Development and experiment of straw chopping and plastic film strip-collection combined machine

Abstract: The plastic film mulch has the function of increasing soil temperature and preserving moisture, and it also can suppress weeds and maintain soil structure. Because of these special physical and chemical properties, agricultural mulching is extensively applied to cotton and other crops. Xinjiang is currently the largest cotton planting region in China, and all cotton cultivation involves film mulching. However, because plastic film itself is difficult to degrade and without scientific management and recovery in long-term use, a large amount of residual plastic film is left in the fields after harvesting, which has caused serious pollution problem to both the soil and the ecological environment. The mechanical collection of the plastic mulch is one of the effective ways to resolve plastic mulch pollution at present. Therefore, it is significant and urgent to study the residual film recovery methods and operation machines. Many kinds of mulching residues recovery machines have been developed and used, but there are some problems with the machines such as bad adaptability, low recovery rate, poor work efficiency in removing the collected film, and plastic films being easy to wind in cotton straw chopping, which needs further improvement for the machines. With a view to solving the above problems, a new method of operation step by step was proposed, which could collect plastic film in strip at first and then recover it, and a cotton straw chopping and plastic film strip-collection combined machine was designed. The machine mainly consisted of suspension device, power transmission system, straw chopping device, straw conveying device, strip-collection device, stripping device, and so on. Compared with the existing cotton straw chopping and plastic film collection combined machines, the machine proposed in this paper was simplified and efficient. The machine adopted the way of throwing cotton stalk into a certain height and distance to create a condition to separate cotton stalk from the residual film. Moreover, because of the ground profile modeling, this machine could be adapted to complex operating environments and operating requirements, and had a good performance on the strip-collection ratio. It could not only realize the straw chopper returning and the straw separation with plastic film, but also collect plastic film in strip with one operation, which ensured that it was easy to recover plastic film and recycle it. Based on the underlying theory analysis and experimental study, its basic structure and main parameters were determined, and the rational kinematic relationship among the knife-roller speed, the forward speed of unit, and the speed of strip-collection device was obtained by experiments. Field trials were conducted in Manas County of Xinjiang. The experiment results showed that the working efficiency could reach 1.15 hm2/h, plastic film collection stripe ratio was 92.6%, the straw chopping qualification rate was 97.5%, and the film-straw separation ratio was 90.5%, when the machine operating speed was 5-7 km/h, the cutter shaft speed was 1 880 r/min, and the speed of strip-collection device was 150-160 r/min, which could satisfy not only the agricultural requirements but also national standards. The research results can provide a reference to solve the problem of plastic film pollution in cotton-growing areas of China.