Hydroponics

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Example of a water-cultivated crocus plant

Hydroponics ( ancient Greek ὕδωρ hydōr , German 'water' and Latin cultura 'cultivation' ) is a form of plant management in which the plants are not rooted in the ground , but in water-filled containers (with or without an inert supporting substrate) or in nature in a wetland .

differentiation

A distinction is made here:

  • Hydroponics of indoor plants for indoor greening. Expanded clay balls are usually used as the substrate . The plant containers have floats to indicate the water level. The water level is allowed to drop to a certain level (through water consumption by the plants and evaporation) before it is refilled. This ensures that the roots receive oxygen for root breathing , otherwise the roots would rot. The nutrient salts added to the water are either absorbed by the plant or are concentrated in the solution; the next time the water is watered, they are diluted and possibly re-fertilized by the user. The long watering intervals are welcomed by the users of the plants, maintenance is therefore not as time-consuming as with plants in soil, the plants grow more slowly (i.e. do not change the height as quickly) and come with the lower because of the slower growth (also depending on the species) Light from inside.
Hydroponically grown onions
Closed container for growing wheatgrass (as supplementary feed for cattle) directly on the pasture

The plants are kept in artificial nutrient solutions or watered intensively with them ( fertigation ), the seepage water is usually collected and reused in the cycle . However, the seepage water is not circulated in all hydroponic methods, especially with metered drip irrigation, any residues can also seep into the groundwater.

Plant roots need oxygen in order to be able to absorb nutrients. During the root respiration that takes place, oxygen is consumed in the root area and carbon dioxide (CO 2 ) is produced. With hydroponic systems it is possible to optimize the oxygen supply to the plant roots. This knowledge led to the triumph of hydroponics (in commercial vegetable growing under glass ).

Other methods of hydroponics:

history

The first publication on plant cultivation without soil was the book Sylva Sylvarum or A Natural History by Francis Bacon , published in 1627 ( posthumously ) . In 1699, John Woodward published water culture experiments with spearmint . By 1842 a list of nine chemical elements was known that would be essential for plant growth. The discoveries of the German botanists Julius von Sachs and Wilhelm Knop in the years 1859–1875 resulted in the development of soilless cultivation of plants. In 1940 William Frederick Gericke of the University of California at Berkeley published the book The Complete Guide to Soilless Gardening and in 1937 introduced the term hydroponics , which the phycologist WA Setchell had proposed.

Hydroponic Plant Nutrition

When cultivated in containers, the plants are nourished by an aqueous solution of inorganic nutrient salts . Since the chemical soil properties differ greatly from the natural state due to the lack of fine organic soil components , normal plant fertilizer is only partially suitable for hydroponics.

Remedy, a special hydroponic fertilizer , by additives the pH of the solution in an appropriate range for many plants buffers . For this purpose, so-called ion exchange granules are also used, which supply the plants with nutrients through ion exchange and at the same time bind minerals such as lime that are in excess of the water and which are incompatible with the plants .

During the microbial conversion of ammonium ions into nitrate ions , oxygen is consumed, which is lost in root respiration. In hydroponic fertilizers, ammonium salts are therefore used less than nitrogen fertilizers , but rather nitrates.

In hydroponics, the electrical conductivity of the nutrient solution is usually continuously monitored. If the concentration of the dissolved substances increases (for example through exudates or extraction from the soil), the solubility for oxygen in the nutrient solution decreases. If the solutions are too concentrated, it becomes more difficult for the plants to absorb water (see also osmosis ). Different stages of the plant also require different conductivity of the nutrient solution depending on the variety, cuttings around 0.2-0.4 m S / cm, which can increase to 2.4-2.6 mS / cm until fruiting. The morphology of the plant growth is complete also depending on the concentration of the nutrient solution, for example whether compact plants are growing or elongated. If the nutrient solution is too concentrated, it can be diluted with deionized water or rainwater.

Ensuring and increasing root breathing

In hydroponic processes, great importance is attached to optimally supplying the roots with oxygen. Plants need root respiration to absorb and transport ions, for root growth and for maintaining growth.

Environmental parameters that have an influence on root respiration are: temperature, emersed flooding, salinity, water stress and dry soil, nutrient supply, irradiance, pH value and the partial pressure of CO 2 .

Transposition of plants

Plants in hydroponics develop the same kind of roots as plants in soil culture; their own "water roots" do not exist. All roots that absorb and transport water are water roots, otherwise various root transformations .

The conversion from soil to hydroponics usually only works with young plants. When soil components are washed away, the fine root hairs of older plants are usually broken off, resulting in an imbalance between “too much leaf mass” and “too few fine roots” and leaves wither or the plant dries up despite the excess supply of water.

When changing from hydroponic plants and cuttings to soil culture, the reduced oxygen supply sometimes causes roots to rot.

Systems

Hydroponics in indoor plants

The horticultural hydroponics for indoor plants with backwater irrigation was adapted based on hydroponics by the German Paul Rößler and published by Heide Lau in 1951 as part of the Saarland International Horticultural Exhibition. The master gardener Günter Gregg initially tried to sell indoor plants in a nutrient solution without a substrate, experimented with all kinds of substrates and then developed the well-known containers with a separate water filling opening and expanded clay balls, with Gerhard Baumann being considered the inventor of the Luwasa clay substrate.

