Effects of aeration on hydraulic and anti-clogging performance of subsurface drip irrigation emitters

The efficacy of drip irrigation systems is fundamentally determined by the hydraulic performance and clogging resistance of emitters. There is evidence that subsurface aerated drip irrigation (SADI) promotes plant growth and enhances yield, but a further investigation of its effects is required. In the present study, an assessment of the hydraulic performance of SADI emitters was conducted. A range of nominal discharges (ND) (1.00, 1.35, and 2.30 L<middle dot>h(-1)), working heads (WH) (2, 4, 6, 8, 10, and 12 m), aeration amounts (AA) (0, 0.3, 0.5, 0.7, and 0.9 L<middle dot>min(-1)), and soil depths (SD) (0 and 15 cm) were designed for the assessment. The effects of ND, WH, AA, and SD on the discharge rate and exponent of the emitter were also explored. Moreover, the relative discharge rate of the emitter in short-term clogging scenarios was evaluated to figure out the effect of aeration on the anti-clogging performance of the emitter. A three-phase flow simulation method developed based on one- and two-phase flow simulation methods was used to analyze the changes in velocity, air concentration distribution, particle passing rate, and particle concentration distribution in the flow channel after aeration. The results demonstrated that ND, WH, AA, and SD had significant effects on the discharge rate of the emitter (P < 0.01), and ND and SD had significant influence on the discharge exponent of the emitter (P < 0.05). However, the impact of AA on the discharge exponent of the emitter was not significant (P > 0.05). In addition, compared with that in low-pressure condition (2 and 4 m), subsurface outflow had a markedly smaller negative impact on emitter performance in high-pressure conditions (10 and 12 m). After aeration, the frequency of muddy water irrigation increased. The growth rates of the high-speed mainstream areas of the three types of emitters studied, namely, E1 (1.0 L<middle dot>h(-1)), E2 (1.35 L<middle dot>h(-1)), and E3 (2.3 L<middle dot>h(-1)), ranged between 3 and 10%, 20-46%, and 7-17%, respectively. Additionally, the particle transit rates of E1, E2, and E3 improved by 10%, 9%, and 4%, respectively. The present research substantiates that SADI has the capability to significantly enhance the performance and efficiency of drip irrigation systems. The study results offer a basis for the promotion and application of drip irrigation systems in sustainable agriculture practices.