Effect of Land Use Change on Molecular Composition and Concentration of Organic Matter in an Oxisol

Land use change from native vegetation to cropping can significantly affect the quantity and quality of soil organic matter (SOM). However, it remains unclear how the chemical composition of SOM is affected by such changes. This study employed a sequential chemical extraction to partition SOM from a...

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Bibliographic Details
Published in:Environmental science & technology 2024-06, Vol.58 (23), p.10095-10107
Main Authors: Yang, Zongtang, Ohno, Tsutomu, Singh, Balwant
Format: Article
Language:English
Subjects:
Biogeochemical Cycling
Carbon compounds
Chemical composition
Chemical extraction
Cyclotron resonance
Dithionite
Fourier transforms
Land use
Mass spectrometry
Mass spectroscopy
Organic carbon
Organic Chemicals - analysis
Organic matter
Organic soils
Sodium pyrophosphate
Soil - chemistry
Soil organic matter
Soil quality
Vegetation
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Summary:Land use change from native vegetation to cropping can significantly affect the quantity and quality of soil organic matter (SOM). However, it remains unclear how the chemical composition of SOM is affected by such changes. This study employed a sequential chemical extraction to partition SOM from an Oxisol into several distinct fractions: water-soluble fractions (ultrapure water (W)), organometal complexes (sodium pyrophosphate (PP)), short-range ordered (SRO) oxides (hydroxylamine-HCl (HH)), and well-crystalline oxides (dithionite-HCl (DH)). Coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), the impact of land use change on the molecular composition of different OM fractions was investigated. Greater amounts of OM were observed in the PP and HH fractions compared to other fractions, highlighting their importance in SOM stabilization. The composition of different OM fractions varied based on extracted phases, with lignin-like and tannin-like compounds being prevalent in the PP and HH fractions, while aliphatic-like compounds dominated in the DH fraction. Despite changes in the concentration of each OM fraction from native vegetation to cropping, there was little influence of land use change on the molecular composition of OM associated with different mineral phases. No significant selective loss or preservation of organic carbon compounds was observed, indicating the composition of SOM remained unchanged.
ISSN:0013-936X
1520-5851
1520-5851
DOI:10.1021/acs.est.4c00740