Soil is an important environment in which nitrogen is transformed. The nitrogen cycle in the soil depends on microorganisms, without them, nitrogen transformation processes cannot occur. They determine the continuity of the circulation of this element in the environment and ensure the renewal of its resources. The presence of microorganisms involved in nitrogen transformation in the soil, their activity and the intensity of the reactions taking place are influenced by many factors, including the type of soil, moisture, oxygenation, pH, vegetation and fertilization.