). This causes the clay to expand, like popcorn, and become porous. It

1386-585: Is a non-hazardous, non-carcinogenic material, falling under Note Q of the European Union Classification Packaging and Labeling Regulation (CLP). Mineral wool products can be engineered to hold large quantities of water and air that aid root growth and nutrient uptake in hydroponics; their fibrous nature also provides a good mechanical structure to hold the plant stable. The naturally high pH of mineral wool makes them initially unsuitable to plant growth and requires "conditioning" to produce

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1452-403: Is a technique involving delivering highly oxygenated nutrient solution direct to the root zone of plants. While deep water culture involves the plant roots hanging down into a reservoir of nutrient solution, in top-fed deep water culture the solution is pumped from the reservoir up to the roots (top feeding). The water is released over the plant's roots and then runs back into the reservoir below in

1518-420: Is a time when the roots have not reached the water yet. With top-fed deep water culture, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a deep water culture system. Once the roots have reached the reservoir below, there is not a huge advantage with top-fed deep water culture over standard deep water culture. However, due to the quicker growth in

1584-433: Is a traditional and sometimes effective means of preventing a parasitic population from becoming well-established. For example, protection against infection by Agrobacterium tumefaciens , which causes gall diseases in many plants, by dipping cuttings in suspensions of Agrobacterium radiobacter before inserting them in the ground to take root. Plant pathology has developed from antiquity, starting with Theophrastus in

1650-406: Is difficult to build a base for channels that is sufficiently true to enable nutrient films to flow without ponding in locally depressed areas. As a consequence, it is recommended that slopes of 1:30 to 1:40 are used. This allows for minor irregularities in the surface, but, even with these slopes, ponding and water logging may occur. The slope may be provided by the floor, benches or racks may hold

1716-458: Is drained away, recirculated, or actively aerated, eliminating anoxic conditions in the root area. In soil, a grower needs to be very experienced to know exactly how much water to feed the plant. Too much and the plant will be unable to access oxygen because air in the soil pores is displaced, which can lead to root rot ; too little and the plant will undergo water stress or lose the ability to absorb nutrients, which are typically moved into

1782-477: Is light in weight, and does not compact over time. The shape of an individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach , or hydrogen peroxide ( H 2 O 2 ), and rinsing completely. Another view

1848-400: Is possible in this way not only to maintain plants alive and growing for a long time, as had long been known, but also to bring about a vigorous increase of their organic substance, and even the production of seed capable of germination ." Growth of terrestrial plants without soil in mineral nutrient solutions was later called "solution culture" in reference to "soil culture". It quickly became

1914-416: Is that clay pebbles are best not re-used even when they are cleaned, due to root growth that may enter the medium. Breaking open a clay pebble after use can reveal this growth. Growstones , made from glass waste, have both more air and water retention space than perlite and peat. This aggregate holds more water than parboiled rice hulls . Growstones by volume consist of 0.5 to 5% calcium carbonate – for

1980-545: Is the fact that 1 kilogram (2.2 lb) of water can only hold 8 milligrams (0.12 gr) 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. Another limitation of hydroponics is that certain species of plants can only survive for so long in water before they become waterlogged . In contrast, suspended aeroponic plants receive 100% of

2046-408: Is the most widely used medium in hydroponics. Rock wool is an inert substrate suitable for both run-to-waste and recirculating systems. Rock wool is made from molten rock, basalt or 'slag' that is spun into bundles of single filament fibres, and bonded into a medium capable of capillary action, and is, in effect, protected from most common microbiological degradation. Rock wool is typically used only for

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2112-452: Is the study of factors affecting the outbreak and spread of infectious diseases. A disease triangle describes the basic factors required for plant diseases. These are the host plant, the pathogen, and the environment. Any one of these can be modified to control a disease. Plant disease resistance is the ability of a plant to prevent and terminate infections from plant pathogens. Structures that help plants prevent pathogens from entering are

