EFFECT OF SULPHUR FERTILIZATION ON YIELDING AND TOTAL CONTENT OF NITROGEN, NITRATES(V) AND SULPHUR IN WHITE MUSTARD

In 2-year pot experiments the direct and consequent effect of sulphur contained in the new fertilizer: ammonium nitrate sulphate designed for manufacturing, on yielding and the contents of nitrogen and sulphur in white mustard were analyzed. Effectiveness of the new fertilizer was compared with ammonium sulphate and NPK fertilization without sulphur. Two doses of sulphur fertilizers were applied in the 1 st year of the experiment, while in the 2 nd its consequent effect was researched at the identical NPK treatment. Mustard was harvested at flowering stage. In the 1 st year of the experiment increase in mustard yields depended on NPK fertilization without any significant sulphur effect. In the second year the consequent effect of sulphur led to an increase in yields by between 10 and 27 % and the greatest was registered in treatments where the new fertilizer was used. Sulphur fertilization had no significant effect on nitrogen content or the degree of this element utilization from fertilizers. In comparison with NPK treatment application of fertilizers containing sulphur caused a considerable increase in sulphur content in mustard. Fertilization with sulphur caused an increase in nitrate(V) content in mustard shoots in the 1 st year of the experiment, particularly in treatments where a double dose of this element was used. In the 2 nd year of the experiment at absolutely higher N-NO3 content a decline in the level of this nitrogen form was detected in plants under which sulphur was applied. The share of N-NO3 in total nitrogen content in mustard ranged between 1.73 and 7.46 % in the 1 st year of the experiment, whereas it was higher in the second year and ranged from 6.14 to 11.45 %.