Tighter industrial emission laws have gradually cut the amount of sulfur released into the atmosphere in recent years, and combined with a growing trend for non-sulfur based fertilizers, is causing sulfur deficiency in many crops planted in lighter, sandier soils in the Southeast.

Sufur deficiencies began showing up sporadically across the Southeast early this year in corn.

Though often confused with nitrogen deficiency, lack of sulfur in the soil causes more pronounced yellowing of young corn leaves, primarily because sulfur doesn’t translocate in the corn plant as readily as does nitrogen.

Other symptoms of sulfur deficiency include delayed maturity, stunting of plants and interveinal chlorosis.

Sulfur deficiency is most likely to occur on sandy soils, on soils with low organic matter or on cold, wet soils — all of which are very common any year in the Southeast, but especially so this year in the Upper Southeast.

Most growers in the Southeast are well aware of the need for nitrogen fertilizers in non-legume crops, but few are aware that without sulfur nitrogen is of little value.

Both nitrogen and sulfur are building blocks for for protein. A shortage of either N or S results in shortages of chlorophyll rubisco — the enzyme that converts carbon dioxide to sugar and nitrate reductase, which converts plant nitrate into ammonium.

Yield losses from sulfur deficiency, especially in corn, can be catastrophic, if the problem isn’t addressed quickly.

Research has shown that for each day sulfur is deficient, past the first 21 days after corn emerges from the soil, there is a loss of 1-2 bushels per day.

If sulfur is deficient when corn is in the silking stage, yields could be reduced by as much as 75 percent.

From 1985 until 2005 changes in sulfur emission management, primarily due to the Federal Clean Air Act, have significantly reduced the amount of sulfur released into the atmosphere. While a good thing for the environment in general, these stricter laws have created some severe shortages of sulfur for farmers already struggling to grow crops on marginal lands.