In principle, almost all plants can also be grown in hydroponics. However, it depends on the type of whether a better or only a worse result can be achieved compared with conventional soil culture. For example, some species are sensitive to waterlogging or are more adapted to dry soils.

Correct use of the water supply and the concentrations of nutrients in the nutrient solution is always necessary for a serious comparison, which is not always easy at first.

The liquid reserve at the bottom of the vessel means that it has to be poured less often. Since the plant develops less root volume, it has to be repotted less often . For regular, but still less frequent ventilation of the roots, the water level in the vessels, which is indicated by a float, is allowed to drop to a minimum and only then poured up again.

As an inorganic substrate for house plants, granular, granulated expanded clay is usually used. However, depending on the requirements, other substrates such as gravel , basalt or perlite are also used . The substrates must be taken to ensure that the material is free of lime or a suspension in water -neutral pH 's, so that the pH of the nutrient solution is not raised excessively by the substrate.

Usually, expanded clay for hydroponics (as pearls or granules) differs from (cheaper) expanded clay for thermal insulation in terms of pH stability, porosity and swimming behavior. Expanded clay for hydroponics is pH-neutral and has open pores on the surface (expanded clay for thermal insulation is sintered in gas burners. As a result, the surface of closed spheres has few pores, pores are only exposed when the goods are broken). Closed-pore expanded clay floats in water, open-pored clay can soak up with water and thus go under (the air is more likely to be forced out of the pores by immersing the expanded clay pellets in hot water).

In general, there are fewer soil pests in hydroponics because they are difficult to establish in the absence of natural soil. Compared to soil culture, the cultivation of individual ornamental plants in hydroponics is more expensive to buy and maintain: Special planters and special hydroponic fertilizers are required.

The roots of the plants should be protected from light so that algae do not grow in the nutrient solution , the germs of which are easily introduced, and so that the roots of some plant species do not develop chlorophyll .

Due to the lack of soil, allergy-causing substances such as fungal spores are released into the air less often (although molds can also attack the roots), which can be better for allergy sufferers , asthmatics and other sensitive people.

Climbing aids and supports made of wood, bamboo and other natural materials start to rot in the nutrient solution, plastic supports are used instead.

Hydroponics

Example of drip irrigation of several pots with one pump

(Name derivation: Germanized from the English hydroponics , this as neologism υδρωπονικά, derived from γεωπονικά for Geoponica , a collection of writings by ancient authors on agriculture, where, γεω-, earth was replaced by ὑδρο-, water.)

With the various permanent irrigation methods of hydroponics, importance is attached to the fact that the plant roots are intensively supplied with oxygen , otherwise they would rot in the absence of air or not absorb any nutrients - the plant would stop growing. For this purpose, either the permanently available nutrient-containing irrigation water is saturated or oversaturated with oxygen (see saturation concentration), air is sucked into the substrate (by lowering the water level in the planter and thus sucking air into the substrate) or an air space into which the roots protrude, becomes saturated with water vapor or mist droplets. Due to this better supply of nutrient solution and oxygen, plants grow faster than just the usual moistening of the substrate, which makes hydroponic cultivation more efficient.

The industry-like cultivation of crops lowers market prices, which is cheap for consumers, but bad for conventional small-scale producers. One of the largest hydroponic farms in the world is the size of a football field, 10,000 heads of lettuce are harvested there on shelves up to 18 floors high, the trend is towards 30,000 heads of lettuce per day. Due to the mass culture and rather only one type of vegetable per company, the work (especially the distribution) can be designed more rationally and the space can be used better, vegetables can also be grown in large quantities in the city, which reduces costs and CO 2 - Reduces emissions from transport.

With hydroponic plant cultivation, the seepage water is collected, controlled and stored and mostly (but not everywhere) circulated, i.e. reused. In addition, all parameters influencing plant growth are automatically monitored and optimized, which means that hydroponics is more likely to be operated in greenhouses . To be optimized:

  • Water (rainwater collection, natural composition, temperature, pH value )
  • Nutrient content (with automated measurement of the electrical conductivity of the nutrient solution and the main nutrients)
  • Oxygen supply to the roots
  • Soil moisture
  • Humidity (humidity, drying)
  • Air temperature, water temperature (disturbed by heat-generating lamps), day and night temperature
  • Air turbulence (artificial wind leads to better drying and thickening of the trunk so that plants can bear more fruit or do not bend over before they are sold and also serves for wind pollination )
  • Light irradiation ( phototrophy , photosynthesis , wavelengths , light power density and artificial day length )
  • CO 2 content of the air
  • Mycorrhizal inoculation
  • Distance between plants (because some species form more roots in association with other individuals of the same species than raised alone)
  • and other optimization methods as well as in soil culture such as plant refinement on rootstocks (cucumbers), selection of male / female plants (cucumbers, hemp) etc.

advantages

The advantages of growing plants using hydroponics are:

