Field Evaluation of a Watermelon Loading Machine

The area under cultivation of watermelon in Iran is 1.2 percent of total area of agricultural land or 42.3 percent of the total area under cultivation of different species of cucurbits in this country. Unfortunately, the share of mechanical devices in watermelon cultivation, particularly in harvesting period, is low. Harvesting of watermelon, especially in loading stage, is extremely costly and time-consuming because of absence of appropriate machines. Based on what have been derived from questionnaire completed by some farmers of Fars province, of total manpower required to harvest watermelon, 70% goes for loading of this product. The aim of this study is designing and testing the deployment of the watermelon harvesting machine to improve harvesting efficiency. Farm experiments were carried out with different ways of machine working, including: harvesting and loading watermelon at the same time, loading pre-harvested products, different belt speeds (0.25, 0.4 and 0.55  m/s), and different number of labors for loading (putting harvested watermelon on conveyor belt) and for unloading (receiving watermelon from moving belt to fill up trailer). Loading capacity and losses of products (during loading and unloading) were also calculated. The highest rate of loading capacity (13.2 tons per hour) was in loading pre-harvested products with 7 labors and belt speed of 0.55 m/s. The highest losses (0.38%) was also in this case. The lowest rate of farm capacity (6.15 tons per hour) has been found when harvesting and loading of watermelon were done at the same time (three labors, 0.25 m/s belt speed). No losses could be found when 5 or 7 labors were involved in harvesting and loading and speed of belt limited to 0.25 and 0.4 m/s. Results indicated that combination of 7 labors and the speed of belt equal to 0.4 m/s was the best way of harvesting the products in terms of maximum field capacity and minimum losses. In this method, the manpower needed to pick up and to load one ton of watermelon reduced to 0.61 labor-hr. compared with 1.14 labor-hr.  in traditional way of harvesting.