EFFECT OF FORWARD SPEED OF POTATO HARVESTER ON TUBERS DAMAGE

The effect of the forward speed of a potato harvester on tubers damage was in-vestigated. The potato harvester type is a two-row potato digger with riddle chain. The experiments were conducted in a potato field of Haradh Project of the National Agricultural Development Company (NADEC) east of Riyadh, in a sandy loam soil, and for a potato crop planted during the spring season of 2004. The potato type was Hermes (oval graded tubers). The degging depth was set to 22 cm, and the ampli-tudes of riddle chain of the implement were 17 and 25 mm. Results showed that the average values of tubers lifting percentage were in close agreement for all forward speed values (1.5, 1.7, and 2 km/h) of the potato harvester. However, it ranged be-tween 96% and 99%. It was found that there is no significant effect of the forward speed on both total damaged tubers percentage and damage index. However, there was a significant difference for the damaged tubers percentage when the amplitude of riddle chain was changed from 17 to 25 mm, where it decreased as the amplitude was increased. The values of potato damage index for all forward speeds were with-in acceptable limits of damage index. Minimum value of damage index was 0.04 at the speed of 2 km/h and amplitude of 25 mm.