SALTMED-2009: A modelling tool for Precision Agriculture
                                                   R. Ragab
Centre for Ecology and Hydrology, CEH, Wallingford, OX10 8BB, UK
                                                  Rag@ceh.ac.uk

SALTMED model has been developed for Precision Agriculture. The model aims at optimization of water and nutrient input to field crops. It is a water and fertilizer management tool that helps in saving fresh water resources and agrochemical application. The model simulates soil water movement under almost all irrigation systems. The model handles, deficit irrigation, drip irrigation, subsurface irrigation, Partial Root Drying (PRD) and Fertigation strategies to optimize water and fertilizers input. The model is physically based. Soil water movement is based on Richard’s equation, solute movement is based on the convection-dispersion equation and evapotranspiration is based on Penman-Monteith equation. In the latter, the surface conductance is estimated by different models including the leaf water potential and Abscisic Acid (ABA) concentration in the root zone. The model is easy and friendly to use. It has an interactive user interface for input and output. The output includes daily evaporation, transpiration, biomass, soil salinity, soil nitrogen, soil moisture, crop water requirements, salinity leaching requirement, nitrate leaching, and final yield. The model has been tested successfully using field data from several European countries e.g. Italy, Greece (Crete) and Serbia, as part of the EU funded Project SAFIR (www.Safir4eu.org). The field observations of tomato and potato were successfully simulated by the model. The model showed that the use of subsurface irrigation either as deficit normal drip irrigation or as PRD, if managed properly, would save substantial amount of water without compromising the final yield.