Bread‐Making Wheat and Soil Nitrate as Affected by Nitrogen Fertilization in Irrigated Mediterranean Conditions

Mediterranean areas are suitable for the production of high quality bread‐making wheat ( Triticum aestivum L.) because of the high temperatures during grain filling. Wheat quality is also influenced by variety and can be enhanced through the use of N fertilizer. However, N fertilization can increase residual soil NO − 3 after harvest. The purpose of this study was to evaluate the effect of supplemental topdressed N fertilizer on quality and production of high quality bread‐making wheat and on residual soil NO − 3 under irrigated Mediterranean conditions. Field experiments were conducted at two sites during two growing seasons on Calcixeroclic Xerochrept soils of the Ebro Valley (Spain). Five N treatments (100, 200, and 300 kg N ha −1 applied at the end of tillering and 150 or 250 kg N ha −1 at the end of tillering plus 50 kg ha −1 foliar‐applied N at the end of the boot stage) were imposed on two cultivars. Topdressed N increased yields, when increasing from 100 kg N ha −1 to higher rates only, in soils with low residual NO − 3 However, N fertilization increased grain protein contents for all locations and years and bread quality parameters but with a greater effect in soils with low soil NO − 3 Residual soil NO − 3 after harvest increased little with increasing N rates. Grain protein, yield, and quality varied depending mainly on the year and amount of precipitation during grain filling. A topdress N rate of 200 kg N ha −1 would be the most appropriate way to produce high quality bread‐making wheat and minimize the risk of NO − 3 leaching.