Plastics are widely used in agricultural practices, although recently they have been recognized as a new emerging risk in soils. Polyethylene (PE), is commonly used by farmers to cover agricultural practices; geotextile, is used mainly for ground and crop covering; and polyvinyl chloride (PVC) is considered the main material contained in irrigation hoses. The present study aimed to assess the effects of three plastics (polyethylene, geotextile, polyvinyl chloride) on the soils’ fertility. Several pot experiments were conducted in soil samples from the study area (Thessaly) contaminated with adequate amounts of each plastic type (PE, geotextile: 2% v/v and PVC: 5% v/v). Water was added in two quantities: one to maintain typical soil moisture levels according to the crops’ requirements and an elevated amount to form supersaturating soil conditions similar to those following a flood event. Furthermore, temperature effect was also investigated to assess its impact on plastics’ behavior and soil fertility. The levels of all nitrogen forms and the microbial activity were determined at 10, 30, and 60 days. Significant changes were observed in the concentrations of nitrate, nitrite, and ammonium ions under ambient soil moisture conditions especially when the microplastics were incubated for a longer period. PE addition resulted in greater changes, followed by geotextile, although PVC addition did not induce significant changes in the nitrification process during the experimental time. PE and geotextile microplastics appeared to enhance microbial colonization and total microbial activity. In addition, soil characteristics were notably altered when moisture stress conditions were reached (85%) and when soils were flooded for two months, leading to a severe decrease in the availability of all nitrogen forms. The results showed that alterations in soil nitrogen forms in the presence of plastics study are crucial for maintaining the health and improving the productivity of Mediterranean soils.

中文翻译：

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极端气候条件下地中海农业土壤中塑料生物质废物的潜在增值和转化为有用肥料

塑料广泛用于农业实践，尽管最近它们被认为是土壤中新出现的风险。农民通常使用聚乙烯 (PE) 来覆盖农业实践；土工布，主要用于地面和农作物覆盖；聚氯乙烯 (PVC) 被认为是灌溉软管的主要材料。本研究旨在评估三种塑料（聚乙烯、土工布、聚氯乙烯）对土壤肥力的影响。在研究区域（色萨利）的土壤样本中进行了多次盆栽实验，该土壤样本被足量的每种塑料类型（PE、土工织物：2% v/v 和 PVC：5% v/v）污染。添加两种量的水：一种是根据作物的需要维持典型的土壤湿度水平，另一种是增加量以形成类似于洪水事件后的过饱和土壤条件。此外，还研究了温度效应，以评估其对塑料行为和土壤肥力的影响。在第 10、30 和 60 天测定所有氮形式的水平和微生物活性。在环境土壤湿度条件下，观察到硝酸盐、亚硝酸盐和铵离子的浓度发生显着变化，特别是当微塑料孵育较长时间时。 PE 的添加导致了更大的变化，其次是土工织物，尽管 PVC 的添加在实验期间并未引起硝化过程的显着变化。 PE 和土工织物微塑料似乎可以增强微生物定植和总微生物活性。此外，当达到水分胁迫条件（85%）和土壤被淹两个月时，土壤特性显着改变，导致所有氮形式的有效性严重下降。结果表明，塑料研究存在下土壤氮形态的变化对于维持地中海土壤的健康和提高生产力至关重要。