Modeling Nitrogen Balance for Pre‑Assessment of Surface and Groundwater Nitrate (NO3‑−N) Contamination from N–Fertilizer Application Loss: a Case of the Bilate Downstream Watershed Cropland

Abstract

Nitrogen is an essential plant nutrient, but in excess amounts in the soil can cause significant water quality problems. Since nitrate is very soluble and is not retained by soil, it easily leaches into groundwater and contaminates it. Therefore, modeling nitrate concentra tion derived from N-fertilizer in the area where the land dominating crop coverage helps to ensure the security of soil and water and also the environmental sustainability actions in the agricultural watershed. Adding N-fertilizer without understanding the concentration of nitrates in the soil and neglecting responsibilities and lacking con cern of excess application of nitrogen N fertilizers on agriculture can cause further problems on groundwa ter resources. In order to evaluate nitrate contamination on surface water and groundwater, estimating partial nitrogen balance (PNB) in crop land is essential. The objective of this study was to model the crop land par tial nitrogen balance (PNB) for pre-assessment of nitrate