Nitrogen is the main nutrient in soil. The long-term addition of N leads to changes in the soil dissolved organic matter (DOM) and other quality indicators, which affects the adsorption and accumulation of organic pollutants. The use of organic fertilizer is important for the development of green agriculture. However, organic fertilizers (especially sludge organic fertilizers (SOFs) contain phthalates (PAEs) that may accumulate in the soil and result in environmental contamination. How this accumulation response varies with the magnitude of long-term N addition, especially in different soil layer profiles, remains unclear. Here, changes in the content of PAEs in the soil–plant system without and after SOFs application were studied through field experiments in soils with different N addition backgrounds (CK, N1, N3 (0, 100, 300 kg N ha⁻¹ yr⁻¹ respectively)). Our results showed that the application of SOFs increase the accumulation of PAEs in soil profiles and plant systems, increasing human health risks. The content of Σ₅PAEs in the topsoil increased from 0.96 ± 0.10 to 1.86 ± 0.09 mg kg⁻¹. Moreover, under a high N addition background and SOFs application, the characteristics of soil DOM change, and the accumulation of PAEs in soil was nearly 30% higher compared with the low N group. Some suggestions such as removing PAEs from SOFs during preparation, conducting soil surveys before applying PAEs, and using soil amendments, which are provided for optimizing the trialability and environmental safety of SOFs application.

氮是土壤中的主要养分。长期添加氮会导致土壤溶解有机质（DOM）等质量指标发生变化，从而影响有机污染物的吸附和积累。有机肥的使用对发展绿色农业具有重要意义。然而，有机肥（尤其是污泥有机肥（SOFs）含有邻苯二甲酸盐（PAEs），可能会在土壤中积累并导致环境污染。这种积累反应如何随着长期氮添加量的变化而变化，尤其是在不同的土层剖面中） , 仍然不清楚。在这里，通过田间试验，在不同氮添加背景 (CK, N1, N3 (0, 100, 300 kg N ha^-1年^-1分别))。我们的研究结果表明，SOFs 的应用增加了 PAEs 在土壤剖面和植物系统中的积累，增加了人类健康风险。表土中Σ ₅ PAEs的含量从0.96 ± 0.10 增加到1.86 ± 0.09 mg kg ^-1。此外，在高N添加背景和SOFs应用下，土壤DOM变化特征和PAEs在土壤中的积累量比低N组高近30%。一些建议，如在制备过程中从 SOF 中去除 PAE，在应用 PAE 之前进行土壤调查，使用土壤改良剂，为优化 SOF 应用的可试验性和环境安全性提供了一些建议。