Is Sulfur (S) mobile in the plant?

Sulfur (S) is not considered a mobile nutrient within plants. Once it is taken up by the plant and utilized in various metabolic processes, it typically becomes part of tissues and structures in a way that makes it less likely to be moved again to other parts of the plant, particularly under normal circumstances. This immobility means that symptoms of sulfur deficiency are often most pronounced in new growth, as older leaves have already made use of sulfur before it was needed in the younger tissues.

The growth processes using sulfur primarily occur in the chloroplasts, where it is integral to the production of amino acids and proteins that are essential for overall plant function. Because sulfur does not easily relocate from older tissues to newer growth, maintaining adequate sulfur levels in the soil is essential for ensuring that plants have sufficient sulfur available throughout their growth stages. Understanding this immobility helps in managing sulfur applications and diagnosing deficiencies in various crops.