Sulfur is an essential element for crops but soils are often lacking in levels needed to maximize yields, said Ron Chamberlain, lead agronomist for Gypsoil brand gypsum.
New soil test survey results from the International Plant Nutrition Institute (IPNI) indicate sulfur deficiencies are found in soil tests across many Midwestern states. In Wisconsin, for example, 81% of soil tests studied in IPNI’s 2015 survey were found to be low in sulfur. 1
“Corn, soybeans and alfalfa need sulfur to grow and to develop to their genetic potential,” Chamberlain said. “For every 10 pounds of nitrogen that a corn crop needs, it also needs a pound of sulfur. You want seedlings to have readily available sulfate sulfur in the soil profile order to eliminate the stress that occurs when it’s deficient. Yellowing in new leaf tissue and stunted growth in alfalfa, corn and soybeans may indicate a sulfur deficiency. In order to build cells, corn needs a sufficient supply of sulfur from emergence thru V6 and beyond when it’s growing rapidly.”
Unfortunately, as the IPNI survey indicates, many farm fields lack the amount of sulfur crops needed for maximum yields. There are several reasons. First and foremost, the Clean Air Act regulations reduced sulfur dioxide emissions from coal-burning power plants, Chamberlain said. Before these regulations went into effect years ago to reduce “acid rain” caused by sulfur dioxide, farm fields received 25-40 pounds of sulfur per acre every year, depending on their location, Chamberlain explained. Also contributing to the decline in sulfur levels in farm fields are low-sulfur fertilizers and high crop yields that draw heavily on levels of sulfur in the soil.
With challenging crops prices, growers are scrutinizing input costs and, understandably, may wonder if applying sulfur really pays off.
“It’s even more important now to maximize bushels and tonnage when prices are low in order to produce the greatest amount of revenue,” Chamberlain said.
Gypsoil is a sulfur source of calcium sulfate dehydrate which contains 16 to 17 percent sulfate sulfur or about 320 to 340 pounds of sulfur per ton.