Incremental Surface Flooding to Optimize Leaching Efficiency – A Numerical Analysis.

Soil salinity is central global problem, worldwide affecting over 1,000 million hectares and limiting crop productivity in more than 100 countries. Salts are commonly leached from the root zone by flood irrigation and collection of drainage water with equally spaced tile drains. Experimental and theoretical evidence indicates that surface flooding increases infiltration rates thereby rapidly flushing salts from areas directly above the drains. However, the salt leaching efficiency from areas between tile drains is limited, which necessitates the application of considerable quantities of irrigation water for provision of a stress-free plant growth environment. To increase leaching and water use efficiencies, which are of crucial importance for sustainable management of water resources in arid environments, we conducted a numerical modeling study to evaluate and optimize partial sequential flood irrigation strategy. We applied HYDRUS to model water flux densities, streamline patterns and solute transport under varying boundary conditions to optimize partial sequential surface flood irrigation for leaching efficiency and water use. Simulation results will be compared to laboratory leaching experiments and potentially efficient farm-scale salt leaching strategies will be discussed.