|MadSci Network: Botany|
Epsom salts is magnesium sulfate, which contains two essential mineral nutrients for plant growth, magnesium and sulfur. Thus, in the proper concentration, it may be beneficial to plant growth. However, at too high a concentration, it can harm plant growth due to a salinity effect by making water more difficult for the plant to absorb. A hydroponic nutrient solution often used by scientists, Hoagland solution, contains 0.5 grams of epsom salts per liter. Plants also require 12 other mineral nutrients, nitrogen, phosphorus, potassium, calcium, iron, boron, manganese, copper, zinc, molybdenum, chlorine, and nickel. All but chlorine and nickel are often included in fertilizers. Chlorine and nickel have never found deficient under natural conditions because they are required in such small amounts relative to normal soil concentrations. Therefore, if you just provide magnesium sulfate, it may not do the plant too much good, because it will be deficient in some other essential mineral nutrients. When a plant is deficient in a single mineral nutrient, it will develop distinctive deficiency symptoms such as leaf yellowing (chlorosis) or shoot tip death. To find deficiency symptom info, search google.com or other search engine for plant magnesium deficiency or plant sulfur deficiency. Reference Hershey, D.R. 1994. Solution culture hydroponics: History and inexpensive equipment. American Biology Teacher 56:11-118.
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