Performance Evaluation of a Push Type Cassava Harvester

Abstract

Cassava harvesting is regarded as the most laborious operation in its production, involving three main sequential operations from stem cutting, soil loosening and then uprooting of the tubers. Relevant properties soil, stem and tuber were determined in evaluating the performance of the cassava harvest. Some of such properties being moisture content were investigated for the soil and stem of cassava in determining the harvesters cutting efficiency, soil loosening and uprooting efficiencies. Soil moisture tests revealed that at harvest, 10 MAP (months after planting), unconditioned (class-C) soil moisture was between 1.5 and 3%, while on conditioning with specific quantities of water (5 – 10 litres), under class A and B treatments, revealed the soils moisture to between 17 – 20% and 10 – 12% respectively. Mean soil moisture content on d.b was evaluated for Class A, B and C treatments as 18.7%, 10.8% and 1.94% respectively. Moisture in the stem was also determined from fifty randomly selected stalk samples and found to be between 45.84 – 81.02%, with a mean of 68.97%.Other properties comprise of mean tuberspread 44.83 cm, mean tuber yield per plant 4.86kg, while average root tuber depth was 16.59 cm. Diameter of stems ranged from 2.08 cm – 4.31 cm with an average of 2.82 cm.Mean cutting efficiency was 48.72%. Optimisation design revealed optimum cutting efficiency as 97.664%, at a moisture content of 70 – 85%, lever arm length of 65 cm, region of cut above ground surface 30 cm and at 4 cutting attempts. Soil loosening efficiency ranged from 52.22 – 100%, with a mean efficiency of 82.952%. Optimisation analysis revealed an optimum soil loosening efficiency for LED and LET as 96.31% and 93.74% at soil moisture of 17 – 20%, lever arm length of 100 cm and loosened depth of 3 cm respectively. Uprooting efficiency ranged from 63.03 – 100% with a mean uprooting efficiency of 77.706%. Optimum uprooting efficiency was 96.678%, observed at the highest soil moisture range of 17-20% and at a lever length of 105 cm. ANOVA test results revealed the effect of moisture content on the stems cutting efficiency, soil loosening efficiency and uprooting efficiency of the harvester, significant at p<0.05. Significant effect of number of cutting attempts was observed for the cutting efficiency and length of lever arm for the uprooting efficiency. Field capacity for uprooting operation alone was evaluated as 27.77 man-h ha-1, while for the combined operations of stem cutting, soil loosening and uprooting, it was found to be 86.81 man-h ha-1.