Common ragweed is one of the most dangerous weed species in Europe and especially in Hungary. The reason of wide spreading is very good adaptability to environmental factors. Ambrosia artemisiifolia can be found on all soil types, but it multitudinous on brown forest soil and loose sandy soil. Biomass production and seed yield of plants are influenced by nutrient supply, first of all by the nitrogen nutrition. Common ragweed is known as a nitrofil weed. We had no data's about growth and biomass production of common ragweed influenced by nitrogen forms. The aim of our pot experiment was to study the effect of soil type and different nitrogen fertilizers -péti-salt, ammonium-nitrate and carbamide -on early growth of Ambrosia artemisiifolia. The experiment was set up on meadow soil, sandy soil with acidic pH and Ramann type brown forest soil. We also had control pots without fertilization on all three soil types. Plants grew poorly on settled meadow soil, fresh mass of ten plants was 5,06 g without fertilizers, while on sandy soil was 13,17 g, and on Ramann-brown forest soil was 10,39 g. Height, leaf area and dry mass of plants also staid behind plants grown on other soil types. Nitrogen treatments increased fresh mass, it was significant in ammonium-nitrate (15,36 g) and carbamide (16,6 g) treatments on sandy soil. Nitrogen forms influenced the examined parameters differently on all three soil types.