Sulfur Forms and Cycling Processes in Soil and Their Relationship to Sulfur Fertility
Bibliographic record
Abstract
Sulfur may be present in soil in a variety of organic and inorganic forms. In well-drained, upland agricultural soils, organic forms of sulfur dominate, while inorganic sulfate is the main inorganic sulfur form. Sulfate present in soil solution represents immediately plant-available sulfur. The microbial conversion of organic sulfur in the form of humus and crop residues to sulfate, termed mineralization, is a dominant mechanism for replenishment of available sulfur. Typically, 1 to 5% of the organic sulfur in a soil is mineralized to sulfate over a growing season. Warm, moist soils with large amounts of organic matter containing easily mineralized organic sulfates exhibit the highest mineralization rates. Microbial oxidation of sulfur is also an important process when reduced sulfur fertilizers such as elemental sulfur are added to soil. Like mineralization, the oxidation of reduced sulfur forms to sulfate is maximized when soils are warm and near field capacity moisture content. The conversion of elemental sulfur fertilizers to plant-available sulfate is increased when particle size is small and the particles are dispersed in the soil. Sulfate can be adsorbed to minerals and organic matter surfaces in soils of acid pH. A portion of the adsorbed sulfate is plant available and adsorption can be beneficial by reducing leaching losses in humid environments. In semiarid environments, sulfate salts can accumulate within the soil profile, especially when drainage is restricted. Sulfates found at depth in the soil profile can contribute to supplies of plant-available sulfur later in the growing season.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".