The present study was carried out during 2006 winter season at Monshat
Abbas village, Kafer EI-Shiekh Gavernora, to evaluate and compare the performance
of two different principles potato digging machinery techniques namely: the application
of the normal ridger, and the application of the elevator digger for digging and lifting
potato tubers the performance of the two investigated harvesting machinery system
were evaluated in terms of the lifted, damaged tubers, harvesting efficiency, energy
requirements, effective field capacity, field efficiency and cost of harvesting potato
operation. The mechanical harvesting methods were investigated at four levels
forward speed of 2.5, 3.78, 5.00 and 6.25 km/h and share tilt angel of 0.227, 0.297
and 0.384 rad. (13, 17 and 22 deg). It must be denoted that, the tested elevator
forward speeds are adapted as an equivalent speed ratio (forward speed to elevator
speed) of 1, 1.5, 2 and 2.5. Elevator potato digger speed ratio of 2 gave the proper effective filed capacity
of 0.91 fed/h, lifted tubers of 93.93%, total damage of 3.13%, harvesting efficiancy of
96.84 and energy requirement of 15.72 kW.h/fed. Whereas, normal ridger the forward
speed of 5 km/h gave the proper effective field capacity of 1.01 fed/h, lifted tubers of
86.57%, total damage 4.63%, harvesting efficiency of 95.37% and energy requirement
of 7.33 kW.h/fed for. The best values of previous technical indicators were found to be at tilt angles
of 0.297 and 0.384 rad (17 and 22 deg) for elevator potato digger and normal ridger,
respectively. The elevator potato digger exhibited the maximum net profit of 6611.80 L. E'/fed
compared with 5856 L.E/fed for normal ridger.