PBAT生物降解地膜降解特征对不同土壤水分的响应

The Impact of Soil Moisture on Degradation of Biodegradable PBAT Mulching Films

【目的】探究土壤水分条件对地膜降解的影响。【方法】以3种聚己二酸/对苯二甲酸丁二酯(PBAT)生物降解地膜为试验材料,采用室内培养试验,设15%、25%、35%土壤质量含水率条件,研究了各地膜在3种土壤水分条件下的降解特征,测定了羰基指数及其相应的土壤微生物、酶活性。【结果】以PBAT为主要成分的生物降解地膜在施入土壤后均能够发生降解;扫描电镜(SEM)图像显示,生物降解地膜在培养130d后出现了大量微观孔洞,羰基指数也随着降解时间的增加而逐渐升高;在25%土壤质量含水率条件下,各生物降解地膜降解速率最快,显著优于15%、35%的土壤质量含水率条件(P<0.05),地膜降解速率与微生物活性变化规律一致。【结论】PBAT生物降解地膜能够发生降解,25%水分条件下降解最快,土壤水分条件及地膜三维结构差异是影响生物降解地膜降解速率差异的主要原因。

【Background】There had been a steadily increase in use of mulching plastic films to boost crop yield by keeping top soil warming and moist while in the meantime preventing weed growth.However,most plastic films used in agriculture are slow or not biodegradable and their continuous use has resulted in plastic pollution.One mitigation is to use biodegradable mulch films,one of which is the Aliphaticearomatic biodegradable copolyester,poly-butylene adipate-co-terephthalate(PBAT)films.While PBAT biodegradable films are mechanically and thermally durable,the response of their degradation to soil environmental change is obscure.【Objective】This paper presents the results of an experimental study on change in degradation of PBAT mulching film under different soil moisture contents.【Method】The experiment was conducted in lab under three soil moistures:15%,25%and 35%;degradation of four PBAT biodegradable films were investigated.In each treatment,we measured the degradations rate,soil microbial and enzymatic activities in the soil.【Result】Films containing PBAT degraded in the soil.Scanning electron microscope(SEM)images showed large numbers of micro holes in the films after 130 days of incubation,and the carbonyl groups index increased as the experimental time elapsed.When soil moisture was the same,the change in microbial and enzymatic activities in soil amended with the four films was ranked in film A>film B>film C>film D,consistent with the degrading rate measured for each film,indicating that microbial decomposition was the dominant degrading process.Microbial and enzymatic activities under moisture of 15%and 25%were comparable,both being higher than that under 35%(P<0.05),indicating that the difference in microbial and enzymatic activities was instigated by soil moisture.【Conclusion】PBAT mulch films degraded in soil and the degradation was fastest when soil moisture was 25%.Soil moisture and the interior 3D structure of the film are the main factors that affect the film degradation.Choosing the biodegradable mulch film for a field needs to consider the soil moisture change to ensure that the film does degrade but not too fast to compromise its service or too slow to leave residuals.