© 2007 Donald G. McGahan (aka soilman) All Rights Reserved
Magnesium is a macronutrient essential for all plants. The ability of a soil to supply magnesium to plants is intimately tied to soil acidity (and for agricultural soils, to liming).
- The deficiency of Mg is much more common than that of Ca
- The most common symptom of Mg deficiency is interveinal chlorosis on the older leaves. Magnesium is mobile in the plant.
- The main source of plant-available Mg in most soils is the pool of exchangeable Mg on the clay-humus complex.
- Variable amounts of Mg are made available by the breakdown of plant residues and soil organic matter.
- In some soils, replenishment also takes place from a pool of slowly available Mg in the interlayers of certain 2:1 clays.