Long-term effect of fresh and composted cattle manure on the size and nutrient composition of dry-sieved soil aggregates
Bibliographic record
Abstract
Miller, J. J., Bremer, E., Beasley, B. W., Drury, C. F., Zebarth, B. J. and Larney, F. J. 2012. Long-term effect of fresh and composted cattle manure on the size and nutrient composition of dry-sieved soil aggregates. Can. J. Soil Sci. 92: 673–683. Application of feedlot manure to cropland may impact the size distribution and nutrient content of soil aggregates. The objective of this study was to determine the effects of fresh or composted feedlot manure containing straw or wood-chip bedding on dry-sieved aggregate size distribution and nutrient contents. Surface (0–15 cm) soil samples were obtained from a long-term field experiment where treatments were fresh (FM) or composted manure (CM) containing straw or wood-chips applied annually at 0 (control) or 77 Mg ha−1yr−1for 11 yr. Air-dried soil samples were separated using a rotary sieve into six aggregate size fractions ranging from <0.47 mm to >12.7 mm. Total C, total N, C:N ratio, soil mineralizable N (41-d incubation), total P, soil test P, and P saturation index were determined on the six aggregate fractions. The amendments significantly (P≤0.05) increased the proportion of smaller (<0.47 mm) aggregates and decreased the proportion of the larger (>12.7 mm) aggregates relative to the unamended control. The geometric mean diameter (GMD) was also lower and wind erodible fraction (WEF) was greater for the amended treatments than unamended control. We attributed this manure effect to increased organic matter content in the soil making the aggregates more friable and susceptible to breakdown by tillage. Carbon, N, and P concentrations were not shifted to smaller aggregate sizes where root growth and nutrient uptake are generally greater. The exception was mineralizable N, which tended to be greater in the finer<0.47 mm fraction. Mineralizable soil N in all aggregate sizes ≥0.47 mm was reduced for wood-chip compared with straw bedding, and resulted in net N immobilization in aggregate sizes ≥1.2 mm. Phosphorus sorption was lower in soil amended with wood-chips compared with straw bedding for aggregates ≥0.47 mm. Long-term manure application may shift soil aggregates from larger to finer fractions because of greater friability and suggests that these soils should be managed to avoid the greater risk of wind erosion.
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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 | 0.001 | 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 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".