Long-term analysis of soil water regime and nitrate dynamics at agricultural experimental site: Field-scale monitoring and numerical modeling using HYDRUS-1D

Intensive agricultural practices increase agrochemical pollution, particularly nitrogen (N) based fertilizers, which present an environmental risk. This study aims to evaluate long-term (2009–2020) data on soil water regime and nitrate dynamics at experimental site fine-textured soils better understand the implications of N management in relation groundwater pollution. The field is located Biđ (eastern Croatia), proximity Sava river. Zero-tension lysimeters were installed six selected locations. Lysimeters used monitor regime, i.e., outflows concentration was measured, while additional soil-water samples collected via 4 15-meter-deep monitoring wells. Soil hydraulic parameters estimated by combining laboratory measurements, estimation RETC software. Water leaching simulated using HYDRUS-1D for each year allow crop rotation their effects individually. model successfully reproduced lysimeter dynamics, confirmed with high R2 values (water: 93% above 0.7, nitrate: 73% 0.7) indicating good performance simulating nitrification chain reactions. Principal component analysis (PCA) performed identify relationships among all properties characteristics. results showed complex interaction properties, precipitation patterns, plant uptake, application. All locations have a decreasing trend over investigation period. Most elevated concentrations connected wet period when saturated, evapotranspiration low. this show that it important optimize fertilizer applications particular condition reduce loss. indicates importance studies, key agro-hydrological modeling improvement practices.