  • Lush growth in a shorter time with more plants on the area leads to higher yields. As a result of the better supply of nutrients and oxygen, growth increases, vegetables are ready for harvest earlier and an optimal yield is guaranteed over time. Similar quantitative increases in performance can otherwise only be achieved with fruit vegetables with plant refinement.
  • By propagating cuttings (see also cuttings ) and rooting using hydroponic methods (see below), germination times and the time it takes to grow to the size of the cuttings are saved
  • circulation of seepage water leads to ...
    • Saving of (watering) water
    • Reduced entry of fertilizers and nutrients (extracted or fertilized from the soil) into the groundwater
    • Reuse of washed-out plants exudates the next watering in the entire rhizosphere , none of which is lost (through seepage into the groundwater). This is because up to 20% of the carbon fixed by photosynthesis in a vegetation period is released from the roots into the soil (or, in the case of hydroponics, into the seepage water). According to a study in soil culture, 64 - 86% of the exudate substances were inhaled by microorganisms, 2 - 5% remained in the soil. Most of the root exudates from maize (79%) were water-soluble (64% of which were carbohydrates , 22% amino acids or amides and 14% organic acids).
  • Saving of fertilizer (which is otherwise washed out or bound in the soil)
  • Control of missing nutrients through (automated) examination of the circulating water,
    • thus better adaptation of the nutrient concentrations to the needs of the plants in the various phases (growth, flowering time, fruit formation),
Hydroponically grown strawberries no longer come into contact with the ground, so there are no more failures due to snail damage or mold. The use of varieties with the fruit hanging down (rather than standing between the leaves) enables easier harvesting.
  • Due to the lack of soil and mostly almost sterile working methods (lock systems, UV lamps), reduction of damage caused by microorganisms and small animals ( e.g. root lice , nematodes ) and harmful fungi (e.g. mold ) and associated therewith
  • Lush growth of mother plants for propagation from cuttings
  • better supply of the roots with water and oxygen,
  • takes up less space because the roots don't have to spread as far to get water and nutrients
  • no hassle of weeding or weeding
  • sometimes easier harvest (for example strawberries that grow overhead in irrigation pipes)
  • easier checking of the health of roots
  • continuous harvesting of roots (interesting for those medicinal plants that collect active substances in the roots)
  • longer freshness of lettuce if it is sold with roots, it can then be watered by consumers;
  • fewer washing processes (for example of potatoes) necessary than with soil culture
  • Plants need less energy than when the roots have to penetrate hardened substrate

The higher costs for substrates are less significant here than for indoor greening.

It also makes it easier or even possible to grow plants under extreme conditions, in halls, in urban buildings and apartments, in research stations at the South Pole, on exposed islands with poorly fertile soil or when there is a lack of drinking water or in space.

disadvantage

The disadvantages are:

  • For hydroponics, mostly energy-intensive produced artificial fertilizers are used
  • When using rock wool or potassium polyacrylate ( super absorber ) as a substrate, large amounts of waste are generated. After a season, rock wool blocks or sacks with roots are deposited. For the Netherlands alone (according to a source from 2008) , around 200,000 cubic meters of rock wool residues are produced annually as waste that has to be disposed of.
  • Rockwool and glasswool substrates emit short fibers that can penetrate the lungs and may contain lubricants (as binders). (Rockwool waste is considered hazardous waste in many places).
  • Even if only biogenic fertilizers are used, hydroponics is not approved for growing organic vegetables (and therefore little research is done in this direction).
  • Pumping, conducting and storing and monitoring the parameters requires (expensive) technology and technical know-how and constant attention and control of the technology,
  • If pumps fail, regular watering is stopped, roots and plants grown without substratum then dry up faster than roots in soil (which can store a certain amount of water)
  • The increased pumping work consumes more electrical energy than with less irrigated crops
  • Plant diseases and harmful organisms (such as Fusarium , Phytophthora and Pythium ; see also fallback disease ) can spread through the irrigation system. Pathogens that are pathogenic to humans (for example from the faeces of wild animals in the wild) can generally penetrate plants via roots, stems, leaves, sprouts and fruits, infect them and multiply there. Feeding or sucking stings by insects can also be entry points. Such germs can multiply in the hydroponic circuit water. In larger irrigation systems, the irrigation water is therefore disinfected with UV light .
  • Human pathogenic bacteria living or multiplying in water , such as Legionella , can endanger personnel if the water is sprayed or misted
  • Problems with the irrigation water (pH value changes, concentration due to evaporation, deposition of salts on the substrate surface due to increased evaporation) can quickly damage plants
  • During the microbial degradation of plant residues, CO 2 is formed in the soil , which plants need for photosynthesis. In soilless cultivation, CO 2 is only produced when the roots breathe (and then mostly comes from the plant), so it has to be added to the greenhouse air for the carbon input in the course of photosynthesis.
  • Plants form aromatic substances in order to protect themselves against microbial and herbivorous pests and predators (see also feeding defense ); reducing the contamination of such pests by hydroponics can also lead to a loss of flavor
  • In the case of wine, it is said that the type of soil determines the character of the wine, i.e. an influence can be tasted, and differences can also be determined in the case of fruit and vegetables. With uniform fertilizer solutions in hydroponics, aroma differentiations of the grown vegetables were lost due to different soil types (see also vineyard soils and wine , terroir and choice of vineyards ).
  • In hot parts of the world, the (energy-consuming) cooling of the circulating water is a problem

Substrates

Hydroponics exhibit in the Belgian pavilion at Expo 2015 in Milan

In some hydroponics methods, the plant roots hang directly in nutrient solutions or in an air space enriched with nutrient mist or droplets without a substrate . Substrate only serves to give the roots a hold and to keep the plants upright and to provide cavities for the roots, but does not contribute to the nutrition of the plants.

