Less sulfur in rain
Sulfur deposits on farm fields have decreased over the years, in part as a result of emission-reducing technologies used at coal-fired power plants. There is less sulfur in the atmosphere and in rain that hits farm fields. The maps compare deposits in 2008 versus 1985.
There is no simple test for determining sulfur deficiency on individual farms, says Warren Dick, a researcher and professor in Environmental and Natural Resources at Ohio State University. Researchers have found, however, that certain factors can increase the likelihood of seeing a response to sulfur.
Soil type, cropping history and the crop planted can help determine on which acres farmers should try using sulfur. Soils with low organic matter are a good place to start as mineralization from organic materials is one of the leading sources of soil sulfur.2
“Soils with low organic matter, such as coarse texture (sandy) soils or eroded soils likely found on sloping hills, are more likely to be low in sulfur and respond to sulfur applications,” Fernandez says.
Sulfur is an essential ingredient for creating proteins, so high-protein crops (alfalfa, canola, soybean, corn silage) require more sulfur than low-protein producing crops.3 A lack of sulfur can impact nitrogen (N) utilization and yield.
Estimates vary, but roughly 1 lb. of sulfur is needed to be applied to balance up to 16 lbs. of applied N for a corn plant to produce proteins and grow2, 3 “If there’s adequate N but deficient sulfur the plant won’t grow to its potential until it has the sulfur to balance that N,” says Ron Chamberlain, GYPSOIL founder and chief agronomist. “Deficiencies are particularly critical in early growth corn because that’s when yield potential is set. If the upper soil profile, where seedlings are growing, is deficient of sulfur there will be less yield potential.”
Sulfur can be recycled back into the soil system through crop residue, Dick says, but in crops such as corn and alfalfa much of the protein – and sulfur – is removed with harvest.
“A 250-bu. corn crop removes quite a bit of sulfur every year without replacing it,” Dick says. “The same is true of hay fields. A lot of nutrients are removed when hay is cut and taken from the field, making alfalfa fields and mixed hay pastures good places to try sulfur applications.”