Long-term fertilization regimes mitigate dissolved organic matter leaching and alter its chemodiversity in...

The impacts of dissolved organic matter (DOM) in agricultural soil leachate on the water environment have been recognized globally, yet how fertilization regulates the DOM in soil leachate remains largely unknown. Here, we conducted a soil column leaching experiment to study the leaching characteristics and mechanisms of DOM under different long-term fertilization regimes. Replacing 20 % of chemical nitrogen with organic materials (organic fertilizer, straw, or a combination of both) increased DOM. Replacing chemical nitrogen with organic fertilizer and straw (CFOS) significantly reduced DOC leaching loss. CFOS reduced the loss of humic acid-like substances and lignin-like compounds in leachate. CFOS increased the complexity and degree of oxidation of DOM. The CFOS treatment increased DBEw value, indicating that DOM saturation increased to a certain extent. The fertilization regime inhibited leachate generation by altering soil structure, thereby reducing the leaching loss of DOM. Our study identifies a fertilization regime that can not only increase the soil organic matter but also mitigate the leaching loss of DOM. Furthermore, it comprehensively reveals the chemodiversity of DOM in the agricultural soil leachate and the mechanism of its output, thereby providing a theoretical foundation for effectively promoting sustainable agricultural development and mitigating water pollution.