1. Recognizing Soil Texture & Structure

2. PS U6 L4

3. Soil Texture Soil texture = proportions of sand, silt and clay
Property of the soil controlled by the size of individual grains or particles
Soil is usually made up of particles of widely varying sizes.
Soil texture expresses the average or combined effect of all these grain sizes

4. 3 Soil Textures
Sand
Silt
Clay

5. Feel that soil!
Sand: In the moist condition sand should feel gritty and will be loose and single grained. Squeezed when wet, it will fall apart when the pressure is released
Clay: when moist is quite plastic and sticky when wet. When the moist soil is squeezed out between the thumb and fore finger, it will form long flexible ribbons.
Silty Soil: when dry and pulverized will feel soft and floury. When wet the soil readily runs together and puddles. When squeezed between the thumb and finger it will ribbon but the ribbon will appear checked and cracked.

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

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

9. Coarse Soils
Sand
Loamy Sand
Sandy Loam

10. 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)

11. 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

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

13. 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

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

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

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

17. 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

18. Types of Soil Structure
Platy
Prismatic
Columnar
Angular Blocky: Block-like – three dimensions of same magnitude
Subangular blocky: same as angular except the vertices are more rounded
Granular
Crumb: similar to granular except the peds are porous

19. Class of Structure
Size of individual ped

20. Good Soil Structure Good Soil Structure:
Necessary for good water penetration into the soil
Water holding capacity
Ease of working the soil
Good root penetration
Favorable movement of soil air
Availability of plant nutrients
Good internal drainage

21. 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