Most substrates for hydroponics are more porous than earth, the pore space is 1.3 to 3 times larger. More air space means more oxygen in the root area, more space for roots and less energy expenditure or stress for the plants in order to "drill in" roots.

The roots expand according to the structure of the pore space of the substrate: wide pores with diameters greater than 50 μm are accessible to all roots. Medium pores with a diameter of 0.2 - 50 μm can only be opened up by root hair. Fine pores smaller than 0.2 μm can store water, but are not visited by root hairs or fungal hyphae.

Important factors for substrates are:

  • Water holding capacity (the amount of water a substance can hold)
  • Retention (soil) : The force that holds the water in the substrate and the suction force the roots have to develop in order to be able to adsorb the water from it
  • Roughly dense (generally dry and wet weight), air-containing expanded clay balls with insufficient density or organic substances (such as wood chips) can float up
  • Particle size , depending on the grain size, the cavities between the particles are larger or smaller
  • Permeability to water
  • pH of the eluates
  • Ion binding capacity and exchange capacity
  • Phytotoxicity (in terms of, for example, copper-free rock or the (sea) salt content in coconut fibers)
From the outer fiber sheath ( mesocarp ) of coconut are coconut fibers recovered. These are often contaminated with chlorides from seawater and must be washed free of chloride before the plants are planted for the first time.

Mineral wool is often used for sowing and drip irrigation , from which the young plants are converted into other substrates. Other substrates used are

irrigation

The diameter of supply pipes and hoses should be selected as large as possible. The volume flow is dependent on the fourth power of the radius (due to the Hagen-Poiseuille law ). For example, reducing the pipe diameter by half would increase the flow resistance 16 times or increasing the pipe diameter by three times (one and a half inches instead of half an inch) the volume flow by 81 times. Increasing the pipe diameter can therefore increase the pumping capacity of a pump (with the effect of a greater pumping height or more flow), which means that weaker pumps can be selected, which significantly reduces energy costs.

With hydroponic systems, it is important to identify the cause of any water loss. Water loss through evaporation only requires supplementation with fresh water, water loss through leaks also leads to loss of fertilizer , the content of which must be supplemented with water supply.

Cultivation forms

In addition to the cultivation in substrates, which is common for ornamental plants, other forms of cultivation are used, particularly in commercial horticulture:

Ebb and flow system

Plants on plant tables in nurseries and in hydroponic systems in plant cultivation are often watered and drained with an ebb and flow system (English "ebb and flow" or "flood and drain"). The plants are placed in watertight tubs, and watering takes place using water pumps . The plant tub is flooded and then the nutrient solution is removed again. The rising water dissolves the soil respiration metabolic product carbon dioxide or pushes it up into the air space (where the plants need it for photosynthesis ) and removes it from the substrate, the falling water level then sucks in fresh air from above, whereby nutrients from the plant again can be included.

One method of the ebb and flow system works with a water pump controlled by a timer . The inlet opening for the nutrient solution is at the lowest point of the plant tub. The water level rises until it reaches an overflow pipe, where too much nutrient solution flows back into the reservoir. When the pump is switched off, the nutrient solution slowly flows back into the collecting container via the same line through which it was pumped up.

In the case of small plant containers and far away from the power supply, the water reservoir can be connected to the plant container with a flexible hose and "high and low tide" are brought about by manually raising and lowering the collecting container.

In some hydroponic ebb and flow systems, the irrigation water is pumped continuously (i.e. without intervals, without an error-prone timer ) from a water reservoir into the plant tub ("upper water"). After the desired water level has been reached in the plant tub , the water is drained again in a gush through a drain siphon into the water reservoir ("underwater") below, thus emptying the plant tub.

For the ebb and flow system and inert substrates, watering intervals of half an hour are recommended for moistening. The higher the water storage capacity of a substrate, the less often it has to be watered. If organic substrates such as wood chips, peat or coconut fibers are used, an irrigation interval of a few days is sufficient. As the rooting progresses, the time intervals are shortened until it is finally watered once or twice a day.

If there is a lack of water in the plant roots, the plant protects itself by shedding or corking parts of the roots, especially by "lignifying" older roots. With renewed water supply, new fine roots must first be formed again, which is energy-intensive.

Too fast drainage of water can lead to the breakage of fine roots and the washing out of the surrounding carbohydrate-rich mucus (which in turn feeds mycorrhizal fungi, which in turn improve the water balance of the plant roots) (see also water absorption of the rhizodermis ).

Deep Water Culture (DWC)
Plant cultivation in deep water culture
The roots of a hydroponically grown plant

Deep Water Culture is a form of cultivation in which the plants are kept floating in nutrient solution and the roots hang directly in the well-ventilated nutrient solution.

Usually the plants are put into appropriately perforated styrofoam plates with mesh pots filled with substrate and these are then placed in basins with nutrient solution.

Since roots need oxygen as well as water and nutrients, the nutrient solution basin must be well ventilated so that air bubbles rise permanently. If this is not done, the roots and with them the plants die quickly. With floating islands , the water is saturated with oxygen down to a depth of around 4 meters through air pressure and wave movements alone. In nutrient solution basins there is less free surface available for oxygen entry, which is why they are artificially aerated. Water aeration with CO 2 with the help of a so-called "carbonator" is also intended to allow taller plants to grow better (by lowering the pH value by influencing the carbonate hardness ).

