Role of Sulfur in Onion Production

Sulfur is an important component of enzymes and other proteins, and is required for chlorophyll formation. It has a marked effect on the pungency of the onion through increasing the pyruvic acid content of the bulb – a key quality characteristic.

Sulfur effect at growth stages

Stage Sulfur effect
Pre-Planting Encourage plant growth
Bulb Fill Depending upon the desired pungency of the onion
See more on Onion Growth Stages.

General guidelines for Sulfur application

Most sulfur uptake occurs in late season during bulb growth. Sulfur helps to improve the crop's utilization of nitrogen. Plants with a high sulfur content have greater tolerance to pest and disease attack. Sulfur has also been linked to increasing skin strength and color.

Sulfur deficiencies in onion

Leaf production is affected and the plant produces fewer leaves. Younger leaves are uniformly yellow in color.