2178-418: The cell wall . The vast majority of these act on pectins (for example, pectinesterase , pectate lyase , and pectinases ). For microbes, the cell wall polysaccharides are both a food source and a barrier to be overcome. Many pathogens grow opportunistically when the host breaks down its own cell walls, most often during fruit ripening . Unlike human and animal pathology, plant pathology usually focuses on

2244-490: The NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen, and nutrients. In all other forms of production, there is a conflict between the supply of these requirements, since excessive or deficient amounts of one results in an imbalance of one or both of the others. NFT, because of its design, provides a system where all three requirements for healthy plant growth can be met at

2310-573: The University of California at Berkeley began publicly promoting that the principles of solution culture be used for agricultural crop production . He first termed this cultivation method "aquiculture" created in analogy to "agriculture" but later found that the cognate term aquaculture was already applied to culture of aquatic organisms . Gericke created a sensation by growing tomato vines twenty-five feet (7.6 metres) high in his backyard in mineral nutrient solutions rather than soil. He then introduced

2376-406: The air in nature. Additional advantages of passive hydroponics are the reduction of root rot. In its simplest form, nutrient-enriched water is pumped into containers with plants in a growing medium such as Expanded clay aggregate At regular intervals, a simple timer causes a pump to fill the containers with nutrient solution, after which the solution drains back down into the reservoir. This keeps

2442-416: The available oxygen and carbon dioxide to their 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 also uses 65% less water than hydroponics. NASA concluded that aeroponically grown plants require ¼

2508-877: The beginning, grow time can be reduced by a few weeks. Hydrozone is a term used to describe spaces dedicated to cultivating rare or exotic plants under specific conditions, particularly through hydroponics . These areas, often compact and purposefully designed, recreate optimal environments for the development of plants that require controlled settings. Hydroponics—a soilless cultivation method—is central to these setups, employing inert substrates and nutrient-rich solutions to promote plant growth. Hydrozones are especially valued for conserving rare or endangered plants, propagating them in urban settings, or advancing scientific research. They can be found in high-tech greenhouses, adapted domestic environments (such as grow tents equipped with LED lights , ventilation systems, and humidity controllers), or research facilities. Hydrozones lie at

2574-627: The channels and provide the required slope. Both methods are used and depend on local requirements, often determined by the site and crop requirements. As a general guide, flow rates for each gully should be one liter per minute. At planting, rates may be half this and the upper limit of 2 L/min appears about the maximum. Flow rates beyond these extremes are often associated with nutritional problems. Depressed growth rates of many crops have been observed when channels exceed 12 meters in length. On rapidly growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may be depleted over

2640-426: The claim that hydroponic crop yields were no better than crop yields obtained with good-quality soils. Ultimately, crop yields would be limited by factors other than mineral nutrients, especially light and aeration of the culture medium. However, in the introduction to his landmark book on soilless cultivation, published two years later, Gericke pointed out that the results published by Hoagland and Arnon in comparing

2706-678: The cuticular layer, cell walls, and stomata guard cells. Once pathogens have overcome these barriers, plant receptors initiate signaling pathways to create molecules to compete against the foreign molecules. These pathways are influenced and triggered by genes within the host plant and can manipulated by genetic breeding to create resistant varieties. Ancient methods of leaf examination and breaking open plant material by hand are now augmented by newer technologies. These include molecular pathology assays such as polymerase chain reaction (PCR), RT-PCR and loop-mediated isothermal amplification (LAMP). Although PCR can detect multiple molecular targets in

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2772-403: The discoveries of German botanists Julius von Sachs and Wilhelm Knop , in the years 1859–1875, resulted in a development of the technique of soilless cultivation. To quote von Sachs directly: "In the year 1860, I published the results of experiments which demonstrated that land plants are capable of absorbing their nutritive matters out of watery solutions, without the aid of soil, and that it

