Soil Survey: Backing Up to Look Forward and Revise the Map

1. Soil Survey:Backing Up toLook Forward andRevise the Map Ron Taskey Professor Emeritus California Polytechnic State University and Natural Resources Conservation Service

2. THE MAPPER’S JOB: Recognize, record, interpret, and convey meaningful soil geographic patterns. CONCEPTUAL METHOD Create taxonomicunits: Locate, describe, and classify a range of soils (pointdata). Create mapunits: Infer and delineate patterns of taxonomic units as revealed by spatialchanges in one or more of the soil-forming factors.

3. Develop soil-landscape models that correlate pointdata (taxonomic units) with landscape features to create spatialpatterns (map units).

4. Sounds good, but As much art as science. Relies on tacit knowledge. Learn and proceed by trial and error. Little written guidance. Concept––––––GAP–––––––Practice

5. Taxonomic units: based on elaborate, exacting, uniform criteria arranged in a strict written hierarchy (Soil Taxonomy). Map units: created from vague, unwritten criteria based on inferences from soil forming factors and anticipated land uses.

6. Challenges in Creating Map Units • Assigning priorities to soil forming factors. • Maintaining consistent priorities among mappers. • Maintaining consistency year to year. • Maintaining consistency across landscapes. • Dealing with problems of scale. • Adapting future survey updates. • Anticipating land uses and judging their longevity.

7. Problems • Different pedologists–different approaches–different priorities–different decisions. • Models rarely written. Few mappers record hypotheses, or explain rationale for map unit designs. • Taxonomic units: exacting, written criteria. Map units: uncertain, unwritten criteria. • Taxononomic units and map units are different concepts, but are named similarly. • Unclear, uncertain, or misleading connections between soil taxonomic units and map units. • Different scales require different approaches. • Confusion and misconception among clients, trainees, and other professionals.

8. What’s the root of the problem? What can we do about it? Back up and reconsider map unit concept.

9. To createtaxonomic units: • Select sites • Describe soils • Classify soils-Soil Taxonomy Rational-deductive-analytical –certain outcome

10. To createmap units: Infer taxonomic patterns revealed by spatial changes in one or more soil forming factors. Empirical-inductive-synthetic –uncertain outcome

11. Deduction Induction Established Principle, Definition, or Guidance New Principle, Definition, or Guidance Certain outcome Uncertain outcome

12. System for classifying soil-landscapes that isrational-deductive-analytical and structured as a natural hierarchy.i.e., a soil-landscape taxonomy to accompany soil taxonomy What’s Needed?

13. Soil-Landscape Taxonomy Land Type Component Subcomponent Element Modifier Soil Taxonomy Order Suborder Great Group Subgroup Family “Soil-Landscape Series” Series

14. Soil-Landscape Taxonomy (natural landscape hierarchy) Soil Taxonomy (Keys to Taxonomy) Map units and taxonomic units can be developed concurrently, nonetheless they are separate and distinct products. Interpretations (empirical-inductive-predictive)

15. Easy to teach, easy to learn.Not only what was done, but also how it was done.