Supplement with Sulfur?

Consider supplementing your wheat nutrient plan with sulfur, which can influence yield and protein. Similar to nitrogen, sulfur is a soil-mobile nutrient, and its deficiency can impact a wheat crop, particularly on hilltops and in soils that are sandy or have low organic matter.

Sulfur may not be included in a common soil test analysis, and even when it is, readings may not be very accurate in evaluating the real availability of this nutrient, says Dave Franzen, NDSU extension soil scientist. While sulfur can pollute the air and water (acid rain) it is a soil nutrient that aids in crop development. Thus, ironically, while environmental restrictions limiting sulfur dioxide as a pollutant have helped protect the air and water, soils have become more prone to sulfur deficiencies.

Honeywell Nylon Inc, which markets the ammonium sulfate product Sulf-N, points out on its web site (www.sulfn.com) that “plants use sulfur to produce chlorophyll, the compound that gives them their healthy green color. In addition, sulfur works closely with nitrogen to build protein and maximize yield.” Further, the company says that while sulfur fertilizers come in many forms, sulfate is the only form that crop roots can absorb.  A common liquid fertilizer form of this nutrient is ammonium thiosulfate.

Canola is by far and away the most sensitive crop to a sulfur deficiency.  “You can go from a 2,000 lb yield potential to 100 lbs, just with a lack of sulfur.  It’s really quite amazing,” says Franzen. Sulfur needs to be applied at planting; in-season applications appear to be subject to the same risks of rainfall timing as post applied N.

Research near Fertile, Minn. in the early 1990s indicated a yield response with sulfer in spring wheat grown on sandy soils, but not on heavy soils, according to George Rehm, U of M extension soil scientist. There is little research on how much sulfur impacts wheat protein, but Rehm says there is likely to be a correlation, since sulfur is a component of three amino acids which, in turn, are part of grain protein. Rehm says the U of M is hoping to learn more about the role of sulfur and micronutrients on wheat development, including protein, in a study beginning this summer.

Producers are encouraged to consult with their local agronomists and ag retailers about the availability and use of sulfate products in wheat and other crops.

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2005 USDA Outlook Info on the Web
The early outlook for the three major field crops (wheat, corn, soybeans) in 2005 is shaped by large domestic supplies, lower prices (to be offset in part by higher farm program payments), and strong world competition, according to USDA, in its initial baseline production projections for 2005/06. The projections, released at the USDA’s annual Ag Outlook Forum, assume normal weather conditions for spring planting and summer crop development. Read (and watch, via recorded webcasts) market and ag trends presented during the Forum, online at www.usda.gov/oce/forum .