Comparative Evaluation of Automatic and Manual Drip Irrigation Control Systems Under Variable Valve Opening Levels

Abstract

This study compared the hydraulic performance of manual and automatic drip irrigation control systems under three valve opening levels full (Q1), half (Q2), and quarter (Q3) at a constant operating pressure of 1.0 bar. Performance indicators, including coefficient of variation (CV), distribution uniformity (DU), and emission uniformity (EU), were calculated from emitter discharge measurements at four points along the lateral (0, 5, 15, and 25 m). The automatic system consistently outperformed the manual system, maintaining higher DU and EU values, especially under reduced valve openings. This stability was attributed to integrated pressure regulation and solenoid-based control, while the manual system exhibited greater performance declines and flow losses at downstream emitters. To assess agronomic implications, the automatic system was applied to irrigate maize (Zea mays L.) under three irrigation strategies: T1: full water requirement in one dose, T2: two equal doses, and T3: three equal doses, all at full valve opening. T3 enhanced early plant height and leaf surface area, indicating improved vegetative growth with more frequent irrigation. However, grain yield was highest under T1 (24.0 ton/ha), followed by T2 (21.3 ton/ha) and T3 (20.2 ton/ha), suggesting that less frequent but deeper irrigation favored reproductive development and yield formation. The findings confirm that automatic drip irrigation systems deliver superior hydraulic stability and uniform water application compared to manual systems. Moreover, coupling automatic control with optimized scheduling such as single-dose full water application can enhance maize yield potential and water use efficiency, contributing to more sustainable irrigation practices in large-scale agricultural production.