Handout # 4.1

1. Handout # 4.1 • Map Unit Design • 12 EXERCISES: Based on the information provided, what would you do in designing and naming the map unit. PROVIDED: 12 exercises

2. Exercise 1 • Scenario: • Texas High Plains • Amarillo and Patricia soils; both are fine-loamy, mixed, superactive, thermic Aridic Paleustalfs • These soils are 95 percent cultivated • Almost all cultivated areas have been deep plowed to depths of 60 to 80 cm. • No range land vegetative indicators remain to help you • Very gently undulating with slope ranging from 0-3 percent but mainly 0-2 percent. Some areas have been leveled. • Surface horizon is loamy fine sand and ranges from 15 to 50 cm thick for both soils • The Argillic horizon is sandy clay loam and extends below 200 cm in both soils • In some areas, the depth to the Calcic horizon (Btk) is dominantly (>90%) less than 150 cm (90-150 cm) • In some areas, the depth to the Calcic horizon (Btk) is dominantly (>90%) greater than 150 cm • In other areas, the depth to the Calcic horizon (Btk) ranges from 90 to more than150 cm within a horizontal distance of less than 15 meters (depths intermingled, cannot be separated at scale) • There is no correlation between the undulation of the soil surface and the waviness of the Bt and the Btk (Calcic horizon) • Area is dominantly cropped to cotton with yields of ¼ bale to 1 bale for dryland and 1 bale to 3 bales for irrigated land, for both soils • Series separation criteria: • Depth to the Calcic horizon • Amarillo = 100-150 cm • Patricia = 150-200 cm • Using this information, complete the map unit design process for this landscape model.

3. Exercise 2 • Original Landscape: • Labelle-Spindletop complex • Labelle = Fine, smectitic, hyperthermic Oxyaquic Vertic Argiudolls • Somewhat poorly drained, plane to slightly concave intermound landscape position (45% of map unit) • Spindletop = Fine, smectitic, hyperthermic Oxyaquic Argiudolls • Moderately well drained, nearly level, 23-61 meters diameter circular mounds 30 to 91cm above the intermound landscape positions (45% of map unit) • Area is bulldozed to level mounds for rice production • Area is then water-leveled, covering the area with several inches of water and making a slurry of the surface by driving a tractor around until entire landscape stays under water • A 13-15 cm silt loam surface remains over entire area • Epipedon of Spindletop is destroyed but diagnostic horizon and features remain • Epipedon and diagnostic horizon and features of Labelle remain • The Levac series = Fine, smectitic, hyperthermic Oxyaquic Vertic Hapludalfs. It is somewhat poorly drained and has other properties similar to the Spindletop • New Landscape: • Labelle-Spindletop complex Labelle-Spindletop complex

4. Exercise 2 Original Landscape: Labelle-Spindletop complex • 6 Options: • Labelle-Spindletop complex • Alfic Udarents • Labelle-Levac complex • Labelle consociation • Levac consociation • Mollic Udarents

5. Exercise 3 • Scenario: • Variable depth to paralithic contact on the landform • Theta is very deep, Beta is moderately deep • Gamma, the “deep” (100-152 cm) component, has no known series • It is decided that Gamma is dissimilar to both Theta and Beta by current guidelines, and is nonlimiting to the Beta but limiting to the Theta • The unknown deep component’s extent is: • 10% on interfluves (summits and shoulders- 26B, 3-8% slopes). Interfluves are 7,500 acres in extent. Theta=50%, Beta=35%. • 18% on side slopes (shoulders and back slopes- 26C, 6-12% slopes). Side slopes are 11,000 acres in extent. Beta=50%, Theta=25%. • Past tradition followed in the previous survey of this area was to “bracket” this ‘component’ and not be concerned about recognizing it (map unit interps for mod deep and very deep). • Some thought has been given, during current map unit design, to combining the two map units (26B & 26C) because of overlapping slope phases • What would you do with this component? • What would you do with these 2 segments of the landscape model as far as map unit design?

