{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.cation-exchange-capacity","code":"thing-q898477","url":"https://ver.cy/models/thing/q898477/","name":"cation-exchange capacity","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.QTY"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A measure of the capacity of a soil, sediment or material to hold exchangeable positively charged ions on the surfaces of clay minerals and organic matter, expressed in centimoles of charge per kilogram or milliequivalents per 100 grams; cation-exchange capacity indicates a soil ability to retain nutrients such as calcium, magnesium and potassium, depends on clay type, organic matter and pH, and is a standard measure in soil science and fertility management.","purpose":"Let an agent explain cation-exchange capacity and what it indicates, relay measurement methods and typical values from soil science sources, and help interpret values for soil management in general terms.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Surface charge property","Depends on clay and organic matter","pH dependent in part","Fertility indicator"],"structure":{"bundles":[{"id":"understand","name":"Understand","description":"What CEC is.","layers":[{"id":"definition","name":"Definition","description":"Definition and basis.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is cation-exchange capacity, and what gives soils their exchange sites?","kind":"definition"},{"text":"Is the question about CEC, anion exchange or nutrient content?","kind":"boundary"}]}]},{"id":"factors","name":"Factors","description":"Factors.","findings":[{"id":"factors-finding","name":"Factors","description":"Factors.","questions":[{"text":"How do clay type, organic matter and pH affect CEC?","kind":"definition"},{"text":"Which entry fits clay mineral?","kind":"action"}]}]}]},{"id":"measure","name":"Measure","description":"Measurement.","layers":[{"id":"methods","name":"Methods","description":"Methods.","findings":[{"id":"methods-finding","name":"Methods","description":"Methods.","questions":[{"text":"How is CEC measured, and why do methods give different values?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]},{"id":"units","name":"Units","description":"Units and conversion.","findings":[{"id":"units-finding","name":"Units","description":"Units.","questions":[{"text":"How are cmol(+)/kg and meq/100 g related, and how are values converted?","kind":"action"},{"text":"What is the result for the values in question?","kind":"measurement"}]}]}]},{"id":"apply","name":"Apply","description":"Interpretation and management.","layers":[{"id":"interpret","name":"Interpret","description":"Interpreting values.","findings":[{"id":"interpret-finding","name":"Interpret","description":"Interpret.","questions":[{"text":"What do CEC values indicate for fertility, liming and fertiliser management, in general terms?","kind":"provenance"},{"text":"Is the question about a specific field, which needs a local soil adviser?","kind":"boundary"}]}]},{"id":"materials","name":"Materials","description":"Other materials.","findings":[{"id":"materials-finding","name":"Materials","description":"Materials.","questions":[{"text":"How is CEC used for zeolites, clays and ion-exchange materials?","kind":"provenance"},{"text":"Which entry fits ion exchange?","kind":"action"}]}]}]},{"id":"context","name":"Context","description":"History and teaching.","layers":[{"id":"history","name":"History","description":"History.","findings":[{"id":"history-finding","name":"History","description":"History.","questions":[{"text":"How was cation exchange in soils discovered and quantified?","kind":"provenance"},{"text":"Which entry fits the history of soil science?","kind":"action"}]}]},{"id":"teach","name":"Teach","description":"Teaching.","findings":[{"id":"teach-finding","name":"Teach","description":"Teaching.","questions":[{"text":"How is CEC taught, and which misconceptions arise?","kind":"provenance"},{"text":"Which sources are cited?","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Explain cation-exchange capacity and report measurements with method and units.","Interpret soil test results for a farmer who asked, stating limits."],"mustNot":["Report a measurement without the method, since methods give different values.","Recommend fertiliser or liming amounts that ignore local rules on runoff.","Present a single test as the full picture of a field."],"requiresHuman":["Decisions on fertiliser applications near watercourses."]},"ethics":{"considerations":["Soil advice affects farmers' income and water quality downstream.","Soil is slow to recover from mistakes."],"affectedParties":["Farmers","People downstream of farmland","Soil scientists"]},"owners":{"steward":"Nobody owns the measure; the landowner holds the soil and labs answer for their results.","roles":[],"masterSystems":[]},"relations":[{"target":"Q5034494","type":"parent","note":"registry parent class"},{"target":"capacity","type":"related","note":"in registry terms"},{"target":"soil","type":"related","note":"and other materials"},{"target":"base saturation","type":"related","note":"the share filled by base cations"},{"target":"ion exchange","type":"related","note":"the underlying process"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.cation-exchange-capacity","Wikidata: Q898477 (https://www.wikidata.org/wiki/Q898477)","unit: cmol(+)/kg equal to meq/100 g"]},"properties":{"applicability":"not-applicable","items":["sandy soils: about 1-5 cmol(+)/kg","clay and organic soils: about 20-50 or more cmol(+)/kg"]},"recognition":{"applicability":"optional","items":["Capacity to hold exchangeable cations","cmol(+)/kg or meq/100 g","Anion-exchange capacity and base saturation are related measures","Not a visible object; a number on a soil test report."]},"capabilities":{"applicability":"required","items":["explain the concept and units","relay measurement methods","relay typical values","help interpret values in general terms"]},"hazards":{"applicability":"required","items":["Method-dependent values","Misinterpreting CEC without pH and base saturation","Confusing CEC with nutrient content"]},"interfaces":{"applicability":"required","items":["ISO 11260 and other soil analysis standards","National soil testing protocols"]},"context":{"applicability":"required","items":["Assessing nutrient retention in soils and materials.","effective and potential cation-exchange capacity","CEC of clay minerals such as kaolinite, illite and smectite","CEC of organic matter","CEC of zeolites and ion-exchange materials"]}},"sources":[{"title":"Wikidata item Q898477: cation-exchange capacity","url":"https://www.wikidata.org/wiki/Q898477","note":"identity and sense of the item"},{"title":"Wikipedia: Cation-exchange capacity","url":"https://en.wikipedia.org/wiki/Cation-exchange_capacity","note":"general description of the item"}],"openQuestions":["Should base saturation be a separate entry?","How should analysis standards be linked?","How should method differences be recorded?"],"resources":{"spec":"/models/things/publications/thing-q898477/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q898477/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T23:27:52Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-06T19:52:02+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}