The Hoagland solution is a

hydroponic Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions in aqueous solvents. Terrestrial or aquatic plant ...

nutrient solution that was newly developed by Hoagland and Snyder in 1933, modified by Hoagland and Arnon in 1938, and revised by Arnon in 1950. It is one of the most popular

artificial Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...

solution Solution may refer to: * Solution (chemistry), a mixture where one substance is dissolved in another * Solution (equation), in mathematics ** Numerical solution, in numerical analysis, approximate solutions within specified error bounds * Solutio ...

compositions for growing

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...

s, in the scientific world at least, with more than 17,000 citations listed by

Google Scholar Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes ...

. The Hoagland solution provides all essential elements for

plant nutrition Plant nutrition is the study of the chemical elements and compounds necessary for plant growth and reproduction, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element i ...

and is appropriate for supporting normal

growth Growth may refer to: Biology * Auxology, the study of all aspects of human physical growth * Bacterial growth * Cell growth * Growth hormone, a peptide hormone that stimulates growth * Human development (biology) * Plant growth * Secondary grow ...

of a large variety of plant species. The solution described by Dennis Hoagland in 1933, known as Hoagland solution (0), has been modified several times, mainly to add ferric chelates to keep

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...

effectively in solution, and to optimize the composition and

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', ''number concentration'', ...

of other

trace element __NOTOC__ A trace element, also called minor element, is a chemical element whose concentration (or other measure of amount) is very low (a "trace amount"). They are classified into two groups: essential and non-essential. Essential trace elements ...

s, some of which are not generally credited with a function in plant nutrition. In Hoagland's nutrient recipes of 1938, referred to as Hoagland solution (1, 2), the number of trace elements was subsequently reduced to the generally accepted essential elements ( B, Mn, Zn, Cu, Mo, Fe, and Cl). Later research confirmed that their concentrations had been adjusted for optimal plant growth. In Arnon's revision of 1950, only one concentration (Mo 0.011 ppm) was changed compared to 1938 (Mo 0.048 ppm), while the concentration of macronutrients of the Hoagland solutions (0), (1), and (2) remained the same since 1933, with the exception of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

(160 ppm) in solution (2). The main difference between solution (1) and solution (2) is the different use of

nitrate Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

and

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaterna ...

-nitrogen based stock solutions to prepare the respective Hoagland solution of interest. Accordingly, the original 1933 and the ''modified'' concentrations of 1938 and 1950 for each essential element and

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

are shown below, the calculation of the latter values being derived from Tables 1 and 2: *N 210 ppm *P 31 ppm *S 64 ppm *Cl 0.14 ppm / ''0.65 ppm'' *B 0.11 ppm / ''0.5 ppm'' *Na 0 ppm / ''0.023 ppm'' / ''1.2 ppm''* *Mg 48.6 ppm *K 235 ppm *Ca 200 ppm / ''160 ppm'' *Mn 0.11 ppm / ''0.5 ppm'' *Zn 0.023 ppm / ''0.05 ppm'' *Cu 0.014 ppm / ''0.02 ppm'' *Mo 0.018 ppm / ''0.048 ppm'' / ''0.011 ppm'' *Fe 1 ppm / ''5 ppm'' / ''2.9 ppm''* Plant nutrients are usually absorbed from the

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

solution. The Hoagland solution, originally intended to imitate a (nutrient-) rich soil solution, has high concentrations of N and K so it is very well suited for the development of large plants like

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

and

bell pepper The bell pepper (also known as paprika, sweet pepper, pepper, or capsicum ) is the fruit of plants in the Grossum Group of the species ''Capsicum annuum''. Cultivars of the plant produce fruits in different colors, including red, yellow, orange ...

. For example, a half-strength macronutrient solution (1) of Hoagland can be combined with a full micronutrient solution of

Long Ashton Long Ashton is a village and civil parish in Somerset, England. It falls within the unitary authority of North Somerset and is one of a number of large villages just outside the boundary of city of Bristol urban area. The parish has a populati ...

and a tenth-strength ferric EDTA solution to fertilize tomato

seedling A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (emb ...

s. Due to relatively high concentrations in the

aqueous An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be re ...

stock solutions (cf. Tables 1 and 2) the Hoagland solution is very good for the growth of plants with lower nutrient demands as well, such as

lettuce Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, ...

and

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments ( saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s, with the further dilution of the preparation to or of the modified solution.

Salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively c ...

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...

s and complex ions to make up the Hoagland hydroponic solution formulations ( 1) and ( 2): # Potassium nitrate, KNO₃ # Calcium nitrate tetrahydrate, Ca(NO₃)₂•4H₂O # Magnesium sulfate heptahydrate, MgSO₄•7H₂O # Potassium dihydrogen phosphate, KH₂PO₄ or # Ammonium dihydrogen phosphate, (NH₄)H₂PO₄ # Boric acid, H₃BO₃ # Manganese chloride tetrahydrate, MnCl₂•4H₂O # Zinc sulfate heptahydrate, ZnSO₄•7H₂O # Copper sulfate pentahydrate, CuSO₄•5H₂O # Molybdic acid monohydrate, H₂MoO₄•H₂O or # Sodium molybdate dihydrate, Na₂MoO₄•2H₂O # Ferric tartrate or Iron(III)-EDTA⁻ or Iron chelate (Fe-EDDHA⁻)

Components for Hoagland solution (1)

To prepare the stock solutions and a full Hoagland solution (1)

Components for Hoagland solution (2)

To prepare the stock solutions and a full Hoagland solution (2)

Alternatives for some components

Sprint 138 iron chelate is produced as Na-Fe-

EDDHA EDDHA or ethylenediamine-''N'',''N′''-bis(2-hydroxyphenylacetic acid) is a chelating agent. Like EDTA, it binds metal ions as a hexadentate ligand, using two amines, two phenolate centers, and two carboxylates as the six binding sites. The ...

(C₁₈H₁₆FeN₂NaO₆), while Hoagland's original solution formulations contain ferric tartrate (C₁₂H₁₂Fe₂O₁₈), but no sodium ions. Synthesizing a sodium-free ferric EDTA complex (C₁₀H₁₂FeN₂O₈⁻) in a

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physi ...

is sometimes preferred to buying ready-made

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

. Variable

micronutrient Micronutrients are essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for example, huma ...

s (e.g., Co, Ni) and rather non-essential elements (e.g., Pb, Hg) mentioned in Hoagland's 1933 publication (known as "A-Z solutions a and b") are no longer included in his later circulars. Most of these

metallic elements A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

, as well as

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

s, are not necessary for normal plant nutrition. As an exception, there is evidence that, for example, some

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

require

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

for the synthesis of

vitamin B12 Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. ...

References

External links

Modified composition of the Hoagland solution

* ttp://www.bdsoft.de/demo/index.htm?/demo/biologie/lexikon/a/a-z-loesung.htm "A-Z solution", Supplementary Nutrient Solution (Solution A), according to Hoagland and Snyder (1933)
The Hoaglands Solution for Hydroponic Cultivation
{{Plant nutrition Hydroponics

Components for Hoagland solution (1)

Components for Hoagland solution (2)

Alternatives for some components

See also

References

External links