THE EFFECT OF 2 FORMS OF NITROGEN-FERTILIZER APPLIED NEAR ANTHESIS ON THE GRAIN QUALITY OF IRRIGATED WHEAT

In 1976, the feasibility of using nitrogen (N) fertiliser to raise the protein levels of irrigated wheat was investigated using 3 rates of fertiliser (0, 40 and 80 kg N/ha) applied either at anthesis or 3 days later to the soil surface (ammonium nitrate), or as a foliar spray (urea). Each 40 kg/ha increment in N applied as ammonium nitrate or urea produced a 1.1% increase in grain protein. Ammonium nitrate produced significantly (P < 0.01) higher protein levels than urea. The relationships between grain protein level and several grain quality criteria (farinograph absorption, extensibility, loaf volume, bake score) were examined to determine whether protein quality was maintained when protein levels were increased by late application of N fertiliser. All the criteria examined indicate that protein quality was maintained. Although it is possible to raise protein levels with N fertiliser, large price premiums for high protein would be necessary to make the practice economic.