Kratky methods

These “passive” methods (without technology), named after BA Kratky, professor at the University of Hawaii , are variants of deep water culture, but do not require aeration or circulation pumps. They are used for simplified lettuce growing. The seeds germinate in the coconut fiber spring pots, which are either immersed in the nutrient solution in the final container on a base plate or in plastic tubes that are immersed in the nutrient solution. As the roots develop, the liquid level of the nutrient solution is continuously lowered, with the aim of making the water roots longer. Only the air space above the nutrient solution, which is saturated with water vapor through evaporation, supplies those roots that are not immersed in the nutrient solution with the necessary oxygen.

Kratky also developed a simplified hydroponic cultivation variant for potatoes (because Hawai'i has to import 99% of the potatoes). The seed potatoes are wrapped in newspaper and the "tubes" are then placed in a nutrient solution.

Nutrient Film Technique (NFT)
Hydroponic growing of lettuce. In the foreground NFT channels

The nutrient solution film technique is also a method of cultivation in which the plants are grown in channels or pipes that are laid on a slight slope (1–2%) and through which nutrient solution flows. The plants are usually placed in suitable holes in the channels with net pots filled with substrate.

The roots of the plants are partly in the nutrient solution, partly above in the air-filled area of ​​the canal. In NFT, the plants can be harvested and changed very easily. Very long canals (> 100 m) can be problematic, in which the nutrient solution heats up too much when exposed to sunlight or has too low a nutrient salt content at the end of the canal, so that the last plants show less good growth.

The size of the channels and the distance between the plants must be adapted to the root growth of the plants so that the channel does not become clogged over time and the flow is interrupted.

Growing food crops with hydroponics; in space travel for a lunar base
Aeroponics and Fogponics

In aeroponics , the nutrient solution is atomized into air using high-pressure nozzles or sprinklers . This method makes roots grow stronger than the green herb , so it is mainly used for rooting cuttings. Propagating cuttings as a variant of cloning , for example of tomato plants, shortens the cultivation time because the times for the germination phase of the seeds are saved.

In Fogponics , a special form of aeroponics, the nutrient solution is finely nebulized in air using ultrasonic nebulizers. This method works without pumps and with a minimum of water. It was developed by NASA employees for plant cultivation in space stations , as little water has to be transported into space and the fine water droplets reach the plant roots regardless of the lack of gravity. Due to the simple implementation at low costs and the low volume weight of the systems and thus easier stacking of plant tubs, this method is considered to be the hydroponic method "with the greatest future".

The disadvantage of this method is that all the energy ( work ) that is introduced into the system for atomizing the nutrient solution is ultimately released as heat (by releasing the interface work of the coagulating, divided droplets) and heats the nutrient solution. Heat exchangers are sometimes necessary for cooling.

Other hydroponic systems
Cubes of rock wool, which for indoor cultivation of cannabis use
  • Drip irrigation of substrate blocks, sacks or film tubes (as a container). It is mostly used for growing tomatoes because tomatoes are sensitive to waterlogging
  • Aero-hydroponics : A pipe that is open at the bottom extends into the water reservoir at the bottom of a plant container. If air is pumped into the tube below, the rising air bubbles pull the nutrient solution upwards and at the same time enrich it with oxygen. The water is distributed via drip irrigation systems. Systems with water pumps for drip irrigation, in which the seepage water flows back into the water reservoir, are also called aero-hydroponics. A variant of this is Air-dynaponics , in which air is blown in on the surface of the nutrient solution in such a way that drops of water are thrown into the root space over it and thus moisten the roots.
Cultivation in vertically placed tubes
  • Vertical cultivation in plant towers that are permanently moistened from above by drip irrigation or mist. Large-diameter pipes with openings for individual plants are better than all-round open mesh baskets, because they can minimize water evaporation and thus water consumption. Such towers are usually grouped around a plant lamp. Such plant towers are optimized by supplying the roots with a nutrient solution mist (as with fogponics), which is blown through the pipes with the help of fans. The disadvantage of vertical pipes (with fogging) or diagonally horizontal gutters (with irrigation) is that lush root growth can hinder the mist or water supply and that the following plants are undersupplied in the moisture flow.
  • passive systems (without technology):
  • Aquaponics is a combination of fish farming and hydroponics in which fish excrement is used as fertilizer. Aerated water from a collecting tank is first pumped into the fish tank, the overflow of which runs over a nitrification filter (to convert ammonium nitrogen into nitrate nitrogen) to the plants and from there back to the collecting tank .
  • The Integrated Floating Cage Aquageoponics System (IFCAS) combines aquaponics and plant cultivation in the ground.
  • In Vermiponics is Wurmtee ( "AACT"; "actively aerated compost tea" for actively aerated compost tea) from a Wormery used as a natural fertilizer for hydroponics.
  • Combinations of different processes: If only organic fertilizers are used in various processes , an ebb and flow system often serves as a trickle filter and system for the oxidation of ammonium to nitrate. In some greenhouses only one type of vegetable, for example only lettuce in deep-water culture, is grown and the entire downstream processing, packaging and distribution chain is optimized accordingly, in other greenhouses 50 different vegetables and herbs are grown, the requirements of which are different need.
Cultivation in closed halls
Growing plants on shelves. Each shelf with extra lighting.

