Review of Agricultural Plastic Mulching and Its Residual Pollution and Prevention Measures In China

Agricultural plastic film mulching is one of important technologies, but the plastic film pollution has been a serious issue for agri-cultural sustainable development in China. System analysis of this technique and its residue pollution and control ways have vital practical significance for rational application of agricultural plastil film. In this paper, on the basis of our previous work,agricultural plastic film mulching, its residue pollution and control technologies were concluded. Some important conclusions were found that, the amount of plastic film and mulching area had kept increasing with annual increasing rate about 8% since the 80s of the 20th century. From 1991 to 2011, the density of plastic film utilized increased 3~10 times, but it has very sharply different spatial pattern in different province. In general, the north and west China has high value, and the increase rate is also huge in the past 20 years. The crops of utilized mulching plastic film have extended from cash crops to grain crops, and the order of crop area is followed by maize, vegetable, cotton, tobacco and peanut. The main functions of mulching plastic film are keeping soil moisture and increasing soil temperature, against weeds and insect. At the same time, its side effects appear with continuous utilization. The main problems are residues left in soil to destroy soil structure, impress soil permeability, impede seed germination as well as water and nutrients uptaking, and block crop root system development. It has very serious pollution for the field utilized plastic mulching film for long term. The residual amount in soil is about 71.9~259.1 kg·hm-2, and has sharply spatial difference. The residual amount in soil. In Northwest China, is more serious than that in North China and Southwest China. Because of difference of tillage and appli-cation ways, there are great differences on the area and shape of the plastic film piece left in soil. The main types of shapes are flaky, crispat-ural cylindric and spherality existed in soil as horizontal, vertical and incline state. In present, there are machinery harvesting technique, re-ducing plastic film mulching technique, replacing technique with biodegradable plastic film to against this pollution. For plastic film residues pollution countermeasures, it is necessary to revise the standard of plastic film and strive monitoring the quality of plastic film, improve the retrievability of plastic residue; It is also necessary to extend reducing plastic film mulching technique, harvesting techniques and increase harvesting rate of residue; strength the adaption study and promote the rational utilization of agricultural plastic film.