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Variations of dissolved organic matter vertically in the scenario of sludge composting acting as nitrogen fertilizers: perspectives of spectral implications

  • 0College of Agriculture, Henan University of Science and Technology, Luoyang, 471023, PR China; State Key Laboratory of Soil and Water Conservation and Desertification Control, Yangling, 712100, Shaanxi, PR China.
Journal of Environmental Management +

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August 16, 2025

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August 16, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

Sludge composting significantly altered soil dissolved organic matter (DOM), impacting its vertical distribution and composition. This study reveals how DOM changes in soil after sludge application, offering insights into decomposition processes.

Area Of Science

  • Environmental Science
  • Soil Science
  • Biogeochemistry

Background

  • Soil dissolved organic matter (DOM) is crucial for ecosystem function due to its reactivity and mobility.
  • Sludge composting is a common practice for recycling organic waste in agriculture.
  • Understanding DOM transformation under sludge amendment is vital for soil health and nutrient cycling.

Purpose Of The Study

  • To investigate the vertical characteristics of soil DOM after sludge composting and winter wheat cultivation.
  • To analyze the composition and origin of DOM using advanced spectroscopic techniques.
  • To elucidate the factors influencing DOM distribution and transformation in amended soils.

Main Methods

  • UV-visible spectroscopy and excitation-emission matrices (EEMs) coupled with parallel factor (PARAFAC) analysis.
  • Quantification of DOM release and characterization of fluorescent components (C1-C5).
  • Partial Least Squares Structural Equation Modeling (PLS-SEM) to assess influencing factors.

Main Results

  • DOM amounts significantly increased from 0.31 to 0.82 g kg<sup>-1</sup> in sludge-amended soils.
  • Five distinct fluorescent DOM components were identified, with C2 (31.2%) and C1 (28.8%) being most abundant.
  • DOM origin varied with depth: terrestrial/allochthonous in topsoil and microbial in subsoil.

Conclusions

  • Sludge composting significantly impacts soil DOM quantity and composition.
  • Vertical distribution of DOM components is influenced by soil depth, DOM content, and spectral properties.
  • Findings enhance understanding of soil DOM dynamics under agricultural sludge application.

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