Sulfur (S)

Function:

Constituent of amino acids and hormones

Deficiency:

Initially developing as an uniform, light yellowish-green color of the younger leaves. A corrective fertilization with S will return the chlorotic tissue to the normal green color within 1 to 2 weeks.

Sulfur deficiency of the younger foliage.
Click on image for larger version. (image ©Roy Larson, NCSU)

Excess:

Can reduce uptake of: boron (B), iron (Fe), or molybdenum (Mo)

Confirm your actual S levels by conducting a routine root substrate (medium) test and/or a plant tissue analysis.

Monitoring and Management Strategy for Sulfur (S) Fertilization Rate:

25 to 64 ppm. The amount of sulfur contained in a fertilizer may not be listed on the fertilizer label. See the Fertilization Rate Table for specific fertilization recommendations based on growth stage and irrigation practices.

Ratio:

For many crops the recommended N : S ratio is 10 : 1 to 15 : 1.

Tissue Concentration:

Normal range of 0.1 to 0.3%. Levels below 0.05% are considered deficient.

Options:

Preplant:

Incorporation of magnesium sulfate (Epsom Salts) (MgSO₄·7H₂O).

Irrigation Water:

S in irrigation water (test water to determine available levels). Supplement with additional S in your fertilization program.

Continual Fertilization:

1. Use a fertilizer that provides S. Monthly magnesium sulfate (Epsom Salts) applications at the rate of 1 pound per 100 gallons of water. Do not mix with other fertilizers.

Corrective Fertilization:

1. Magnesium sulfate (Epsom Salts) application at the rate of 2 pounds per 100 gallons of water. Do not mix with other fertilizers. A corrective fertilization of S will return the chlorotic tissue to the normal green color within 1 to 2 weeks. Do not over apply.

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