INFLUENCE OF THE RATE OF NITROGEN-FERTILIZATION ON THE MINERAL-CONTENT OF WINTER-WHEAT IN ONTARIO

The influence of the rate of N fertilization on the mineral content of winter wheat grown in Ontario, Canada, was studied. Treatments were main plots of wheat type, either soft white winter or hard red winter, and subplots of 40, 80, 120, 160, 200, or 240 kg of N ha-1. Grain yield, yield components, nitrogen concentration, and grain ash concentration were determined for each subplot, and the concentrations of K, P, Ca, Mg, Fe, Zn, and Mn in the whole grain were determined for the 40 and 160 kg of N ha-1 treatments. Total ash concentration decreased with increasing N rate in a curvilinear fashion for both wheats and was negatively correlated with grain yield. Increasing the N application rate from 40 to 160 kg of N ha-1 resulted in small, < 10%, decreases in the concentration of P and K but increased the concentrations of Ca, Mg, and Fe. Variation in grain mineral concentration as a result of N management was minor relative to variation in grain mineral concentration between local environments.