Wiktionary, the free dictionary, has a entry on hydroponics. Hydroponics[1] is a kind of horticulture that involves growing plants, particularly crops, without soil using water-based mineral nutrient solutions in aqueous solvents. Roots can oxidize the pH of the rhizosphere and root exudates may affect the rhizosphere’s biological and physiological balance by producing secondary metabolites.
Many different sources of nutrients may be used in hydroponic systems, such as fish excrement, duck manure, purchased chemical fertilizers, and artificial nutrient solutions.
Plants such as tomatoes, peppers, cucumbers, strawberries, lettuces, and cannabis are commonly grown hydroponically in a greenhouse on inert media for commercial purposes.
Hydroponics Is A Type Of
Table of Contents
Water usage in agriculture is one of the benefits of hydroponics. 400 liters (88 imp gal; 110 U.S. gallons) of water are required to produce 1 kilogram (2.2 lb) of tomatoes using intensive farming techniques With hydroponics, 70 liters (15 imp gallons; 18 US gallons) of water are used. Only 20 liters (4.4 imp gal; 5.3 U.S.) are needed to treat the sewage. It may be feasible in the future for people in harsh places with little accessible water to grow their own food, thanks to the use of aeroponics.
History
Francis Bacon’s work Sylva Sylvarum, or ‘A Natural History,’ was published a year after his death in 1627. It was the first published book on growing terrestrial plants without soil. Water culture became a popular research technique as a result of his work. John Woodward’s experiments with spearmint in water were published in 1699. Plants grown in less-pure water accounted for greater growth than plants grown in distilled water, according to him.
“Solution culture” was first used in 1842, and the findings of German botanists Julius von Sachs and Wilhelm Knop in the years 1859–1875 resulted in a development of the technique of soilless cultivation. A kind of hydroponics where there is an inert medium for maintaining plant development is now known as solution culture or water culture.
During the 1930s, plant researchers looked into diseases afflicting specific plants, which allowed them to see signs linked to existing soil circumstances such as salinity. In this situation, Dennis Robert Hoagland led water culture experiments with the goal of inducing comparable symptoms under controlled circumstances[13]. Later, in 1929, William Frederick Gericke of the University of California at Berkeley began publicly advocating that the concepts of solution culture be utilized for agricultural crop production. He coined the term “aquaculture” to describe this cultivation method. Gericke grew tomato plants twenty-five feet (7.6 meters) high in his back yard without soil, which generated a stir. He then coined the term hydroponics, water culture, in 1937. A. Hydroponics is based on the neologism υδρωπονικά (derived from Greek ύδωρ=water and πονέω=cultivate), which replaces the earth with water. It concerns agriculture, as does geoponica, which pertains to soil.
However, since the technology he used was too delicate and required excessive monitoring at the time to be utilized in commercial applications, reports of Gericke’s work and his assertions that hydroponics would revolutionize plant agriculture drew a large number of inquiries. Due to the administration’s skepticism, Gericke was refused access to the university’s greenhouses for his experiments, and when he sought greenhouse space and time to further improve his home-based preliminary nutrient formulas, he requested that they be provided using suitable research facilities. The university assigned Hoagland and Arnon to re-evaluate Gericke’s claims and demonstrate that his formula had no advantage over soil produced plant yields, a conclusion shared by Hoagland. After leaving his academic position in 1937 in a climate that was politically unfavorable, Gericke published the book, Complete Guide to Soilless Gardening, in 1940, which is considered to be the basis for all forms of hydroponic growing. He there presented his core recipe for hydroponically-grown plants, which included the macro- and micronutrient salts for the first time[21].
As a consequence of the Director of the California Agricultural Experiment Station at the University of California, Claude B. Gericke’s assertions were investigated. The Water Culture Method for Growing Plants Without Soil, written by Hutchison, Dennis Robert Hoagland, and Daniel Israel Arnon in 1938, claimed that hydroponic crop yields were no better than those obtained with good-quality soils[22], which is a common mistake when growing plants. To identify precisely how much water to supply the plant in the soil, a grower must have extensive experience. When the air in the soil pores is displaced, the plant will be unable to get oxygen; if it loses the ability to take nutrients, which are normally transported into the roots when dissolved, it will experience nutrient deficiency symptoms like chlorosis. These two scientists were inspired to create numerous new formulas for mineral nutrient or culture solutions, popularly known as Hoagland solution[25], thanks to Hoagland’s perspectives and the university’s valuable assistance.
