Land Judging in Oklahoma

James H. Stiegler, Extension Soils Specialist
Department of Plant and Soil Sciences

Guide to Capabilities and Treatment Practices
In order to insure uniformity in teaching, Tables 1 to 5 have been specially prepared. These tables are designed to show various combinations of soil, texture, permeability, depth, slope, erosion, runoff, wetness, and flooding that could occur, and the resulting capability class. Applicable treatments are also shown. Please study the special notes at the beginning and end of each table.

The following abbreviations are used in Tables 1 to 4.

V.S. = very slowly permeable or very slow surface runoff
S. = slow permeability or slow surface runoff
M. = moderately permeable, moderate erosion, or moderate surface runoff
R. = rapid permeability or rapid runoff
N. = none to slight erosion
Sev. = severe erosion
V.Sev. = very severe erosion
N.L. = nearly level
G.S. = gently sloping
M.S. = moderately sloping
Str. = strongly sloping
Steep = steep slopes
V.Steep = very steep slopes

 General Notes
Coarse Textured Soils -- Deep and Moderately Deep
1. Coarse surface soil texture is a major factor that keeps a soil out of Class I.

2. The best land capability class for coarse textured soils is Class III.

3. Slopes from 1 to 3 percent are considered a major factor, but will not lower the land capability class.

4. Moderate erosion will be checked as a major factor, but will not lower the land capability class.

5. Either very slow or rapid surface runoff will be checked as a major factor, except where the soil is rapidly permeable, but these factors will not lower the land capability class. 

6. Rapid permeability will be checked as a major factor, but it will not lower the land capability class. 

7. In combination with texture, slopes over 3 percent and severe or very severe erosion are major factors that lower the land capability class from III or IV to VI.

8. The best land capability class for coarse textured soils on slopes of less than 3 percent with severe or very severe erosion is Class VI.

9. The best land capability class for coarse textured soils on moderately sloping or strongly sloping soils is Class IV.

10. The best land capability class for coarse textured soils on moderately sloping or strongly sloping soils with severe or very severe erosion is Class VI.

11. The best land capability class for coarse textured soils on steep or very steep slopes is Class VI.

12. Shallow or very shallow, coarse textured soils will not be used in contests.

Table 1. Coarse Textured Soils -- Deep and Moderately Deep

Slope Erosion Perm-
eability		 Surface
Runoff		 Capability
Class		 Factors
that keep
land out
of Class I		 Vege-
tative
Treatment		 Possible
Mechanical
Treatment
use one
or more
N.L. N S S III 1 3,5,6 14,20
N.L. M S S III 1,4 3,5,6 14,20
N.L. Sev & V. S S VI 1,4 7,8,9,10 14,19,20
Sev 
G.S. N S M III 1,3 3,5,6 14,20
G.S. M S M III 1,3,4 3,5,6 14,20
G.S. Sev & V. S M VI 1,3,4 7,8,9,10 14,19,20
- Sev  - - - - - -
N.L. N M V.S. III 1,6 3,5,6 14,20
N.L. M M V.S. III 1,4,6 3,5,6 14,20
N.L. Sev & V. M V.S. VI 1,4,6 7,8,9,10 14,19,20
Sev 
G.S. N M M III 1,3 3,5,6 14,20
G.S. M M M III 1,3,4 3,5,6 14,20
G.S. Sev & V. M M VI 1,3,4 7,8,9,10 14,19,20
- Sev  - - - - - -
M.S. N M R IV 1,3,6 4,5,6 14,20
M.S. M M R IV 1,3,4,6 4,5,6 14,20
M.S. Sev & V. M R VI 1,3,4,6 7,8,9,10 14,19,20
Sev 
Str. N M R IV 1,3,6 4,5,6 14,20
Str. M M R IV 1,3,4,6 4,5,6 14,20
Str. Sev & V. M R VI 1,3,4,6 7,8,9,10 14,19,20
- Sev  - - - - - -
Steep All M R VI 1,3,6 also 7,8,9,10 14,19,20
V.Steep 4 if eroded
N.L. N R V.S. III 1,5 3,5,6 14,20
N.L. M R V.S. III 1,4,5 3,5,6 14,20
N.L. Sev.& V. R v.S. VI 1,4,5 7,8,9,10 14,19,20
- Sev. - - - - - -
G.S. N. R M III 1,3,5 3,5,6 14,20
G.S. M R V.S. III 1,3,4,5 3,5,6 14,20
G.S. Sev & V. R V.S. VI 1,3,4,5 7,8,9,10 14,19,20
Sev 
M.S. N R V.S. IV 1,3,5 4,5,6 14,20
M.S. M R V.S. IV 1,3,4,5 4,5,6 14,20
M.S. Sev & V. R V.S. VI 1,3,4,5 7,8,9,10 14,19,20
- Sev  - - - - - -
Str. N R V.S. IV 1,3,5 4,5,6 14,20
Str. M R V.S. IV 1,3,4,5 4,5,6 14,20
Str. Sev & V. R V.S. VI 1,3,4,5 7,8,9,10 14,19,20
Sev 
Steep, V. all R all VI 1,3,5 also 7,8,9,10 14,19,20
Steep 4 if eroded

Moderately Coarse, Medium, Moderately Fine, and Fine Textured Soils --- Deep and Moderately Deep
1. Surface soil texture is not a major factor that keeps a soil out of Class I.

2. The best land capability class for moderately coarse, medium, moderately fine, and fine soils is Class I.

3. Slope of less than 1 percent is not a major factor.

4. Slope over 1 percent is a major factor and will lower the land capability class.

5. Very slow permeability is a major factor and will further lower the land capability class by one unit on land Classes I through IV.

6. Very slow surface runoff is a major factor and it will lower the land capability by one unit.

7. Rapid surface runoff is a major factor, but it will not lower the land capability class.

8. Moderate erosion is a major factor that will lower the land capability class on slopes less than 3 percent. Moderate erosion is a major factor, but it will not lower the land capability class on slopes over 3 percent.

9. The best land capability class for severe and very severely eroded soils is Class VI.

10. The best land capability class for moderately coarse, medium, moderately fine and fine soils on 0 to 1 percent slopes that is moderately wet is Class II. Wet soils can be no better than Class V. The degrees of wetness will be given. Wetness will be checked as a major factor and will lower the land capability class.

11. On nearly level slopes, moderate erosion can occur. However, such a condition will not be used in land judging contests.

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