Extractable phosphorus in alkaline soils amended with high rates of organic and inorganic phosphorus
Bibliographic record
Abstract
Information on the extractable P in soils treated with different organic amendments and how it changes with time is important to a sound management of manure addition to agriculture soils. This laboratory study investigated the impact of adding municipal biosolids, hog and cattle manures and monoammonium phosphate (MAP) on extractable P in soils. Phosphorus was added at rates of 0, 110, 220, 440 and 880 mg P kg-1 for the Osborne soil (Gleysolic Humic Vertisol), and 0, 123, 307 and 614 mg P kg-1 for the Lakeland soil (Gleyed Rego Black Chernozem) in the form of biosolids, hog manure, cattle manure and MAP. The soils were incubated at field capacity for 1, 4, 16 and 32 wk after which they were extracted using H2O, NH4Cl, NaHCO3 (Olsen P), and the Kelowna and Mehlich-3 extracts. Regardless of extractant and soil, extractable P was small 1 wk after adding biosolids (17-93 mg kg-1 as Olsen P) and large with MAP (59-672 mg kg-1 as Olsen P) while hog and cattle manures were intermediate between biosolids and MAP (20-461 mg kg-1 as Olsen P). In biosolids-amended soils, extractable P increased slightly with increasing incubation time indicating net P mineralization. With MAP, extractable P declined from 672 mg kg-1 after 1 wk to 157 mg kg-1 after 16 wk of incubation at the highest P application rate in the Osborne soil. In the Lakeland soil, the decrease in extractable P with MAP addition was small (from 398 to 332 mg kg-1) and was similar to the changes with cattle manure P with incubation time. Extractable P with cattle manure in the Osborne soil and with hog manure in the Lakeland soil did not change with incubation time. In both soils, extraction efficiency was in the order of H2O < NH4Cl < NaHCO3 < Kelowna < Mehlich-3. Across P application rates, the efficiency of added P as measured by NaHCO3 increased only with biosol ids from 12% after 1 wk to 21% after 32 wk of incubation, while it decreased in the same period from 55 to 44% with hog manure, from 34 to 32% with cattle manure and from 74 to 17% with MAP in the Osborne soil. Soil samples taken 4 wk following addition o f hog and cattle manures should reflect plant-available P, while soil samples taken within the same period following the application of biosolids are likely to underestimate plant-available P. Key words: Extractable phosphorus, organic amendments, soils, single extraction, incubation
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".