Response of emitter clogging characteristics to fertilizer type and concentration based on fertigation

Drip irrigation technology can directly transport fertilizer and water to the root zone of crops and effectively improve the fertilizer utilization rate, but improper fertilization can lead to emitter blockage, reducing fertilization uniformity and resulting in crop yield loss. This paper tested the clogging performance of common emitters (inlaid cylindrical labyrinth emitter, E1; inlaid patch labyrinth emitter, E2; flanking labyrinth emitter, E3) with urea (UREA), sulfate of potassium (SOP), muriate of potash (MOP), monoammonium phosphate (MAP), and diammonium phosphate (DAP) at different concentrations (0 g/L, 0.4 g/L, 0.8 g/L, 1 g/L, 1.2 g/L, 1.6 g/L). Using field emission scanning electron microscopy (FESEM), surface energy spectrum analysis (EDS), and X-ray diffraction (XRD), the effects of fertilizer type and concentration on blockages and blocked substance accumulation were analyzed in an indoor accelerated irrigation experiment. The results showed that UREA and DAP are sensitive fertilizers for E2 and E3, respectively. With increasing fertilizer concentration, the decrease rate of the relative flow for E3 accelerated, and the Dra and CU of irrigation in E2 decreased with increasing irrigation events. The dry weight of blocked substances increased with the increase in irrigation events, which is consistent with the trend that the relative flow and uniformity of the emitter decreased with the increase in irrigation events. Upon increasing fertilizer concentration, the more chemical clogging substances increase, the less significant the water shear force. Therefore, we recommend that fertilizer concentration of DAP and UREA should not exceed 1.2 g/L. The results of this study can provide a basis for controlling chemical clogging and extending the service life of emitters.