2018 - The year the Sulfur Ran Out

I have written posts on Sulfur in the past, but the past year bears mentioning more than any time date concerning Sulfur.  we saw many fields that were low in sulfur this spring.  It was easy to spot fields needing sulfur even at 55 MPH.  At 55 MPH sulfur deficiency looks a lot like nitrogen deficiency.  If you stop and walk into the field, you will find interveinal chlorosis.  Sulfur is found in all living things and in plants, it is a key to photosynthesis. Sulfur is also needed for the formation of some amino acids and in turn proteins. Sulfur is one of the key nutrients for drought resistance.   

As our air has become cleaner and easier to breathe, less sulfur is deposited from the air for our crops to utilize. We have found that when available sulfur gets down to less than 10 ppm, we are most likely going to have sulfur issues.  On one of our larger clients, I have data as far back as 2007.  Soil test levels have gone from an average of 24 ppm to an average of 6 ppm with no sulfur added. Sulfur is available in the sulfate form.  Sulfate is a negative ion, so it is more mobile in the soil than positive ions.

Because of mobility, sulfur buildup is not necessary. Sulfur fertilizers include, elemental sulfur, gypsum, ammonium sulfate, and ammonium thiosulfate.  Elemental sulfur needs to be converted microbially to the sulfate form, so I recommend higher rates of that material. A 200 bushel corn crop will take up 30 pounds per acre of sulfur.  60 bushel soybeans will remove 20 pounds of sulfur.  Recent research has found response to sulfur in both corn and soybeans, 

Pioneer has a thorough article on sulfur if you want to know more.