6. Exercise 4 • Scenario: • Area occurs on forested mountain sideslopes • Two major components by extent, both classify as loamy-skeletal, isotic, mesic Andic Dystrudepts with gravelly medial loam surface texture • Both components correlate to the same ecological site • Area is 50% Theta, 25% Beta, 25% other minor soils • Theta is 50-100 cm deep to bedrock with a site productivity index of 120 • Beta is 100-152 cm deep to bedrock with a site productivity index of 150 • They are intermingled on the landscape with no consistent predictable landscape position to correlate components to. • How would you name this map unit? • Alternatives: • Theta-Beta complex, 20 to 50 percent slopes • Theta and Beta soils, steep • Theta gravelly medial loam, 20 to 50 percent slopes, with Beta as a similar inclusion • Theta gravelly medial loam, 20 to 50 percent slopes, with Beta as a dissimilar minor component • Other

7. Exercise 5 • Scenario: • Area is in rangeland with an undulating, complex 0 to 2 percent slope • The dominant soil is a fine, smectitic, frigid Typic Palexerolls • Soil has a dense claypan that limits rooting depth, occurring at 10-38 cm • 50 percent of the area has the claypan at 10-20 cm, with an ecological site dominated by low sagebrush • 30 percent of the area has the claypan at 20-38 cm, with an ecological site dominated by mountain big sagebrush • The difference in depth to the claypan is assumed to be from past erosion and re-deposition of the loam A horizon • The depth to the claypan has no predictable landscape position • Vegetation (type of sagebrush) consistently correlates to the depth to claypan • Area is of large extent • Given this setting, these properties, and the correlation to vegetation, what would you do? • Alternatives: • Recognize two components from two series (Theta and Beta) and two map units (consociations) • Recognize two components from two series and one map unit (complex) • Recognize two components from one series and one map unit (complex) • Recognize two components from two series and one map unit (undifferentiated group) • Recognize two components from one series and one map unit (undifferentiated group) • Recognize one component (Theta) and one map unit

8. Exercise 6 • Scenario: • Omega series • Omega series is; euic Typic Cryosaprists • Two map units with Omega soils named, but one has mineral soil material at 64 to 114 cm and it classifies as an ashy-skeletal, glassy, euic Terric Cryosaprists. • This soil is correlated to a different ecological site than the series. • There is 180 acres of Omega soils with mineral material below 130 cm in the survey area, 90 acres with the material between 64 to 114 cm in a National Park survey area where management concerns are high. • Is this soil a taxadjunct? YES NO • What would you design in this situation? • Alternatives: • One consociation map unit of Omega series with inclusions of mineral soil material in some areas • An undifferentiated group, Omega soils • A single map unit complex, Omega-Omega, mineral phase complex • Two map units, both consociations

9. Exercise 7 • Scenario: • Area is in glaciated Northeast on drumlin landforms, and was dominantly cropland and pasture, with some woodland when originally mapped. • Urban sprawl is eating up much of this area. MOU for maintenance project concentrates on data for engineering interpretations. Municipal waste water treatment is not available. Onsite treatment will not be permitted on slopes greater than 15%. Other uses may be permitted. • First generation survey recognized fragipans (Cx horizons) but did not distinguish differences in depth (one series fit all). Moderately deep root restricting layers were not recognized. All soils greater than 100 cm to a root restriction were called deep soils. All well drained soils with a Cx horizon were correlated to the Theta series in those days. • The current Theta OSD typical pedon has a densic contact at 81 cm, ranging from 50 to 100 cm. • Landform segments are well delineated in the old survey. • Documentation in the maintenance project found soils with Cd horizons at depths of 50 to 100 cm and 100 to 152 cm to the densic contact. • On the interfluve segment of the drumlin (map unit ThA, 0-3% slope), the depth is consistently moderately deep. • On the side slope and nose slope segments of the drumlin (map units ThC, 8-15% slope and ThD, 15-25% slope delineations), the depth is both moderately deep and deep, is somewhat inconsistent from one delineation to another (60% deep/40% moderately deep in one delineation; 40% deep/60% moderately deep in another), and cannot be correlated to any surface features. • What would you do? • How many map units and how many components? • What kind of map units and components would you use?

10. Exercise 8 • Scenario: • Map unit in a 1972 soil survey • Map unit Be–Beta clay, 0 to 1 percent slopes • Beta is poorly drained, a Aquic Chromoxererts and has frequent long duration flooding • **Current investigation findings: • Delineations of Be occur on an active flood plain and a low terrace • Delineations on the flood plain have frequent, long duration flooding and redox features from 30 to 150 cm • Delineations on the low terrace are in depressions, have frequent long duration ponding, rare flooding and redox features from 0 to 150 cm • What would you do to this soil component, its map unit and its delineations during project soil survey work? • 1) Nothing; clay is clay, surface water is surface water and interpretations are not significantly different. • 2) Something; but what? • How many map units? Name the map unit(s) • How many series? Give classification (subgroup) of the series; if classification is the same, what is the series criteria for separation?

