1. Soil Profiles and Sampling

2. Objective 5.02
Discuss the soil profile and soil sampling for surface and subsurface layers

3. What is the physical make up of soil?

4. Soil Profile Layers of soil are called horizons Typical profile in NC
A Horizon-topsoil
most fertile
most organic matter
top or first layer
B Horizon-subsoil
C Horizon-bedrock

5. Soil Profile
A Horizon
B Horizon
C Horizon

6. Soil Profile

7. O-Horizon
Rich soil found where a plant cover has been in place for an extended time
Rich in organic matter
O horizon is rich in organic matter in various stages of decomposition and is dark in color
Most fertile layer in the soil profile

8. A-Horizon Topsoil and most fertile in absence of O horizon
Lies just below O horizon
Home to earthworms and soil organisms
Brown in color due to organic matter in soil

9. B-Horizon Subsoil Clayey soil that has a high mineral content
Usually brown or reddish due to large amount of clay

10. C-Horizon Parent material
Consist mainly of clumps of un-weathered rocks

11. R-Horizon Bed rock Cannot be dug by hand
Very few roots can penetrate bedrock

12. Soil Structure How particles cluster together single grain
granular (best for most plants)
blocky
platy
massive

13. Soil Structure How the soil particles fit together
Sandy soils typically have loose soil structure
Silty soils have a granular soil structure
Clayey soils have a blocky or platy structure
Granular soil structure is best
Plants have good root development
Water movement isn’t too fast or too slow

14. Soil Structure
Single Grain

15. Soil Structure
Granular

16. Soil Structure
Blocky

17. Soil Structure
Platy

18. Soil Structure
Massive

19. Soil Structure
Soil structure is more important to producers who grow plants in natural soils
Producers of container grown plants add ingredients to make growing media desirable

20. Soil Texture Size of particles Types of textures clayey loamy Sandy
silty

21. Clayey Texture Small particles Has a high water-holding capacity
most common texture in western NC

22. Loamy texture About equal parts of sand, clay and silt
Ideal texture for most non-container outside plants

23. Silty Texture Medium sized particles
Good moisture and nutrient holding capacity

24. Sandy texture Large particles Low moisture-holding capacity
Most common in eastern NC

25. Soil pH Measurement of acidity or alkalinity from 0 to 14
Acid-less than 0-6.9
Alkaline-more than 8-14
Neutral - 7
Most organic matter is acid
Most artificial media is neutral
Ideal pH for most gardens is 5.5 to 7.0

26. Soil pH Lime will raise the pH value in soils (make it less acidic)
Calcium or sulfur will lower the pH value in soils (make it more acidic)

27. Physical Properties of Soils
Permeability
rate at which water moves through the soil
Water holding capacity
ability of a soil to hold water for plant use
Porosity
amount of air space between soil particles

28. Physical Properties of Soils
50% of soil should be pore space
25% water space
25% air space.
50% of soil should be soil particles
45% mineral matter
5% organic matter

29. Soil Makeup

30. Soil Sampling
Soil sampling and testing is essential for an accurate fertilizer recommendation for growing plants.

31. Soil Sampling Procedures
Create a visual grid of the area to be planted.
For gardens and landscapes, take 5-10 sub-samples
Sample before the growing season.
Use a stainless steel soil-sampling probe.
Take the surface sample to tillage depth
about 3-4 inches for lawns
6-8 inches for crops
Mix the soil samples together.

32. Soil Sampling Procedures
Remove any grass, rocks or other material besides soil.
Avoid unusual spots
Problem areas need to be sent in a separate box.
Place soil samples in a box
Obtain from the County Extension Office along with Soil Sample Information sheet
Send the box and information to:
Agronomic Division Soil Test Lab in Raleigh for a free soil test.

33. FFA Land Judging CDE