Effects of inorganic and organic amendments on soil phosphorus chemistry in calcareous soils
Bibliographic record
Abstract
Organic amendments provide both plant-available nutrients and organic matter to soils, resulting in improvements to soil chemical, physical and biological quality as well as fertility. These amendments can directly affect the chemistry of soil phosphorus (P) by altering the amounts, distribution and transformations of various soil P fractions. The overall goal of this thesis is to understand the effects of inorganic and organic amendments on soil P chemistry in calcareous soils for establishing more effective P fertility management. Transformations of various P forms in the soils amended with either animal manure compost or inorganic P fertilizer and with or without plant growth were studied. The dynamics of P in calcareous soils and analytical techniques for quantifying and characterizing forms of inorganic and organic P in either calcareous soils or in animal manure composts were also studied to assist in designing appropriate experiments to evaluate plant P availability. \tThe highlights of this thesis were (1) forms of P in animal manure composts were clearly different from those in inorganic P fertilizers, and mainly associated with calcium and magnesium, which were extractable with weak acids, (2) turkey litter compost increased weak acid-soluble inorganic P in soils, which transformed into plant available P with plant growth, (3) ryegrass took up P from the inorganic P extractable with a weak base extractant (NaHCO3) in all soils and from the inorganic P extractable with a weak acid extractant (NH4Ac) in the soils rich in P, (4) ryegrass promoted mineralization of organic P in the soils relatively deficient in P, and (5) the plant availability of P in turkey litter compost could be equivalent or greater from that in synthetic inorganic P fertilizers in the long term. \tThe current soil P fertility management system in Ontario only considers NaHCO3 extractable inorganic P (Olsen P) as an indicator of plant available P. This may result in significant underestimation of the plant available P in soils where organic amendments, such as animal manures and composts, as they affect soil P chemistry differently from that of inorganic P fertilizers. This research has shown that weak acid extractable P should be considered as an alternative indicator of soil P fertility, especially in soils receiving organic amendments.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".