| Aksu is the main production base of cotton in Xinjiang,which is the main production base of cotton in China,and the cotton play an greatly important role on the economic development of Aksu.The technology of plastic film mulching and cultivation play a key role in cotton production.In Aksu area,the rate of cotton film mulching has reached 100%.With development and application of plastic film,the pollution of cotton plastic film is becoming more and more serious.Previous researches are less reported about the pollutions of cotton plastic film in Aksu area.Therefore,the investigation and analysis of pollution status of plastic film in cotton fields of Aksu area are particularly important.The Aksu area consists of the cities and counties of autonomous region and the first division of the Corps,and the mode of land management is respectively managed.By investigating the film history data,the application and coverage area of film are increasing year by year from 1990 to 2014.Through the grey forecasting model to forecast the pollution situation of plastic film in next 20 years,the level of film application will reach maximum value in 2030,and it will sustain for some years and down to the best stabilized values in a certain period of time.The plum point method was used to take samples of cotton field in Aksu area,and other methods also widely used,such as the interview survey of farmers,agricultural bureau and so on,so as to the pollution situation of residual plastic film were analyzed.In Aksu area,the average content of residual film in cotton field is up to 240.19kg/hm~2,and the average is 286.20kg/hm~2,209.24kg/hm~2,respectively in all counties and regiments of the first division.Due to the different management mode,leading to the regiments of first division is better than others countries of Aksu area in plastic film pollution degree cotton field.The residual plastic films are distributed in the soil of 0 ~ 30 cm arable layers,the plastic film residue content is most in 0 ~ 12 cm,accounted for60% of the total plastic film residue,and the number of plastic film residue accounted for 20% of the total proportion that the block areas of residual film greater than 25cm~2,but it accounts for major proportions in the total weight of the plastic film residue,accounted for nearly 70%.The number of plastic film residue that the area is less than 4cm~2 and 4 ~ 25cm~2 is high,significantly more than 25cm~2;The content of plastic film in cotton fields is related to the film coated life,planting mode,operation mode and so on.The broken degree of plastic film is related to the natural conditions and human factors.Due to the different soil properties,recycling methods of residual,covered cycle in the South and North of Xinjiang,leading to northern Xinjiang is higher than the southern Xinjiang in the pollution of plastic film.According to the research of residual plastic film on the germination rate,operation of agricultural mechanization,crop yields and so on,combing with previous studies,a set of plastic film pollution level was develop,and less than 60 kg/hm~2 for the first level of pollution,60~150kg/hm~2 for secondary level of pollution,150~200kg/hm~2 for third level of pollution,200~250kg/hm~2 for fourth level of pollution,250~300kg/hm~2 for fifth level of pollution,morethan 300kg/hm~2 for sixth level of pollution.The pollution degree of Aksu area is above the third grade,and the pollution grade of Baicheng County,awat County,Kalpin County is up to the highest level.The governances of Plastic film pollutions are needed to conduct a thorough treatment from all aspects,such as the market planning,the consciousness of environmental protection of farmers,research and application of residual film recovery machine and degradable mulch film,improvement of agronomic technology. |
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