1. Soil Properties
Unit 5.02

2. Soil profile Soil layers are called horizons O Horizon A Horizon
B Horizon
C Horizon
R Horizon

3. Soil profile

4. Soil profile
O Horizon
Rich in organic matter in various stages of decomposition
Dark in color
Most fertile layer in soil profile

5. Soil profile A Horizon Is the topsoil Lies just below the O Horizon
Home to earthworms and soil organisms
Brown in color due to organic matter in the soil

6. Soil profile B Horizon Is the subsoil
Is a clayey soil with a high mineral content
Usually brown or reddish due to the large amount of clay

7. Soil profile C Horizon Is parent material
Consists mainly of clumps of un-weathered rocks

8. Soil profile R Horizon Is bed rock
Cannot be dug by hand and very few roots can penetrate the bedrock

9. Soil profile foldable
Use construction paper and markers/crayons/colored pencils to show the layers of soil.
Fold paper hotdog style.
Open paper and draw the horizons.
Cut a flap for each horizon.
Write the horizon names on the top flaps and the information about each horizon from our notes on the back.

10. Soil texture
Sand
Silt
Clay
Loam

11. Soil texture Sand Largest particles
Low moisture and nutrient holding capacity

12. Soil texture Silt Medium sized particles
Good moisture and nutrient holding capacity

13. Soil texture Clay Smallest size particles
High water and nutrient holding capacity

14. Soil texture Loam Equal parts of sand, silt, clay
Ideal texture for most non container outside plants

15. Soil structure Refers to how the soil particles fit together
Sandy soils typically have a loose soil structure
Silty soils have a granular soil structure (best for plants)
Clayey soils have a blocky or platy structure

16. Soil structure
Sandy – single grain

17. Soil structure
Silty - granular

18. Soil structure
Clayey – blocky or platy

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

20. 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

21. Profiling Soil

22. Soil pH Soil pH is a measure of the acidity or alkalinity of soils
Soil pH ranges from 0-14
7 is neutral
The ideal pH value for vegetable gardens are 5.5-7

23. Soil pH Acidic Soils 0-6 (low pH) is considered an acid soil
Lime can be added to raise the pH value and make it less acidic

24. Soil pH Basic Soils 8-14 (high pH) is considered an alkaline soil
Calcium or sulfur can be added to lower the pH value and make it more acidic

25. Soil sampling
Soil sampling and testing is essential for an accurate fertilizer recommendation for growing plants
For gardens and landscapes, take 5-10 subsamples from the site to be evaluated
Sample before the growing season

26. Soil sampling Soil sampling procedures
Create a visual grid of the area to be planted
Use a stainless steel soil-sampling probe
Take the surface sample to tillage depth or about 4” for lawns and 6-8” for crops
Mix the soil samples together
Remove any grass, rocks, or other materials not soil
Avoid unusual spots in the lawn or field (those areas can be sampled and sent separately)
Place soil samples in a box (provided by your County Extension Office) and send in with a Soil Sample Information sheet to the Agronomic Division Soil Test Lab in Raleigh for a free soil test