Variations in fluorescence properties of humic acids from calcareous soils amended with different swine manures in a long‐term soil experiment
Bibliographic record
Abstract
Abstract Molecular properties of soil humic acid (HA) can play an important role in the mechanisms regulating plant nutrient availability. This study explores how the structure of HA is altered by long‐term treatment with different forms of swine manure and how these changes may influence nutrient availability. Liquid swine manure (LSM), solid swine manure (SSM), and swine manure compost (SMC) were applied to a calcareous soil over 17 years in a long‐term soil fertility study. HA was extracted from site soil samples and analyzed using fluorescence spectroscopic techniques, including a Cu2+ quenching experiment, in order to assess differences in the structure and functionality of the soil organic matter (SOM) resulting from these different treatments. Emission spectra of the SSM‐HA and SMC‐HA are similar, while the LSM‐HA is distinct. Procedures such as parallel factor analysis (PARAFAC) decomposition of emission–excitation matrices showed that structures in the SSM‐HA and SMC‐HA samples have lower complexity, whereas the structures of LSM‐HA are of higher complexity. Interactions with Cu2+ at different pH levels indicate that the LSM‐HA shows more dynamic conformational changes as well as stronger interactions and higher quenching efficiency compared to the other treatments. Conversely, SMC‐HA demonstrates relatively stable binding constant (Ka) values across different pH levels. The binding constants and quenching efficiency of SSM‐HA are significantly affected by changes in pH. This study shows distinct structural characteristics of HA formed under different manure management systems and provides valuable insights into how these variations may impact nutrient dynamics in soils.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 source (direct Gemma or distilled Codex), 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".