Early prediction of grain protein content to guide nitrogen management in winter milling wheat

With the introduction of high-yielding winter milling wheat varieties, robust recommendations on nitrogen (N) management strategies are required, if optimum protein quality, under various soil and environmental conditions, is to be achieved. As part of its commitment to the Nutrient management guide (RB209), AHDB continually invests in nutrient management research. As there is some uncertainty associated with the N and sulphur (S) recommendations for milling wheat, AHDB has invested in a series of trials (project code: 21140040 / duration: 2018–22) to inform revisions of RB209. Currently, RB209 states that extra N may be economically worthwhile in milling wheat crops to boost the grain protein concentration. Typically, application of an extra 40 kg N/ha could increase grain protein by up to 1%. When it comes to protein, relatively late applied N is influential. Additional N applied during stem extension is associated with an increase in grain protein content, but only a small increase in grain yield. A foliar urea spray during the milky ripe stage is associated with an even larger increase in grain protein content, but no (or very little) increase in grain yield. The application of additional N increases production costs. This investment can be worthwhile, if wheat secures a suitable milling premium. To make informed decisions on the requirement for additional N, farmers need early and robust information on the potential of their crops to hit milling wheat specifications (typically, 13% grain protein).