Abstract
The growing demand for irrigated crops, coupled with water scarcity and climate change, has made the adoption of efficient irrigation systems and water-saving strategies essential. However, concerns remain regarding the long-term effects of localized soil wetting and deficit irrigation (DI) on soil health and crop productivity, particularly in clayey soils. In that concern, a three-season study was conducted on citrus trees in clayey soils at the Faculty of Agriculture farm, Benha University, Egypt, to evaluate the application effects of surface (FDI) and subsurface drip irrigation (SDI) systems, with and without deficit irrigation, on soil properties and crop yield, compared to traditional flood irrigation (FI). Treatments was conducted as Deficit surface drip irrigation (DFDI), Deficit sub-surface drip irrigation (DSDI), full surface drip irrigation (FFDI) and full sub-surface drip irrigation (FSDI). Under full water requirements (FWR), FSDI outperformed FFDI and FI in terms of water savings (31.58%), water use efficiency (WUE) (58.87%), nutrient uptake (N-P-K) (2.44, 10.52, and 5.69%, respectively), and yield (8.70%), with the lowest rates of deterioration over time. In contrast flood irrigation, despite its higher water consumption, it maintained lower levels of root-zone salinity, alkalinity, and sodicity. Under deficit irrigation (DI), DSDI achieved the highest water savings (48.68%), followed by DFDI at 45.82%. However, applying DI caused the highest deterioration rates over time under both irrigation systems for all studied parameters.