{
  "$schema": "https://terraevidence.com/evidence-record.schema.json",
  "recordId": "EP-PUB-004",
  "version": "1.0",
  "status": {
    "code": "reviewed-for-stated-scope",
    "label": "Reviewed for stated scope",
    "meaning": "Checked for the stated wording, sources, methods, context, limits, and review period; not universally proven."
  },
  "topic": "Method and context",
  "title": "Keep the number attached to what produced it.",
  "claim": "A soil-test result should remain attached to the method, unit, and reporting context that produced it.",
  "summary": "A soil-test result should travel with its analyte, original value, unit, method or extractant, reporting basis, laboratory flag, sample context, and report date so people and machines do not silently treat unlike measurements as equivalent.",
  "evidenceSupports": [
    "Preserve the laboratory wording and reported value before any conversion. Record the method or extractant, preparation, reporting basis, flags, reference ranges, and sample context. Compare results only when the measured property, method, unit, basis, and relevant sampling conditions are compatible—or mark the comparison as unresolved."
  ],
  "doesNotEstablish": [
    "Matching units or a documented unit conversion do not make unlike methods equivalent. Different extractants, soil-to-solution ratios, preparation steps, measurement procedures, reporting limits, and calibrations can produce results that represent different measured fractions or support different interpretations."
  ],
  "sources": [
    {
      "sourceId": "EP-PUB-004-S1",
      "sourceType": "institutional-guidance",
      "institution": "University of Minnesota Soil Testing Laboratory",
      "title": "Extractable Phosphorus",
      "url": "https://soiltest.cfans.umn.edu/extractable-phosphorus",
      "relevance": "Documents distinct Bray-1 and Olsen procedures that both report phosphorus in ppm while using different extractants, soil-to-solution ratios, shaking times, and reporting limits."
    },
    {
      "sourceId": "EP-PUB-004-S2",
      "sourceType": "institutional-guidance",
      "institution": "University of Minnesota Soil Testing Laboratory",
      "title": "Our Methods",
      "url": "https://soiltest.cfans.umn.edu/about-us/our-methods",
      "relevance": "Lists laboratory analyses with their named extractants and procedures, demonstrating that a reported result remains method-dependent."
    },
    {
      "sourceId": "EP-PUB-004-S3",
      "sourceType": "institutional-guidance",
      "institution": "University of Minnesota Extension",
      "title": "Nutrient Management Calculator",
      "url": "https://apps.extension.umn.edu/calculators/crop/index.html",
      "relevance": "Requires the phosphorus test method and reported value as separate inputs and directs users to select Olsen or Bray according to the soil-test context."
    }
  ],
  "scope": {
    "reviewedPeriod": "2026-08",
    "applicability": [
      "Preserving, transcribing, comparing, or machine-processing soil-test results while retaining their laboratory and sample context."
    ],
    "limitations": [
      "Does not establish equivalence between laboratory methods merely because units match or can be converted.",
      "Does not provide personalized fertilizer, lime, amendment, crop, environmental, pest-control, or safety recommendations."
    ],
    "openQuestion": "Which minimum laboratory-result fields are necessary for reliable human and machine comparison across time without implying that unlike methods are equivalent?"
  },
  "useBoundary": "This reviewed record preserves reporting context and supports method-aware comparison. It does not determine that unlike methods are equivalent and does not provide personalized fertilizer, lime, amendment, crop, environmental, pest-control, or safety recommendations. Use the reporting laboratory's documentation or contact the laboratory when a method, unit, fraction, reporting basis, flag, or conversion is unclear.",
  "humanReadableUrl": "https://terraevidence.com/earth-project-reviewed-foundations#ep-pub-004",
  "machineReadableUrl": "https://terraevidence.com/evidence-records/ep-pub-004.json",
  "revision": {
    "version": "1.0",
    "publishedDate": "2026-08-17",
    "lastReviewedPeriod": "2026-08"
  }
}