Effect of Phosphate and Sulfate Application on Wheat Grain Yield and Selenium Content.

The interest in Selenium (Se) has increased over the past few years due to its potential anti-cancer attributes in human health. Wheat (Triticum aestivum) is considered one of the most efficient Se accumulators of the common cereal crops and is one of the most important food sources for humans. Agricultural soils in some regions of western South Dakota have high Se content. There is interest in developing a consistent grain supply of high Se wheat for markets in Europe and Asia. It would be important to document how nutrient management factors influences grain Se content. The objectives of this study were to investigate the optimum management of phosphate (P) and sulfate (S) fertilizer on Se uptake and wheat growth. Field studies were conducted at two locations (Lyman and Tripp County) in central South Dakota. Phosphorus fertilizer was applied with three different methods (band with seed, broadcast after planting, and broadcast in Spring) and six different P rates (0, 1, 1.5, 2.0, 2.5, and 3.0 times the P fertilizer recommendation rates as determined by soil testing). Sulfate was applied at four different rates (0, 100, 200, 400 kg ha^-1) as broadcast topdressing of gypsum at planting. Grain yield was significantly affected by interactions of Location-Method and Method-Rate of P fertilizer. However, grain yield and protein content were not affected by S fertilization. The Se concentration in wheat grain was found to be strongly influenced by parent material. Phosphorus fertilization did not affect Se concentration in the wheat grain.  However, the sulfate application significantly decreased Se concentration in grain.