When they are upgraded to an asymmetrical structure, the streamlined transitions in the contraction and diffusion sections become smoother along the upper part of the throat, resulting in a semi-ring distribution of negative pressure, a smaller cavitation region, and a 16.5% to 49.2% increase in \(Q_{\text{inj}}\) under the same inlet pressure [14; 15]. Further optimization of the center axis offset distance in the diffusion section of asymmetrical venturi injectors reduced \(H_{\text{min}}\) by 8.2% and increased \(Q_{\text{inj}}\) by 13.7% [16]. Proportional fertilizer pumps have much more complex structures than venturi injectors do. Factors such as the diameter of the suction chamber and the stiffness of the reversing spring significantly impact performance. For example, increasing the suction chamber diameter from 15 mm to 21 mm resulted in a 21.9% average increase in \(Q_{\text{inj}}\) but a 10.3% decrease in the fertilizer chamber utilization efficiency [17]. Additionally, optimizing the piston rod diameter and the stroke of the sealing ring can improve the fit between moving components, thereby increasing \(Q_{\rm inj}\)[18]. While these studies have reduced \(H_{\rm min}\) and improved \(Q_{\rm inj}\) for venturi injectors and proportional fertilizer pumps to some extent, the improvement in performance is inherently limited by their operating principles. Venturi injectors, as jet pumps, rely on high-pressure and high-velocity driving water to create negative pressure in the throat for suction. The mixing and collision of driving water with low-pressure, low-velocity fertilizer solution in the throat results in significant energy loss. Proportional fertilizer pumps, on the other hand, generate negative pressure through the reciprocating motion of a piston driven by water flow, but only half of the work performed by the piston is used for suction. Moreover, the use of multiple check valves, directional valves, and moving seals results in low efficiency when water energy is converted to pressure energy. Under an outlet pressure (\(H_{\rm out}\)) of 0.1 MPa, the optimized venturi injectors and proportional fertilizer pumps require \(H_{\rm min}\) values ranging from 0.12 to 0.15 MPa. At an inlet pressure of 0.14 MPa, \(Q_{\rm inj}\) ranges from 25.2 to 78.3 L/h. However, current hydraulic fertilizer injectors still require high operating pressures, and their efficiency remains to be improved [10]. Many researchers have proposed using impact-type [19], axial-flow [20], or mixed-flow water turbines [21] recently as the power source for hydrodynamic fertilizer injectors, converting hydraulic energy to mechanical energy to drive diaphragm pumps and inject fertilizer into the pipeline system. These authors generally believe that hydraulic fertilization devices based on water turbines have a higher energy conversion efficiency than venturi fertilization devices do and proportional fertilization pumps do and that under the same energy input conditions, they can increase the \(Q_{\rm inj}\). However, most of the research has remained at the conceptual stage, primarily in patents, with no physical devices yet presented. Water turbines are typically used in hydraulic engineering projects, especially ultralow-head hydropower stations and tidal power stations. For these stations, the flow rate is \(\geq\)30 m\({}^{3}\)/h, with a head (\(H\)) \(<\) 0.1 MPa, which is similar to the operating conditions of an irrigation unit. Therefore, it is highly feasible to apply the turbine to the irrigation pipeline system, and there have been examples of applying the turbine to the agricultural irrigation system at home and abroad [22]. Under these conditions, axial-flow turbines (AFTs) are better suited than mixed-flow and impact turbines because of their higher specific speed [23]. The impeller is the core component of the turbine, and optimizing the impeller structure can significantly improve the output power of the turbine [24].