Nitrogen fertilization of spring barley at the DC 20-23 growth stage
Kovacik, P.(Slovenska polnohospodarska univ. v Nitre (Slovak Republic). Katedra agrochemie a vyzivy rastlin, Tr. A. Hlinku 2, 949 76 Nitra)
The effects of two terms and various rates of nitrogen fertilizers which were applied either at pre-seeding soil preparation or during the growing season on the yield parameters of spring barley were investigated in a field experiment on orthic luvisol with a low supply of Nmin and Cox. The pre-seeding application took account of the Nmjn content of the soil layer of 0.0-0.6 m and the application during the growing season, i.e. at the DC 20-23 growth stage, considered not only the Nmjn content of soil (0.0-0.6 m), but also the N content taken up by barley plants. The said effects of terms and rates of N fertilizers were investigated in combination with sufficient and insufficient phosphorus nutrition. The results showed that with the complete NPK nutrition, nitrogen fertilization during the growing season resulted increased barley grain yield in comparison with pre-seeding nitrogen fertilizing and maintained the appropriate level of quality parameters, although the difference in yield was not statistically significant. Fertilization during the growing season required lower rates of nitrogen fertilizers, these rates being 18.5 kg per ha lower on average. The highest grain yield and reduced cost of fertilizers caused that this treatment produced the highest profit per hectare. Therefore, this calculation method of a rate of nitrogen fertilizer can be recommended, particularly for soils with the low Nmin content or low mineralization potential. Although an increase in the crude protein content of grain after nitrogen fertilizing during the growing season can be small, it is evaluated as positive in the soil where low levels of grain crude protein are obtained. Nitrogen fertilization at the DC 20-23 growth stage also reduced the adverse effect of insufficient phosphorus nutrition on the yield and quality of barley grain.
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