捡拾方式对绿洲棉田地膜残留和棉花产量的影响

为研究不同捡拾方式对绿洲棉田地膜残留量和棉花产量的影响，2016—2018年开展田间定位试验，设不捡拾、部分捡拾和彻底捡拾地膜3个捡拾方式处理。结果表明：捡拾后0~30 cm土壤地膜残留量明显减少，彻底捡拾处理减少量多于部分捡拾处理，0~20 cm残膜量增减占总增减量的57.1%~80.0%，连续3 a棉花产量高低依次是彻底捡拾、部分捡拾、不捡拾处理。研究表明，土壤地膜残留量存在“危害阈值”，超过阈值后棉花产量迅速大幅降低。每年进行多次残膜回收并持续若干年，能遏制棉田地膜残留或根除土壤残留地膜。

Located researching effects of plastic film picking-up methods on soil residual film and cotton yield in oasis

Soil plastic film residues and cotton yield in an oasis cotton field were location-researched for three consecutive years with no picking(CK), partial picking(Cp)and thorough picking(Cf). The results showed that the amount of residual film decreased after picking; the decrement of Cf was larger than that of Cp, the amount of residual film of 0~20 cm and 20~30 cm decreased in the same proportion, and the increment or decrement of 0~20 cm soil level accounted for 57.1%~80.0% of the total increase and decrease of the 0~30 cm residual film. The descending order of residual amounts of 0~30 cm plastic film in the three consecutive years was no picking-up, partial pickingup and thorough picking-up. Under different plastic film picking degrees, the cotton yield in the first year was different and the yield was in the descending order of thorough picking and partial picking. The difference in cotton yield will increase among these treatments if these methods are continued. In conclusion, if the picking method is effective, the plastic film residue can be eliminated, and the picking intensity is strong enough, the soil residual plastic film can be eradicated for several years. Moreover, if a theoretical threshold value of film residues exists, the cotton yield would decrease significantly if the plastic film concentration were more than the threshold.