Content and structural features of humic acid in black soil affected by long-term no-tillage and conventional tillage
Bibliographic record
Abstract
To evaluate the effects of tillage history and changes of tillage practices on the content and structural features of humic acid( HA),a 29-year stationary field experiment was conducted in a black soil field in southwestern Ontario,Canada. The experiment was designed to have four tillage treatments with different tillage histories,i. e. a 29-year conventional tillage beginning from 1983( CT83),a 29-year no-tillage beginning from 1983( NT83),a 15-year no-tillage converted from a 14-year conventional tillage( NT97),a 15-year conventional tillage converted from a 14-year no-tillage( CT97). Soil samples were collected from 0- 10 cm soil depth and the contents of HA,and the carbon( HA-C)and nitrogen( HA-N) in HA were determined. Structural features of HA were analyzed using Fourier-transform infrared spectroscopic( FTIS) and Solid-state13 C NMR spectroscopic methods. The results showed that the contents of HA and HA-C increased with the increase of tillage age and tillage intensity. When the 14-year no-tillage was converted into conventional tillage,the contents of HA,HAC,HA-N,as well as the oxidizability and aromaticity of HA started to increase. The contents of O-alkyl-C,carboxyl-C,and acetal-C in HA differed significantly in the soils of NT83 and NT97. The aromaticity of HA in the soils of NT83,NT97,CT97 and CT83 were 32. 1%,36. 0%,46. 1% and46. 8%,respectively. The contents of microbial decomposition products were 37. 2%,22. 9%,21. 0 and 20. 9% in soils of NT83,NT97,CT97 and CT83,respectively,indicating that microbial activity in soils under long-term no-tillage is more active than that under conventional tillage. Accordingly,soil disturbance intensity tended to accelerate the aging of soil HA. Compared to no-tillage,conventional tillage promoted the humification of the soil and the complication of HA structure.
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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 | 0.000 | 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 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".