Comparative Evaluation of Mechanical and Pneumatic Mixers in Fertigation Systems Regarding Homogeneity and Energy Efficiency

Efficient nutrient management through fertigation is a key requirement in modern fruit cultivation, as it directly influences yield, quality, and resource use efficiency. Uniform mixing of fertilizers within fertigation tanks is essential for ensuring consistent nutrient delivery, yet limited research has compared the performance of different mixing technologies. This study presents a comparative evaluation of a mechanical vertical shaft mixer (VSM) and three pneumatic mixers (B1, B2, B3), focusing on mixing efficiency, energy consumption, and operational performance. Experiments were conducted in a 1.5-ton vertical tank using an ammonium sulfate solution, and key performance indicators included pH and electrical conductivity (EC) stabilization time, mixing uniformity, and power usage. The mechanical mixer (VSM) achieved the target pH (6.98) and EC (27,100 µS/cm) in 190 and 250 s, respectively, whereas pneumatic mixers required 480–790 s. Energy analysis showed that the VSM had the lowest average power demand (0.414 ± 0.017 kW), while B1 recorded the highest (1.494 ± 0.005 kW). Although vortex formation was observed during VSM operation, simple design adjustments (e.g., tank geometry and vortex suppression) may mitigate this limitation. Overall, the findings indicate that mechanical mixers offer superior efficiency for high-frequency fertigation systems, providing faster and more homogeneous nutrient preparation with lower energy costs. These results have direct implications for improving the sustainability and reliability of large-scale fruit production systems.