Effects of saline water with different concentrations of calcium and magnesium ions on emitter clogging in drip irrigation integrated water-fertilizer system

The application of saline water in drip irrigation is severely constrained due to its high salt content, which causes precipitation and emitter clogging. Therefore, the effects of calcium and magnesium ions at 100, 150 and 200 mg/L in saline water coupled with humic acid nitrogen fertilizer on emitter clogging were studied. Compared with ground saline water, all treatments significantly increased the emitter clogging risk. In the calcium and magnesium ion treatment groups, clogging fouling increased by 23.94-58.35 and 14.55-51.21 mg/cm(2), the discharge variation ratio (Dra) decreased by 22%-59% and 14%-49%, and the Christiansen coefficient of uniformity (CU) decreased by 29%-79% and 15%-74%, respectively. Higher ion concentrations caused more clogging. Saline water with a high calcium content caused more clogging. Under similar concentration conditions, the Dra and CU in high magnesium saline water were 9%-32% and 8%-51% higher, respectively. In addition, the increase in magnesium ion concentration changed the crystal form of carbonate, slowed the formation rate of precipitated dirt and significantly reduced the carbonate content by 19%-40%. Our results provide support for the popularization of saline water drip irrigation systems.