Impact and control of fertilization on emitter clogging behaviors in drip irrigation systems using high-sediment water

High-sediment water drip irrigation (HSWDI) has the potential to alleviate agricultural water shortage, but it is hampered by emitter clogging. Controlling sediment concentration can alleviate emitter clogging, but optimal sediment concentration under fertilization remains unknown. This 400-h study evaluated the effects of three sediment concentrations (0.5 g L<SUP>-1</SUP>, 1.0 g L<SUP>-1</SUP>, and 1.5 g L<SUP>-1</SUP>) and two fertilization strategies (no-fertilization and ammonium polyphosphate application) on emitter clogging. Results showed that fertilization promoted sediment flocculation, reduced the sediment discharge capacity of the emitter, reduced the sediment discharge rate by 6.2% on average, and increased the median diameter of inner sediment by 14.3%, thereby increasing emitter clogging. Specifically, at a sediment concentration of 0.5 g L-1, the relative flow rate (Dra) of the emitters following fertilization decreased by only 7.1% compared with no-fertilization group, while at 1.0 g L-1 and 1.5 g L-1, the Dra decreased by 27.3% and 43.9%, respectively. This was mainly due to sediment flocculation, which was promoted under fertilization by increasing sediment concentration. Under no-fertilization treatments, the Dra at the maximum concentration studied was 33.0% lower than the Dra at 0.5 g L-1, compared to a 59.5% reduction under fertilization. These findings show that sediment concentration and fertilization have a strong coupling effect on emitter clogging. Therefore, the sediment concentration needs to be reduced under fertilization in HSWDI. It should be less than 1.0 g L-1 under the application of ammonium polyphosphate. These results contribute to the control of HSWDI emitter clogging, with implications for the application and promotion of HSWDI technology.