This paper aims to study the factors leading to eutrophication in Calarasi county and then in the Danube, due to the fact that this county has many cultivated areas. In this regard, many factors that lead to nitrate pollution, especially from agricultural sources have been taken into account. In order to model soil nitrate nitrogen in Calarasi county, which can be partially used by plants or leached, researches on soil with the largest share of the county, a chernozem, were made. This study tried to model in the laboratory the influence of three factors on which groundwater pollution by nitric oxide depends: soil type, environmental conditions (temperature and humidity) and the amount of mineral fertilizers incorporated. The amount of nitrate increased with dose of nitrogen fertilizer, the maximum temperature was 200C and was favourably influenced by humidity of 70-80% of field capacity.