辽西半干旱区不同类型地膜降解特性及其对玉米产量的影响

【目的】明确不同类型可降解地膜在辽西半干旱区的降解特性及其对玉米产量的影响,为可降解地膜的区域筛选和应用提供理论依据和数据支撑。【方法】以国家农业环境阜新观测实验站为平台,采用田间试验与室内分析相结合的方法,田间试验共设置3个处理,分别为普通地膜覆盖（T1）、添加剂型降解膜覆盖（T2）和全生物降解膜覆盖（T3）。通过2年田间试验,定期进行田间观察和取样分析,测定不同地膜覆盖处理下的玉米产量,并结合扫描电镜（SEM）和傅里叶红外光谱（FTIR）,对地膜表面形态、力学特性以及化学结构等指标进行测定,系统全面地分析不同类型地膜在辽西半干旱区的降解过程及程度。【结果】各覆盖处理的玉米产量无显著差异,不同类型地膜的田间降解过程表明,2种可降解地膜的降解进程相似,均从覆盖后第38天表面开始出现裂纹,第58天开始出现明显降解,T3处理的降解进程总体上快于T2处理,普通地膜几乎无降解。随着地膜在田间置留时间加长,破碎程度加剧,可降解地膜的水蒸气透过量显著增加,力学性能（最大负荷、拉伸强度和断裂标称应变）显著下降,膜面微观形态和化学结构变化显著,普通地膜覆盖处理各项指标前后变化不明显。不同类型地膜的水蒸气透过能力总体表现为T3>>T2>T1,力学性能表现为T1>T2>T3,覆盖后98 d地膜微观表面粗糙度表现为T3>T2>T1,与田间观测效果及地膜相应物理指标结果相一致。通过计算（失重法）得出可降解地膜T2和T3的当季降解率分别为37.4%和47.8%,降解残片以<4 cm²和4—25 cm²的中小规格为主。【结论】可降解地膜可在保障玉米产量的同时实现自身降解,减少农田残留。从产量、降解特性和残留率等方面综合评价,以PBAT全生物降解地膜替代普通地膜应用于辽西半干旱区玉米覆盖栽培更具潜力。

The Degradation Characteristics of Different Plastic Films and Their Effects on Maize Yield in Semi-Arid Area in Western Liaoning

【Objective】This study clarified the degradation characteristics of degradable mulching films and their effects on maize yield in semi-arid area in western Liaoning, which may provide a basis for regional screening and application of degradable plastic films. 【Method】A field study combined with laboratory analysis was conducted in National Agricultural Experimental Station for Agricultural Environment in Fuxin, with three treatments, including conventional plastic film mulching (T1), additive degradation film mulching (T2) and biodegradable film mulching (T3). Through 2 years of field experiment, the regular field observation and sampling analysis were carried out to determine the maize yield under different mulching treatments. By using scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR), the surface morphology, mechanical properties and chemical structure of the mulching film were measured. The degradation process and degree of different types of mulching film in semi-arid area in western Liaoning were systematically analyzed. 【Result】There was no significant difference in maize yield among different treatments, and T2 and T3 had similar degradation process, in which T2 and T3 all showed cracks from the 38th day after mulching and significant degradation from the 58th day after mulching. The degradation process under T3 treatment was generally faster than that under T2 treatment, while the conventional plastic film showed almost no degradation. As plastic film degraded, the water vapor transmittance of degradable plastic film increased significantly, while the mechanical properties (tensile load, tensile strength and elongation at break) decreased significantly. The micro-structure and chemical structure of plastic film surface changed remarkably, while these indexes of conventional plastic film did not change significantly. The water vapor transmission capacity of different plastic film was in the order of T3>>T2>T1, while the mechanical properties was in order of T1>T2>T3, and the change of micro-structure of plastic film on the 98th day after mulching was in the order of T3>T2>T1, which were consistent with the field observation results and the corresponding physical indexes of mulching film. The degradation rates under T2 and T3 were 37.4% and 47.8%, respectively. The small and medium sizes of 4 cm² and 4-25 cm² were predominant. 【Conclusion】Biodegradable plastic film mulching could guarantee maize yield, achieve self-degradation and reduce plastic film residue. In terms of yield, degradation characteristics and residual rate, PBAT biodegradable plastic film was more feasible to replace common plastic film for maize mulching cultivation in semi-arid areas in western Liaoning.