Optimized selection of clean nitrogen fertilizers for high-sediment water pressure-compensating drip irrigation systems based on system failure perspective

High-sediment water pressure-compensating drip irrigation (PCDI) has become a widely adopted technique for perennial crops, such as mountain fruit trees, in response to agricultural irrigation water shortages. However, the long-term reliability of pressure-compensating emitters (PCEs) remains a major concern, as emitter failure leads to frequent system malfunctions, increased maintenance costs, and hinders progress toward sustainable and clean agricultural production. Despite its practical importance, the mechanisms of PCES failure under high-sediment water and fertigation conditions remain insufficiently understood. This study investigated the effects of three commonly used nitrogen fertilizers—ammonium sulfate, calcium nitrate, and urea—on emitter clogging and diaphragm degradation in PCDI systems operating under high-sediment water conditions. Over long-term operation, the relative average discharge (Dra) showed significant variation across fertilizer treatments. Urea and ammonium sulfate mitigated emitter failure, increasing Dra by 0.42 %–20.91 % and 0.12 %–51.20 %, respectively. In contrast, calcium nitrate markedly accelerated failure, with Dra decreasing by 6.21 %–91.63 %. The fertilizers also significantly affected the dry mass and mineral composition of clogging materials and the mechanical properties of the PCES diaphragm. Urea resulted in the least structural and performance degradation, while calcium nitrate induced the most severe impacts. Structural equation modeling indicated that emitter performance decline was primarily driven by clogging material accumulation (standardized path coefficient β = –0.83) and diaphragm mechanical deterioration (β = 0.59). Moreover, clogging materials indirectly exacerbated performance loss by altering diaphragm properties. Considering both physical clogging and diaphragm stability, urea is recommended as the preferred nitrogen source in PCDI systems to enhance emitter longevity, reduce maintenance demands, and support sustainable irrigation practices. These findings provide a scientific basis for fertigation strategy optimization and cleaner agricultural production in sediment-laden water environments.