Untargeted Metabolomics Reveals Distinct Soil Metabolic Profiles Across Land Management Practices.

Area of Science:

• Soil Science
• Analytical Chemistry
• Biogeochemistry

Background:

• Land management significantly impacts soil biochemical processes.
• Conventional soil analysis often misses dynamic small-molecule variations crucial for nutrient cycling and microbial activity.
• Distinct land management practices create unique soil biochemical profiles.

Purpose of the Study:

• To assess if MS1-based untargeted metabolomics can differentiate soil systems under various land management practices.
• To identify key biochemical markers distinguishing different land uses.
• To evaluate the utility of analyzing both identified and unidentified metabolites.

Main Methods:

• Analysis of soils from six land-use types using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS).
• Application of multivariate statistical analyses, including Partial Least Squares Discriminant Analysis (PLS-DA), for metabolic profiling.
• Utilizing NPClassifier for biosynthetic class assignment of unknown spectral features.

Main Results:

• Metabolic profiling clearly separated different land management systems, revealing distinct chemical fingerprints.
• Phosphorus-related stoichiometric ratios (C/P, N/P) showed significant land-use dependency, unlike conventional C/N ratios.
• Forest soils were rich in secondary metabolites, cultivated soils had simplified profiles, and pasture soils were dominated by lipids and alkaloids.

Conclusions:

• MS1-based untargeted metabolomics is a powerful tool for differentiating soil systems based on land-use practices.
• This method reveals ecologically relevant biochemical variations even without complete structural identification of all compounds.
• An MS1-only workflow, including unknown spectral features, robustly distinguishes soil systems, proving valuable in untargeted metabolomics.