Assessing nitrogen transport through soil layers in weighable lysimeter under climate change scenarios using HYDRUS1D model

Field monitoring is often limited by factors such as time, labor, weather, crop types, and soil properties.To overcome these limitations, process-based modeling can complement field observations.This study evaluated soil moisture dynamics and nitrate-N leaching using data from weighable lysimeters and the one-dimensional HYDRUS-1D model, incorporating future climate scenarios (SSP2-4.5 and SSP5-8.5) to assess potential impacts under projected climate conditions.Model performance was evaluated using the Coefficient of determination (R 2 ), Willmott's index of agreement (d), and the Nash-Sutcliffe efficiency (NSE).HYDRUS-1D showed good agreement between observed and simulated soil water content and nitrate-N concentration.Soil moisture content in loam soils, R ranged from 0.37 to 0.72, d from 0.18 to 0.40, and NSE from 0.13 to 0.59.In sandy loam, values were higher: R from 0.52 to 0.77, d from 0.27 to 0.47, and NSE from 0.39 to 0.67.Nitrate-N concentrations were accurately predicted at all depths in loam and at 30 cm in sandy loam.Short-term simulations (2025 -2054) under Shared Socioeconomic Pathway (SSP) 2-4.5 and Shared Socioeconomic Pathway (SSP) 5-8.5 scenarios showed that soil moisture at 10 and 30 cm depths increased significantly under SSP5-8.5 due to greater rainfall and evapotranspiration.Nitrate-N concentrations gradually declined compared to 2025.In loam, nitrogen leaching remained relatively low overall, with only a slight increase under SSP5-8.5 compared to SSP2-4.5, particularly during heavy rainfall.In sandy loam, however, nitrogen leaching was consistently higher under SSP5-8.5 and gradually over time.These findings underscore the importance of nitrogen management strategies that respond to climate variability.Integrating field monitoring with modeling offers an effective approach for predicting nitrogen dynamics and supporting sustainable fertilizer use under changing climate conditions.