The effect of sowing date and nitrogen rate on the grain yield, grain quality and malt analyses of spring malting barley for distilling in Ireland

Abstract

AbstractThe significant expansion of whiskey distillation in Ireland has increased requirements on the Irish malting barley industry to supply spring barley with low grain nitrogen concentration (GNC). Published literature suggests that genetics, soil type and environmental conditions are the predominant drivers controlling production of malting barley with low GNC values. However, it is acknowledged that agronomic practices such as sowing date and nitrogen (N) application are also important factors in determining the grain yield (GY) and grain quality (GQ) of malting barley. The effects of four N fertilizer rates (90, 110, 130 and 150 kg N/ha) and two sowing dates (March and April) on GY and GQ of a two-row spring barley variety (Hordeum vulgare L. cvar Overture) was evaluated at two different sites over a 3-year period (2014–2016). Earlier sowing dates resulted in significantly higher mean GY (7.98 t/ha) compared with later sowing dates (7 t/ha). GY and GNC also increased consistently with greater increments of fertilizer N. Earlier sowing dates also significantly improved several distilling malt quality parameters, such as soluble extract (SE), fermentable extract, predicted spirit yield and fermentability. Later sowing dates increased diastatic power and soluble N. The results of the current study suggest that the likelihood of producing spring malting barley with low GNC values and better malting quality is enhanced through earlier sowing dates on suitable soil types. Earlier sowing dates also facilitated the use of higher fertilizer N rates, enabling high GY potential without crossing the GNC threshold for the distilling market.