By Dave Franzen
NDSU Extension Soil Specialist
Traveling around the eastern part of the state almost half of the corn fields show some signs of S deficiency. The record May rainfall probably had a lot to do with it, as did the nearly non-existent mineralization from last fall’s and this spring’s low moisture conditions, and the continued exodus of organic matter from topsoil wind erosion.
The image was takenssci.franzen.1.S deficient corn yesterday a minute after our Extension news director asked if I had an image of S deficient corn. I drove down the road near Valley City a quarter mile, stepped out of the car and took the picture. It is everywhere. Sulfur deficiency makes sense on sandier soils on hilltops, but its presence in higher clay soils is a new phenomenon that began a few years ago. Last year I had a site that looked like it would die at V5 before we rescued it with a gypsum application in the rain.
To be truly diagnostic, taking a plant sample from a bad area and a good area within the same field and hybrid and having each analyzed for a suite of nutrients including S is best. Don’t bother taking a soil sample. The soil sulfate test is garbage (common tongue for non-diagnostic).
If treatment is necessary, 50 pounds per acre of ammonium sulfate dry over the top with a granular spreader would work, as would applying 3 gallon per acre of ammonium thiosulfate to a stream between the corn rows or through the UAN coulter applicator.