On Wake Island, a rocky Pacific Ocean island utilized as a refueling stop for Pan American Airlines, one of the earliest triumphs of hydroponics occurred. In the 1930s, hydroponics were utilized to supply fresh vegetables to the passengers. Since there was no soil on Wake Island, hydroponics were required, and bringing in fresh veggies was prohibitively costly[26].
Daniel I. served as a member of the House from 1943 to 1946. Since there was no arable land available, Arnon worked as a major in the US Army and used his previous knowledge with plant nutrition to cultivate crops in gravel and nutrient-rich water on barren Ponape Island in the western Pacific.
The Land Pavilion at Walt Disney World’s EPCOT Center, which opened in 1982, prominently features a variety of hydroponic techniques. Allen Cooper of England invented the “nutrient film technique” in the 1960s.
NASA’s Controlled Ecological Life Support System (CELSS) has performed extensive hydroponic research in recent decades. LED lighting is used in Hydroponics research to grow in a different color spectrum and with considerably less heat than those grown indoors. Hydroponics, according to Ray Wheeler, a plant physiologist at Kennedy Space Center’s Space Life Science Lab, will bring advancements in space travel as a bioregenerative life support system[29].
Hundreds of acres of large-scale commercial hydroponic greenhouses producing tomatoes, peppers, and cucumbers are now located in Canada as of 2017.
The global hydroponics market is expected to expand from US$226.45 million in 2016 to US$724.87 million by 2023 as a result of technological improvements within the industry and numerous economic factors[31].
Techniques
Sub-irrigation and top irrigation[specify] are the two most common variations for each medium. Most hydroponic tanks are now made of plastic, although other materials have been used in the past, such as concrete, glass, metal, vegetable solids, and wood. To avoid algae and fungal growth in the nutrient solution, the containers should be opaque.
Static solution culture
Plants are cultivated in glass Mason jars (typically, in-home applications), pots, buckets, tubs, or tanks in a static solution culture. The answer is normally aerated gently, although it may not be. The solution level is maintained low enough that adequate roots are above the solution so they can get sufficient oxygen if the aerator is not used.
Each plant is given a hole (or drill) in the top of the reservoir, which may be used to store its lid if it’s a jar or tub, but otherwise is made out of cardboard, foil, paper, wood, or metal. A single facility or several facilities may be assigned to a single firm. As the plant expands, the reservoir size may likewise be expanded. Using food containers or glass canning jars, an aquarium pump, aquarium airline tubing, and/or aquarium valves, a home-made system may be built using photosynthesis to provide aeration.
To eliminate the effects of negative phototropism, transparent containers can be covered with aluminium foil, butcher paper, black plastic, or other materials. The concentration of the nutrient solution is measured using an electrical conductivity meter, and the solution is changed either on a schedule, such as once per week.
Water or a fresh nutrient solution is added whenever the answer is depleted below a certain threshold. The solution level can be automatically maintained by using A Mariotte’s bottle or a float valve. Plants are grown in a sheet of buoyant plastic that sits on top of the nutrient solution in raft solution cultivation. The answer level is never reduced below the roots in this way[32].
Continuous-flow solution culture
The nutrients in continuous-flow solution culture pass via the roots on a daily basis. Sampling and adjustments to temperature, pH, and nutrient concentrations can all be done in a huge storage tank that may hold thousands of plants, making it much simpler to automate than the static solution culture. The nutrient film technique, or NFT, is a common variation in which a very shallow stream of water flows past a bare root mat of plants in a watertight channel with an upper surface exposed to air. It is sometimes called the nutrient film method.
As a result, the roots of the plants are supplied with an abundance of oxygen. The proper channel slope, flow rate, and channel length are all important factors in the construction of a properly constructed NFT system. The fact that the plant roots are supplied with enough water, oxygen, and nutrients is the primary benefit of the NFT system over other types of hydroponics.
Since excessive or insufficient amounts of one component affects the balance of both others, there is a struggle in all other sorts of production over supplying these needs. Since of its architecture, NFT allows for all three requirements for good plant development to be met concurrently, as long as the fundamental idea of NFT is kept in mind and performed. As a consequence, over an extended period of cropping, greater yields of high-quality produce are achieved. NFT has a major shortcoming when it comes to flow interruption buffering (e.g., power outages): it has very little of it. Nonetheless, it is perhaps one of the most efficient approaches available[citation required].
Flow rates for each gully should be one liter per minute as a general guideline[vague] until planting, when they may be reduced to half. Above-mentioned flow rates are frequently linked to nutritional concerns. When channels exceed 12 meters in length, crops’ growth rates have been shown to be depressed.
