1. SOIL!
SOIL: Particles of minerals, organic matter (plant and animal), water, and air; that is found on most surfaces of the land.
It takes 100+ years to form 1-inch of topsoil

2. Soil Basics

4. Why do we study soils? Agriculture Engineering Construction
Conservation
Exploration/Mining
Natural History
Biodiversity

5. Basic Soil Facts
An average soil sample is made up of minerals, water, air, and organic matter.
A renewable resource- forms at rate of ~1 in in a 100 years
Plant roots loosen the soil, allowing oxygen to penetrate.
Plant Roots also hold soil together to prevent erosion.

6. Fertilizers Make plants grow faster- increase crop yields.
Key Macronutrients: N,P,K
Too much- causes soil acidification= stunts growth and/or kills plant. Results in crop reduction.

7. Soil Horizons
Weathered rock mixed with organic material (humus), mineral nutrients, microorganisms, water and air form soil.
Soil horizons
O horizon: organic material/surface
litter “HUMUS”
A horizon:”topsoil” layer; most
productive layer; Some HUMUS
- B horizon: subsoil; minerals
present here
C horizon/ parent material: lower
subsoil and Bedrock

8. Why Humus is Important? How humus improves soil conditions:
Provides nutrients/fertility for plants and soil organisms
Helps topsoil hold water (water-holding capacity)
Improves habitats for soil organisms
Improves buffering capacity, which stabilizes pH
Prevents erosion
Improves porosity

9. Soil Textures Soils have varying amounts of:
Clay – finest particles of rocks and minerals
Silt – fine particles of rock
Sand – medium-sized particles
Relative amounts of these materials determine soil texture

10. Chemical Properties of Soil
Cation Exchange Capacity
Cation: + charged mineral ions.
Cation exchange capacity (CEC)- nutrient holding capacity. It’s a function of the type and amount of CLAY particles present.
Clay and Organic Matter (HUMUS) have HIGH CEC
Soils with HIGH CEC = HIGH PRODUCTIVITY

11. High CEC soil retain the fertilizer and pesticides; Leaching occurs with low CEC (sandy soils)

12. Three Key test to KNOW for my TEST and APES TEST
PHYSICAL TESTS
Soil texture by measurement- use soil triangle.
Soil by texture- ribbon test.
Color of soil
CHEMICAL TESTS
Nitrogen level 2.Phosphorus level 3. pH

14. Soil texture by measurement

15. Soil Triangle
Provides a percent (%) composition of sediments that compose a soil
Loam soil has EQUAL parts of Sand, Silt, Clay. It’s ideal for most plants.

16. Soil Triangle Example: 50% sand 20% clay 30% silt
The percentage of sediments in the soil triangle must equal 100%

17. Soil Texture Determines porosity, permeability and structure of soil
Porosity: space between soil particles. Depends on the soil texture.
Permeability: rate at which water and air move from upper to lower soil layers. Clay has a low permeability.
Structure: way in which soil particles are organized and clumped together
pH: determines plants’ ability to take up nutrients from soil

18. Soil Lab Part II- DAY 2

19. Using the Soil Triangle
You will record your measurements for each layer of sediment- Amt clay, silt, etc. Recall clay will be at the top, followed by silt, then sand.
Calculate the %: Volume of X/ 25 x 100
Ex: silt= 15/25 x 100= 60% Repeat with clay and sand.

21. Soil Triangle Example: 50% sand 20% clay 30% silt
The percentage of sediments in the soil triangle must equal 100%

22. Animated Soil Triangle

23. What do the test tell you about your soil?
Did the ribbon test match your soil by measurement results? If not, why?
Consider the texture, porosity & permeability?
CEC? Recall combo of clay and humus= High CEC and High productivity
Level of nutrients?
What would you need to do to this soil to improve it?