{
  "title": "Central Valley Field Manual — Machine Constants",
  "author": "Basimah Gomez",
  "location": {
    "ecoregon": "California Central Valley Grasslands",
    "wikidata": "Q104715382",
    "wwf_code": "NA0801",
    "coordinates": {
      "latitude": 37.0,
      "longitude": -120.3,
      "altitude_min_m": 0,
      "altitude_max_m": 400
    },
    "realm": "Nearctic",
    "country": "United States",
    "state": "California"
  },
  "classification_system": {
    "name": "Unified Soil Classification System",
    "wikidata": "Q905795",
    "standards_body": "ASTM International",
    "bartoc_id": "1082"
  },
  "uscs_groups": [
    {
      "symbol": "GW",
      "name": "Well-graded gravel",
      "particle_size_mm": { "min": 4.75, "max": null },
      "thermal_behavior": "rapid_drainage_minimal_retention",
      "garden_application": "foundation_stability_drainage_layers",
      "water_holding_capacity_ml_per_g": 0.08,
      "thermal_conductivity_w_per_mk": 2.1
    },
    {
      "symbol": "SW",
      "name": "Well-graded sand",
      "particle_size_mm": { "min": 0.075, "max": 4.75 },
      "thermal_behavior": "quick_heat_transfer_low_water_holding",
      "garden_application": "root_zone_warming_nightshade_family",
      "water_holding_capacity_ml_per_g": 0.15,
      "thermal_conductivity_w_per_mk": 1.8
    },
    {
      "symbol": "ML",
      "name": "Silt, lean clay",
      "particle_size_mm": { "min": 0.002, "max": 0.075 },
      "thermal_behavior": "moderate_plasticity_moderate_retention",
      "garden_application": "seed_beds_legumes_brassicas",
      "water_holding_capacity_ml_per_g": 0.35,
      "thermal_conductivity_w_per_mk": 1.2
    },
    {
      "symbol": "CH",
      "name": "High-plasticity clay",
      "particle_size_mm": { "min": 0, "max": 0.002 },
      "thermal_behavior": "slow_heating_extreme_water_retention",
      "garden_application": "water_reservoirs_terracing_cores",
      "water_holding_capacity_ml_per_g": 0.65,
      "thermal_conductivity_w_per_mk": 0.9
    },
    {
      "symbol": "GM",
      "name": "Gravel-silt mix",
      "particle_size_mm": { "mixed": true },
      "thermal_behavior": "thermal_buffering_zone",
      "garden_application": "perennial_root_zones_compost_bins",
      "water_holding_capacity_ml_per_g": 0.28,
      "thermal_conductivity_w_per_mk": 1.5
    }
  ],
  "hand_test_protocol": {
    "steps": [
      "dry_state_grinding",
      "moist_state_addition_dropwise",
      "ribbon_length_measurement_cm",
      "heat_proximity_cracking_observation"
    ],
    "ribbon_thresholds": {
      "sand": "<2cm",
      "silt": "2-5cm",
      "clay": ">5cm"
    }
  },
  "citizen_tools": {
    "feast_calculator_url": "https://basimah-gomez.4ort.net/calculator/",
    "film_render_url": "https://basimah-gomez.4ort.net/films/turmeric-at-dawn/",
    "homepage_url": "https://basimah-gomez.4ort.net/"
  },
  "metadata": {
    "created_utc": "2026-07-18T03:00:00Z",
    "version": "1.0.0",
    "license": "CC0-1.0",
    "citation_urls": {
      "ecoregon_source": "https://4ort.xyz/entity/california-central-valley-grasslands",
      "uscs_source": "https://4ort.xyz/entity/unified-soil-classification-system"
    }
  }
}