Two-Dimensional Analysis of Nitrate Nitrogen Movement under Drip Irrigation

The objective of this paper was to clarify the temporal and spatial two-dimensional variations of volu- metric water content and NO3-N concentration in soil under drip irrigation. A numerical model was used for estimating temporal and spatial movements of water and NO3-N in soil. Laboratory experiments were con- ducted to estimate the physical properties such as soil water retentivity and conductivity. A field observa- tion was conducted to evaluate the model accuracy. The temporal and spatial changes of volumetric water content and NO3-N concentration in soil were measured in a 1 m× 1m ×1 m lysimeter where NH4NO3 solu- tion was supplied in a row. The results of simulation calculated by the model agreed well with observed data. By using the model, temporal and spatial variations of soil water content and NO3-N concentration were calculated. The results described simultaneous movements of water and NO3-N spreading in a soil profile. The numerical model introduced here can be effective to estimate variations of water and NO3-N in soil.