EVALUATION OF NITROGEN FERTILIZATION EFFECT ON THE CONTENT AND ACCUMULATION OF PHOSPHORUS IN YELLOW LUPINE IN SOIL CONDITIONS WITH VERY HIGH AVAILABLE FORMS OF THIS ELEMENT

Background. In view of the possibility to ensure the crop's demand for phosphorus from soils with a high content of available forms of this element, as well as to increase the amount of mobile forms of phosphorus after the effect of nitrogen fertilization, a study was undertaken on the effect of different of nitrogen doses applied into soil on the phosphorus content and accumulation in yellow lupine roots, stems, leaves, flowers, pods and seeds.  Material and methods. In two-years field experiment the influence of development stages (BBCH 65 and BBCH 90) at which harvest was performed as well as nitrogen doses (0, 30, and 120 kg·ha-1) introduced into the soil prior to sowing were the factors under study.The experiment was set up on slightly acid soil with very high concentration of available phosphorus content for plant. Results. A 10.7% higher average content of phosphorus was obtained in the whole mass of lupine harvested during the full maturity stage than during the flowering stage. The phosphorus content in the seeds was more than four times higher than in the roots and stems, more than three times higher in the pods and more than two times higher than in the leaves. Differentiated nitrogen fertilization in the form of mineral fertilizer had no significant effect on the phosphorus content of the seeds or, on average, in the whole mass of lupine. Lupine fertilized with 120 kg·ha-1 N took up more phosphorus in total than it did without nitrogen fertilization and following the application of 30 kg·ha-1 N. The amount of phosphorus accumulated in the biomass harvested at the full maturity stage was two times higher than that in the flowering stage. Conclusion. Irrespective of the applied nitrogen fertilization and non-use of phosphorus fertilization, soil with a high content of P in forms available for plants, ensured appropriate supply of yellow lupine to phosphorus, which is important in the protection of non-renewable resources of phosphorites.