Design and Performance Evaluation of a Four-Row Vacuum Seeder Powered by a Walking Tractor for Precision Soybean Planting

Abstract A previously developed two-row vacuum-type seeder showed promising singulation performance but its operational productivity was limited due to its low row capacity. This study aimed to design, develop, and evaluate a four-row vacuum-type soybean seeder to improve sowing capacity while maintaining high precision. The seeder, mounted on and powered by a walking tractor, used a centrifugal suction blower to generate vacuum pressure for four seed metering devices. Seed disks were driven by a chain-and-sprocket mechanism linked to the tractor’s wheel shaft. Bench tests were conducted at two seed disk speeds (12.7 and 26.1 rpm) and six blower speeds (3500, 4000, 4500, 5000, 5500, and 6000 rpm) using two soybean varieties. Singulation efficiency and the percentages of multiple and missing seeds were recorded. Results showed that higher vacuum pressures (>1.70 kPa) at lower disk speeds (12.7 rpm) significantly improved singulation, achieving 99–100% efficiency with minimal missed and multiple seeds (<1.25%) and no seed damage. Higher disk speeds (26.1 rpm) reduced accuracy. Field tests at three blower speeds (5000–6000 rpm) and two tractor speeds (Low-1 and Low-2) confirmed consistent seed spacing (19.2–19.6 cm) and optimal planting depth (4.8–4.9 cm), with minimal variation due to wheel slip. The best field performance (98% singulation) was achieved at Low-1 tractor speed and 6000 rpm blower speed. Increasing tractor speed enhanced field capacity from 0.16 to 0.31 ha·h⁻¹. The results validate the prototype’s effectiveness for precise and efficient soybean planting.