Management Aspects of Combine Harvesting in the Sudan

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Mohmoud, Ali El mahi
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Field work was conducted in season 97/1998 – 98/1999 in both rainfed agricultural mechanized sector which is represented by Gadarif and Damazine area, and the irrigated agricultural sector which is represented by Gezira, Rahad and Newhalfa schemes aiming to detect the combine harvester performance in sorghum and wheat harvest. The self-propelled combines of CLAAS make model dominator 68s which represents 95% of the prevailing fleet of combines working in the Sudan for more than 25 years were followed-up and monitored, 43 of this make which work in both wheat and sorghum harvest were selected using randomized sampling technique of the same age “10 years old” i.e. imported in season 97/1998. The parameters and data required are used to detect the performance of these machines in the field in different types of harvesting systems practiced in the Sudan either direct combining harvest or partially “stationary” combining harvest and the manual harvest to detect the breakdowns, types, causes, frequency of occurrence, and the cost for the repairs, also to see the machine utilization and consequently the effect on the harvest losses, different machine components behavior and most frequent parts to be repaired and their cost, in turn this indicates the reliability of the machine to finish the job in an acceptable manner qualitatively and quantitatively, with the minimum cost and time during the machine life span and to justify owning of the machine with regard to management aspects on different types of maintenance and operations. The study cleared that the cost of direct combining harvest system is higher in sorghum than wheat harvest and the rate of breakdowns is also higher in Sorghum and hence higher cost of repair and maintenance. The harvest losses proved to be higher in sorghum than in wheat harvest at different functional units of the harvester i.e. pre-harvest losses 3.9%, header losses 15.4%, cylinder 1.6% and tailing losses 7.4% in sorghum “Gadam Elhamam” of the total yield. Of total harvest losses 27.86% which amount about $38.6 and the operating cost of harvest is $ 23.2/ton so $61.8/ton is the total cost of harvesting (value of lost crop + value of harvest operation cost ). In wheat the pre-harvest losses are 3.27%, the header losses are 8.88%, cylinder and tailing 2.55% of total harvest yield. In the partial combine harvest system “stationary” the sorghum heads are cut and gathered with minimum losses then the machine used for threshing and packing. The cylinder and tailing losses are 7.8% of total yield :(590 kg/feddan) and that cost about $ 9.4 per ton and the cost of harvest $ 20/ton i.e. total cost is $ 29.4/ton. In this system the life span of the machine tends to increase till 12-15 years. The farmer has free hand to cultivate any variety or crops irrespective of their combinability. The manual harvesting system is very limited and only restricted to family subsistence farming using a stick “Mudgag” for threshing the gathered heads, the value of harvest losses are $11.6/ton and $ 23.24/ton for harvest operation cost with total harvest cost $34.4/ton (value of lost crop + value of harvest operation cost)but with much impurities and cracked seeds. The study indicated that depreciation charges about 42.8% and interest rate of 12.6% of total operation cost of the machine which represent a bigger portion of the fixed cost. The taxes 1%, oil and lubricants are 3.11%, fuel 8.9%, labour 8.4% and insurance and housing is 4.8% of total operation cost. The repair and maintenance cost represents 18.4% and if calculated in hour basis costs 14.3% of total operating cost. Assuming the life span of the machine 6000 hours we found that cost amount to 49% of replacement value of the machine and this give guidance for replacement policy. The study indicated that drivers and operators, spare parts, the place and standard of repair and maintenance and utilization of the machine whether used as stationary or direct combine and field combine are the main factors affecting the rate of breakdowns and reliability of the machine during harvest season. It is very clear that components of cutting and feeding system, threshing, cleaning and hydraulic systems got the highest breakdown occurrence rate than other highly expensive systems like engine, transmission and chassis. The study showed that 98% of the combines in the Sudan are used as stationary threshers minimizing annual repair and maintenance cost by less spare parts consumption like tyre and header to amount 4.8% of initial purchasing price, so it is lower compared to the rates in the developed countries due to low cost rate of labour in the Sudan performing intensive repairs which led to increase of operational life span of the machine to more than the assumed 8 years. It is very clear that reduction in wheat cultivation in the last years tend to decrease in machines import and tendency towards repairing and maintaining of the prevailing machines and introduction of small P.T.O driven stationary threshers.