Nitrogen fertilization of spring barley at tillering stage

The effect of two terms and various rates of nitrogen fertilizers applied either at pre-seeding soil preparation or during growing season on the yielding parameters of spring barley was investigated in a field experiment located in south-western part of the Slovak Republic (10 km far from Nitra city) on haplic luvisol with a low supply of Nmin and Cox. A pre-seeding application took into account the content of Nmin in the soil layer of 0.0 -0.6 m and an application during growing season at the tillering growth stage (DC 20-23) considered not only the content of Nmin in the soil (0.0 - 0.6 m), but also the content of nitrogen taken up by barley plants. The above stated effect of the terms and rates of N-fertilizers was investigated in combination with sufficient and insufficient phosphorus nutrition. The results have shown that nitrogen fertilization at the growth stage of tillering was economically more effective in the amount considering soil inorganic nitrogen supply as well as nitrogen content of barley plants in comparison with a pre-seeding fertilization. Fertilizing during growing season increased the grain yield statistically significantly when applying lower amounts (approximately by half) of nitrogen. The quality of yield was not influenced significantly. The verified approach to the calculation of the amounts as well as the date of nitrogen fertilizer application can be possibly recommended for the soils with a low content of Nmin and Cox or a low mineralization potential. NPK-fertilization resulted in a higher yield of grain and straw as compared to NK-fertilization, independently on the date of application of nitrogenous fertilizers. Absence of phosphorus nutrition procured a highly significant decrease in grain yield. Deficiency of phosphorous was manifested more significantly in pre-seeding nitrogen fertilization. Nitrogen fertilization during the vegetation period softened the symptoms of phosphorous deficiency. The yield parameters of spring barley were influenced significantly not only by variants of the experiment, but also by seasonality. Nutrition variants determined more significantly the quantitative parameters, while seasonality determined the qualitative parameters of spring barley yield.