SOIL MOISTURE MODELING FOR OPTIMAL PLACEMENT OF DRIP LINE.

Soil water content and understanding water dynamics is crucial for agricultural practice. Direct measurements of the soil moisture are being slowly replaced by the mathematical simulations and models. One of the most used models for the simulation of the soil moisture is the HYDRUS 1D model, which simulates how the water is transported through or within the soil profile. The soil water model HYDRUS can simulate water movement through a porous media during transient (irrigation) and steady state (between irrigations) conditions. Incorporating defined initial and boundary conditions as well as soil profile and soil hydraulic properties into the model enables HYDRUS to predict movement and location of water in unsaturated soil profile by solving the Richards equation. Subsurface drip irrigation systems, compared to other irrigation systems, enhance the delivery of water and nutrients directly into the root zone. However, in light-textured soils, certain quantities of water may leak out below the root zone due to the subsurface position of drip lines and/or poor management of irrigation systems. Our initial effort was therefore to create a model in which we would subsequently verify the location of the underwater drip irrigation in the given soil profile. The next step was to verify the equilibrium state during a simulated event (water pulse), the task was to verify predictions with the expected and real results that correspond to the measured data. Though this process still requiring further validation, these results suggest that it may be possible to engineer more water efficient and also to more effective irrigation scheduling, which when combined can increase water retention and subsequent crop water use efficiency. [ABSTRACT FROM AUTHOR]