# Design, Simulation and Experimentation of a Polythene Film Debris Recovery Machine in Soil
## 1 Introduction  
In the middle of the 20 th century, with the development of the plastic industry, and especially the emergence of agricultural polythene film (PF), some industrially developed countries used agricultural PF to cover the ground. As a result, the production of vegetables and other crops achieved good results [1, 2]. Agricultural PF multiching technology changes the growing environment of vegetables and other crops, improves the yield and quality of crops and has achieved remarkable production and economic benefits in agricultural production [3, 4, 5]. However, agricultural PF multiching technology has some adverse effects, for example, multichting for many years will cause the removal of agricultural PF with difficulty. In addition, agricultural PF is not clean, resulting in farmland environmental pollution, soil fertility decline, seed emergence rate decreases and other problems which have attracted the attention of some researchers [6, 7, 8]. At present, the agricultural PFmultiching area in China exceeds 20 million \(\text{hm}^{2}\), and the annual use of agricultural PF exceeds 1.5 million tons, accounting for about 90% of the total annual use of agricultural PF in the world. Xinjiang is China's main agricultural PF covering area, mainly growing cotton, corn, pepper and other crops [9]. According to statistics, in 2018, the total sown area of crops in Xinjiang was 6.126 million \(\text{hm}^{2}\), and the total area of agricultural PF mulching was about 3.478 million \(\text{hm}^{2}\), including 2.491 million \(\text{hm}^{2}\) of cotton. In Xinjiang, agricultural PF, seeds, chemical fertilizers, pesticides and so on have become indispensable means of production in agricultural production [10; 11]. The researchers call the residue of PF debris the plough layer, which have not been reverted to a clean state for many years and has remained in the soil for a long time. The problem of soil contaminated by residual PF is becoming more and more serious, and people are paying more and more attention [12; 13; 14]. It is a great challenge and urgent problem to recover and reuse the residual PF debris of the plough layer [15; 16]. Although a lot of research has been performed on degradable PF at home and abroad, it is still in the stage of research, development and experimentation, and has not been popularized on a large scale [17]. Currently, the most widely used agricultural PF is a PE material that naturally degrades over hundreds of years, whereas biodegradable film is costly and less effective [18]. The harmful substances decomposed by agricultural PF directly enter the soil and enter the crop body with water and nutrients, which again affect the growth of crops and the quality of agricultural products. Residual PF debris hinders the infiltration of water in soil, reduces soil moisture content, weakens the drought resistance of cultivated land, leads to a decrease in soil porosity and permeability and destroys soil gas phase exchange. Residual PF not only has adverse effect on soil properties but also endangers crop growth, such as reducing seed emergence rate and affecting seedling survival [19]. The thickness of 0.008 mm PF is commonly used in agricultural production in China, so it is difficult to recycle mechanically. Most farmers give up on the recovery of PF, instead directly discarding it in the soil. The hazards of agricultural PF, especially those of residual PF debris in the soil, have attracted increasing interest in China [20; 21]. The promulgation of the Action Plan for Soil Pollution Control in China has defined the goal of recovery and reuse of agricultural PF. The area covered by agricultural PF throughout China has basically achieved zero growth, and the regions with serious PF pollution are the first to realize negative growth. Relevant local standards and policies have been formulated to address the problem of residual PF pollution, and a governance system has been established for the benefit of the government, scientific research institutions, enterprises and farmers [22].