Flexible orifice seed metering plate to address variability in seed shape, size and orientation enhances field performance of a pneumatic planter

Abstract

Abstract Pneumatic planters are widely adopted in precision agriculture due to their superior field performance and minimal seed damage. However, variations in seed size, shape, and orientation can affect the ability of each orifice to pick and release a single seed accurately. Seed metering units typically incorporate seed cut-off and knock-out devices to improve singulation and ensure timely seed dropping, enhancing the quality feed index and reducing the precision index. These auxiliary devices—whether mechanical, electronic, pneumatic, or magnetic—increase system complexity, require skilled operation, necessitate additional maintenance, consume more energy, and heighten the risk of seed damage. The suctioned seed experiences impact from the seed metering plate during picking, and orifices are not fully sealed after seed pick-up, leading to a need for higher vacuum pressure. Additionally, field vibrations can adversely affect planter performance. To overcome these issues, this study developed a novel flexible orifice seed metering plate and optimised its operating parameters for cotton seed, adopting a central composite rotatable design (CCRD). The plates were developed by adding a layer of elastomeric material on rigid seed metering plate. The experiments were conducted using a developed electronic sticky belt setup in laboratory. An orifice diameter of 3 mm, vacuum pressure of 3.40 kPa, forward speed of 4.67 km/h, extended radius of 1 mm and coating thickness of 0.25 mm were found optimum with a quality feed index of 97.289% and precision index of 4.653%. Minimal difference between laboratory and field performance was noted when operated by an electronic planter. The miss index, multiple index, and precision index obtained under field conditions with rigid seed metering plate were found to be 4.4, 2.8, and 9.08% higher than coated seed metering plate, respectively. A comparatively lower optimal vacuum pressure and higher operation speed was achieved when coated seed metering plate was used in place of rigid seed metering plate. Hence coated seed metering plate can be a low-cost solution to achieve higher speed of precision planting with improved seeding performance. Graphical Abstract

Keywords

• Pneumatic planter
• Seed metering
• Optimisation
• Flexible orifice
• Precision agriculture