| Degradable plastic films are effective to solve the films' residue. However, the degradation of the films can advance or delay because of environmental factors, which hence influence the effect of films. The study was conducted in the field to have a survey of the degradation of films and examine the effect of degradable films on crop by comparing it with the uncovered plots and polyethylene films. And the laboratory experiment on the effect of different soil moistures (air-dried, 0.10 g/g, 0.15 g/g, 0.20 g/g, 0.25 g/g, 0.30 g/g) and temperatures (5℃, 15℃, 25℃, 35℃ , 45℃ ) on degradable ratio and content of films was studied. The conclusions were as follows:(1)The film can be degradable at every treatment but its degradation was best when the temperature and water content in soil was 35℃ and 0.25 g/g.(2)During the degradation, its composition can be degradable and PVA depends on the soil moisture. The decomposition of starch and others were primary in the air-dry soil when the temperature was above 25℃ and soil moisture was no less than 0.10 g/g.(3)Soil microbe was the main factor that influenced the degradation of films. However, other factors maybe influence it too.(4) The degradation of films includes: small holes, breaking at the edge of film, growing thinner and degrading. Their degradation was earlier than the production time and the extent was affected by environment. Films including sixty percent of starch could degrade thoroughly than films including fifty percent of starch and the degradation buried in soil lagged behind the soil surface. (5)During the covering, the film could regulate the temperature and conserve the moisture. With the crop growing, the effect was not gradually obvious. Comparing with increasing at high temperature, the effect of lowing the temperature was obvious.(6)The degradable film could advance the crop growth. However, its yield had not been improved obviously.
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