Nitrogen and Water Stress Affect Winter Wheat Yield and Dough Quality

Nitrogen recommendations designed to increase wheat (Triticum aestivum L.) yields may diminish wheat quality. By understanding fertility management impacts on quality, it may be possible to optimize N recommendations to sites and climates. The objective of this study was to quantify the combined and individual impacts of N and water stress on winter wheat grain yield, grain protein, dough quality, and water and N use efficiency. A field experiment using five N rates (ranging from 0 to 1.5 times the current university recommendation) and two water levels (adequate and deficient) was conducted in South Dakota in 2007 and 2008. Dough characteristics were measured using a farinograph. In 2007, soil N mineralization was high (192 kg N ha−1), supplemental water increased grain yield and grain N use efficiency (GNUE) by 25% and reduced yield loss due to N stress from 1141 to 480 kg ha−1, whereas relative to 0 N, the recommended N rate increased water use efficiency by 21% and reduced yield loss due to water stress from 737 to 481 kg ha−1. These benefits were achieved without a loss of dough quality. In 2008, N mineralization was low (99 kg N ha−1), water did not impact GNUE, and the adequate water treatment had lower grain protein (12.5 vs. 13.1 g kg−1) and arrival (3.3 vs. 4.3 min) and peak times (6.1 vs. 7.8 min) than the deficient water treatment. These findings suggest that the implementation of strategically applied N fertilizer may require improved estimates of N mineralization