Sulfur is a rather interesting mineral when it comes to plants. It is essential for growth and photosynthesis. Legumes also use it for nitrogen fixation.
But sulfur in plants is of direct significance to the humans that eat them, as well. This mineral is what gives onions, garlic, and plants of the mustard family their hallmark aromas, and it is the key to oil production in oilseed crops. Furthermore, sulfur is a constituent of some vitamins and amino acids.
Natural Sources
Many plants can absorb sulfur from the air. They also tend to receive it from natural water sources.
Most sources of organic matter contain sulfur. This makes compost, manure, and decaying plant matter useful for providing sulfur to plants.
Finally, you may be surprised to learn that Epsom salts contain sulfur, as well.
Deficiency
Sulfur can become depleted by leaching on sandy and even some silty soils if they are deficient in organic matter. It may also be rendered unavailable to plants if the soil temperature or pH is too low or if there is excess phosphorus competing for uptake.
Sulfur deficiency is a particular problem in high-yield plants and varieties. The plant species most prone to sulfur deficiency include alfalfa, corn, wheat, and brassicas.
Symptoms of sulfur deficiency in plants include:
- Stunted, spindly growth.
- Uniform paling, sometimes more pronounced on younger leaves.
- Reduced yield.
Fortunately, correcting a sulfur deficiency is quite simple—just add organic matter.
Toxicity
Sulfur toxicity used to result from air pollution due to industrial activities. These days, toxicity isn’t typically a problem unless sulfur-based pesticides are being used in excess.
Most plants do not directly show the effects of sulfur toxicity. Typically, their symptoms result from the associated nitrogen deficiency and a drop in soil pH.
Should excess sulfur build up in your soil, water heavily to flush it out.
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