Effectiveness of Controlled Tile Drainage in Reducing Outflow and Nitrogen at the Scale of the Drainage System

The impact of controlled drainage (CD) on the groundwater table (GWT), outflow, surface runoff, and nitrogen reduction at system scale in Wielkopolska region was analyzed this study. Based field research, mainly by monitoring GWT changes 2019–2020, DRAINMOD model calibrated validated. Hydrological soil water balance simulations were carried out with 36 9 combinations for CD free (FD), respectively. modelling period March-September 10 different dry, wet, normal years from 1961 to 2020. next step use results outflow chemical constituent analyses samples determine NO3-N concentrations calculate pollution loads. As a result simulations, importance timing start retention adopted variants determined, indicating earliest assumed date 1 March. appropriate as well initial has significant effectiveness application reducing volume amount entering open it. under conditions facility makes it possible retain up 22 kg per hectare.