Function:

• Synthesis in plansts of protein and vitamins.
• Effective utilization of nitrogen and potassium.
• Deficiency produces:
  • Plants which are small and spindly with short, slender stalks.
  • Growth retarded and maturity often delayed.
  • On most plants, young leaves light green to yellowish, with even lighter-colored veins. (Young leaves because Sulphur, like Calcium, moves little within plant tissue.) Growth is slow and leaves tend to get brittle and stay narrower than normal.
  • Fruits often not fully maturing, remaining light green. and the first signs of a deficiency are
    
• Timing:
  • some needed all the time
  • highest demand durinq the stage of rapid growth when the demand for Nitroqen is at its peak.
  • also more during the latter stage of development — "filling" — when proteins are produced
• reducing pH (for alkaline soils)

Recommended Product: Gypsum

• Necessity? The North Carolina Cooperative Extension Service says "Sulfur deficiencies are less frequent in high-organic-matter soils because the sulfur mineralizes from the organic matter."
• Application: This site, which sells a non-organic sulfur product says, "For many crops the Nitrogen to Sulphur ratio should be in the 10: 1 range, however. there are many crops for which the demand for sulphur is higher and therefore the Nitrogen to Sulphur ratio should be nearer to 7:1 or even 5, 1." This is mainly referring to farm crops, which take a lot out of the soil.

For more information, see the North Carolina Extension Service's page Sulfur as a Plant Nutrient.