What is in this article?:
- Sulfur deficiency cutting yields in sandy Southeast soils
- National statistics
- Several factors involved
• 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.
NORTH CAROLINA STATE University Soil Scientist Carl Crozier says sulfur deficiencies are likely to increase in the future.
By 2011 over half the states in the U.S. had reported some level of sulfur defiency.
A study on corn by Iowa State University showed increased corn yields 82 percent of the time, when sulfur was applied to the soils. If this is true in the heavier soils of the Midwest, with high levels or organic matter, it is likely to create a greater response on lighter soils more common in the Southeast.
Though sulfur deficiency isn’t typically associated with cotton, recent studies at the University of Tennessee indicate it may be a factor in reduced yields in fields with low sulfur and/or heavy hardpans that make it difficult for sulfur to move through the soil.
Several factors that influence cotton yield were negatively impacted by low sulfur in the University of Tennessee study. Sulfur deficiency reduced seed cotton weight per boll and per plant, averaged over the 3 years.
Sulfur deficient plants usually produced fewer bolls per plant,with a greater proportion of bolls at first-position fruiting sites. Sulfur deficiency also reduced locules per boll on a 3-year average in the tests conducted by Xinhua Yin and Chris Main at the University of Tennessee.
In corn, North Carolina State University Soil Scientist Carl Crozier has studied the impact of sulfur deficiency on corn for a number of years.
He saysin addition to restricted amounts of sulfur available from the atmosphere, several weather-related and biological factors have resulted in the increasing number of cases where sulfur is being diagnosed as deficient or limiting in young corn plants in North Carolina.
First, extended periods of frequent and intense rainfall events cause rapid leaching of sulfur from the soil. Since sulfur is a mobile nutrient and is water soluble, this sulfur in the upper soil profile (top 2- 4 inches) has been leached into the lower rooting zone.
Sulfur will typically accumulate in the subsoil horizon at a depth where clay content increases, which may be within 6 inches, but could be 18 or more inches below the surface in many of the sandy Coastal Plain soils.
Producers should study soil profiles from their fields to see if crop roots are likely to reach this zone. The reduction in sulfur emissions brought about by the clean air act means these same rainfall events are not replacing the sulfur leached, Crozier explains.
The second key factor is the size of the root system.
Following germination, the radicle emerges from the corn seed and is the primary root system for the first two weeks after emergence. However, as the corn plant develops the radicle deteriorates and is replaced by seminal roots coming off of the first node of the corn plant.
These seminal roots are initially very shallow (one half inch or less) and then grow deeper over time. Therefore, during the period when the plant switches from the radicle to the seminal root the lack of nutrients in the upper 2- 4 inches becomes a severe problem.