Evaluation of a Power Tiller Operated De-Topper-cum-Digger for Onion Crop Harvesting

To enhance mechanization of onion harvesting on small farms and increase the annual utilization of power tillers, a de-topper-cum-digging unit was evaluated for simultaneous removal of onion leaves and digging of topped bulbs using a 9.7 kW power tiller. The field evaluation was conducted at the rake angle of 21° and a digging depth of 70 mm. The height of cut above crown was measured to be 31±7 mm. The absolute cutting torque and total maximum cutting torque for the de-topping unit were measured to be 2.12±0.49 N-m and 2.64±0.49 N-m, respectively at a rotational speed of 1790.95 rpm. The average maximum torque for the conveying unit was observed to vary between 8.46 and 13.21 N-m when operated in first gear with an idle torque of 1.41 N-m as compared to that observed in the range 15.40 to 23.28 N-m with an idle torque of 1.69 N-m when operated in second gear of rotor shaft of the power tiller. The de-topping efficiency, digging efficiency, field efficiency, actual field capacity and damage percentage of onion bulbs were found to be 82%, 92%, 65%, 0.042 ha h^-1 and 10%, respectively. The total power requirement for harvesting onion crop (including de-topping, digging, and conveying) was found to be 0.81 kW. The performance assessment indicated satisfactory results, suggesting the viability of the de-topper-cum-digger for use by small landholding farmers cultivating onions.