Dissipation of Antimicrobials in a Seasonally Frozen Soil after Beef Cattle Manure Application
Bibliographic record
Abstract
Land application of manure containing antimicrobials results in the dispersion of the antimicrobials in agro‐ecosystems. Dissipation of excreted antimicrobials in seasonally frozen agricultural soils has not been fully characterized under field conditions. This study investigated the field dissipation kinetics of chlortetracycline, sulfamethazine, and tylosin over a 10‐mo period after fall application of manure from cattle ( Bos taurus ) administered 44 mg chlortetracycline (chlortetracycline treatment [CTC]), 44 mg each of chlortetracycline and sulfamethazine (CTCSMZ), or 11 mg tylosin per kg feed daily. Antimicrobial concentrations in manured soil reflected the same relative concentrations in manure: chlortetracycline > sulfamethazine > tylosin. The first‐order dissipation half‐life (DT 50 ) for chlortetracycline from the CTCSMZ treatment was 77 d during the growing season and 648 d during the nongrowing season when the soil was frozen for an extended period. By comparison, dissipation of chlortetracycline added alone (treatment CTC) did not differ significantly between the two seasons (mean DT 50 , 121 d). During the nongrowing season, chlortetracycline from CTC dissipated faster ( P = 0.004) than that from the CTCSMZ treatment, indicating that the presence of sulfamethazine may have altered the dissipation of chlortetracycline. Dissipation kinetics for sulfamethazine and tylosin were not determined due to low detection in the manure‐amended soil. Sulfamethazine was detected (up to 16 ± 10 µg kg −1 ) throughout the 10‐mo monitoring period. Tylosin concentration was ≤11 ± 6.6 µg kg −1 and gradually dissipated. Chlortetracycline was detectable 10 mo after application in the seasonally frozen soil, indicating a risk for residue build‐up in the soil and subsequent offsite contamination. Core Ideas Manure application can disperse antimicrobials in the environment. Chlortetracycline dissipation followed first‐order kinetics. Seasonal effects on chlortetracycline dissipation varied with the source of the antimicrobial. The presence of sulfamethazine slowed down the dissipation of chlortetracycline. Concentrations of tylosin and sulfamethazine in manured soil were low.
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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 | 0.000 |
| 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) | 0.002 | 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".