Models, admin and fixtures for WRB soil types

[dokterbob]

Overview

Implement comprehensive World Reference Base for Soil Resources (WRB) soil classification system to replace the current basic soil texture preferences. This will provide scientifically accurate soil classification data for plant species in the agroforestry platform.

Background

The WRB is the international standard for soil classification, endorsed by the International Union of Soil Sciences (IUSS). It provides a two-tiered system:

• 32 Reference Soil Groups (RSGs) - primary classification level
• 202 qualifiers - additional descriptors (principal and supplementary)

Scope

1. Data Models

• Replace current SoilPreference model with new WRB-specific models
• Create WRBReferenceGroup model for the 32 RSGs with categories and codes
• Create WRBQualifier model for the 202 qualifiers (principal/supplementary)
• Create appropriate through models following existing patterns (SpeciesWRBReferenceGroup, SpeciesWRBQualifier)
• Update SpeciesProperties model to use new WRB relationships

2. Data Structure

Reference Soil Groups organized by categories:

• Thick organic layers (1 RSG): Histosol
• Strong human influence (2 RSGs): Anthrosol, Technosol
• Root growth limitations (5 RSGs): Cryosol, Leptosol, Solonetz, Vertisol, Solonchak
• Fe/Al chemistry (8 RSGs): Gleysol, Andosol, Podzol, Plinthosol, Planosol, Stagnosol, Nitisol, Ferralsol
• Organic matter accumulation (4 RSGs): Chernozem, Kastanozem, Phaeozem, Umbrisol
• Salt/substance accumulation (3 RSGs): Durisol, Gypsisol, Calcisol
• Clay-enriched subsoil (5 RSGs): Retisol, Acrisol, Lixisol, Alisol, Luvisol
• Little profile differentiation (4 RSGs): Cambisol, Fluvisol, Arenosol, Regosol

3. Database Migrations

• Migration to remove old SoilPreference model and relationships
• Migration to create new WRB models
• Data migration with fixtures for all 32 RSGs and 202 qualifiers
• Update existing species data relationships

4. Admin Interface

• Admin classes for WRBReferenceGroup and WRBQualifier management
• Inline admin for species-WRB relationships
• Filtering and search capabilities in admin
• Bulk import/export functionality for WRB data

5. API Integration

• Update existing API endpoints to use WRB data instead of soil preferences
• Maintain backward compatibility where possible
• Add filtering by WRB categories and codes
• Update serializers and viewsets consistently

6. Fixtures and Initial Data

• Complete fixture with all 32 Reference Soil Groups including:
  • Official WRB codes (e.g., 'LV' for Luvisol)
  • English names (non-translatable as per WRB standard)
  • Category classifications
  • Descriptions
• Complete fixture with all 202 qualifiers including:
  • Qualifier codes and names
  • Principal vs supplementary classification
  • Descriptions

7. Testing

• Unit tests for new models and relationships
• Migration tests to ensure data integrity
• API tests for updated endpoints
• Admin tests for management interface

Implementation Notes

• Follow existing patterns from ClimateZone, HumanUse, and other categorized properties
• Use CategorizedPlantPropertyBase and CategorizedSpeciesPropertyThroughBase
• Maintain confidence scoring and source tracking for AI-enriched data
• Ensure natural key lookups and proper slugification
• Update enrichment chains to use WRB terminology

Acceptance Criteria

• All 32 WRB Reference Soil Groups are available as fixtures
• All 202 WRB qualifiers are available as fixtures
• Species can be associated with multiple WRB soil types
• Admin interface allows full WRB data management
• API endpoints consistently expose WRB data
• Existing soil preference data is migrated or replaced
• Tests pass for all new functionality
• Documentation is updated

Breaking Changes

This implementation will replace the current soil preference system, requiring:

• Database schema changes
• API response format changes
• Admin interface updates
• Potential data loss of existing soil texture preferences (acceptable per requirements)