CHANGES IN NITROGEN AND MAGNESIUM CONTENTS IN PEA UNDER THE EFFECT OF NITROGEN FERTILIZATION
Background. The aim of the conducted research was to determine the changes in nitrogen and magnesium contents in pea (Pisum sativum L.) and in soil under the effect of diversified nitrogen doses, as well as to calculate bioaccumulation factors and to demonstrate the relationships between the studied characteristics.
Material and methods. In a two-year-long field experiment, carried out at the experimental plot of the Siedlce University of Natural Sciences and Humanities, four plots with different fertilization levels were established: 0 (control plot), N1, N2, and N3 (N1 – 10, N2 – 20, and N3 – 30 kg·ha-1). No phosphorus or potassium fertilization was applied because soil richness in assimilable phosphorus was established as very high, and in assimilable potassium as high. In the plant and soil material, total nitrogen content was established with the CHN/S method and total magnesium content with the ICP-AES method. Nitrogen and magnesium bioaccumulation factors and a coefficient of correlation were calculated.
Results. Nitrogen fertilization (10, 20 and 30 kg·ha-1) significantly diversified nitrogen content in seeds, straw, and pod walls of pea (Pisum sativum L.) and magnesium content in seeds and pod walls. Average nitrogen contents in pea were as follows: seeds (37.3) > roots (14.0) > straw (10.6) > pod walls (9.2) g·kg-1 d.m. Magnesium content went in the opposite direction: pod walls (2.97) > straw > (2.20) > roots (1.68) > seeds (1.18) g·kg-1 d.m. Total nitrogen content in the soil varied between 1.96 g·kg-1 and 2.31 g·kg-1 of soil, and total magnesium content between 0.75 g·kg-1 and 0.79 g·kg-1 of soil. Nitrogen and magnesium bioaccumulation factors in the pea biomass were high.
Conclusion. The established nitrogen and magnesium contents in the dry matter of pea were within the limits of partition values that determine the acceptable amounts of those elements in fodder. The applied nitrogen fertilization at the doses of 10-30 kg·ha-1 did not affect negatively the changes in nitrogen and magnesium contents in pea and in the soil.