Photolytic Model of Six Degradable Mulch Plastic Films

[Objective] This study aimed to solve the mulch plastic film pollution problems in Xinjiang, in order to provide reliable theoretical basis for the research on the degradation mechanism of biodegradable plastic films. [Method] The effect of illumination intensity on the decomposition of decomposable mulching films was investigated through simulating the field condition in laboratory. Regression analysis was employed to fit the processes of film decompositions. [Result] The weight loss ratios of different types of plastic films were closely related with the illumination. There was no sundry produced during the degradation process, but the weight was reduced, indicating that degradation produced gas, thus, ultraviolet rays had destructive effect on mulch plastic films. Different types of plastic films showed significant differences in the degradation speeds, and under the same conditions, the degradation speed of S4# with the induction period of 30 d was the fastest. With the extension of uv illumination time, the degradation became cumulative degradation process. [Conclusion] Under the uv rays, the weight loss ratio and illumination hours is regarded as a positive correlation relationship. The significant inspection shows that the data fitted degradation model can be described by the logistic model of Y = a/（1＋b×e -ct）, and all the parameters show significant differences （P0.01）.

Preparation and Applications of Biodegradable Mulch

[Objective] The aim was to introduce preparation methods of biodegradable mulch of starch, and analyze the comprehensive properties, including structure, me- chanical property and degradation. [Method] Environmental factors of biodegradable mulch of starch and common mulch were collected to make analysis and compar- isons on temperature, ground temperature, and illumination intensity with different mulches. Furthermore, the germination rates of broach bean and garlic were mea- sured with mulches covered. [Result] The comprehensive property of biodegradable mulch of starch performed better. [Conclusion] The biodegradable mulch of starch could reduce environmental pollutions and the application would be recommended.

Applicability of Biodegradable Mulch in Maize Production in Northeastern Yunnan

[Objective] The aim was to explore adaptability of degradable mulches in maize production in northeastern Yunnan. [Method] The tests of sun drying, burying and maize mulching were conducted based on 15 controllable degradable mulches in northeastern Yunnan. [Result] Of the test mulches, the induction period last the longest of 56 d, and the induction period can not be well controlled. Besides, the degradable mulches proved similar with common mulches in terms of heat preser- vation and yield increasing for crops, and performed excellently in covering strength, extension degree and toughness. Additionally, degradable mulches left few residues after maize harvesting, which would remove mulch pollution. [Conclusion] The biodegradable mulch functions well in heat preservation and yield increasing, as well as resolving the issue of plastic pollution, which is of great significance in environ- ment protection, agricultural sustainable development, and eco-agriculture, green agri- culture and modernized agriculture.