Summary:

The paper presents the results of the survey of the daily load of total nitrogen outflowed with drainage system and ditches in Lower Silesia.
The volume of daily load shows large seasonal variation. The maximum daily loads were found in object located in the submontane area. These loads amounted for the drainage systems 6,27 kg N  d-1  ha-1 and for the ditches were noted until 12,2 kg N  d-1 ha-1. Significantly lower values were found in the lowland object. In lowland area, risk of polluting the receiver with total nitrogen
effluents from agricultural areas, occurs mainly during early spring. At the object located in the submontane area, which is characterized by greater rainfall, there is a second critical period attributable to the July and August. Load of nitrogen outflowed from submontane catchment during the year was 75,5 kg N  ha-1, while from lowland's catchment outflowed much less nitrogen - 12,7 kg N  ha-1. Con-ducted research and analysis clearly show, that the size of nitrogen load outflowed from catchment is determined, to a large extent, the course of weather conditions, particularly amount of rainfall.