Managing nitrogen fertility of irrigated soft white spring wheats for optimum quality

Irrigated wheat growers often choose to apply only part of the crop’s nitrogen fertilizer requirement at planting to avoid over-fertilizing the crop at early stages of growth. Later in the growing season, producers will apply additional nitrogen fertilizer as needed to optimize production. This study evaluated effects of top-dress nitrogen fertilizer application timing and rate on the milling and baking quality of two soft white spring wheat cultivars produced in an irrigated environment when the pre-plant fertility rates were insufficient for optimal crop yield. Top-dress N increased lactic acid solvent retention capacity (SRC), a measure of gluten strength, of the resulting flour by increasing flour protein concentration. Although lactic acid SRC response and the grain yield response to top-dress fertilizer were unaffected by application timing, other quality parameters, including break flour yield, flour ash, and, in the case of the cultivar Alturas, sugar snap cookie diameter, were affected by application timing. Earlier timing of top-dress fertilization minimized the detrimental effects of the fertilizer application on break flour yield and flour ash concentration. Key words: Soft wheat, nitrogen, gluten, flour ash