Document Type : Complete scientific research article
Authors
1
MSc of Biosystems Engineering, Faculty of Agricultural Engineering, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran
2
Biosystem Mechanical Engineering Department, Faculty of Agricultural Engineering, Sari University of Agricultural Sciences and Natural Resources
3
Department of Biosystems Engineering-Faculty of Agricultural Engineering- Sari Agricultural Sciences and Natural Resources University
Abstract
Background and purpose: The size of the clods is of great importance in terms of tillage quality and soil protection and erosion prevention along with the amount of energy consumption in seed bed preparation. The purpose of this study is to measure the draft force required by the rotary plow and mean weight diameter (MWD) due to the independent variables of the forward speed, the rotational speed and the plow cover position in field conditions and training the design expert software of the response surface methodology (RSM) section to predict the unmeasured values and optimize the output variables in order to reduce soil erosion.
Materials and methods: Field experiments were conducted in the form of a randomized complete block design (RCBD) with 3 replications. Each block was divided into 27 plots with a width of 3 meters and a length of 20 meters. The effect of three input variables, including the rotational speed at three levels (150, 200 and 250 rpm), the forward speed of the tractor at three levels (3, 4 and 5 km/h) and the position of the cover at three levels (top, middle and bottom) on the draft force required by the rotary plow and the MWD of soil as dependent variables. The draft force was measured based on the two-tractor test method and the MWD of the soil was measured using sieves with 10, 4, 2.36, 1.4, 1, and 0.5 and 0.18 mm meshes.
Findings: The results showed that the effect of forward speed, rotational speed of the plow and the cover position on the draft force and soil fragmentation are significant. The cover position had the greatest effect on the draft force and soil fragmentation. As the bottom position of cover and the forward speed and rotational speed of the plow were adjusted high, the draft force increased. In addition, bottom position of cover, reducing the tractor speed and increasing the rotational speed of the plow, greatly increased the fragmentation and as a result the high soil erosion. The highest draft force in the bottom cover position, the forward speed of 5 km/h and the rotational speed of 250 rpm is 657 newtons and the lowest MWD in the bottom cover position, the forward speed of 3 km/h and the rotational speed of 250 rpm It was obtained in the amount of 5 mm. Also, the results showed that the response surface methodology has a high ability in modeling the darft force of rotary plow (R2=0.96) and soil fragmentation (R2=0.99).
Conclusion: In the studied range, the position of the plow cover had the greatest effect on the darft force and soil fragmentation. The results of the simultaneous optimization of the draft force of 600 newtons and the MWD of 7.5 mm introduced 9 solutions in the studied range, and the best solution represents the optimal point at the forward speed of 4.82 km/hr, the bottom cover position and the rotational speed of 170.2 rpm with a satisfaction of 0.979.
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