Adjustment of Soil Saturated Paste Extract Electrical Conductivity and Sodium Adsorption Ratio for Excess Gypsum Dissolution Using Equilibrium Geochemical Modeling
Bibliographic record
Abstract
Core Ideas In gypsum‐bearing soils, excess dissolution occurs in the soil saturated paste extract. EC and SAR may be adjusted for dissolution effects using geochemical modeling. Characterization of salinity and sodicity hazard is improved. Soil saturated paste extract (SPE) electrical conductivity (EC e ) and sodium adsorption ratio (SAR e ) are widely used measures of soluble salts used to evaluate the salinity hazard to crop growth and the sodicity hazard to soil permeability. In gypsum‐bearing soils, sparingly soluble gypsum dissolves during preparation of the SPE as a result of soil water dilution. This produces a higher measured EC e and lower SAR e than would be measured if only field‐soluble gypsum were present. As part of a soil remediation project, samples were collected from the location of a former oil and gas production facility with highly saline‐sodic, brine‐affected soils. The naturally calcareous silt loam soil with a smectitic clay fraction was previously amended with gypsum to mitigate elevated sodicity, of concern for sodic effects on soil permeability. The equilibrium geochemical modeling software program ExtractChem was used to model EC e and SAR e in the absence of excess gypsum dissolution by first modeling EC and SAR at field water content and then modeling EC e and SAR e at saturated paste water content while excluding gypsum from the modeled reaction. For samples with measured EC e <3 dS m −1 , EC e modeled in the absence of excess gypsum dissolution was up to 52% lower than measured, and for samples with measured SAR e <2, modeled SAR e was up to 53% higher than measured. As remediation progressed, and EC e and SAR e decreased toward target values, the magnitude of the excess gypsum effect was sufficient to affect the evaluation of remedial progress. Equilibrium geochemical modeling adjustment of EC e and SAR e for gypsum dissolution that occurs as a result of SPE preparation is recommended to improve the evaluation of the progress of remediation of gypsum‐bearing, salt‐affected soil.
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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) | 0.001 | 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 | 0.000 |
| Open science | 0.001 | 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".