Study On Degradation Characteristics Of Degradable Plastic Film And Its Effect On Cotton Growth

At present,the effective way to solve the"white pollution"of agriculture is to use new degradable plastic film.The main products of degradable film are hydrocarbons,which can be further decomposed into small molecular compounds in soil,providing carbon source for microorganisms and increasing soil nutrients.By controlling its degradation cycle,the mulching period of degradable plastic film is similar to that of cotton,and then the plastic film is degraded,which can promote the growth of cotton without causing"white pollution".At present,there are many kinds of degradable mulching films,and their degradation characteristics are different.This paper mainly studies the degradation characteristics of three kinds of degradable mulching films and their effects on cotton growth and yield,analyzes their degradation principles,and selects suitable types of degradable plastic films suitable for Southern Xinjiang,so as to provide scientific basis for the application of degradable plastic films in production practice.(1)The degradation characteristics of degradable mulching film were studied by weight loss rate method.It was found that all degradable mulching films were degraded in different degrees under different conditions,and the degradation effect was not obvious in a short time,and the degradation rate increased with time.The degradation efficiency of the film was the highest at the depth of 20 cm,and the degradation rate of the film was the fastest at the same soil depth,which was the result of the interaction of oxidation and microorganism.According to the data simulation,it takes 14147.60 days for ordinary plastic film to degrade 50%,4 6548.73 days for 100%degradation,187.68 days for photodegradation plastic film,3223.03 days for 100%degradation,147.45 days for 50%biodegradation,2 811.45 days for 100%degradation,75.76 days for 50%of oxidation biological double degradation film and 1 099.39 days for100%degradation.The application of bio organic fertilizer can accelerate the degradation rate of biodegradable film and oxidation biological double degradation film.It takes 73.48 days and 39.71 days for50%degradation,732.25 days and 246.26 days for 100%degradation,which is beneficial to cotton growth and environmental protection.The degradation rate of double-layer plastic film was higher than that of single layer,which indicated that concentrated ploughing of residual film was more conducive to degradation.The results showed that the degradation efficiency of photodegradable mulching film and oxidation biodegradation mulching film were higher under ultraviolet irradiation.After 60 days of ultraviolet irradiation,the degradation rates of ordinary film,photodegradable film,biodegradable film and oxidation biodegradable film were 12.78%,51.23%,33.66%and 50.33%,respectively The light degradation film and the oxidation biological double degradation film are more sensitive to ultraviolet light,and the root is favorable for degradation in the surface layer of farmland soil.(2)The temperature and water content of the soil were monitored at fixed points,and it was found that the film mulching had a certain effect of moisture conservation and heat preservation.In the early stage of plastic film mulching,the effects of photodegradable film,biodegradable film,oxidation biological double degradation film and ordinary film on soil temperature and water content have certain differences,and have a greater impact on the surface and shallow layer temperature and water content.With the extension of time,the difference gradually decreases.In terms of the average soil temperature and water content in the whole period,the photodegradable film and the biodegradable film have a certain difference.There was no significant difference in soil temperature and water content between the two kinds of film.(3)The effects of different degradable plastic films on agronomic characteristics,physiological indexes,yield and quality of cotton were studied.The results showed that the film mulching of oxidation and biodegradation had positive effects on improving the agronomic characteristics of cotton(growth process,plant height,stem diameter,green leaves,flower number of buds and bolls,leaf area index).Compared with the common plastic film,the growth period of cotton covered with oxidation biological double degradation film was 4 days earlier,plant height increased by 7.05 cm at flowering and boll stage,and stem diameter increased by 0.66 at boll opening stage The results showed that the number of green leaves on main stem increased by 1.23,the number of flower buds and bolls increased by 4.33,and the average leaf area index increased by 0.35;the dry matter accumulation was 1 404.97 g/m~2,SPAD value was63.73,which was 123.57 g/m~2and 9.42 g/m~2,respectively,compared with the ordinary film mulching.The yield and quality of cotton can also be improved by the use of oxidation biological double degradation plastic film.The yield is 6.43 T/hm~2,which is 5.06%higher than that of ordinary plastic film.The results showed that the specific strength,uniformity,lint percentage,spinning index and maturity of cotton covered with oxidation biological double degradable film were the largest.It can be seen that the effect of different types of mulching film on cotton fiber quality was not obvious,but on the whole,the quality of cotton covered with oxidation biological double degradation film was better,which ensured certain quality characteristics.