A field experiment was conducted over two successive seasons of 2017 and 2018 in Egypt. The aim was to study the effect of irrigation systems (surface and subsurface drip irrigation) and irrigation amounts (100%, 80%, and 60% of crop evapotranspiration, ETc) on the yield of bean crop (Phaseolus vulgaris) and evaluate the SALTMED model performance on simulation of soil moisture, total dry matter, and yield. Despite the highest yield values being achieved with the 100% of ETc treatment, there were no significant differences between the 100% and 80%. This means a water saving of 20% can be achieved without significantly compromising the yield. Yield and water productivity under subsurface irrigation was slightly higher than under surface drip irrigation. This is because under subsurface drip irrigation, there is no wetted surface area contributing to evaporation losses as is the case for surface drip. In addition, the soil moisture under subsurface drip is kept within the root zone for the longest possible time without subjecting the crop to water stress. The SALTMED model accurately simulated soil moisture, total dry matter, yield, and water productivity. Hence, the model could be applied as crop, water, and land management tool under current and future Egyptian climatic conditions.

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Due to rising food demand and the limitation of water resources, achieving water security is essential. The lettuce crop is affected when grown under limited water supplies as it produces small heads, especially during the late growing stage. For this reason, it is important to maximize water use efficiency and crop productivity. Two successive experiments were conducted during 2021 and 2022 to reduce losses via deep percolation using a geotextile layer at different soil depths under different irrigation levels of the lettuce crop (Lactuca sativa L. var. capitata). This study aims to reduce water losses due to deep percolation and improve crop growth and yield parameters for iceberg lettuce under subsurface drip irrigation in sandy loam soil conditions. In order to achieve these aims, different amounts of irrigation (100, 80, and 60% of crop evapotranspiration “ETc”) and a geotextile layer at different soil depths (20, 30, and 40 cm from the soil surface) were used. The results revealed that the use of a geotextile layer with 20 and 30 cm depths significantly improved irrigation application efficiency and noticeably increased soil water content in the root zone. The observed results during both seasons showed that geotextile layers at 20, 30, and 40 cm depths under irrigation of 100% ETc significantly increased vegetative growth characteristics (plant height, head diameter, head circumference, head volume, plant fresh weight, and leaf area) and crop productivity compared to the control (without geotextile). In particular, the geotextile layer at a 30 cm depth under irrigation of 100% of ETc was the most statistically effective treatment in this study, with yield values of 69.3 and 67.5 t ha−1 in the two seasons, respectively. However, the treatments of geotextile layers at 20 and 30 cm depths under irrigation of 80% of ETc also recorded statistically effective results for crop growth parameters and yield in this study. In general, geotextiles can be used at different depths as an irrigation management practice to reduce deep percolation in the field.

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