During the period 2017-2018, a field study with winter barley (Hordeum vulgare L.)
was conducted. The experiment was situated in the experimental field of the base for training
and implementation of the Agricultural University of Plovdiv, Bulgaria. The trial was
conducted by the randomized block design in 4 replications with the winter barley variety
“Emon”. The experiment included unfertilized control and three variants with fertilizer
application that included Urea 125 kg/ha, Urea 165 kg/ha and Urea 250 kg/ha. The fertilization
was performed in late winter - February. With the increasing of the fertilizer rates
the nitrogen content in grain also increased. The highest nitrogen content was reported
after the application of Urea 250 kg/ha – 2,62% average for the period. No influence of
fertilization on the phosphorus content in the grain was found. At all variants, including the
unfertilized control, the content of this macronutrient varied from 0,53% to 0,54% and the
difference between the variants was not statistically proved. With increasing of the fertilizer
rates, the potassium content in grain decreased. The potassium content in barley’s grain
was the highest for the unfertilized control – 0,41% and was the lowest after the application
of Urea 250 kg/ha – 0,32% average for the period. The differences in the potassium content
in grain between the two variants were statistically proved. A positive correlation regarding
the crude protein content in grain was established. With increasing of the urea rates the
grain crude protein content increased. The highest content of crude protein was recorded
after the application of Urea 250 kg/ha – 14,90% average for both experimental years.
Key words: Barley, Content of N, P and K in grain, Fertilization, Urea