Based on research by Japanese companies, plant cultivation was relocated from greenhouses to closed halls. The plants are raised on stacked shelves. The roots protrude into a (fogponics) fog space or aerated nutrient solution, the leaves are illuminated in every shelf compartment with plant lamps (nowadays mostly LED lamps ) with photosynthetically active radiation and optimized quantum efficiency with optimal McCree curves (color-coded light frequency spectrum ).

Grow box for indoor plant cultivation
Growing cannabis in a grow box . The inside is lined with aluminum foil in order to optimize the light yield of the plants.

Cannabis cultivation (for intoxicants ) tends to take place in closed rooms. The resourceful industry (in the Netherlands ) has developed a wide range of equipment for this purpose.

Beneficial organisms

Harmful organisms such as Fusarium, Phytophthora and Pythium multiply in hydroponic systems. For example, Pseudomonas chlororaphis is used as a beneficial bacterium against Pythium ultimum .

Market development

The global economic market for hydroponic equipment was forecast to grow 18.1% annually in 2017 , increasing from $ 226.45 million in 2016 to $ 724.87 million in 2023. According to another source from 2018, the market included 2016 $ 21.2035 billion with an annual growth rate of 6.5%

criticism

Plant nutrition with artificial nutrient salts alone would lead to “inharmonious plant nutrition” because of the interrelationships between the nutrients, nutrient antagonism and synergism ; from the nutritional point of view, “at least different plants” would emerge that “only have the same anatomical structure, but not their content and therefore not the quality "are equal. Trace element composition and active ingredient structure are different.

Opposed to this are the opinions that precisely knowing the composition of the nutrient solution can avoid such nutrient antagonisms and that missing nutrients can easily be supplemented. This means that the plants have optimized nutrient media in the right composition at all times.

The WWF criticizes the high energy consumption of the soilless culture from greenhouses, since it would even "make more sense to buy vegetables imported out of season".

Trivia

Medicinal plants are grown using aeroponics when the active ingredients are extracted from the roots (aeroponics makes the roots grow stronger than the herb ). According to a new process, taxol , which is used to fight cancer and only occurs in low concentrations in nature, is to be obtained from the circulating water of a hydroponic system.

Because wet rice cultivation in flooded fields is responsible for around 17% of the emissions of the greenhouse gas methane , attempts are being made to use hydroponics to generate higher yields on conveyor belts in halls.

See also

literature

Indoor plant hydroponics

  • Margot Schubert: More flowers thanks to hydroponics. 7th revised edition. BLV, Munich 1980, ISBN 3-405-12222-8 .
  • Hans-August Rotter Hydroponics: Effortlessly caring for plants without soil. Falken, Niedernhausen 1980, ISBN 3-8068-4080-6 .
  • Gabriele Vocke, Karl-Heinz Opitz: Magnificent flowers and plants in hydroponics. 3rd new edition. Lenz, Bergneustadt 1988, OCLC 633566436 ; Hydroponics: beautiful flowers and plants in the home with ease . Revised and expanded new edition, Frech, Stuttgart 1988, ISBN 3-7724-1144-4 .
  • Günther Kühle: Indoor plants in hydroponics. 6th edition. Neumann, Leipzig et al. 1990, ISBN 3-7402-0014-6 .
  • Karl-Heinz Opitz: hydroponics. The simple plant care. Lush houseplants without soil. With tips for choosing plants and vessels (= GU guide for indoor plants ). Gräfe and Unzer, Munich 1995, ISBN 3-7742-1681-9 .
  • Margot Schubert, Wolfgang Blaicher: 1 × 1 of hydroponics (= BLV Garden and Flower Practice ), 8th reviewed edition, new edition. BLV, Munich et al. 1998, ISBN 3-405-15339-5 .

Hydroponics

  • William Texier: Hydroponics made easy - Everything about growing plants indoors, translated by Astrid Schünemann, illustrations by Loriel Verlomme, Mama Editions publishing house, Paris, 2013, 2014, 2015, ISBN 978-2-84594-087-1 .
  • WF Gericke: Soilless Gardening , Putnam, London, 1940, ( archive.org ).
  • Joachim Herbold: Soil-independent cultivation methods in vegetable growing: production technology, economic efficiency and environmental compatibility , 136 tables (= Hohenheimer work ). Ulmer, Stuttgart 1995, ISBN 3-8001-8238-6 (Dissertation University of Hohenheim 1994, 277 pages, illustrated, under the title: Soil-independent cultivation methods in greenhouse vegetable growing ).
  • Jiancun Liu: Development of a system for growing vegetables in trough cultures using the “cultan” method. 1996, DNB 950185590 , OCLC 64543471 (Dissertation University of Bonn 1996).

