EFFECTS OF NITROGEN ON THE PROTEIN CONTENT OF BARLEY

Abstract

Soil NO 3 -N to 30 cm plus added fertilizer N accounted for approximately half of the variance associated with %N and total N in Galt barley and one third of that associated with barley yield. Variance explained by regression was similar for both 30- and 60-cm soil depths and for each of these depths was greater than for the 15-cm depth. Barley yield and total N in grain increased quadratically with increasing soil plus fertilizer NO 3 -N, whereas %N increased linearly. The change in %N with added increments of fertilizer N was dependent on the amount of soil NO 3 -N to 30 cm. Below a level of 20 kg/ha, %N remained constant or decreased slightly with the addition of 34 or 67 kg fertilizer N/ha and then increased with additional increments. At levels between 20 and 99 kg NO 3 -N/ha, %N in the grain generally increased with each added increment of fertilizer N whereas at soil levels of 133–314 kg NO 3 -N/ha, %N did not change or increased very slightly with increasing fertilizer N.