Potassium transformation in clay soil with contrasting K budgets in long‐term experiment
Bibliographic record
Abstract
Abstract Canadian Shield clay soils are high in potassium (K) reserves. The differential contribution of soil K fractions to crop nutrition is an important issue for ley farming systems of Eastern Canada where nitrogen (N)‐based manure application rate leads to K surplus and redistribution. Our objective was to assess the long‐term change in K offtake, K budget, and K forms under a 3‐yr‐cycle ley farming system (barley [ Hordeum vulgare ]–mixed forage–mixed forage) initiated in 1989 and ended in 2016. The liquid dairy manure (LDM) supplied higher amounts of K than mineral fertilization (MIN) and led to larger K offtake across crop cycles. The cumulative K budgets averaged −579 kg K ha −1 cycle −1 for MIN and +69 kg K ha −1 cycle −1 for LDM. Despite cyclic variations, topsoil showed a surplus of exchangeable K (>100 kg K ha −1 ) at the end of experimentation under MIN and LDM compared to the initial state in 1989. Exchangeable and non‐exchangeable K fractions increased between 2001 and 2016 in 0‐ to 30‐cm depth even under K deficit (MIN), due to K release from slowly available forms and recycling from lower layers. There were no significant relationships between K budget and exchangeable K down to 90 cm. The approach relating soil exchangeable K and K budgets to support buildup and maintenance of soil fertility proved to be inappropriate in clay soils high in illite‐like minerals. Potassium dynamics in clay soils under ley farming highlighted the importance of considering non‐exchangeable and subsoil K in K fertilization recommendations.
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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 | 0.001 |
| 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".