Field response of N2O emissions, microbial communities, soil biochemical processes and winter barley growth to the addition of conventional and biodegradable microplastics
Field response of N2O emissions, microbial communities, soil biochemical processes and winter barley growth to the addition of conventional and biodegradable microplastics
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DOI：
10.1016/j.agee.2022.108023
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Lucy M. Greenfield;Martine Graf;Saravanan Rengaraj;R. Bargiela;Gwion B. Williams;P. Golyshin;D. Chadwick;Davey L. Jones
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文献类型：
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作者：
Lucy M. Greenfield;Martine Graf;Saravanan Rengaraj;R. Bargiela;Gwion B. Williams;P. Golyshin;D. Chadwick;Davey L. Jones
由于在农业中直接使用塑料(例如地膜)和通过污染改良剂(例如堆肥、生物固体应用)，农业生态系统中的微塑料污染正变得更加普遍。长期使用农业塑料和微塑料污染可能导致土壤退化和作物健康下降，因为产生遗留塑料的传统塑料降解缓慢。可生物降解塑料由于其可生物降解的性质，越来越多地被用于家庭和农业，以最大限度地减少塑料污染。然而，可生物降解塑料在田间尺度上对土壤功能的影响在很大程度上是未知的。通过田间试验，研究了常规(聚乙烯)和可生物降解(PHBV)微塑料对大麦N2O排放和土壤生化过程的影响。在土壤中添加了实际水平的微塑料(100千克/公顷)，用于传统和可生物降解的处理。在整个生长季节测量了N2O的排放量，同时测量了关键的土壤质量指标(微生物群落组成、氨氮、硝酸盐、水分含量、pH和EC)。总体而言，添加微塑料对作物产量、微生物群落或土壤生化性质没有明显影响。然而，我们发现，与不添加塑料和可生物降解的微塑料处理相比，添加传统微塑料后，累积N2O排放量减少了三分之二。我们认为，这种反应是由于传统微塑料处理的冬季土壤水分水平较低所致。总体而言，关键土壤参数对微塑料添加的响应显示出比高剂量实验室中观实验中看到的更少的负面影响。因此，必须在实际剂量率下进行长期田间试验，以量化微塑料对农业生态系统健康构成的真正风险。
Microplastic contamination in agroecosystems is becoming more prevalent due to the direct use of plastics in agriculture (e.g., mulch films) and via contamination of amendments (e.g., compost, biosolids application). Long-term use of agricultural plastics and microplastic pollution could lead to soil degradation and reduced crop health due to the slow degradation of conventional plastics creating legacy plastic. Biodegradable plastics are more commonly being used, both domestically and in agriculture, to minimise plastic pollution due to their biodegradable nature. However, the influence of a biodegradable plastics on soil function at the field scale is largely unknown. We investigated the effect of conventional (polyethylene) and biodegradable (PHBV) microplastics on N2O emissions and soil biochemical processes in a field trial of winter barley. Microplastic was added to the soil at realistic levels (100 kg ha-1) for both conventional and biodegradable treatments. N2O emissions were measured throughout the growing season alongside key soil quality indicators (microbial community composition, ammonium, nitrate, moisture content, pH and EC). Overall, microplastic addition had no observable effect on crop yield, microbial communities or soil biochemical properties. Yet, we found cumulative N2O emissions were reduced by two-thirds following conventional microplastic addition compared to the no-plastic and biodegradable microplastic treatments. We believe this response is due to the lower soil moisture levels over the winter in the conventional microplastic treatment. Overall, the response of key soil parameters to microplastic addition show fewer negative effects to those seen in high dose laboratory mesocosm experiments. Thus, it is imperative that long-term field experiments at realistic dose rates be undertaken to quantify the real risk that microplastics pose to agroecosystem health.