by Jochum Wiersma and Albert Sims
Interest in improving grain protein in hard red spring wheat (HRSW) with in-season applications of nitrogen (N) fertilizer usually peaks following years with large grain protein
discounts/premiums. The current price outlook of N fertilizer and the desire to reduce overall fertilizer input costs indicates that in-season applications of nitrogen warrants some review.
There is an intuitive appeal to split apply N (N applied preplant and more N applied during the growing season) in HRSW since the crop takes up the majority of its N between jointing and flag leaf emergence. The practice of splitting the total N fertilizer gift in three or even four separate applications is commonplace in winter cereal production in the maritime regions of Europe, including the countries of Denmark, the Netherlands, the United Kingdom, and France. The objective of split N applications is to supply N when the crop needs it, improve N use efficiency, and consequently achieve maximum grain yield and/or grain protein with fewer N fertilizer inputs.