Web links

Commons : hydroponics  - collection of images, videos and audio files

(Ornamental) hydroponics

Hydroponics

Hydroponic gardener with his products

Videos

Individual evidence

  1. ↑ Duden online
  2. ↑ Hydroponic Mushrooms!
  3. ↑ a b c d e f g h i j k l m n o William Texier: hydroponics made easy - About crops in the house. Verlag Mama Editions, Paris, 2013, 2014, 2015, ISBN 978-2-84594-087-1 (translated by Astrid Schünemann, illustrations by Loriel Verlomme).
  4. ↑ Kirsten Engelke: The root - the nutrient absorption. In: innovation. 1/2011, p. 17 ( magazin-innovation.de PDF), accessed on June 7, 2019.
  5. ↑ a b c hydroponics.
  6. ↑ a b Federal Ministry of Education and Research : Use of hydroponic systems for resource-efficient agricultural water reuse ( bmbf-wave.de PDF, December 2016), accessed on June 7, 2019.
  7. ↑ a b James S. Douglas: Hydroponics. 5th edition. Oxford UP, Bombay 1975, pp. 1-3.
  8. ↑ HH Dunn: Plant "Pills" Grow Bumper Crops . In: Popular Science Monthly . October 1929, p. 29.
  9. ↑ G. Thiyagarajan, R. Umadevi, K. Ramesh: Hydroponics. ( Memento from December 29, 2009 in the Internet Archive ) (PDF) In: Science Tech Entrepreneur. (January 2007), Water Technology Center, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641 003, India.
  10. ↑ Berkeley, biography ( Memento from March 5, 2015 in the Internet Archive )
  11. ^ BW Veen: Relation between root respiration and root activity , Structure and Function of Plant Roots, Developments in Plant and Soil Sciences
  12. ↑ Luo Yiqi: Soil Respiration and the Environment. Elsevier, 2010, ISBN 978-0-080-46397-1 , p. 45 ( limited preview in Google book search).
  13. ↑ a b c d e f g LAMBERS et.al 1998, quoted in: Luo Yiqi: Soil Respiration and the Environment. Elsevier, 2010, ISBN 978-0-080-46397-1 , p. 45 ( limited preview in Google book search).
  14. ↑ Bryla et.al 1997, quoted in: Luo Yiqi: Soil Respiration and the Environment. Elsevier, 2010, ISBN 978-0-080-46397-1 , p. 45 ( limited preview in Google book search).
  15. ↑ a b Change / reverse polarity [from earth plants to hydroponics].
  16. ↑ Hydroculture facility "System Rößler". German Society for Hydroculture eV
  17. ↑ A life for plants. German Society for Hydroculture eV
  18. ^ Obituary by Gerhard Baumann , German Society for Hydroculture
  19. ^ Hans G. Hirschberg: Handbook of process engineering and plant construction. Springer-Verlag, 2013, ISBN 978-3-642-58357-5 , p. 622 ( limited preview in the Google book search).
  20. ↑ a b The advantages and disadvantages of hydroponics.
  21. ↑ Hydroponics and Mold.
  22. ^ Henry George Liddell, Robert Scott: A Greek-English Lexicon geoponikos
  23. ^ The hanging gardens of Kreuzberg , at zeit.de
  24. ↑ "Herbert": When the vegetables grow in the living room , at kurier.at
  25. ↑ Salad innovations from the "assembly line"
  26. ↑ Chilling Root Zones in Lynette Morgan: Subterranean Tactics: Root Zone Manipulation in Hydroponics
  27. ↑ Sharing Substrates in Lynette Morgan: Subterranean Tactics: Root Zone Manipulation in Hydroponics
  28. ↑ Refining of fruit vegetables
  29. ↑ Birgit W. Hütsch, Jürgen Augustin, Wolfgang Merbach: Plant rhizodeposition - An important source for carbon turnover in soils , Journal of Plant Nutrition and Soil Science, 165 (4): 397 - 407 August 2002
  30. ^ Springer-Verlag: Plant and Water / Water Relations of Plants. Springer-Verlag, 2013, ISBN 978-3-642-94678-3 , p. 1 ( limited preview in the Google book search), p. 206.
  31. ↑ Michaela C. Theurl: CO2 balance of tomato production: Analysis of eight different production systems in Austria, Spain and Italy. In: Social Ecology Working Paper. 110, Vienna, December 2008, ISSN  1726-3816 ( aau.at PDF).
  32. ↑ Bavarian State Office for the Environment: Artificial mineral fibers. ( lfu.bayern.de PDF).
  33. ↑ Waste classification (pdf)
  34. ↑ a b S. Lee, J. Lee: Beneficial bacteria and fungi in hydroponic systems: types and characteristics of hydroponic food production methods - Scientia Horticulturae, 2015 - Elsevier, (PDF file)
  35. ↑ Irene Esteban Cuesta: Investigations on the endogenous microbial contamination of melons (Cucumis Melo) , Department of Veterinary Science at the Faculty of Veterinary Medicine at the Ludwig Maximilians University in Munich, Chair for Food Safety, Munich 2016, PDF file
  36. ^ "Volatile" medicine from plants - essential oils against difficult to treat fungal diseases ,pflanzenforschung.de, March 22, 2018
  37. ↑ Noll, Daniela (2011) Comparison of different methods for describing the quality of apples of the "Goldrush" variety, taking into account integrated and biological production methods and radiesthetic pollution of the micro-location. Diploma thesis, University of Vienna. Faculty of Life Sciences
