Changes in phosphorus fractions of a Humic Gleysol as influenced by cropping systems and nutrient sources
Bibliographic record
Abstract
Information about the dynamics of soil P fractions is useful to predict their bioavailability and risk of P transfer from soils to surface waters. The objective of this study was to assess the effects of cropping systems and nutrient sources on P fractions in a Labarre silty clay (Humic Gleysol). Soil samples (0-15 cm) were collected in 1989, 1994 and 1997 from a field with four cropping systems, combining two crop rotations, barley (Hordeum vulgare L.) monoculture and 3-yr barley-forage rotation, with two tillage operations (chisel and moldboard plowing) as main plots, and two nutrient sources (mineral fertilizer and liquid dairy manure) as subplots. A modified Hedley sequential fractionation scheme was used. The inorganic P (P i ) fractions (resin-P, NaHCO 3 -P i , and NaOH-P i ) increase with time in all cropping system and nutrient source combinations. Organic (P o ) fraction (NaHCO 3 -P o and NaOH-P o ) changes were related to C inputs and total soil C contents. The barley monoculture combined with mineral fertilizer slightly reduced NaHCO 3 -P o and NaOH-P o . The barley-forage rotation increased labile P o fractions. Rotation, chisel plowing and liquid dairy manure addition result in a buildup of labile P. A larger labile P increment per unit of P added, in surplus to plant exports, was observed with dairy manure than for mineral fertilizer, suggesting a higher risk of surface water contamination by P. Cropping systems and nutrient sources have a large influence on the changes in P fractions in this fine-textured Gleysolic soil. Key words: P fractions, crop rotations, liquid dairy manure, chisel plowing, moldboard plowing
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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 | 0.001 | 0.000 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 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 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".