Laboratory Evaluation of a Solenoid-Operated Hill Dropping Seed Metering Mechanism for Pre-germinated Paddy Seeds

摘要

Abstract Purpose A precision hill drop seed metering mechanism was developed for sowing of pre-germinated paddy seeds.Methods The metering mechanism comprised a rectangular metering plate with a hole in the middle, and it was kept at the outlet of the hopper, which was actuated by a push–pull type solenoid to drop the seeds in the form of hill. The triggering of solenoid was controlled by a sensor wheel fitted with an inductive proximity sensor. To reduce choking and bridging of seeds at the hopper outlet, agitation was made by rotating a rod in the hopper. The performance of the developed metering mechanism was evaluated using a grease belt. The effect of main operating parameters—forward speed (0.7, 1, and 1.3 km/h), metering plate hole diameter (9, 10, 11, 12, and 13 mm), and speed of the agitator (20, 40, and 60 rpm)—on the performance of the seed metering mechanism was studied in terms of missing index, multiple index, quality of feed index, mean hill spacing, coefficient of hill distribution uniformity, and coefficient of seed dropping uniformity in hills.Results The multiple index was found to be 0% in all the treatments. No visible damaged seed was found in any treatment. By applying response surface method, the optimum operating condition was found to be 0.84 km/h forward speed, 11.18-mm hole diameter, and 37.37-rpm agitation speed. The missing index, multiple index, quality of feed index, mean hill spacing, coefficient of hill distribution uniformity, and coefficient of seed dropping uniformity in hills at an optimized operating condition were obtained as 6.25%, 0%, 93.75%, 23.5 cm, 90.32%, and 65.22%, respectively. The frequency of occurrence of 3 to 5 seeds per hill was found in 64.8% of the solenoid strokes. The germination percentage of hill drop seeds was 91%.Conclusions Test results showed that the seed rate variation was much lower than drum seeder, and the number of seeds dropped per hill was closer to the pneumatic rice seeder.