Post on 14-Dec-2015
STRUKTUR TANAH
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.
Struktur tanah
Struktur granular
Struktur prismatic
Cause and Effect
(description in laboratory)
+ Flocculation
Pembentukan strktur tanah
(chemical)
Luas Permukaan
- aggregate of small particles
- large grain
vs
Agregasi
Pembentukan struktur tanah
Organik dan Anorganik ‘glues’
Lateral
Stress Forces(what breaks the ‘glue’)
Verti
cal
Spheriodal
Granular
Sruktur tanah :
Surface Horizons
Pengelolaan yang tidak baik
Granular
Massive
Pemadatan horison permukaan
- Platy Structure - compaction
---- Prismatik ----
Struktur tanah:Lapisan bawah
Increased length in vertical direction
lateral stress > vertical stress
Blocky Structure:(subsurface horizons)
Increased (relative) age equates stress fractures
Volcanic Ash Soil
Timber Harvest
(With Structure)Granular Block
y
Prismatic
Columnar
Platy
Soil Structure
Columnar structure occurs in dry, desert soils with high sodium content
Single GrainedMassive
Soil Structure (continued)Without Structure
Pencil is 19 cm
Soil ConsistenceSqueeze 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.*
Extremely Firm The ped can’t be crushed with your
fingers (you need a hammer!).
Firm The ped breaks when you apply a good amount of pressure and dents your fingers before it breaks.
Friable The ped breaks with a small amount of pressure
* Soils with “single grained” structure always have loose consistence.