The distribution of nitrogen in the soil in different chemical associations is a resultant of action of many factors of which three deserve mention: plants, nitrogen fertilization and sprinkling. The main objective of this research project was to analyze the impact of these factors, acting separately as well as jointly, in conditions of long-term plant cultivation without cereals, on the content of individual soil nitrogen forms. Sequential nitrogen determination of soil nitrogen forms was applied in the experiments which allowed identification of mineral nitrogen as well as its easily-, poorly-hydrolyzed and non hydrolysable forms It was found that sprinkling exerted the strongest, significant influence on the concentration of all examined nitrogen forms with the exception of the easily hydrolysable nitrogen fraction. This impact was also noticeable in the interaction with nitrogen doses, primarily in the content of mineral nitrogen forms and easily hydrolysable nitrogen. Irrespective of the experimental treatment, no significant effect of nitrogen applied in different doses on the examined forms of the component was recorded. On the other hand, the percentage proportion of nitrogen forms in total nitrogen depended significantly, primarily, on sprinkling irrigation and only in relation to mineral nitrogen forms.