Nitrogen may be depleted over the length of the gully when conditions are quickly growing crops, according to tests. Channel length should not exceed 10–15 meters as a result of this. The decreases in development may be compensated for by placing another nutrient supply halfway down the gully and reducing the flow rates at each outflow[citation required][5] in situations when this isn’t feasible.
Aeroponics
For propagation, seed germination, seed potato production, tomato production, leaf crops, and micro-greens, aeroponic techniques have shown to be commercially viable since 1983 when they were invented by inventor Richard Stoner.
Another benefit of aeroponics over hydroponics is that anaerobic microorganisms such as bacteria can be cultivated in a true aeroponic system, which allows for precise control of the environment. Certain species of plants can only survive in water for so long before they become waterlogged, which is the limitation of hydroponics. Suspended aeroponic plants use 100% of the available oxygen and carbon dioxide to the roots zone, stems, and leaves, speeding up biomass development while lowering rooting times[37].
According to NASA studies, aeroponically cultivated plants contain 80% more dry weight biomass (essential minerals) than hydroponically cultivated plants. In comparison to hydroponics, aeroponics required 65% less water. Aeroponic plants need just a quarter of the nutrients as hydroponic plants, according to NASA, and they may be moved to soil without experiencing transplant shock. In research on plant biology and disease, aeroponics is also very popular. Because a mist is easier to handle than a liquid in a zero-gravity environment, NASA has given aeroponic techniques special attention[38][5].
Fogponics
Passive sub-irrigation
Plants are grown in an inert porous medium that uses capillary action to move water and fertilizer to the roots from a separate reservoir, reducing labor and providing a consistent supply of water to the roots. Passive sub-irrigation, sometimes known as passive hydroponics, semi-hydroponics, or hydroculture[42], is a technique where plants are cultivated in an inert porous medium. The pot is placed in a shallow nutrient solution or on a capillary mat saturated with nutrient solution in the most basic method. Increased oxygen to the roots is important in epiphytic plants like orchids and bromeliads, whose roots are exposed to the air in nature, and different hydroponic media available contain more air space than more traditional potting mixes. The reduction of root rot and the additional ambient humidity provided via evaporations are additional advantages of passive hydroponics.
Hydroculture is around 10 times more efficient than conventional agriculture in terms of crops yield per area in a controlled environment, uses 13 times less water during one crop cycle than conventional agriculture, and uses 100 times more kilojoules per kilograms of energy. [43]
Ebb and flow (flood and drain) sub-irrigation
A tray is placed above a nutrient solution reservoir in its most basic form. Plant directly or place the pot over growing medium, stand in the tray, if the tray is filled with growing medium (clay granules being the most common). After each period, a basic clock drives the upper tray with nutrient solution, and the liquid drains back into the reservoir at set intervals. The medium is kept flush with nutrients and air on a regular basis. The water in the upper tray is recirculated until the pump turns off and the water in the upper tray drains back into the reservoirs once it fills past the drain stop.
Run-to-waste[edit]
The medium surface is periodically treated with nutrient and water solution in a run-to-waste system. The technique was developed in Bengal in 1946, hence it is sometimes referred to as “The Bengal Method.” [45]
This approach may be configured in a variety of ways. A nutrient-and-water solution is poured into a container of inert growing media, such as rockwool, perlite, vermiculite, coco fiber, or sand in its most basic form. It is poured into the container one or more times each day. It is automated using a delivery pump, a timer, and irrigation tubing to deliver nutrient solution at a certain frequency controlled by the key parameters of plant size, plant growth stage, climate, substrate, and substrate conductivity pH, and water content in a somewhat more complicated system.
Washing frequency in a business environment is multi-factorial, and computers or PLCs control it.
Large-scale hydroponic cultivation of tomatoes, cucumbers, and peppers employs various types of run-to-waste hydroponics in some capacity.
The nutrient-rich waste is collected and processed using an on-site filtration system, which is very productive, in environmentally responsible applications.
Some bonsai are watered and nourished in a run-to-waste method, with soil-free substrates (typically consisting of akadama, grit, diatomaceous earth, and other inorganic substances) providing water and nutrients.
Deep water culture
Top-fed deep water culture
Top-fed deep water culture is a process that includes delivering a high-oxygenated nutrient solution to the root zone of plants. In top-fed deep water culture, the solution is pumped from the reservoir up to the roots (top feeding), as opposed to being pulled down into a nutrient solution reservoir by plant roots.
In a constantly recirculating system, water is released over the plant’s roots and flows back into the reservoir below. There is an airstone in the reservoir that pumps air into the water via a hose from outside, just like there is in deep water culture. The water is supplemented with oxygen via the airstone. The airstone and water pump operate 24 hours a day, 365 days a year.
