Modeling the Effects of Water and Salinity Stresses On Evapotranspiration and Crop Yield.

Water and salinity are interrelated factors affecting yields in irrigated cropland. The sustainability of crop productivity in California is being severely challenged by the combination of diminishing water supply and rising salinity. It is imperative to continue to refine best management practices to conserve water resources and control soil salinization. This requires understanding the interactions between irrigation, soil salinity, and crop water use. In this research, the effects of matric and osmotic potentials on corn water uptake under the climate conditions of central California are evaluated using the ENVIRON-GRO model, in which water flow is simulated by Richards¡¯ equation with van Genuchten¡¯s hydraulic functions. Plant growth and water uptake are adjusted in response to matric and osmotic stresses. Water uptake compensation from non-stressed layers of the root zone is also considered.  Simulations of 4 irrigation water salinity levels and 4 water application levels are conducted to evaluate water uptake, corn yields and salt distribution in the root zone and to assess the leaching requirement as a result of reduced yield under water and salinity stresses. The ENVIRON-GRO model can be used as a tool for evaluating irrigation management options on crop growth, water use efficiency and soil salinization.