Soil Classification Survey

1. Soil Classification & Survey

2. Objectives Describe the current USDA soil classification system Explain how soil surveys are prepared and used List soil capability classes

3. Soil Classification Soil survey Depends on system of grouping soils of like properties Soil classification Helps us to understand, remember, and communicate knowledge about soils

4. History of Soil ClassificationA continual process 1900s – soils grouped based on soil forming-factors that created them 1938, 1949 – further systems developed 1960 - USDA introduced current classification system 1975 – modified this system 1998 – 12th soil order added

5. Current system in publication: Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys Based on soil properties System is still evolving Other countries have different systems

6. Soil Classes Hierarchical system of levels: Order (12) Suborder (66) Great Group (>320) Subgroup (>1,400) Family (>8,000) Series (>19,000) (Phases) – not an official level

7. Soil Orders Highest level, Broadest group 12 orders Based on: diagnostic horizons climate

8. Soil Orders Alfisols Andisols Aridisols Entisols Gelisols Histosols Inceptisols Mollisols Oxisols Spodosols Ultisols Vertisols

11. Distribution Map of Soil Orders US Map: http://www.nrcs.usda.gov/technical/land/lgif/m4025l.gif World Map: http://soils.ag.uidaho.edu/soilorders/i/worldorders.jpg Soil Orders: http://soils.ag.uidaho.edu/soilorders/maps.htm

12. Soil Order Maps and Descriptions Classification of each order: http://soils.usda.gov/technical/classification/orders/ Posters: http://soils.usda.gov/technical/soil_orders/

13. Gelosols Very cold soils of tundra, cold deserts, or high peaks with subsoil permafrost Often with muck or peat surfae soil Mostly Alaska Very fragile Typical profile: O-A-Cf Uses: None safely, except wildlife http://soils.usda.gov/technical/classification/orders/gelisols.html

14. Histosols Organic soils, usually wetlands Organic matter >20-30% Very low density Must be drained for use, then prone to subsidence and fire Northern Midwest and Atlantic/Gulf coastal areas Typical profile: O1-O2-O3-C Uses: wetlands, forest, horticulture, fuel http://soils.usda.gov/technical/classification/orders/histosols.html

15. Spodosols Light colored, arid coarse soils, typically under coniferous forest Usually of cool humid regions, but not always Illuviation of iron or aluminum-humus complexes in B horizon Low base saturation, infertile Upper Midwest to Northeastern states Typical profile: A-E-Bs (or Bhs) - C Uses: Forest, pasture, cropland http://soils.usda.gov/technical/classification/orders/spodosols.html

16. Andisols Recent volcanic material Dark, fertile, high CEC and OM Often on volcanic slopes and high altitude Pacific Northwest, Hawaii, Alaska Uses: Cropland, forest http://soils.usda.gov/technical/classification/orders/andisols.html

17. Oxisols Highly weathered tropical soils, often under rainforests Subsurface horizon low in weatherable minerals but high in aluminum or sesquioxide clays Low native fertility, but can be fertilized Hawaii and Puerto Rico Typical profile: A-Bo (or Bv)-C Uses: cropland, forest, shifting agriculture http://soils.usda.gov/technical/classification/orders/oxisols.html

18. Vertisols High in swelling clays in climates with dry season When dry, large, deep cracks form that surface soil falls into, mixing the soil Unstable for engineering uses Most common in Southcentral states, especially Texas, some in upper plains states Typical profile: A-AC-C Uses: range and pasture, cropland http://soils.usda.gov/technical/classification/orders/vertisols.html

19. Aridisols Arid soils of cool to hot deserts and dry shrublands Oftlen alkaline with salted horizons Thin or no O or A High base Western states Typical profile: A-Bt-Ck or Ckm, Cy, Cz Uses: range, irrigated cropland http://soils.usda.gov/technical/classification/orders/aridisols.html

20. Ultisols Highly weathered soils of humid warm climates, often under forest Low base saturation (<35%), acid, leached Soilsoil layer with illuviated silicate clays Surface layer light colored, subsoil often red clay Productive, if properly fertilized and limed Southeast states mostly Typical profile: A-E-Bt-C Uses: forest, cropland

21. Mollisols Mostly grassland soils Dark, thick, high organic matter and base A horizon Low to moderate rainfall May have illuvial or calcareous subsoil Highly fertile and productive Great Plains and Northwest states Typical profile: A1-A2-A3-Bw-C Uses: croplands, range

22. Alfisols Deciduous forest soils of temperate moist climates Light colored Slightly to moderately acidic Illuvial layer high in silicate clays Medium to high saturation Fertile soil North central states Profile: O-A-E-Bt-C Uses: cropland, forest, range http://soils.usda.gov/technical/classification/orders/alfisols.html

23. Inceptisols Minimal horizon development, but more than Entisols Often young May have weak B horizon by color/structure; no illuviation Extremely variable, widely scattered in US Typical profile: A-Bw-C Uses: Cropland, forest, range http://soils.usda.gov/technical/classification/orders/inceptisols.html

24. Entisols Lack well-developed horizons Young, or conditions inhibit horizon development – sandy, wet, alluvial, steeply sloped Least developed soil order Typical profile: A-C Uses: range, cropland, forest, wetlands http://soils.usda.gov/technical/classification/orders/entisols.html

