| Straw-soil-disc tool interaction is currently an important field of agricultural engineering research. Understanding of soil-straw-disc tool interaction behaviors, and high resistance and energy consumption are the main features of tillage operation. Improving the efficiency of energy utilization of tillage machinery, soil processing machinery and decreasing the energy consumption of the machinery under the condition that the agriculture requirement is satisfied is widely concerned. For paddy fields, a large proportion of total cultivated area is in China, since the lack of the profound understanding for the interaction between straw, soil and the agricultural implements.This research work was carried out to evaluate the performance of disc tool at three working speed (1.25,1.98and2.47m.s-1) and depths (5,10and15cm) with wheat and rice straw cover (156m2) on paddy field soil simulate in soil-bin. However, moisture content and bulk density kept constant throughout the study. The results are generalized as following1. Mechanical properties of wheat and rice straw such as shear strength, specific shearing energy, bending strength and cutting forces were determined at three loading rates (15,20and25mm min’1) and three internode positions (N1upper, N2medium and N3lower region) mm down from the ear. Results showed that the shear strength, specific shearing energy and cutting force were higher at higher loading rate at the third internode of both type of straws. The shear strength, specific shearing energy and cutting force of wheat straw were significantly higher (p<0.05) than that of rice straw. Furthermore, when loading rate increased, bending strength and young modulus of wheat and rice straw decreased.2. The draft, vertical and side disc forces of tillage tool represented an increasing trend with increased in implement forward speed and depth with their highest values at15cm depth and highest experimental speed of2.47m.s-1. 3. Burial straw rate was observed also increase with increase in speed and depth and the smallest size straw has maximum burial status whereas the large length has minimum buried. The soil disturbance area and profile increased with an increase in the depth of operation, the highest soil disturbance area was observed at higher speed and depth.4. Results indicated that increasing working speed of disc toolresulted in increase in lateral and longitudinal straw movement for wheat and rice straw cover, whereas further decrease in depth resulted in decrease of lateral and longitudinal straw movement. At higher speed and depth of tool more soil movement occurs resulting in a larger area for disturbed. Moreover lower speed and depth decreased lateral (44%with wheat and40.47%with rice) and longitudinal (47%with wheat and33.33%with rice) soil movement.5. Based on the discrete element method (DEM) a model was developed and simulate the disc tool through EDEM. The model nonlinear motion of straw, soil particles and coupling disc tool were used to simulate silt clay soil cohesive behaviors. The measured draft forces were used in calibrations of the most sensitive model parameter, particle stiffness1x108and straw2x104. Results showed that the tillage process has changed the surface morphology of the original soil and straw positions, tillage of the soil surface showed some ups and downs; with the continuous advance of farming, some particles were separated then straw lengths moved from original positions to final position. Increasing the speed from1.25to2.47m.s-1, increased soil particles movement, lateral and longitudinal straw movement, to a certain extent, the leading edge of the soil reaction suffered larger, shorter time to peak force.6. Lower working speed is recommended to reduce forces of disc tillage tool, soil and straw movement. Deep depth of disc tool improves the bulk density to provide better platform for seed germination. |
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