1. Envirothon
Soil

2. Topics Soil Soil Formation Soil Texture Soil Color Organic Matter pH
Salinity
Soil Air
Compaction/Shrink-Swell
Drainage
Erosion
Soil Surveys

3. Typical Loamy Soil

4. Typical Clayey Soil

5. Typical Sandy Soil

6. Forming Factors Climate Living Organisms Parent Material Topography
Time

7. Climate Most influential factor
Temperature and precipitation in particular
Determines the nature and speed of formation
High Heat, High humidity, abundant rain=a lot of power

8. Living Organisms
Plants and animals
Grasses vs trees
Microorganisms

9. Parent Material Geology Gulf Coast was a fluvial deltaic system
Soils are derived from loamy and clayey sediments
About 14,000 years old

10. Topography
Nearly level
Slope occurs along drainage

11. Time Soils on flood plains and coast line are youngest
Stable landscapes have older soils
Takes about 500 years to form an inch of soil from hard parent material

12. Texture USDA % of Sand, Silt and Clay
Key factor chemically and physically
100% Clay
100% Sand
100% Silt
Percent Clay
Percent Silt
Percent Sand 90 80 70 60 50 40 30 20 10

13. Clayey Soils High Shrink-Swell High Organic Content
High Water Holding Capacity
Agriculturally productive
Difficult to work with

14. Sandy Soil High pore space Low organic matter Low fertility
Low water holding capacity
Easy to work with

15. Loamy Soil Wide array of soils Low to High Fertility
Low to High Organic content
Low to High Water Holding Content
Moderate to work with

16. Soil Color Dark=high organic content Light=low organic content
Red, yellow, brown is well drained
Gray could mean excessive wetness

17. Dark= High Organic
Most clayey soils in our area are dark and have high organic content

18. Light=Low organic content
<1 percent
Most loamy and sandy soils in our area are low in organic content

19. Well Drained High on the landscape Ridges and sloping areas
Yellow, red or brown
Black is usually well drained

20. Gray Could Be Wet Gray surface
Contains mottles (oxidized or reduced iron)
Concave landscape
Wet soils could be associated with wetlands!

21. Organic Matter
Accumulation of partially decomposed plant and animal residues
Loosens soil
Nutrient source for plants
Increases water holding capacity
Food for microbes

22. Soil Organic Matter
Highest in the surface where the majority of biotic activity occurs
Important to stockpile surface layer
Easily destroyed when disturbed

23. Increasing Organic Content
Warm and humid conditions are ideal for microorganisms
Constant struggle
Leave grass clippings, leaves, and twigs
Add mulch

24. Organic Matter Considerations
Carbon to Nitrogen ratio
Microbes use nitrogen to eat carbon
Could cause nitrogen deficiency in plants
Add nitrogen fertilizer
Will correct over time
Use good compost

25. Soil pH Ideal pH range is 5.5 to 7.5
pH >8.5 could mean high salt content
pH<4 Aluminum and Iron toxicity
pH meters
Add lime for soils less than 5.5 and sulfur for soils above 7.5
Local soils are in good pH range
Best to not get too worried about changing pH

26. Salinity A localized problem on Gulf Coast
Almost all soils have some salinity
Causes soil to become hard
Damages roots and stunts plants
Damages steel

27. Soil Air Well aerated soils support better plant growth
Mechanical aerator
Incorporate organic matter into the soil for a long term solution

28. Soil Compaction Occurs in high traffic areas
Occurs when soils are manipulated when wet
Plowing or incorporating organic matter decreases compaction
Minimize hazard of compaction by having a good thick layer of mulch on surface

29. Shrink and Swell All clayey soils do it
Swell when wet and shrink when dry
$$$$$ to fix damage

30. Soil Drainage Classes
Very poorly Drained—Water is at or near the surface during much of the growing season
Poorly drained—The soil is wet at shallow depths periodically during the growing season or remains wet for long periods.
Somewhat Poorly drained—The soil is wet at a shallow depth for significant periods during the growing season.
Moderately Well drained—Water is removed from the soil somewhat slowly during some periods of the year
Well drained—Water is removed from the soil readily, but not rapidly.
Somewhat Excessively Drained—Water is removed from the soil rapidly.
Excessively Drained—Water is removed from the soil very rapidly.

31. Drainage Poorly drained soils are gray with oxidized iron zones
Concave landscapes
Usually have water loving plants

32. Drainage Well drained are brown, yellow or red and most black soils
Convex landscapes
Avoid making depressions if you want the soil to stay well drained

33. Erosion Soil moved by wind or water
Occurs in high traffic areas where surface vegetation is gone
Areas with more than 3 percent slope are susceptible
Mulch and terraces (anything to slow wind and water down)

34. Soil Surveys
An inventory of soils that includes maps, interpretative tables, and soil descriptions for use in general land use planning

35. Using a Soil Survey
Locate your area of interest in the soil map section
Identify all of the soil map unit symbols at your area of interest

36. How to Use Soil Surveys
Go to the table that contain the information you seek
Find your map unit symbol and then find the land use practice
Table provides information on suitability for that soil for that particular land practice

37. References The Nature and Properties of Soils by N.C. Brady
NRCS Soils
Natural Resources Conservation Service – Texas
Soil Data Access
TAMU Department of Soil and Crop Sciences

38. Contacts USDA-Natural Resources Conservation Service
Rosenberg: ext 3
Angleton:
Temple State Soils Staff:
Rosenberg Soil Survey Office: ext 124