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.