JWSS - Journal of Water and Soil Science

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Wheat as a main food source is partly lost in different ways such as planting, harvesting, storage and even in consumption processes. This calls for attention to reducing these losses through application of the results from agricultural research, use of new farming practices, improvements in management system and repair and renewal of farm machinery. The present study considers the design, development and evaluation of a new pneumatic air reel system as a replacement for the conventional mechanical reel. To evaluate the new system, laboratory and field tests were conducted.

 In the laboratory tests, the air velocity was measured along the fan outlet width at a 10 centimeter interval from the outlet to 40 centimeters away from it, and corresponding curves of air velocity distribution along the fan outlet width were drawn. On the basis of the results, 13 fans were calculated to be required on the cutting platform of a 14-foot (4.3 meter) combine. The results from the field tests of mechanical and air reels show that grain losses of air reel during harvesting are less than those of the mechanical reel because the air reel has no mechanical contact with the crop and applies less shock on plant stem than the mechanical reel. According to the results, grain losses increased linearly with increasing fan speed. In addition to the change of fan speed (2247, 2503, 2860, 3218 and 3932 RPM), three air discharge directions of 10, 20 and 30 degrees from horizontal line were examined. According to the data analysis in Randomized Complete Block Design (RCBD) through Tukey’s procedure (15 treatments and 6 samples in each treatment), there were significant differences between grain loss at these directions and mechanical reel at a level of 5%. A wind direction of 20 degrees and fan speeds of 2503 to 2860 RPM are recommended.

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Oil seed rape is an important non-cereal crop used mainly for edible oil production. Canola pods are fragile and its branches are twisted together at harvesting time. Harvesting with a conventional combine can pull off twisted branches and cause appreciable losses in the vicinity of divider at combine header. In this study, a hydraulic rotary divider was designed and developed to separate twisted pods and reduce the grain loss. The device is made up of two cylinders and a number of fingers, the cylinders rotate in opposite direction and fingers move in and out through holes on cylinder walls. The assembly was expected to separate the twisted pods and reduce grain loss. A hydraulic motor driven by combine hydraulic system was used to rotate the separating cylinders. The separating assembly was installed on righthand side of the combine harvester header. A split-plot experiment was used to evaluate the performance of the unit. Field tests were carried out at combine forward speed of 1.5 kmh-1. Variables were: cylinders rotary speed in three levels (50, 75 and 100 rpm), the number of fingers in three levels (16, 12 and 8), and the tests were conducted with and without combine reel. Two different positions of finger protrusion were also considered in field tests. The results were compared with those of a conventional combine header. The results show that the medium rotational speed (75 rpm) exhibited lowest seed loss. Furthermore, as the number of fingers increased, the seed loss tended to decrease. The seed loss also decreased in the presence of combine reel. Also, findings showed there is no significant difference between the two protrusions trajectories of fingers. A twenty percent decrease in seed loss was observed at rotary speed of 75 rpm and number of fingers of 16 in the presence of combine reel.

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Sand and gravel mining from the most of our country rivers causes morphological, hydrological and geomorphological changes in these rivers. This study investigates the effects of removal of sand and gravel from the river bed on sedimentological features of Zaremrood River in Mazandaran province. For this purpose, by determining four sections before and four sections after the sand removing point, the river bed sediments sampling in combined approach and in a plot within the river were performed and sedimentology features such as the large, medium and small diameters (a, b and c), roundness (R_c), form factor (S_f), normal diameter (D), sphericity (S), and width ratio (W), were measured and calculated in the laboratory and analyzed by SPSS software. The results showed that the variations of sediment statistics a, b, c, Sf, D, S and W in the pre- and post- harvest location has a significant difference but the Rc statistic does not show any significant difference. The reduction of the triple diameters after the excavation site is caused by the fracture of the sediments in the mining area, so that the sphericity of grains also decreased in the mining area. Roundness of sediment particles after the excavation site is decreasing up to 600 meters reach and then it tends to increase.
 

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