2838-409: The dissolved nutrients required for plant growth is recirculated in a thin layer past a bare root mat of plants in a watertight channel, with an upper surface exposed to air. As a consequence, an abundant supply of oxygen is provided to the roots of the plants. A properly designed NFT system is based on using the right channel slope, the right flow rate, and the right channel length. The main advantage of

2904-444: The droplets allows them to diffuse through the air more easily, and deliver nutrients to the roots without limiting their access to oxygen. Passive sub-irrigation, also known as passive hydroponics, semi-hydroponics, or hydroculture , is a method wherein plants are grown in an inert porous medium that moves water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labor and providing

2970-475: The earliest successes of hydroponics occurred on Wake Island , a rocky atoll in the Pacific Ocean used as a refueling stop for Pan American Airlines . Hydroponics was used there in the 1930s to grow vegetables for the passengers. Hydroponics was a necessity on Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh vegetables. From 1943 to 1946, Daniel I. Arnon served as

3036-432: The entire growth cycle of whatever plant is being grown. While system specifics vary, systems typically rotate once per hour, giving a plant 24 full turns within the circle each 24-hour period. Within the center of each rotary hydroponic garden can be a high intensity grow light, designed to simulate sunlight, often with the assistance of a mechanized timer. Each day, as the plants rotate, they are periodically watered with

3102-445: The fact that the roots of the plant have constant access to oxygen and that the plants have access to as much or as little water and nutrients as they need. This is important as one of the most common errors when cultivating plants is over- and underwatering; hydroponics prevents this from occurring as large amounts of water, which may drown root systems in soil, can be made available to the plant in hydroponics, and any water not used,

3168-416: The hydroponic medium. In static solution culture, plants are grown in containers of nutrient solution, such as glass Mason jars (typically, in-home applications), pots , buckets, tubs, or tanks. The solution is usually gently aerated but may be un-aerated. If un-aerated, the solution level is kept low enough that enough roots are above the solution so they get adequate oxygen. A hole is cut (or drilled) in

3234-415: The intersection of urban agriculture innovations, environmental concerns, and biodiversity conservation efforts. Notable examples include specialized botanical gardens, cultivation facilities for threatened endemic species, and domestic spaces for advanced horticulture enthusiasts. A rotary hydroponic garden is a style of commercial hydroponics created within a circular frame which rotates continuously during

3300-543: The length of the gully. As a consequence, channel length should not exceed 10–15 meters. In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed halfway along the gully and halving the flow rates through each outlet. Aeroponics is a system wherein roots are continuously or discontinuously kept in an environment saturated with fine drops (a mist or aerosol ) of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in

3366-641: The macro- and micronutrient salts for hydroponically-grown plants. As a result of research of Gericke's claims by order of the Director of the California Agricultural Experiment Station of the University of California , Claude Hutchison , Dennis Hoagland and Daniel Arnon wrote a classic 1938 agricultural bulletin, The Water Culture Method for Growing Plants Without Soil , one of the most important works on solution culture ever, which made

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3432-474: The medium regularly flushed with nutrients and air. In a run-to-waste system, nutrient and water solution is periodically applied to the medium surface. The method was invented in Bengal in 1946; for this reason it is sometimes referred to as "The Bengal System". This method can be set up in various configurations. In its simplest form, a nutrient-and-water solution is manually applied one or more times per day to

3498-411: 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

3564-402: The nutrient solution constantly flows past the roots. It is much easier to automate than the static solution culture because sampling and adjustments to the temperature, pH, and nutrient concentrations can be made in a large storage tank that has potential to serve thousands of plants. A popular variation is the nutrient film technique or NFT, whereby a very shallow stream of water containing all

3630-435: The plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated by an air pump combined with porous stones . With this method, the plants grow much faster because of the high amount of oxygen that the roots receive. The Kratky Method is similar to deep water culture, but uses a non-circulating water reservoir. Top-fed deep water culture

3696-422: The release of pharmaceutical proteins as part of the root exudate into the hydroponic medium. The nutrients used in hydroponic systems can come from many different organic or inorganic sources, including fish excrement , duck manure , purchased chemical fertilizers , or artificial standard or hybrid nutrient solutions. In contrast to field cultivation, plants are commonly grown hydroponically in

