Abstract

Cassava has become an important food security crop in Ghana over the years and in most parts of sub-Saharan Africa; making it the single most important source of dietary energy. Harvesting, one of the serious bottlenecks in the cassava production value chain, has received little attention in terms of mechanisation. Earlier attempts at mechanising cassava harvesting have been challenged mainly by inappropriate method of planting, field topography and scale of cultivation. The objective of this study was to field evaluate the efficiency of an improved manual cassava harvesting tool under three different planting positions for four cassava varieties in terms of field capacity, level of drudgery and root tuber damage. Force requirement in uprooting different cassava varieties was also determined. The study was conducted at the research field of Crops Research Institute, Fumesua. Field capacity of improved manual harvesting tool ranged from 49.9 to 156 man-h/ha, root tuber breakage from 4.32 to 19.55% and harvesting energy consumption ranging from 470.34 to 773.72 W across cassava varieties and planting positions. Nkabom cassava variety was easiest in uprooting, irrespective of planting position while Sikabankye variety offered the best in terms of root tuber damage and drudgery. Again, it was faster harvesting vertically planted cassava though cassava planted slanted offered the least root tuber breakage and drudgery, regardless of cassava variety. Cassava uprooting force ranged from 86.8 to 143.3 kg, rooting depth from 22.39 to 26.86 cm and cassava yield per plant ranging from 5.84 to 13.14 kg. Further research to identify the relationship between uprooting force requirement and some cassava agronomic parameters is recommended.

Key words: Cassava, field capacity, drudgery, planting position, tuber breakage, uprooting force.