The greatest benefit of top-fed deep water culture over conventional deep water culture is that it allows for faster development during the first few weeks[citation required]. Roots in top-fed deep water culture develop to the reservoir below much quicker than those in a deep water culture system, which has easy access to water from the start. Top-fed deep water culture has little benefit over regular deep water culture once the roots have arrived in the reservoir below. Grow time can be reduced by a few weeks due to the faster development at the start of growth.
Rotary
Substrates (growing support materials)
Which medium to use is one of the most obvious decisions hydroponic farmers have to make. For various growing processes, different media are required.
Rock wool
The most commonly used medium in hydroponics is rock wool (mineral wool). Run-to-waste and recirculating systems both require an inert substrate such as rock wool. Rock wool is essentially protected from most common microbiological degradation and is produced from molten rock, basalt or ‘slag’ that is spun into bundles of single filament fibres.
Seedling growth, or with freshly severed clones, is the most common application of moss, although it may last the whole lifetime of the plant. There are several benefits and drawbacks to using rock wool. Flushing with cold water is usually effective in alleviating skin irritancy (mechanical) and handling discomfort (1:1000). The product’s demonstrated efficacy and suitability as a commercial hydroponic substrate are benefits. Note Q of the European Union Classification Packaging and Labeling Regulation (CLP) classifies most of the rock wool sold to date as a non-hazardous, non-carcinogenic material.
Mineral wool items, due to their fibrous nature and ability to hold large volumes of water and air, may be used in hydroponics to aid root development and nutrient absorption. Mineral wool has a naturally high pH, making it difficult to cultivate plants at first and necessitating “conditioning” to generate a wool with an acceptable, long-term pH[51].
Expanded clay aggregate
In hydroponic systems with precise nutrient control in water solution, baked clay pellets are suitable. Clay pellets are devoid of nutrition and are pH-neutral.
In rotary kilns at 1,200°C (2,190°F), the clay is shaped into spherical pellets and fired. The clay becomes porous as a result of this, much like popcorn. It’s lightweight and doesn’t compact over time. Depending on the brand and manufacturing process, the shape of each pellet can be irregular or uniform. Because of its capacity to be cleaned and sterilized, expanded clay is seen as an ecologically friendly and re-useable growing medium by the producers.
2O
2), and rinsing completely.
Clay pebbles, according to another theory, should not be reused even if they are cleaned because of root development inside the medium. After a crop has been demonstrated, cracking open a clay pebble will reveal this development.
Growstones
Growstones have more air and water retention capacity than perlite and peat, thanks to their glass waste construction. The calcium carbonate content in Growstones ranges from 0.5% to 5%, depending on the size of the bag and the amount of calcium carbonate needed. The remaining part is soda-lime glass.
Coconut Coir
Coconut coir is a natural byproduct produced from coconut processing, regardless of hydroponic demand. Coconut fibers, which are utilized to make a variety of products from floor mats to brushes, make up the outside husk of the coconut. The dust and short fibers are blended together to form coir after the lengthy fibers have been utilized for those applications. Before it can become a viable growth medium, coconuts must go through a maturation process because they absorb high levels of nutrients throughout their life cycle.Using large amounts of water to wash away salt, tannins, and phenolic compounds. The working conditions during the maturation process are dangerous and would be illegal in North America and Europe, despite the need of attention, posing health risks, and environmental impacts. The brown, dry, chunky, and fibrous substance grows almost threefold in size when wet. This property makes coconut coir an suitable growth medium, as well as the ability to retain water and fight pests and diseases. Coconut coir, often known as coir peat, provides superior growing circumstances as a replacement to rock wool.
Rice husks
Parboiled rice husks (PBH) are a agricultural waste that has little value until processed. Rice husks have a limited effect on the effects of plant growth regulators, according to a research[58] that they decay over time and allow drainage.
Perlite
Perlite is a lightweight expanded glass pebble that has been superheated from a volcanic rock. It’s kept in watery sleeves or loose. To lower soil density, it’s also employed in potting soil mixes. In comparison to vermiculite, perlite has comparable qualities and is buoyant. It holds more air and less water.
Vermiculite
Vermiculite is a mineral that has been superheated and expanded into small pebbles, much as perlite. Vermiculite has a natural “wicking” characteristic that allows it to draw water and nutrients in a passive hydroponic system, compared to perlite. It is feasible to gradually lower the medium’s water-retention capability by mixing in increasing amounts of perlite if the plants’ roots are immersed in too much water and not enough air.
Pumice
Pumice is a mined volcanic rock that may be used in hydroponics, similar to perlite.
