DRIFT spectroscopy combined with sodium hypochlorite oxidation reveals different organic matter characteristics in density-size fractions of organically managed soils
Bibliographic record
Abstract
The objective of this study was to characterize the organic matter (OM) in density-size fractions of soil samples from a commercial organic farm using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The soil samples were separated by density fractionation with a sodium iodide (Nal) solution (1.6 g cm –3 ) into free particulate OM (fPOM), occluded particulate OM (oPOM), heavy particulate OM (hPOM), and mineral-associated OM (MAOM) fractions. The OM characterization by DRIFT spectroscopy was the difference in spectra obtained before and after sodium hypochlorite (NaClO) oxidation. However, the infrared absorption bands derived from the soil mineral matrix interfered with the detection of the absorption bands of polysaccharides. An increase in the amount of organic C under organic management was observed for all the density-size fractions, but the functional group composition of the NaClO-oxidizable OM differed among the fractions. The NaClO-oxidizable OM in the fPOM fraction was characterized by a high lignin content, whereas the oPOM fraction had high amounts of aliphatic compounds and lignin. The hPOM fraction contained less lignin and more proteinous materials, and the MAOM fraction was rich in proteinous materials. This study demonstrates that DRIFT spectroscopy combined with NaClO oxidation is a powerful tool for characterizing the relatively unstable OM in soils.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".