1. Recognizing Soil Texture & Structure

2. Student Learning Objectives
After this lesson students will be able to:
Distinguish sand, silt and clay soil particles.
Use the soil texture triangle to determine soil textures.
Describe the texture of soil particles.

3. PS U6 L4

4. Soil Texture Soil texture = proportions of sand, silt and clay
Property of the soil controlled by the size of individual grains or particles

5. Soil Texture
Soil is usually made up of particles of widely varying sizes.
Soil texture expresses the average or combined effect of all these grain sizes

6. 3 Soil Textures
Sand
Silt
Clay

8. Fine Textured Soils Clay Sandy Clay Clay Loam Silty Clay
Silty Clay Loam

9. Medium Textured Soils
Sandy Clay Loam
Loam
Silt Loam
Silt

10. Coarse Soils
Sand
Loamy Sand
Sandy Loam

11. Soil Structure
the combination or arrangement of primary soil particles into secondary particles, units, or peds (which are separated from adjourning aggregates by surfaces of weakness)

12. Soil Aggregation
The cementing or binding together of several soil particles into a secondary unit, aggregate, or granule **clods are different – they are caused by some disturbance such as plowing or digging

13. Consistence
The resistance of a material of deformation or rupture – the degree of cohesion or adhesion of the soil mass

14. Structureless soil
Soil where the particles of coarse soil fail to cling together, when fine soil breaks into large clods, or when the soil is massive, a single compacted substance

15. Platy Structure
Soil aggregates developed along the horizontal direction: flaky

16. Prismatic Structure
A soil structure type with a long vertical axis that is prism shaped, vertical faces are well defined, without rounded caps

17. Columnar Structure
Vertically oriented, round-topped structural prisms – rounded caps

18. Granular Structure
A natural soil ped or aggregate – have plane or curved surfaces which have slight or no accommodation to the faces of surrounding peds

19. Types of Soil Structure
Angular Blocky: Block-like – three dimensions of same magnitude
Subangular blocky: same as
angular except the vertices
are more rounded

20. Good Soil Structure
Good Soil Structure:

21. Good Soil Structure Good Soil Structure:
Necessary for good water penetration into the soil
Water holding capacity
Ease of working the soil

22. Good Soil Structure Good root penetration
Favorable movement of soil air
Availability of plant nutrients
Good internal drainage

23. Binding Agent in the soil
Organic matter converted to humus is the chief binding agent for stable soil structure.
Continuous cultivation and never plowing under any organic matter tends to destroy structure

24. What questions do you have?