Performance of Seed Planter Metering Mechanisms under Simulated Conditions

In rainfed conditions the success of crop production depends on timely seeding. The seed rate for various rainfed crops varies from 4 to 140 kg ha⁻¹. So, selection of a multi crop planter with replaceable metering rotor is crucial to meet the farm requirements and timeliness of operation. Though different types of planters having different seed metering mechanisms are marketed in India, single seed metered mechanical mechanisms are becoming popular as thier seeding performance is relatively better. To evaluate performance of such mechanisms quickly and optimize the parameters, a grease belt test rig was developed at CRIDA. The existing inclined plate metering mechanism and newly developed horizontal metering plate were tested for comparative performance at three speeds, 2.5, 3.5 and 5 km h⁻¹ with castor and maize seeds using the test rig. The average number of seeds metered at different forward speeds for selected variety of maize varied from 367.5 to 239 for inclined plate and 308 to 281 for horizontal plate when compared to theoretical metered seed of 270. In horizontal plate, the seed metering was more consistent and did not varied much with respect to speed of rotor and delivered 14.02 to 4.03% higher seed rate for castor. The mean seed spacing ranged from 19.3 to 23.1 cm. The horizontal rotor metered 94 – 98 frequency percentile seeds within 15 – 30 cm spacing intervals at operation speeds of 2.5 to 3.5 km h⁻¹. It is concluded that, correct seed rate can be achieved with the selected speed ranges by re-designing the seed cells in horizontal plate rotor.