Phosphorus dynamics in boreal podzols converted from forest to agriculture
Bibliographic record
Abstract
Phosphorus (P) is a non-renewable and vital element for all life and the second most yield-limiting nutrient next to nitrogen in agriculture. The global and regional soil P pools, fluxes and the governing biogeochemistry vary with soil, vegetation, and management types. Limited understanding of the dynamics of P fluxes and pools in the Newfoundland (Nfld) natural and agricultural Podzols hampers decisions on best management options. To fill this knowledge gap, I: (a) assessed the levels and status of P in Nfld farm soils and their relationship with the recommended fertilizer rates across locations and managements; (b) evaluated the utility of ten P-extraction and analysis tests (P-test) for P extractability in natural grassland, as well as forested and agricultural soils; (c) determined P adsorption isotherms for forested and agricultural soil horizons; (d) investigated the P adsorption capacity of long-term managed soils; and (e) carried out a greenhouse trial to evaluate the plant uptake of P from soil layers relevant to soils converted from forested to agricultural use. The provincial Mehlich-3 P-test confirmed the relationship between measured P and the recommended P rates, but also suggests possible overfertilization. Soil P-test measurements varied with management status and were affected by the soil organic matter (SOM), Al, Fe, and soil depth or horizon. Citric acid extracted significantly more P for all tested soil conditions except for newly converted soils. Phosphorus adsorption capacity varied by soil horizon, depth, and management. Phosphorus availability and uptake in recently converted soils from forested to agriculture varied with soil depth and P sources. Given the variability in results and the possibility for a mismatch between P application and P uptake for soils, differentially across a range of conversion ages and managements, it is critical that further agronomic work focuses on the detailed understanding of P species and the effect of management on the P biogeochemistry, with a focus on the role of SOM and mineral contents. It is recommended that targeted calibration of P-test and recommendations be carried out to cover all sources of variability in soils that have undergone conversion to confirm the relationship between P sources, extractability, and uptake for different conversion and management states.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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) | 0.000 | 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".