1. STRUKTUR TANAH

2. Soil Structure
Structure – arrangement of individual particles in relation to each other. Soil structure is the arrangement of particles into small groups, or aggregates.
Aggregates may be bound together with other aggregates in larger masses called peds.
Peds come in different shapes that roughly resembel sphere, blocks, columns and plates.
If the individual particles are arranged in small aggregates with rounded edges, we speak granular structure. This is very desirable for plant growth bc it provides both large and small pores.
Some soils lack structure. Sandy soils the individual grains act independently of each other. No binding substances hold the particles together, so the soil has no peds.

3. (description in laboratory)
Struktur tanah
Struktur granular
Cause and Effect
(description in laboratory)
Struktur prismatic

4. Pembentukan strktur tanah
Flocculation +
(chemical)

5. Luas Permukaan vs
- large grain
- aggregate of small particles

6. Pembentukan struktur tanah
Organik dan Anorganik ‘glues’
Agregasi

7. (what breaks the ‘glue’)
Stress Forces
(what breaks the ‘glue’)
Vertical
Lateral

8. Sruktur tanah :
Surface Horizons
Spheriodal
Granular

9. Pengelolaan yang tidak baik
Massive
Pengelolaan yang tidak baik
Granular

10. Pemadatan horison permukaan
compaction
- Platy Structure -

11. Struktur tanah: ---- Prismatik ---- Lapisan bawah
Increased length in vertical direction
lateral stress > vertical stress

12. (subsurface horizons)
Blocky Structure:
(subsurface horizons)
Increased (relative) age equates stress fractures

13. Timber Harvest
Volcanic Ash Soil

14. Soil Structure (With Structure) Granular Blocky Columnar Prismatic
Platy

15. Columnar structure occurs in dry, desert soils
with high sodium content

16. Soil Structure (continued)
Without Structure
Single Grained
Massive
Pencil is 19 cm

17. Squeeze a moist soil ped to see if it is:
Soil Consistence
Squeeze a moist soil ped to see if it is:
Loose* You have trouble picking out a single ped and the structure falls apart before you handle it.*
Friable The ped breaks with a small amount of pressure
* Soils with “single grained” structure always have loose consistence.
Firm The ped breaks when you apply a good amount of pressure and dents your fingers before it breaks.
Extremely Firm
The ped can’t be crushed with your fingers (you need a hammer!).