Sand
Sand is a low-cost and widely accessible material. It is, however, heavy, does not hold water well, and must be sterilized after every use[59].
Gravel
Any small gravel may be utilized, but it must be cleaned first, similar to the aquariums. Plants are in fact cultivated using gravel hydroponics, also known as “nutriculture,” if they grow in a standard conventional gravel filter bed with water circulated using electric powerhead pumps. Gravel is cheap, simple to maintain, drains quickly, and will not rot. Moreover, it is hefty, and the plant roots may dry out if the system does not supply constant water.
Wood fiber
Steam friction of wood produces wood fiber, which is an excellent organic medium for hydroponics. It has the benefit of retaining its structure for a long time. Wood wool (or, more precisely, wood pulp) Nevertheless, more recent research suggests that wood fiber may have negative consequences on “plant growth regulators” (such as wood slivers) from the beginning of hydroponics study[21].
Sheep wool
Shearing sheep wool is a little-used but promising renewable growing medium. Sheep wool had a greater air capacity of 70%, which decreased with use to a comparable 43%, and water capacity that increased from 23% to 44% with use in a study comparing wool, peat slabs, coconut fibre slabs, perlite, and rockwool slabs to grow cucumber plants.
Brick shards
Similar to gravel, brick shards have properties. They also have the potential to change the pH and necessitate extra cleaning before reuse, which is an additional disadvantage.
Polystyrene packing peanuts
Cheap, widely accessible, and with superb drainage, polystyrene packing peanuts are a great option. They might, however, be too light for some applications. Closed-tube systems are the primary application for them. It’s worth noting that biodegradable packing peanuts will degrade into a sludge if non-biodegradable polystyrene peanuts are employed. This is a potential health risk because plants may absorb styrene and deliver it to consumers.
Nutrient solutions
Inorganic hydroponic solutions
Nutrient deficiency symptoms resemble those seen in traditional soil-based agriculture, and the formulation of hydroponic solutions is an application of plant nutrition. The basic chemistry of hydroponic solutions, on the other hand, varies significantly from soil chemistry. The following are some of the most notable differences:
- Nutrient solutions in hydroponic systems lack cation-exchange capacity (CEC) because clay particles and organic matter do not exist. The pH, oxygen saturation, and nutrient levels in hydroponic systems change much more rapidly than in soil since CEC is not present.
- The quantity of counterions in solution is frequently disturbed by selective absorption of nutrients by plants, which affects solution pH and plant capacity to absorb ions with similar ionic charge (see article membrane potential). For example, plants consume nitrate anions fast to generate proteins, resulting in a cation excess in the solution that may cause deficiency symptoms (e.g. Even when all of the nutrients are properly dissolved in the solution, Mg2+) is present.
- Nutrients such as iron may precipitate out of solution and become unavailable to plants depending on the pH or the presence of water contaminants. The use of chelating agents[64] and pH adjustments are common techniques for maintaining the solution.
- Hydroponic solutions are often standardized and require regular upkeep for plant growth, unlike soil types, which may vary greatly in composition. Also, to compensate for transpiration losses and nutrient deficiencies that occur as plants develop and deplete nutrient reserves, water levels must be replenished. The remaining proportions and concentrations of other essential nutrient ions in a balanced solution are sometimes estimated using the regular measurement of nitrate ions.
Nutrient concentrations should be adjusted to meet Liebig’s law of the minimum for each particular plant variety, as they are in conventional agriculture. Nonetheless, most nutrient ions have similar acceptable concentration ranges, with 1,000 and 2,500 ppm as typical upper and lower limits. Nutrient deficiencies are common when essential nutrients are consumed at concentrations below these ranges, whereas nutrient toxicity is common when essential nutrients are consumed at higher doses. Experience or plant tissue tests[62] can be used to determine optimum nutrition concentrations for plant types.
