Hoagland solution


The Hoagland solution is a hydroponic nutrient solution that was developed by Hoagland and Snyder in 1933, refined by Hoagland and Arnon in 1938 and revised by Arnon in 1950. It is one of the most popular solution compositions for growing plants with more than 15,000 citations listed by Google Scholar. The Hoagland solution provides every nutrient necessary for plant growth and is appropriate for supporting growth of a large variety of plant species.
The solution described by Hoagland in 1933 has been modified several times, mainly to add ferric EDTAs and alter the number and concentrations of micronutrients. In the revision of 1950, only one concentration was changed compared to 1938, while the concentration and composition of macronutrients remained the same since 1933. Accordingly, the original and the modified concentrations for each element are shown below, the calculation of these values being derived from Table.
The Hoagland solution has high concentrations of N and K so it is very well suited for the development of large plants like tomato and bell pepper. Due to relatively high concentrations in the stock solutions the solution is very good for the growth of plants with lower nutrient demands as well, such as lettuce and aquatic plants, with the further dilution of the preparation to 1/4 or 1/5 of the modified solution.
Salts and acids to make up the Hoagland hydroponic and soil culture solution formulations:
  1. Potassium nitrate, KNO3
  2. Calcium nitrate tetrahydrate, Ca2•4H2O
  3. Magnesium sulfate heptahydrate, MgSO4•7H2O
  4. Potassium dihydrogen phosphate, KH2PO4 or
  5. Ammonium dihydrogen phosphate, H2PO4
  6. Iron-EDTA or Iron chelate, Fe-EDTA or Fe-EDDHA
  7. Boric acid, H3BO3
  8. Copper sulfate pentahydrate, CuSO4•5H2O
  9. Zinc sulfate heptahydrate, ZnSO4•7H2O
  10. Manganese chloride tetrahydrate, MnCl2•4H2O
  11. Molybdic acid monohydrate, H2MoO4•H2O or
  12. Sodium molybdate dihydrate, Na2MoO4•2H2O.
Table to prepare the stock solutions and a full Hoagland solution :
The Hoagland solution formulation based on H2PO4 instead of KH2PO4 must be prepared according to a different protocol, which is referred to in the circulars of 1938 and 1950 as solution. Sprint 138 iron chelate is produced as sodium Fe-EDDHA, while Hoagland's original solution formulation optionally contains ferric or ferrous tartrate but no sodium ions. Other micronutrients and rather non-essential elements mentioned in Hoagland's 1933 original publication are no longer included in his later circulars. These elements and organic compounds are not necessary for normal plant nutrition. As an exception, there is evidence that, for example, some algae require cobalt for the synthesis of vitamin B12. On the other hand, it is evident that the modified Hoagland solutions of 1938 and beyond are balanced nutrient solutions that answer the question how to compose and concentrate the solutions best suited to the growth of plants.