11. Exercise 9 • Scenario: • 1980 published soil survey having 1975 map imagery. Field mapping completed in 1977 and field sheets were 1968 Black and White aerial photos. • Imagery on web soil survey shows polygon lines not conforming to new 2006 imagery • The problem map units and their delineations are three map units; the map units are: • Rw---Riverwash • Uf----Udifluvents, 0 to 3 percent slopes • W----Water • Users of the soil survey have lost confidence in the quality of the work because the soil lines no longer make sense! Areas mapped as Water now have vegetation. Areas which should have vegetation (Udifluvents) now appear as a miscellaneous area. • What would you do to address this quality issue?

12. Exercise 10 • Scenario: • The MLRA consists of internally drains lake basins, lake terraces and mountains. Livestock grazing and wildlife habitat are the major uses. • The basins in the southern part of the MLRA are mesic with the soils having a frost-free period of 100 to 130 days. The basins in the northern part of the MLRA are frigid with the soils having a frost-free period of 60 to 90 days. • In one of the northern frigid basins, a map unit polygon about 500 acres in size is characterized with a strongly saline-sodic soil component. A existing map unit in the southern warmer basins has a similar soil component. • The ecological site correlated to this soil component is reflecting the strong saline-sodic soil properties and no change is seen in the plant community on this component in the southern and northern basins. However, adjacent non-saline and non-sodic soils in the northern and southern basins do show a change in plant community/ecological site. • What will you do with this 500 acre polygon in correlation? • Use existing map unit and soil (mesic) from the southern basin and expand the frost-free period for the map unit and OSD? • Use existing map unit and soil from southern basin, do not expand the frost-free period for the map unit and put note in NASIS map unit text correlation notes? • Set up a new map unit and propose a new frigid series? • Set up a new map unit and taxadjunct to the mesic series, do or do not expand the frost-free period of the OSD? • Other?

13. Exercise 11 • Scenario: • MLRA-SSO project; initial mapping completed in 1984; two consociation map units have been delineated: • Be—Beta silt loam, 0 to 1 percent slopes • Bd---Beta silt loam, 0 to 1 percent slopes, partially drained • These two map units are intermingled on the same landform and have been delineated adjacent to each other. • Each map unit has a unique data map unit in terms of soil moisture, crop yield, etc. • The “degree” of drainage consists of surface ditches 6 to 12 inches deep to collect and remove ponded water and perimeter ditches upto 24 inches deep to collect the “ponded” water from the surface ditches and provide some internal drainage. Drain tiles are typically not installed. Partially drained areas are cropped and “undrained” areas are used for wildlife or improved pasture. • Over the past 25 years land use has changed, and areas mapped as Be are now drained and some partially drained areas (Bd) have had the drainage removed. • Attempting to delineate consociation map units of partially drained and not drained map units on this landscape is only accurate for the time in which the lines were drawn. Management and land use change quickly and are dependent on crop prices; thus mapping can be “outdated” quickly. • Given this changing land use, is there a map unit design that can be used on this landscape to address the drainage variability and still provide meaningful soil interpretations and soil properties?

14. Exercise 12 Scenario: Map unit—Alpha-Beta complex, 20 to 50 percent slopes. Land use is forlivestock grazing (rangeland) and wildlife habitat. Alpha soil is 50% composition, on south aspects, well drained and moderately deep. Beta soil is 35% composition, on north aspects, well drained and deep. Dissimilar minor components; *Theta soil is 8% composition, on slopes of 5 to 25%, somewhat poorly drained and very deep; Aquic Cumulic Haploxerolls. *Delta soil is 5% composition, on slopes of 20 to 50%, well drained and shallow; Lithic Argixerolls. *Rock outcrop is 2% composition, on slopes of 20 to 50%. In discussion with resource managers, the Theta soil is the most critical component for management as it corresponds tothe riparian areas in the unit. Based on user needs is thecurrent map unit the best design for the area? If yes, why? If no, why and what would you do different? • Nothing; as Theta is dissimilar and limiting but does not account for over 10% of the area, thus not a named major component. • Delineate the Theta component as a line segment map unit. • Delineate Theta as a polygon map unit by zooming into a 1:7,000 scale and digitally creating the polygon. • Include Theta as a third named major or minor component in the map unit name and expand the slope range of the map unit to 5 to 50%. • Other?