Coupled Effects of Fertilizer and Sediment on Drip Irrigation Emitter Clogging and Its Implications for Sustainable Water–Fertilizer Management

Improving water–fertilizer use efficiency and maintaining the long-term operational stability of irrigation systems are critical challenges for sustainable agricultural development, particularly in arid and semi-arid regions. However, emitter clogging in drip irrigation systems significantly reduces irrigation uniformity, increases resource waste, and threatens the sustainability of fertigation practices. This study systematically investigated the coupled effects of fertilizer concentration and sediment content on emitter clogging in drip tape systems through a two-factor, three-level full-factorial experiment using emitters with flow rates of 2.0 and 3.0 L h −1 , under sediment contents of 1.0, 2.0, and 3.0 g L −1 and fertilizer concentrations of 0.2, 0.5, and 0.8 g L −1 . The effects of these factors on the relative average flow rate (Dra), coefficient of variation (Cv), and dry weight of clogging material were analyzed. The results showed that emitter performance gradually deteriorated with operating time. At the end of the experiment (144 h), the relative average flow rate (Dra) decreased by 15.75–54.66%, the coefficient of variation (Cv) increased to 0.12–0.55, and the dry weight of clogging material reached 16.85–43.92 mg. Analysis of variance showed that sediment content was the dominant factor, fertilizer concentration acted as an aggravating factor, and their interaction was significant. The clogging material consisted primarily of silicate and carbonate minerals. Quartz and clay minerals were mainly controlled by sediment content, whereas calcite was mainly associated with fertilizer concentration; these components accumulated over time to form composite clogging deposits. Path analysis indicates that sediment directly drives the clogging process by enhancing particle deposition, while fertilizer indirectly exacerbates clogging development by promoting the accumulation of precipitates; the two factors act synergistically to exacerbate clogging development. Prediction results using the random forest model showed high accuracy (R 2 : 0.843–0.951). In summary, the clogging of drip irrigation emitters is driven by both sediment particle deposition and chemical precipitation of fertilizers, with sediment determining the extent of clogging and fertilizers influencing the accumulation characteristics of clogging material. In agricultural practice, controlling sediment input and optimizing fertilizer concentration can reduce emitter clogging risk, improve system stability, and support sustainable drip irrigation by enhancing irrigation uniformity and water–fertilizer use efficiency.