Amaranth is not only of high dietetic (seeds and leaves), but also pro-health, ecological, agricultural, and ornamental quality. The aim of present research was to analyze the influence of cultivar, plant spacing, and diverse NPK fertilization on yielding and Cu, Zn, Fe, and Mn contents in seeds, leaves, and stems of amaranth (Amaranthus cruentus L.). The paper was based on three-year field experiment established by means of randomized sub-blocks (split-plot) in three replicates and included three variable factors: plant cultivar, spacing (two levels each), and NPK fertilization (four levels). Achieved results indicated that applied experimental factors contributed to a substantial differentiation of Amaranthus cruentus yields. Amaranth reacted with a significant increase of yields due to NPK fertilization. The highest yields were produced when fertilizing was applied at the rate of 90 kg N∙ha^-1, 60 kg P∙ha^-1 and 60 kg K∙ha^-1. Use of the highest NPK fertilization (130 kg N∙ha^-1, 70 kg P∙ha^-1, 70 kg K∙ha^-1) was associated with the decrease of the test plant yielding, regardless of the cultivar or plant spacing. In most cases, the experimental factors exerted significant influence on the contents of analyzed microelements in leaves and seeds of amaranth plants. Analysis of partial eta-squared coefficients indicated that the plant cultivar explained the amaranth’s yielding variability to the highest degree, while NPK fertilization – copper, zinc, and iron levels in leaves, and copper and manganese in seeds. Manganese in leaves and zinc in seeds was the best explained by the cultivar of the test plant.

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