SOIL WATER FLOW AND NITRATE TRANSPORT MODELING USING LYSIMETER DATA

Nitrogen fertilizers are frequently used on agricultural soils in large amounts which cannot be completely absorbed by plants and therefore leaching, which is usually closely linked with the soil water flow, is likely to occur. As computer models are becoming more important in the assessment of groundwater pollution, the objectives of this research were to assess water flow and nitrate transport in gley soils and to validate HYDRUS-1D model based on collected field lysimeter data installed at the Biđ field. The field data was collected at 6 location (12 lysimeters) which included extensive soil physical properties measurement, lysimeter outflow and nitrate concentration, climatic data, cropping rotation and fertilizer application information. The results confirmed good reliability of a model to fit the observed lysimeter water outflow and nitrate dynamics during 2014 – 2016 period. Increased nitrate concentrations were observed mostly during the period without crop or during winter/spring period with a large amount of rainfall. Results indicate that agricultural practices may have a significant role in groundwater nitrate contamination, even in soils with heavier texture. Additionally, tested model can be used as a tool in prevention of groundwater pollution by enabling the optimization of application (amount, timing, type) for different fertilizer.