  38. ↑ Maike Kramer, Anna Maksylewicz-Kaul, Rafal Baranski, Thomas Nothnagel, Reinhold Carle, Dietmar R. Kammerer: Effects of cultivation year and growing location on the phenolic profile of differently colored carrot cultivars ; Journal of Applied Botany and Food Quality 85, 235-247 (2012)
  39. ↑ K.Skwarlo-Sonta, E. Rembialkowska, J.Gromadzka-Ostrowska, D.Srednicka-Tober, M.Baranskia, T.Krolikowskic, K.Wisniewska, A.Rusaczonek, E. Hallmann, L.Lueck, C.Leifert : Response of animal physiology to organic versus conventional food production methods , NJAS - Wageningen Journal of Life Sciences, Volume 58, Issues 3-4, December 2011, pages 89-96
  40. ↑ Singapore's New Business Opportunity: Food from the Roof , at cityfarmer.org
  41. ↑ F. Scheffer, P. Schachtschnabel, and others: Textbook of soil science. Spektrum, Akademischer Verlag, Heidelberg 2010, p. 16 .;
    quoted by Josef Schönleitner: Woody structures on flood protection dams / Woody Plants on Leeves. Vienna, May 2013, Institute for Engineering Biology and Landscaping, Department for Structural Engineering and Natural Hazards, University of Natural Resources and Life Sciences, Vienna (     zidapps.boku.ac.at PDF).
  42. ↑ Hydroponics , Zeolite Manufacturers Website
  43. ↑ a b c d e f Kevin Espiritu: Hydroponic Growing Media.
  44. ↑ Jacek Dyśko, Stanisław Kaniszewski, Waldemar Kowalczyk: Lignite as a new medium in soilless cultivation of tomato. In: Journal of Elementology. 20, No. 3, pp. 559-569. doi: 10.5601 / jelem.2014.19.1.622 .
  45. ↑ Jing Quan Yu, Kwang Seek Lee, Yoshihisa Matsui: Effect of the addition of activated charcoal to the nutrient solution on the growth of tomato in hydroponic culture , Journal Soil Science and Plant Nutrition, Volume 39, 1993 - Issue 1, pages 13– 22nd doi : 10.1080 / 00380768.1993.10416970
  46. ^ Max von Knoop: Irrigation cycles in hydroponics
  47. ↑ Josef Schönleitner: Woody structures on flood protection dams / Woody Plants on Leeves. Vienna May 2013, Institute for Biological Engineering and Landscaping, Department for Structural Engineering and Natural Hazards, University of Natural Resources and Life Sciences, Vienna ( zidapps.boku.ac.at PDF)
  48. ^ Ulrich Maniak: Hydrology and Water Management. ISBN 3642053955 p. 551 ( limited preview in Google Book Search).
  49. ↑ BA Kratky: Three non-circulating hydroponic methods for growing lettuce , 2009, ISHS Acta Horticulturae 843, 65-72, International Symposium on Soilless Culture and Hydroponics, DOI: 10.17660 / ActaHortic.2009.843.6 .
  50. ↑ Bernard A. Kratky: A Capillary, Noncirculating Hydroponic Method for Leaf and Semi-head Lettuce (Abstract) , Hort Technology, American Society for Horticultural Science (Editor), (PDF file)
  51. ↑ BAKratky: Low Technology Hydroponic Methods for growing potatoes in Hawaii , (PDF file)
  52. ↑ NFT Production of Lettuce (English)
  53. ↑ Fogponics: A New Spin on aeroponic Gardens
  54. ^ Haque: Integrated floating cage aquageoponics system (IFCAS): An innovation in fish and vegetable production for shaded ponds in Bangladesh . In: Aquaculture Reports . 2, 2015, pp. 1-9. doi : 10.1016 / j.aqrep.2015.04.002 .
  55. ↑ Matt LeBannister: With a Little Help From Your (Many) Friends: Beneficial Microbe Populations in the Indoor Garden
  56. ↑ What are the differences between PAR, PPF, PPFD and Lumen?
  57. ↑ Seungjun Lee - Google Scholar Citations. In: scholar.google.de. Retrieved July 3, 2018 .
  58. ↑ Global Hydroponics Market Report 2017–2023: Market is expected to grow from $ 226.45 million in 2016 to reach $ 724.87 million by 2023 - Research and Markets.
  59. ↑ Hydroponics Market - Segmented by Type, Crop Type, and Geography - Growth, Trends and Forecasts (2018-2023).
  60. ↑ Hendrik Führs, Reinhard Elfrich: Nutrient interactions in soil and plants , PDF file
  61. ↑ Erwin Lengauer: The activity of microbes on plant roots , Research Center for Mountain Agriculture, University of Innsbruck , PDF file
  62. ↑ Daniel Friedli: Now comes the Hydro Salad at nzz.ch
  63. ↑ Anita L. Hayden: Aeroponic and Hydroponic Systems for Medicinal Herb, Rhizome, and Root Crops , HortScience, Vol. 41 (3), June 2006; Pages 536–538, PDF file available
  64. ↑ Ulrich Lüttge: Fascination Plants. Springer-Verlag, 2017, ISBN 978-3-662-52983-6 , p. 302 ( limited preview in Google book search)
  65. ↑ Intergovernmental Panel on Climate Change Special Reports - Land Use, Land-Use Change and Forestry: Sources and Sinks of Methane ( Memento of the original of September 13, 2018 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. on ipcc.ch, @1@ 2Template: Webachiv / IABot / www.ipcc.ch
  66. ↑ Agriculture of the future - rice on the conveyor belt