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.

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

Pembentukan strktur tanah Flocculation + (chemical)

Luas Permukaan vs - large grain - aggregate of small particles

Pembentukan struktur tanah Organik dan Anorganik ‘glues’ Agregasi

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

Sruktur tanah : Surface Horizons Spheriodal Granular

Pengelolaan yang tidak baik Massive Pengelolaan yang tidak baik Granular

Pemadatan horison permukaan compaction - Platy Structure -

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

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

Timber Harvest Volcanic Ash Soil

Soil Structure (With Structure) Granular Blocky Columnar Prismatic Platy

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

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

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!).