25. Soil Classes Hierarchical system of levels: Order (12) Suborder (66) Great Group (>320) Subgroup (>1,400) Family (>8,000) Series (>19,000) (Phases) – not an official level Suborder – next highest level, differ most often in soil moisture or temperature, maybe other factors, name includes latin or greek root provide info about suborder and ends in several letters that identify the order to which it belongs. Ex: psamment (Entisol), has highly sandy soils. Psamm – sandy, -ent for Entisol Suborders, divided into: Great Groups – often based on certain key horizons but may differ by other traits – soil moisture, temp. Named by adding prefix to the suborder name. Ex: Udipsamment (sandy Entisol, moderately moist – prefix Udi-). Great groups divided into Subgroups – expressed as either typical (Typic Udipsamment) or some variant name in front Subgroups divided into Families – units of a subgroup with similar properties important to growth of plants and soil use, such as subsoil particle sizes or minerals found in soil. Naming system for families fairly complex All words used are in Soil Taxonomy Soil Series – concerns users of soils most Suborder – next highest level, differ most often in soil moisture or temperature, maybe other factors, name includes latin or greek root provide info about suborder and ends in several letters that identify the order to which it belongs. Ex: psamment (Entisol), has highly sandy soils. Psamm – sandy, -ent for Entisol Suborders, divided into: Great Groups – often based on certain key horizons but may differ by other traits – soil moisture, temp. Named by adding prefix to the suborder name. Ex: Udipsamment (sandy Entisol, moderately moist – prefix Udi-). Great groups divided into Subgroups – expressed as either typical (Typic Udipsamment) or some variant name in front Subgroups divided into Families – units of a subgroup with similar properties important to growth of plants and soil use, such as subsoil particle sizes or minerals found in soil. Naming system for families fairly complex All words used are in Soil Taxonomy Soil Series – concerns users of soils most

26. Soil Series Smaller units of soil families More than 19,000 Taxonomic unit with narrowest range of features All pedons within a series have similar soil profiles – polypedon

27. Soil Series (cont’d) Named based on location where first identified – town, county, area Lowest official category in soil taxonomy – but is subdivided into Phases Phase – variation of a series based on some factor that affects soil management Examples: slope, erodibility, stoniness

28. Soil Survey USDA developed soil classification system for use in soil surveys Classifies soils Provides a mapped location of soils Describes soil as appears in field Most surveying done by NRCS – Natural Resources Conservation Service

29. Soil Survey Report Harford County Soil Survey, issued 1975 Contains: Taxonomy of soil Soil description Soil properties of each horizon Suitability rating – engineering, water management projects, recreation, cropping, woodland, habitat for wildlife

30. Land Capability Classes Indicates best long term use for the land Uses include: Cropping, pasture, rangeland, woodland (for lumber), recreation, and wildlife Capability Classes – NCRS recognizes 8 classes

31. Land Capability Classes NRCS recognizes 8 land capability classes Numbered I to VIII Class I soils – fewest limitations Class VIII – most limited, unsuitable for agriculture Erosion hazard due to slope is main criterion

32. Class I Soils Few limitations May be heavily cropped, pastured, or managed for woodlands or wildlife Well drained and nearly level Fertile, easy to manage Crops are most profitable Prime & productive soils are Class I, II, III soils

33. Class II Soils Suitable for all uses Have mild limitations Need moderate soil conservation when cropped Can be: Gently rolling, moderate erosion hazard, shallow soil, less than ideal tilth, slight alkali or saline conditions, or slightly poor drainage

34. Class III Soils Can grow same crops as Class I and II soils, but … Must address serious problems such as: Moderately steep slopes; high erosion hazard; Poor drainage; very shallow soil; Droughtiness; low fertility; moderate alkali or saline conditions; or unstable structure Special conservation methods needed – limit number of row crops, favor closely-grown crops Lowest soil class safely used for all crops

35. Class IV Marginal for cultivated crops Same limitations as Class III, but more severe Maybe grow closely grown crops Must practice careful erosion control

36. Class V Not suited for cultivated crops May be used for range, pasture, woodlands, and recreation Level soils, little erosion hazard, but … Limited by: flooding, short growing season, rockiness, wet areas that cannot be drained

37. Class VI Unsuitable for cultivated crops May be suited for pasture, range, wildlife, and woodland Problems include: Steep slopes, severe erosion hazard, established severe erosion, stoniness, shallowness, or drought

38. Class VII Same problems as Class VI But are more steep Difficult to maintain high quality pasture May be used for: Range, woodlot or forest, recreation, or wildlife, if carefully managed Slopes may be greater than 30%

39. Class VIII Cannot support any commercial plant production, even timber May be preserved for: Recreation, wildlife, or beauty Examples: Sandy beaches, rock outcroppings, heavily flooded river bottoms

40. Summary of Land Capability Classes Class I to III – cultivated crops Class IV – marginal land for cropping Class V to VIII – lands not suitable for cropping

41. Online Soil Data Geographic Information Systems (GIS) used to map soil data Integrates information on: Soils, topography, land cover, land use, ownership, watersheds, and geology http://websoilsurvey.nrcs.usda.gov

42. Land Capability of United States 43% of U.S. soil rates Class I to III Rest suitable for some form of commercial production – grazing or woodland Good soils not distributed evenly through U.S. Corn belt states – highest amount Northern Plains and Delta states West – too mountainous http://www.nrcs.usda.gov/TECHNICAL/land/meta/m6175.html 4343