Mitigating emitter clogging in drip irrigation systems by optimizing irrigation timing: A comparative study of daytime vs. nighttime irrigation

In arid and semi-arid regions, intense solar radiation during daytime operation causes a sharp rise in irrigation water temperature, which may exacerbate emitter clogging. To address this challenge, we propose rescheduling irrigation from high-temperature daytime periods to cooler nighttime periods as a strategy to mitigate clogging risks. However, the efficacy of irrigation timing optimization for controlling emitter clogging, as well as its underlying mechanisms, remains unknown. To investigate this, a pilot-scale experiment was conducted over a 480 h operational period during the summer irrigation season (May to August) to evaluate the performance of drip irrigation systems under daytime (10:00–16:00) versus nighttime (20:00–02:00) irrigation regimes. Compared with daytime irrigation, nighttime irrigation significantly reduced the dry weight of emitter clogging substances by 34.8–43.1%. After 480 h of operation, the nighttime treatment also showed better hydraulic performance, with discharge ratio variation (DRA) and Christiansen uniformity coefficient (CU) increasing by 11.6–24.5% and 18.8–30.9%, respectively. These improvements were accompanied by reductions in chemical precipitates, particulate fouling, and biological fouling of 33.5–46.1%, 35.5–39.1%, and 36.5–47.8%, respectively. In conclusion, optimizing irrigation timing by shifting from daytime to nighttime effectively controls emitter clogging. These findings propose a cost-effective irrigation water management strategy for mitigating emitter clogging, thereby extending the operational lifespan of drip irrigation systems.