Essential Elements for Plant Growth


Magnesium deficiency in corn

Biological function:

Magnesium deficiencies in soils are relatively rare as far as plants are concerned, but animals fed on Mg-deficient forage may develop hypomagesameia (grass tetany). "Excess" Mg is known almost only in soils derived from serpentine or olivene, both Mg-rich rocks, in which the exchangeable Ca/Mg ratio is ~1/5 instead of the more common 4/1 to 1/1; such soils often also contain toxic, high levels of bioavailable metals, among them Ni, which together with high Mg limit the distribution of "normal" vegetation, leading to "serpentine barrens".

Cycle, Forms, Tests:

Very similar to Ca , except Mg weathers out of a differ set of minerals than Ca, but otherwise is present in soluble, exchangeable, and mineral forms, but not organic. As for Ca and K, exchangeable Mg is measured by displacement into 1 M ammonium acetate.

Mg Fertilizers:

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This page was last modified by Phillip Barak, Univ. of Wisconsin, on 5 Jan 1999. All rights reserved.