Magnesium is an essential component of the chlorophyll molecule which is integral in the photosynthesis process that allows the plant to convert sunlight to energy. Magnesium also supports plant growth and function through enzyme activation and acting as a phosphorous carrier, aiding in the plant’s ability to take up phosphorous.
Magnesium deficiency on sandy, acidic soils can be caused by the application of heavy potassium fertilizer rates without magnesium. The deficiency causes older cotton leaves to turn a purplish color between the veins. Soils with high acidity and high annual rainfall respond best to a readily available magnesium fertilizer like Intrepid Trio.