Low sulfur levels affect crops
Kylie Saari — Staff WriterFAIRMONT - Efforts to clean up the air have had an unexpected effect on crop growth, according to Dr. Michael McNeill of Ag Advisory, Ltd, an agriculture consulting company.
Sulfur, a nutrient vital for successful plant production, used to be absorbed directly from the air by crops but reductions in coal and diesel exhaust have dramatically reduced the sulfur available.
McNeill said sulfur is essential for protein synthesis, production of amino acids, necessary for soil microbial activity, and protecting and encouraging appropriate conditions for the rhizosphere, or area located around the plant root.
"Plants use large amounts of sulfur," he said.
McNeill spent Monday morning advising soybean producers how to combat the problem of sulfur deficiency at International Ag Labs' soybean conference.
Jon Frank, partial owner of International Ag Labs, said cleaner air reduces sulfur in the soil as well in the air.
"You have heard of acid rain?" he said. "Sulfur is part of that."
"The sulfur rates are dramatically reduced," McNeill said. "The EPA passed a lot of rules in the industry, and the plants do not necessarily think it is a good thing."
Complicating the matter: Laboratory tests designed to determine the amount of sulfur available to the plants from the soil are not always accurate, he said. The drying process necessary for the tests can produce false high results.
He said observing the plant is a better way to determine if low concentrations of the nutrient are present. Deficiency symptoms include spindly plants, cholorotic plants, uneven crop ripening, slow maturity and poor cold tolerance.
McNeill pointed out that research indicates adding appropriate sulfur to fields can increase soybeans yields by 5 to 20 bushels per acre and corn yields by 5 to 30 bushels per acre.
"I am not against the cleaning of the air," he said. "Super concentration (of sulfur) in the air kills trees and plants. It is OK to clean that out of the air. But it is also OK for me to know that it isn't as available to the plant."
According to McNeill, sulfur is required for vitamin production in the plant, which affects not only the plant, but also the person or animal that consumes the plant.
"Sulfur plays a major role in soil health, plant health, and human health," he said.
He cautions, however, that sulfur should not be added to fields haphazardly and that the best methods for increasing sulfur concentrations vary depending on soil pH and health.
Many fertilizers have added sulfur, and spreading elemental sulfur is an option, although McNeill says it could be nearly three years before elemental sulfur is broken down and usable for the plants.
"This soil is not what your grandfather worked with," McNeill said. "It is not what your father worked with. These soils are really getting low on sulfur and it is having a dramatic impact."
