光降解地膜的农业效果与降解过程（Ⅰ）

Degradation Mechanism of Photodegradation Plastic Mulches(I).

对国内外光降解地膜的２９个品种进行了农用效果、降解过程及光降解残膜碎片对土壤污染的全面分析测试。结果证明：光降解地膜必须具备普通地膜的增产功能；在覆盖６０ｄ以后降解膜才能开始裂解，分子量降低；降解膜残片在小于４×４ｃｍ￣２时，若按每年每公顷４５ｋｇ计，亦不会对土壤产生污染；降解膜成本与普通膜相比，不超过５％左右为宜。

AbstractThe development of agriculture plastic film is an important achievement.Each year the plastic film application areas are about 70 million mu. Itsdebris pollution to soils is a serious problem. Photodegradation film is amain method to reduce the pollution. This paper reports the results on soilpollution,degradation mechanism, residue debris of photodegradation film.Based on the results,we suggest that the degradation film should reach thefollowing standards:1.the plastic film starts to break down after 60 days;2.the sizes of film debris are not bigger than 4*4 cm￣2;3. the cost of degra-dation film is less than 105%of the normal film.