| Element | Role | Ionic form(s) | Low range (ppm) | High range (ppm) | Common Sources | Comment |
|---|---|---|---|---|---|---|
| Nitrogen | Essential macronutrient | NO− 3 or NH+ 4 |
100[63] | 1000[62] | KNO3, NH4NO3, Ca(NO3)2, HNO3, (NH4)2SO4, and (NH4)2HPO4 | NH+ 4 interferes with Ca2+ uptake and can be toxic to plants if used as a major nitrogen source. A 3:1 ratio of NO− 3-N to NH+ 4-N (wt%) is sometimes recommended to balance pH during nitrogen absorption.[63] Plants respond differently depending on the form of nitrogen, e.g., ammonium has a positive charge, and thus, the plant expels one proton (H+ ) for every NH+ 4 taken up resulting in a reduction in rhizosphere pH. When supplied with NO− 3, the opposite can occur where the plant releases bicarbonate (HCO− 3) which increases rhizosphere pH. These changes in pH can influence the availability of other plant nutrients (e.g., Zn, Ca, Mg).[68] |
| Potassium | Essential macronutrient | K+ | 100[62] | 400[62] | KNO3, K2SO4, KCl, KOH, K2CO3, K2HPO4, and K2SiO3 | High concentrations interfere with the function of Fe, Mn, and Zn. Zinc deficiencies often are the most apparent.[63] |
| Phosphorus | Essential macronutrient | PO3− 4 |
30[63] | 100[62] | K2HPO4, KH2PO4, NH4H2PO4, H3PO4, and Ca(H2PO4)2 | Excess NO− 3 tends to inhibit PO3− 4 absorption. The ratio of iron to PO3− 4 can affect co-precipitation reactions.[62] |
| Calcium | Essential macronutrient | Ca2+ | 200[63] | 500[62] | Ca(NO3)2, Ca(H2PO4)2, CaSO4, CaCl2 | Excess Ca2+ inhibits Mg2+ uptake.[63] |
| Magnesium | Essential macronutrient | Mg2+ | 50[62] | 100[62] | MgSO4 and MgCl2 | Should not exceed Ca2+ concentration due to competitive uptake.[63] |
| Sulfur | Essential macronutrient | SO2− 4 |
50[63] | 1000[62] | MgSO4, K2SO4, CaSO4, H2SO4, (NH4)2SO4, ZnSO4, CuSO4, FeSO4, and MnSO4 | Unlike most nutrients, plants can tolerate a high concentration of the SO2− 4, selectively absorbing the nutrient as needed.[21][62][63] Undesirable counterion effects still apply however. |
| Iron | Essential micronutrient | Fe3+ and Fe2+ | 2[63] | 5[62] | FeDTPA, FeEDTA, iron citrate, iron tartrate, FeCl3, Ferric EDTA, and FeSO4 | pH values above 6.5 greatly decreases iron solubility. Chelating agents (e.g. DTPA, citric acid, or EDTA) are often added to increase iron solubility over a greater pH range.[63] |
| Zinc | Essential micronutrient | Zn2+ | 0.05[63] | 1[62] | ZnSO4 | Excess zinc is highly toxic to plants but is essential for plants at low concentrations. The zinc content of commercially available plant-based food ranges from 3 to 10 µg/g fresh weight.[69] |
| Copper | Essential micronutrient | Cu2+ | 0.01[63] | 1[62] | CuSO4 | Plant sensitivity to copper is highly variable. 0.1 ppm can be toxic to some plants[63] while a concentration up to 0.5 ppm for many plants is often considered ideal.[62] |
| Manganese | Essential micronutrient | Mn2+ | 0.5[62][63] | 1[62] | MnSO4 and MnCl2 | Uptake is enhanced by high PO3− 4 concentrations.[63] |
| Boron | Essential micronutrient | B(OH)− 4 |
0.3[63] | 10[62] | H3BO3, and Na2B4O7 | An essential nutrient, however, some plants are highly sensitive to boron (e.g. toxic effects are apparent in citrus trees at 0.5 ppm).[62] |
| Molybdenum | Essential micronutrient | MoO− 4 |
0.001[62] | 0.05[63] | (NH4)6Mo7O24 and Na2MoO4 | A component of the enzyme nitrate reductase and required by rhizobia for nitrogen fixation.[63] |
| Chlorine | Essential micronutrient | Cl− | 0.65[70] | 9[71] | KCl, CaCl2, MgCl2, and NaCl | Can interfere with NO− 3 uptake in some plants but can be beneficial in some plants (e.g. in asparagus at 5 ppm). Absent in conifers, ferns, and most bryophytes.[62] Chloride is one of the 16 elements essential for plant growth. Because it is supposedly needed in small quantities for healthy growth of plants (< 50–100 μM in the nutrient media), chloride is classified as a micronutrient.[72] |
| Aluminum | Variable micronutrient | Al3+ | 0 | 10[62] | Al2(SO4)3 | Essential for some plants (e.g. peas, maize, sunflowers, and cereals). Can be toxic to some plants below 10 ppm.[62] Sometimes used to produce flower pigments (e.g. by Hydrangeas). |
| Silicon | Variable micronutrient | SiO2− 3 |
0 | 140[63] | K2SiO3, Na2SiO3, and H2SiO3 | Present in most plants, abundant in cereal crops, grasses, and tree bark. Evidence that SiO2− 3 improves plant disease resistance exists.[62] |
