Comparative study towards the effect of different irrigation methods on old lands in Egypt

Given the escalating challenges of water scarcity and climate change, enhancing water productivity is crucial for achieving water security, particularly in arid regions with finite water resources. This study assesses the impact of three distinct irrigation systems on wheat yield, water productivity, and soil water–salinity dynamics in the heavy clay soils of the Nile Valley, Egypt, representing typical old lands. The irrigation systems evaluated included traditional border surface irrigation (IrS1), improved surface irrigation using raised beds (IrS2), and surface drip irrigation (IrS3). A combined experimental and numerical modeling approach was implemented over two consecutive growing seasons (2022/2023 and 2023/2024). Field experiments were complemented by numerical simulations using the HYDRUS-2D model, which was calibrated and validated against measured soil water content and soil water electrical conductivity data to simulate soil water movement and salinity distribution under different irrigation scenarios. Compared to traditional surface irrigation (IrS1), improved surface irrigation (IrS2) reduced applied irrigation water by 19%, increased wheat grain yield by 5.3%, and enhanced water productivity by 30%. Surface drip irrigation (IrS3) achieved greater water savings of approximately 42%, resulted in an 8% increase in grain yield, and improved water productivity by 87%. Simulation results indicated that raised-bed systems effectively maintained higher soil moisture and mitigated salinity stress, while optimized drip irrigation configurations demonstrated superior performance in water distribution and salinity control. Overall, both improved surface irrigation and drip irrigation significantly enhanced water productivity and reduced soil salinity in old lands. However, appropriate system design and management are vital to ensure long-term sustainability and prevent salt accumulation in deeper soil layers.