A farmer recently asked me about the use of elemental sulfur (i.e. Sulfur 90) for crop nutrition. I answered the question with a question of my own-Why were they considering using that product?

Their answer included less cost (questionable) and higher concentration of sulfur (true), along with better agronomic benefits (what???). There was a definite opportunity to provide basic agronomic education, regarding a) what can plants utilize, b) what else is present in the material and do we need it, and c) what other effects does the material have.

Sulfur is taken up by plants only in the sulfate (SO4) form, through the roots. Elemental sulfur must be oxidized in the soil to SO4 before it can be taken up by the plant. The time it takes for this conversion depends on the weather, the soil, and the product used. A great reference is found on the Back To Basics website, www.back-to-basics.net/agrifacts/pdf/b2b29a.pdf and www.back-to-basics.net/agrifacts/pdf/b2b29b.pdf. These 2 articles talk about the differences between sulfate and elemental forms, along with the conditions necessary for the conversion to sulfate.

Elemental sulfur has a place in crop production. It also has some drawbacks including being a very acidic product, and taking a long time before it is plant available.

If you need a plant available sulfur source, you need the sulfate form (calcium sulfate, potassium sulfate, ammonium sulfate). Make sure you understand all of the details about elemental sulfur, before making it part of your crop nutrition program.