Magnesium exists in the soil as a cation (Mg⁺²) and is absorbed by plants from the soil solution, predominantly by mass flow. That is, since Mg⁺² is not heavily bound to the CEC, it is free to move through the soil to plant roots. This is in contrast to nutrients that are immobile in the soil (think back to P and K) that require roots to actively move and mine the soil to pull these elements off of the CEC.

Magnesium is also mobile in plant tissue, with deficiency symptoms first appearing on older (lower) leaves. As a primary constituent of chlorophyll, Mg²⁺ is essential in the processes of photosynthesis. It is also required for nearly every process of energy transfer in plant metabolism.

Leaves – Symptoms appear first on older (lower) leaves. Olive green – mustard yellowing & interveinal striping that progresses towards the base of the midrib. Necrosis of leaf tip and margins. Older leaves become reddish-purple.

Plant and Leaf Tissue Deficiency Levels

Early Growth – recently mature leaf Mg < 0.15%¹

At Tassel – recently mature leaf ear leaf Mg < 0.15%¹

Leaves – Symptoms appear first on older (lower) leaves. Plants will be pale green. Leaves will show yellow interveinal mottling progressing to necrosis.

Plant and Leaf Tissue Deficiency Levels

Early Growth – recently mature leaf tissue Mg of < 0.30%¹.

At Flowering – recently mature leaf tissue Mg of < 0.25% ¹.

Analyses

N

Mg

0

10

0

11

0

55

0

4-6