Abstract. Biodegradable mulch films (BDMs) are a sustainable and promising alternative to non-biodegradable polyethylene mulches used in crop production systems. Nitrogen amendments in the form of fertilizers are used by growers to enhance soil and plant-available nutrients, however, there is limited research on how these additions impact biodegradation of BDMs tilled into soils. A four-month soil microcosm study was used to investigate the effects of inorganic (ammonium nitrate) and organic (urea and amino acids) nitrogen application on biodegradable mulch decomposition. We investigated the response of soil bacterial, fungal and ammonia-oxidizing microbial abundance along with soil nitrogen pools and enzyme activities. Microcosms were comprised of soils from two diverse climates (Knoxville, TN, USA and Mount Vernon, WA, USA) and BioAgri, a biodegradable mulch film made of Mater-Bi®; a bioplastic raw material containing starch and poly(butylene adipate-co-terephthalate) (PBAT). Both organic and inorganic nitrogen amendments inhibited mulch decomposition, soil bacterial abundances and enzyme activities. The greatest inhibition of mulch biodegradation in TN soils was observed with urea amendment where biodegradation was reduced by about 6 % compared to the no-nitrogen control. In WA soils, all nitrogen amendments suppressed biodegradation by about 1 % compared to the no-nitrogen control. Ammonia monooxygenase amoA gene abundances were increased in TN soils in all treatments, but reduced for all treatments in WA soils. However, a significantly higher nitrate and lower ammonium concentration was seen for all nitrogen treatments compared to no-nitrogen controls in both TN and WA. This study suggests that addition of nitrogen, particularly inorganic amendments, could negatively affect mulch decomposition but that mulch decomposition does not negatively affect soil nitrification activity.

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有机和无机氮改良剂抑制可生物降解塑料地膜的分解

摘要。生物可降解地膜 (BDM) 是作物生产系统中使用的不可生物降解的聚乙烯地膜的可持续且有前途的替代品。种植者使用肥料形式的氮改良剂来增强土壤和植物可利用的养分，但是，关于这些添加物如何影响耕种到土壤中的 BDM 的生物降解的研究有限。一项为期四个月的土壤微观世界研究被用来研究无机（硝酸铵）和有机（尿素和氨基酸）氮施用对可生物降解的覆盖物分解的影响。我们研究了土壤细菌、真菌和氨氧化微生物丰度以及土壤氮库和酶活性的反应。微观世界由来自两种不同气候（美国田纳西州诺克斯维尔和美国华盛顿州弗农山）的土壤和 BioAgri，由 Mater-Bi® 制成的可生物降解地膜；一种含有淀粉和聚对苯二甲酸丁二醇酯 (PBAT) 的生物塑料原料。有机和无机氮改良剂都抑制了覆盖物分解、土壤细菌丰度和酶活性。观察到尿素改良剂对 TN 土壤中覆盖物生物降解的最大抑制，与无氮对照相比，生物降解减少了约 6%。在 WA 土壤中，与无氮对照相比，所有氮改良剂都抑制了约 1% 的生物降解。氨单加氧酶 观察到尿素改良剂对 TN 土壤中覆盖物生物降解的最大抑制，与无氮对照相比，生物降解减少了约 6%。在 WA 土壤中，与无氮对照相比，所有氮改良剂都抑制了约 1% 的生物降解。氨单加氧酶 观察到尿素改良剂对 TN 土壤中覆盖物生物降解的最大抑制，与无氮对照相比，生物降解减少了约 6%。在 WA 土壤中，与无氮对照相比，所有氮改良剂都抑制了约 1% 的生物降解。氨单加氧酶amoA基因丰度在 TN 土壤中的所有处理中都增加了，但在 WA 土壤中的所有处理中都减少了。然而，与 TN 和 WA 中的无氮对照相比，所有氮处理的硝酸盐浓度和铵浓度均显着升高。这项研究表明，添加氮，尤其是无机改良剂，可能会对覆盖物分解产生负面影响，但覆盖物分解不会对土壤硝化活性产生负面影响。