A progressive knowledge strategy for monitoring soil microbiological activity by microscale spectroscopic detection
Microbial activity plays a critical role in the degradation of soil organic matter (SOM) through intra- and extracellular enzymatic processes. Within SOM, mineral-associated organic matter (MAOM) represents the most transformed microbial material, whereas particulate organic matter (POM) serves as i...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-12-01
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| Series: | Soil Advances |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2950289625000260 |
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| Summary: | Microbial activity plays a critical role in the degradation of soil organic matter (SOM) through intra- and extracellular enzymatic processes. Within SOM, mineral-associated organic matter (MAOM) represents the most transformed microbial material, whereas particulate organic matter (POM) serves as its primary substrate. This study presents a novel approach to characterize microbial activity at the microscale using Vis-NIR-SWIR and Mid-IR reflectance spectroscopy, complemented by synchrotron-based spectro-microscopy techniques, including infrared microspectroscopy and X-ray fluorescence mapping. A total of 35 soil samples were collected from the Piracicaba region (São Paulo, Brazil), targeting POM and MAOM fractions. These samples were analyzed for microbial biomass carbon (MBC) and enzymatic activities of beta-glucosidase, urease, and phosphatase. Distinct spectral features associated with enzymatic activity were identified with R2 ranging from 0.45 to 0.7, particularly in the functional groups CH, NH, CO, COH, and PO. Beta-glucosidase activity was linked to labile SOM compounds, displaying pronounced peaks in the POM fraction that were markedly reduced in the MAOM fraction. Urease activity correlated with NH groups, while phosphatase activity was consistently associated with PO groups across both SOM fractions. High-resolution synchrotron imaging at the Brazilian Synchrotron Light Laboratory revealed that soil particles coated with Fe and Al enhanced enzyme-particle interactions. While the POM fraction provided better spectral resolution for enzyme discrimination, a combined analysis of POM and MAOM offered a more comprehensive understanding of microbial activity and carbon cycling in soils. Our results support Vis-NIR-SWIR and Mid-IR spectroscopy as a practical tool for sustainable soil management, as it is a fast and non-destructive alternative to conventional methods that will facilitate the quantification and characterization of microbial activity and the understanding of carbon destiny. |
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| ISSN: | 2950-2896 |