Magnesium deficiency


Hidden in the heart of each chlorophyll molecule is an atom of magnesium (Mg), making the nutrient actively involved in photosynthesis. Magnesium also aids in phosphate metabolism, plant respiration and the activation of many enzyme seasons.

Plant growth requires energy, and lots of it. During germination alone, a bushel of wheat seed needs about 900 cubic feet of air and produces the same amount of energy needed by a tractor to plow an acre of land. Wheat and all crops require magnesium (Mg) to capture the sun’s energy for growth and production through photosynthesis. Chlorophyll, the green pigment in plants, is the substance through which photosynthesis occurs. Without chlorophyll, plants couldn’t manufacture food.

Magnesium is an essential component of chlorophyll, with each molecule containing 6.7 percent Mg. Magnesium also acts as a phosphorus (P) carrier in plants, which is necessary for cell division and protein formation. Phosphorus uptake couldn’t occur without Mg, and vice versa. So, Mg is essential for phosphate metabolism, plant respiration and the activation of several enzyme systems.

Soils usually contain less Mg than calcium because Mg is not absorbed as tightly by clay and organic matter and is subject to leaching. The supply of available Mg has been and continues to be depleted in some soils, but growers are noticing good responses to fertilization with Mg.

Magnesium’s availability to plants often depends on soil pH. Research has shown that Mg availability to the plant decreases at low pH values. On acidic soils with a pH below about 5.8, excessive hydrogen and aluminum can decrease Mg availability and plant uptake. At high pH values (above 7.4), excessive calcium may greatly increase Mg uptake by plants.

Magnesium is mobile within the plant and easily translocates from older to younger tissues. When deficiencies occur, the older leaves become damaged first, which may include color loss between the leaf veins, beginning at the leaf margins or tips and progressing inward, giving the leaves a striped appearance.


Symptoms of deficiency can vary across crop species, but similarities exist for how nutrient insufficiency impacts plant tissue color and appearance. Nutrient deficiencies are commonly associated with the physical location on the plant
(i.e., whether the symptoms are primarily observed on older versus newly formed plant tissue), but these symptoms can spread as the severity of the deficiency progresses.