3762-442: The roots while dissolved , leading to nutrient deficiency symptoms such as chlorosis or fertilizer burn . Eventually, Gericke's advanced ideas led to the implementation of hydroponics into commercial agriculture while Hoagland's views and helpful support by the University prompted Hoagland and his associates to develop several new formulas (recipes) for mineral nutrient solutions, universally known as Hoagland solution . One of

3828-546: The same time, provided that the simple concept of NFT is always remembered and practised. The result of these advantages is that higher yields of high-quality produce are obtained over an extended period of cropping. A downside of NFT is that it has very little buffering against interruptions in the flow (e.g., power outages). But, overall, it is probably one of the more productive techniques. The same design characteristics apply to all conventional NFT systems. While slopes along channels of 1:100 have been recommended, in practice it

3894-417: The seedling stage, or with newly cut clones, but can remain with the plant base for its lifetime. Rock wool has many advantages and some disadvantages. The latter being the possible skin irritancy (mechanical) whilst handling (1:1000). Flushing with cold water usually brings relief. Advantages include its proven efficiency and effectiveness as a commercial hydroponic substrate. Most of the rock wool sold to date

3960-425: The solution is depleted below a certain level, either water or fresh nutrient solution is added. A Mariotte's bottle , or a float valve, can be used to automatically maintain the solution level. In raft solution culture, plants are placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution. That way, the solution level never drops below the roots. In continuous-flow solution culture,

4026-491: The term Hydroponics , water culture, in 1937, proposed to him by W. A. Setchell , a phycologist with an extensive education in the classics. Hydroponics is derived from neologism υδρωπονικά (derived from Greek ύδωρ=water and πονέω=cultivate), constructed in analogy to γεωπονικά (derived from Greek γαία=earth and πονέω=cultivate), geoponica , that which concerns agriculture, replacing, γεω-, earth, with ὑδρο-, water. Despite initial successes, however, Gericke realized that

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4092-464: The time was not yet ripe for the general technical application and commercial use of hydroponics for producing crops. He also wanted to make sure all aspects of hydroponic cultivation were researched and tested before making any of the specifics available to the public. Reports of Gericke's work and his claims that hydroponics would revolutionize plant agriculture prompted a huge number of requests for further information. Gericke had been denied use of

4158-464: The top of the reservoir for each plant; if it is a jar or tub, it may be its lid, but otherwise, cardboard, foil, paper, wood or metal may be put on top. A single reservoir can be dedicated to a single plant, or to various plants. Reservoir size can be increased as plant size increases. A home-made system can be constructed from food containers or glass canning jars with aeration provided by an aquarium pump, aquarium airline tubing, aquarium valves or even

4224-488: The university's greenhouses for his experiments due to the administration's skepticism, and when the university tried to compel him to release his preliminary nutrient recipes developed at home, he requested greenhouse space and time to improve them using appropriate research facilities. While he was eventually provided greenhouse space, the university assigned Hoagland and Arnon to re-evaluate Gericke's claims and show his formula held no benefit over soil grown plant yields,

4290-555: The yields of experimental plants in sand, soil and solution cultures, were based on several systemic errors ("...these experimenters have made the mistake of limiting the productive capacity of hydroponics to that of soil. Comparison can be only by growing as great a number of plants in each case as the fertility of the culture medium can support"). For example, the Hoagland and Arnon study did not adequately appreciate that hydroponics has other key benefits compared to soil culture including

4356-458: Was the 1627 book Sylva Sylvarum or 'A Natural History' by Francis Bacon , printed a year after his death. As a result of his work, water culture became a popular research technique. In 1699, John Woodward published his water culture experiments with spearmint . He found that plants in less-pure water sources grew better than plants in distilled water. By 1842, a list of nine elements believed to be essential for plant growth had been compiled, and

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