| Titanium | Variable micronutrient | Ti3+ | 0 | 5[62] | H4TiO4 | Might be essential but trace Ti3+ is so ubiquitous that its addition is rarely warranted.[63] At 5 ppm favorable growth effects in some crops are notable (e.g. pineapple and peas).[62] |
| Cobalt | Variable micronutrient | Co2+ | 0 | 0.1[62] | CoSO4 | Required by rhizobia, important for legume root nodulation.[63] Some algae require cobalt for the synthesis of vitamin B12.[73] |
| Nickel | Variable micronutrient | Ni2+ | 0.057[63] | 1.5[62] | NiSO4 and NiCO3 | Essential to many plants (e.g. legumes and some grain crops).[63] Also used in the enzyme urease. |
| Sodium | Non-essential micronutrient | Na+ | 0 | 31[74] | Na2SiO3, Na2SO4, NaCl, NaHCO3, and NaOH | Na+ can partially replace K+ in some plant functions but K+ is still an essential nutrient.[62] |
| Vanadium | Non-essential micronutrient | VO2+ | 0 | Trace, undetermined | VOSO4 | Beneficial for rhizobial N2 fixation.[63] |
| Lithium | Non-essential micronutrient | Li+ | 0 | Undetermined | Li2SO4, LiCl, and LiOH | Li+ can increase the chlorophyll content of some plants (e.g. potato and pepper plants).[63] |
Organic hydroponic solutions
- In terms of minerals and various chemical species, organic fertilizers are extremely variable. Based on the source, similar materials may vary dramatically (e.g., Depending on the animal’s diet, the quality of manure varies.
- Because animal waste is frequently used as fertilizers, disease transmission is a major issue for plants cultivated for human consumption or animal fodder.
- Particulate fertilizers may clog substrates or equipment, and may also plug drains. It’s common to need to sieve or mill the organic stuff into fine dusts.
- In certain organic materials (i.e., Under anaerobic conditions, specially manures and offal, may additionally degrade to emit unpleasant odors.
- There are numerous organic molecules (i.e. During aerobic degradation, which is required for cellular respiration in plant roots, sugars) require additional oxygen.
- Normal plant nutrition does not need organic compounds[75].
Organic fertilizers may, nevertheless, be employed successfully in hydroponics when appropriate steps are followed[62][63].
Organically sourced macronutrients[edit]
The following table lists examples of suitable materials, along with their average nutritional contents in terms of percent dried mass.
| Organic material | N | P2O5 | K2O | CaO | MgO | SO2 | Comment |
|---|---|---|---|---|---|---|---|
| Bloodmeal | 13.0% | 2.0% | 1.0% | 0.5% | – | – | |
| Bone ashes | – | 35.0% | – | 46.0% | 1.0% | 0.5% | |
| Bonemeal | 4.0% | 22.5% | – | 33.0% | 0.5% | 0.5% | |
| Hoof / Horn meal | 14.0% | 1.0% | – | 2.5% | – | 2.0% | |
| Fishmeal | 9.5% | 7.0% | – | 0.5% | – | – | |
| Wool waste | 3.5% | 0.5% | 2.0% | 0.5% | – | – | |
| Wood ashes | – | 2.0% | 5.0% | 33.0% | 3.5% | 1.0% | |
| Cottonseed ashes | – | 5.5% | 27.0% | 9.5% | 5.0% | 2.5% | |
| Cottonseed meal | 7.0% | 3.0% | 2.0% | 0.5% | 0.5% | – | |
| Dried locust or grasshopper | 10.0% | 1.5% | 0.5% | 0.5% | – | – | |
| Leather waste | 5.5% to 22% | – | – | – | – | – | Milled to a fine dust.[63] |
| Kelp meal, liquid seaweed | 1% | – | 12% | – | – | – | Commercial products available. |
| Poultry manure | 2% to 5% | 2.5% to 3% | 1.3% to 3% | 4.0% | 1.0% | 2.0% | A liquid compost which is sieved to remove solids and checked for pathogens.[62] |
| Sheep manure | 2.0% | 1.5% | 3.0% | 4.0% | 2.0% | 1.5% | Same as poultry manure. |
| Goat manure | 1.5% | 1.5% | 3.0% | 2.0% | – | – | Same as poultry manure. |
| Horse manure | 3% to 6% | 1.5% | 2% to 5% | 1.5% | 1.0% | 0.5% | Same as poultry manure. |
| Cow manure | 2.0% | 1.5% | 2.0% | 4.0% | 1.1% | 0.5% | Same as poultry manure. |
| Bat guano | 8.0% | 40% | 29% | Trace | Trace | Trace | High in micronutrients.[63] Commercially available. |
| Bird guano | 13% | 8% | 20% | Trace | Trace | Trace | High in micronutrients. Commercially available. |
Organically sourced micronutrients
Organic fertilizers may also provide micronutrients. Composted pine bark, for example, has a high level of manganese and may be used in hydroponic solutions to fulfill the mineral requirement[63]. To meet a plant’s nutritional requirements, gypsum, calcite, and/or glauconite can also be added.
