EFFECT OF FERTILIZER N ON THE GRAIN-YIELD AND QUALITY OF SPRING MALTING BARLEY GROWN OF 5 CONTRASTING SOILS IN IRELAND

Twenty experiments were carried out in the south-east of Ireland on fi ve intensively cultivated soils with low residual soil N (Index 1) ove r a four-year period (1990-3). Small increments of fertiliser N (12.5k g/ha), ranging from 75kg/ha to 175kg/ha (maximum 137.5kg/ha in 1990), were applied to the cultivar Blenheim in an effort to assess accuratel y the amount of N that could be applied to optimise the yield and qual ity ex-farm of spring-sown malting barley on different soils. Increasi ng increments of fertiliser N, up to a certain level, increased grain yield, but the response varied with season and to a lesser extent with site. There was a gradual and significant increase in grain N with in creasing increments of fertiliser N in all experiments, but there were large seasonal and site differences in the concentrations of grain N recorded. Increasing increments of N also increased the amount of scre enings. Optimum yields of acceptable malting quality (< 17.5g N/kg and < 80g/kg screenings) were obtained, on average, by applying 125kg, 11 2.5kg, 125kg, 100kg and 75kg N/ha, respectively, to the Light gravelly soils at Oak Park, the medium-light sandstone soils at Whitegate, the medium-textured Ferns soils (Clonroche Series), the medium-heavy Knoc kbeg soils (Knockbeg Series) and the heavy Mulhuddart soils (Dunboyne Series), except in 1990 when grain N was seasonally high.