Model of crop growth, water flow, and solute transport in layered soil

Agro-ecohydrological models are essential for managing scarce water resources and ensuring crop productivity. Here, a one-dimensional agro-ecohydrological model, LAWSTAC, capable of simulating water and solute transport in layered soil coupled with crop growth, is presented and validated. LAWSTAC considers eight hydraulic conductivity discretization methods to address the nonlinearity of Richards equation for soil water flow. LAWSTAC includes two root water uptake models and a flexible root distribution model for reliable transpiration simulation. Simulation of infiltration in layered soil demonstrated that the methods of arithmetic mean, geometric mean and triadic mean performed well among the eight discretization methods. The model was further verified by comparison with results from two widely used models, HYDRUS-1D and SWAP, based on the measured data in a spring wheat field for 2007 and 2008 in the Northwest China. The models produced similar results for flow in layered soil, although SWAP showed some instability in the salinity dynamics. LAWSTAC models crop growth with a more efficient parameterization than SWAP. In conclusion, LAWSTAC is suitable for simulating soil water and salinity dynamics, crop growth and their interactions.