A holistic generic integrated approach for irrigation, crop and field management: 1. The SALTMED model and its calibration using field data from Egypt and Syria

The SALTMED project has been carried out by establishing two field experiments in Egypt and Syria between 2000 and 2002. A salt tolerant variety of tomato (Lycopersicon esculentum) known as Floradade has been tried in the field under different water management strategies from which the data were collected to develop and test the SALTMED model. The statistical design of the field experiment comprised two water application strategies: blended and cyclic, two methods of irrigations: trickle and furrow and six water salinity levels. Each treatment was replicated three times. The SALTMED model has been calibrated using the drip irrigation water treatment of 2002 in both Syria and Egypt. The calibration was primarily focused on yield prediction. The irrigation files contained field measurements of flow rate, duration of each irrigation and salinity of irrigation water. Plant parameters such as maximum plant height and rooting depth, length of each growth stage, planting date and harvesting date were based on field measurements and records. Crop coefficients such as Kc, Kcb, Fc were based on () which forms part of the SALTMED built-in crop database. Soil parameters such as the saturated and unsaturated hydraulic conductivity, were largely based on field measurements while the water retention curves were based on laboratory measurements. Initial soil water content and salinity were based on measurements either in laboratory or in the field. Fine tuning of some crop and soil parameters were carried out in order to obtain good calibration, i.e. close agreement between measured and simulated yield. These adjusted parameters successfully predicted the observed yield in both Egypt and Syria. Following successful calibration, the same set of crop parameters such as crop coefficient, Kc, basal crop coefficient, Kcb, fraction cover, Fc, osmotic potential at which the potential water uptake is reduced by 50%, π50, maximum height and maximum rooting depth as well as the calibrated soil parameters were used for model testing in both Egypt and Syria for all seasons. The results are given in part two in this issue.