Development of a Mini-tractor Operated Onion De-topper cum Digger

Harvesting of onion include multiple tasks such as de-topping, digging, soil separation and windrowing. Traditional methods of harvesting are labour demanding, tedious and time-consuming leading to increased labour cost and time. Labour shortages during peak seasons further delay harvesting, which affects product quality and profitability. To address these challenges, a mini-tractor operated onion de-topper cum digger was developed at GBPUA&T, Pantnagar. This intervention combines de-topping, digging, soil separation and windrowing in a single operation suitable for market needs, leading to reduced cost of cultivation and increased profitability among onion growers. The developed machine consists of a de-topping unit that removes onion leaves up to the neck, a digging unit that uproots the de-topped bulbs, a soil separation unit to separate soil adhering to the onions, a power transmission unit to drive de-topping and soil separation unit and a frame for attaching it to the tractor. A Finite Element Analysis (FEA) was also carried out to evaluate structural performance (maximum stress, strain and deflection) acting on the digging blade. Further, the influence of crop and operational parameters (moisture content of onion leaves, cutter bar speed and machine forward speed) on de-topping efficiency was also evaluated. Statistical analysis of the data obtained revealed that de-topping efficiency increases initially with an increase in independent parameters (moisture content of onion leaves, cutter bar speed and machine forward speed) but further increase in independent parameters decreases the de-topping efficiency. The developed machine demonstrated a theoretical field capacity of 0.20 ha/h, an actual field capacity of 0.17 ha/h and a field efficiency of 85%. The developed machine requires 5.88 h/ha costing Rs. 2145 which is 65.6% less than the manual method of harvesting (Rs. 6250/- per ha). The input energy requirement for both manual and machine-assisted (developed machine) were also analyzed, as they are crucial for reducing operational costs and improving the overall sustainability of onion harvesting. The analysis showed that the total input energy needed in manual and with the developed machine were 1381 and 1022 MJ/ha respectively.