Additives
To boost nutrition acquisition and absorption by the plant, compounds may be introduced in both organic and conventional hydroponic systems. Plant growth promoting rhizobacteria (PGPR), which are often applied in field and greenhouse agriculture, have been demonstrated to help hydroponic plant development and nutrient absorption. Azospirillum and Azotobacter genera may aid maintain activated forms of nitrogen in hydroponic systems with higher microbial activity in the rhizosphere, although nitrogen is typically plentiful.
[78] High nitrate concentrations in plant tissue at harvest are common after using traditional fertilizer methods. In comparison to conventional hydroponic fertilizer approaches in leafy greens, Rhodopseudo-monas palustris has been discovered to boost nitrogen use efficiency, increase productivity, and lower nitrate concentration by 88%.[79] Streptomyces species include: By lowering the soil pH, releasing phosphorus bound in chelated form that is accessible in a wider pH range, and mineralizing organic phosphorus, convert varieties of phosphorus in the soil that are unavailable to the plant into soluble anions[78].
According to some research, Bacillus inoculants may help hydroponic leaf lettuce survive high salinity and growth-impairing conditions in regions with strong electrical conductivity or salt concentration in the water supply. This might potentially offer high crop productivity while avoiding costly reverse osmosis filtering processes.
Tools
Common equipment
Successful hydroponic horticulture relies on maintaining proper nutrient concentrations, oxygen saturation, and pH levels. Hydroponic management tools include the following:
- Nutrient ppm is assessed using electrical conductivity meters, which measure how well a solution passes an electric current.
- The pH meter is a device that measures the concentration of hydrogen ions in solution using an electric current.
- An electrochemical sensor for monitoring the oxygen level in solution is known as an oxygen electrode.
- Disposable pH indicator strips that use a chemical reaction to change color are used to measure hydrogen ion concentrations.
- To measure out premixed, commercial hydroponic solutions, graduate cylinders or measuring spoons are used.
Equipment
Accurate chemical analyses of nutrient solutions may also be performed using chemical equipment. The following are some examples:
- Balances for accurately measuring materials.
- Laboratory glassware, such as burettes and pipettes, for performing titrations.
- Colorimeters for solution tests which apply the Beer–Lambert law.
- Spectrophotometer to measure the concentrations of the key parameter nitrate and other nutrients, such as phosphate, sulfate or iron.
Growers of any experience might benefit from using chemical equipment for hydroponic nutrient solutions, since nutrient solutions are regularly reusable and point-source pollution, a frequent source of eutrophication in nearby lakes and streams, is rarely completely depleted.
Software
While many hydroponic enthusiasts and small commercial farmers buy pre-mixed concentrated nutrient solutions from commercial nutrient producers, there are several methods for anybody to make their own without significant chemistry expertise. Professional chemists have devised free and open source software HydroBuddy[82] and HydroCal[83] to assist any hydroponics grower in preparing their own nutrient solutions. The first program is available for Windows, Mac, and Linux, while the second is accessible via a simple JavaScript interface. While HydroBuddy provides extra functionality to utilize and conserve proprietary compounds, save formulations, and predict electrical conductivity values, both tools enable for fundamental nutrient solution preparation.
Mixing solutions
Since commercial items are offered at fair costs, amateur or small-scale commercial farmers often mix hydroponic liquids with specific salts. Multi-component fertilizers, on the other hand, are widely used even when purchasing commercial items. These items are frequently purchased as three-part formulas, with each component emphasizing a specific nutritional purpose.
Vegetative growth solutions, for example, (i.e. Blooming (i.e. nitrogen rich) and high in nitrogen Micronutrient solutions (i.e., high in potassium and phosphorus) Trace minerals are commonly used (together with other ingredients). These multi-part fertilizers should be applied at the proper time for a plant’s development.
A plant should be restricted from high nitrogen fertilizers at the end of an annual plant’s life cycle, for example. Nitrogen restriction helps to promote flowering in most plants and inhibits vegetative growth[63].