Performance of three-point hitch tillage implements in tropical farming systems
Adam, Juma Abdallah Gudo
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The nature of farming in the tropical regions is characterized by scattered small plots, variation of topography even within the same farming area, and presence of obstacles such as rocks and roots of trees. This makes fully mounted tillage implements to be more suitable in these areas than the trailed and the semi-mounted. However in the tropics, information related to the performance of these implements is lacking. This necessitated conducting this study with the aim of determining the effect of topography and obstacles on the performance of three-hitch tillage implements and also to develop a decision management aid tool. The performance of four tillage implements namely; a disc plow, disc harrow, moldboard and chisel plow was investigated in sixteen experimental plots having varying slopes with uniform vegetation. Field experiments were conducted with a Massey Ferguson 275 tractor. Two operating speeds were used namely high operating speed (HOS) of 15 km/hr. and low operating speed (LOS) of 10 km/hr. The measured parameters to determine performance of each implement included draft, operating depth and width, fuel consumption, slope angle and both theoretical and actual speed. Using draft and fuel consumption data, mathematical regression models were generated to serve as a decision management tool for the three-point linkage tillage implements. Results from proximate and ultimate analyses were used for evaluating the draft, fuel consumption and optimum operating range of the four tillage implements. It was found that draft for moldboard plow at HOS ranged from 5.0 to 5.7 kN, and at LOS ranged from 3.70 5to 4.50 KN; for chisel plow at HOS ranged from 3.13 to 6.14 kN and at LOS 4.85 to 7.75 and Disk plow at HOS ranges from 5.10 to 6.65 kN and at LOS ranges from 3.09 to 9.09 kN, whereas draft for Disk Harrow at HOS ranged from 4.0 to 8.1 kN and at LOS ranged from 7.50 to 9.20 kN. From these results, it was found that data for disc and moldboard plows data agreed with the findings in the literature. Whereas for disc harrow and chisel plow data, was not in agreement. RCBD experiment was executed as a screening tool to establish the statistically significance (p<0.05) between draft and fuel consumption for operating these implements. It was found out that tillage operation at HOS resulted in no significant differences between both draft and fuel consumption, whereas at LOS it resulted in significant differences between draft and fuel consumption. Furthermore statistical analyses showed no significant differences between the drawbar power at HOS, whereas there was significant differences between the drawbar power at LOS.ASAE (2006) (D487.4) standard expression for draft determination, adequately predicted the draft values recorded with the load cell. Finally mathematical regression models were generated for draft and fuel consumption of the four implements. In conclusion, using the generated mathematical regression models draft and fuel consumption for accomplishing tillage operations can be determined by knowing the operating speed, slope angle and wheel slippage. Statistical analysis shows significant differences between the tillage implement in terms of drawbar power/draft and fuel consumption was obtained at LOS10 km/hr.; whereas no significant difference between these implements at HOS 15 km/hr. Furthermore, tillage operation was performed better at LOS than HOS based on the recommended range by ASAE for wheel slippage versus drawbar power.