Development of a four-wheel tractor driven peanut digger

Date

12-2025

Abstract

Peanut harvesting remains labor-intensive and costly, as the unavailability of locally developed machinery compels farmers to depend on manual digging. To address this gap, a tractor-mounted peanut digger was designed, fabricated, and tested for its performance. FEA in ANSYS simulated the design structural response under a draft load of 2008.2 N, yielding a maximum von Mises stress of 33.012 MPa, peak strain of 0.00015, and deformation of 1.72 mm, and a factor of safety of 5.74. findings confirm elastic response, limited deformation and sufficient structural strength. The field performance was evaluated in terms of terms of material capacity (Y1) and digging efficiency (Y2) using a Box-Behnken experimental design with three factors, tractor speed (A), digger blade lift angle (B), and clearance angle (C). each tested at three levels. A regression model  was established to analyze the effects of these parameters and optimize operating conditions. Results showed that while interaction effects are insignificant, the main effects had a significant influence on both performance parameters. Extremely low or high lift angles reduced soil penetration, while small clearance angles increased soil drag and adhesion, lowering digging efficiency. Higher forward speeds increased losses. The optimal settings were a lift angle of 14.95°, clearance angle of 15.70° and forward speed of 1.74 km h-1, yielding a material capacity of 0.56 t h-1 and digging efficiency of 96.69%. Validation tests further improved these to 0.59 t h-1 and 97.42%, respectively. The simple financial analysis revealed that the owned tractor + digger and the rented tractor + digger are economically viable, as evidenced by positive NPVs, high BCRs and IRRs above prevailing discount rates. Utilizing an owned tractor has a higher profit of ₱5,519.21 ha-1 at a lower digging cost of ₱ 3,527.95 ha-1 compared to renting at ₱ 2,510.61 ha-1 and ₱6,536.58 ha-1, respectively. This development addressed one key bottleneck in peanut harvesting and recommends harmonized efforts in design refinement and policy support for wider adoption.

Document Type

Dissertation

Degree

Doctor of Philosophy in Agricultural Engineering

College

Graduate School (GS)

Adviser/Committee Chair

Arthur L. Fajardo

Committee Member

Rossana Marie C. Amongo, Kevin F. Yaptenco, Fernando Q. Paras, Jr.

Language

English

En – AGROVOC descriptors

GROUNDNUTS, FOUR WHEEL DRIVE TRACTORS,MANUAL HARVESTING, MECHANICAL HARVESTING, EQUIPMENT RELIABILITY

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