1. LandJudging in Oklahoma

2. The Dust Bowl Reasons? 100-125 Million Acres
April 14, 1935 (Black Sunday)
The Grapes of Wrath
NRCS
Conservation Methods?

3. Judging Land
When judging land we look at clues that tell us how well the land can produce. These clues include: soil texture, depth, slope, degree of erosion, permeability, surface runoff and flood potential

4. Describe Soil Texture?
Soil texture refers to the size of the individual soil particles, called soil separates.
Sand
Silt
Clay

5. Sand Sand has the largest particles of the three soil separates.
Feels gritty
Allows for good water drainage.
Not usually good for growing crops
Nutrients are washed away easily.

6. Silt Silt is finer than sand Feels powdery to the touch
Holds water and nutrients in the soil well, making it a good texture for growing crops.

7. Clay Clay is the smallest soil particles. Very hard when dry
Sticky when wet.
Don’t allow water to penetrate or drain well, making them less desirable for growing crops.

8. Just how big are these soil particles?
Sand Millimeters
Silt Millimeters
Clay Lower

9. What makes the best soil?
Most soils are a combination of sand, silt, and clay.
Soils that contain a mixture of:
52% sand
28-52% silt
7-27% clay
This mixture is called a loam and is ideal for crop production.

10. Soil Texture Affects? Soil permeability Water content Pore size
Water drains quickly through sandy soils
Water drains slowly through clay soils
Water content
Pore size
Aeration
Root penetration

13. Texture Classes
Coarse
Moderately Coarse
Medium
Moderately Fine
Fine

15. What is a soil profile?
Soil profile is a vertical; cross-section of a soil that exposes all of the built-up layers it is made of. In the soil profile you can usually see distinct layers of soil. These are called soil horizons.

16. Soil Depth
Soil depth is the total thickness of surface and subsoil soil that is favorable for root development.
Depth determines: amount of water, volume of soil available for root growth, and supply of nutreints

17. Soil Depth Deep: 40 inches or greater Moderately Deep: 20” to 40”
Shallow: 10” to 20”
Very Shallow: less than 10”

18. Slope Slope factors water runoff, erosion, and use of farm machinery.
Slope is the percentage of rise or fall over a 100-foot horizontal distance.
6 slope classes are recognized in Oklahoma Land Judging (CDE)

19. Slope Classes Nearly Level: less than 1% Gently Sloping: 1-3%
Moderately Sloping: 3-5%
Strongly Sloping: 5-8%
Steep: 8-15%
Very Steep: greater than 15%

20. Erosion Soil erosion is the detachment and movement particles.
Factors affecting erosion are water and air movement.
Four erosion classes are recognized.

21. Erosion Classes
None to slight: less than 25% of the surface soil has been removed and no gullies are presents
Moderate: 25-75% of the original surface soil is present. May have crossable gullies.
Severe: more than 75% of the original surface soil has been removed. May have crossable gullies.

22. Erosion Classes
Very Severe: more than 75% of the original surface soil has been removed. Uncrossable gullies are present.
Uncrossable Gullies: 6 inches deep X 12 inches across

23. Permeability
Refers to the movement of air and water through the soil profile.
Subsoil Texture
Permeability classes
Rapid- coarse texture
Moderate- moderately coarse/ medium
Slow- moderately fine
Very- fine

24. Surface Runoff Rate water is removed off the soils surface. Slope
Surface Runoff classes
Rapid-greater than 3%
Moderate- 1-3%
Slow- 0-1%
Very Slow- coarse texture subsoils

25. Land Capability Classes
I - suited cultivation, no limitations II
III IV
V - frequent flooding/ poor drainage
VI - grazing
VII - grazing
VIII – wildlife / recreaction

26. Land Capability Class Classes I-IV are considered Cultivated
Classes V-VIII are considered Non-Cultivated

27. Recommended Land Treatments
Vegetative
Mechanical
Fertilizer and Soil Amendments

28. Field Card