Abstract:
Mulch film has been widely used in large-scale agricultural production in recent years. The ever-increasing mulch film has covered various food crops from fruits and vegetables, indicating the largest coverage in China. The residual film can be accumulated to cause some risks in the soil, such as the microbial survival in the soil, the disruption of the soil agglomeration structure, the blocked water circulation, soil salinization, and consolidation. A residual film recovery machine can be commonly used for subsequent pickup, packaging, and transportation of the residual film. However, the high impurity rate of residual film often occurs in the recovery of side film during operation in the field. Therefore, the residual film has posed a major constraint on crop growth and development in sustainable agriculture. In this study, a combine machine with cotton-stalk crushing and film following strip collector was designed to realize the cotton stalk crushing and returning to the field, and concurrently the collecting stripe operation on the residual film. A cotton stalk chopping device and a conveying device were also designed to throw the crushed stalk to the rear side handing row of the stalk collecting device, according to the requirements of cotton stalk and residual film processing. As such, the stalk and residual film were picked up at the same time during the combined operation of stalk crushing and residual film recovery. A plastic film master-slave strip-collection device was developed to bring the side film up to the surface, and then to collect the stripe for a better pick-up and recovery rate of the side film. The finger discs were also arranged to determine the main structural parameters. A transmission system was then designed, according to the agronomic requirements. A three-factor and three-level quadratic regression test was carried out to verify the operation performance and reliability of the machine. Among them, the machine advance velocity, the shaft center height of stalk chopping cutter from the ground, and the depth of finger disc into the soil were taken as the test factors, whereas, the film collection stripe rate, the length pass rate of stalk chopping, and the impurity rate of the residual film were taken as the response value. The response surface mathematical model of each factor was obtained to optimize the influence of each factor on the operation performance. The results showed that the machine advance velocity had the highly significance effects on the film collection stripe rate, and the depth of the finger disc into the soil had significance effects, while the height of the center of the stalk chopping cutter shaft from the ground had no significance. The machine advance velocity and the height of the center of the straw chopping cutter shaft from the ground had the highly significance effects on the length pass rate of stalk chopping, and the depth of the finger disc into the soil had no significance effects. The machine advance velocityand and finger disc into the soil had the highly significance on the impurity rate of the residual film, and the height of the center of the straw chopping cutter shaft from the ground had significance effects. An optimal combination was achieved for the best operation performance, when the advance velocity of the machine was 5 km/h, the height of the center of the stalk chopping cutter shaft from the ground was 340 mm, and the depth of the finger disc into the soil was 60 mm. In this case, the film collection stripe rate was 94.5%, while the length pass rate of stalk chopping was 96.5%, and the impurity rate of the residual film was 20.2%. The finding can provide a strong reference for the optimal working parameters of the cotton-stalk crushing and mulch-film strip collector.