2Soil StructureStructure – 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 tanahStruktur granularCause and Effect(description in laboratory)Struktur prismatic
4Pembentukan strktur tanah Flocculation+(chemical)
5Luas Permukaanvs- large grain- aggregate of small particles
6Pembentukan struktur tanah Organik dan Anorganik ‘glues’Agregasi
7(what breaks the ‘glue’) Stress Forces(what breaks the ‘glue’)VerticalLateral
8Sruktur tanah :Surface HorizonsSpheriodalGranular
9Pengelolaan yang tidak baik MassivePengelolaan yang tidak baikGranular
10Pemadatan horison permukaan compaction- Platy Structure -
11Struktur tanah: ---- Prismatik ---- Lapisan bawah Increased length in vertical directionlateral stress > vertical stress
12(subsurface horizons) Blocky Structure:(subsurface horizons)Increased (relative) age equates stress fractures
15Columnar structure occurs in dry, desert soils with high sodium content
16Soil Structure (continued) Without StructureSingle GrainedMassivePencil is 19 cm
17Squeeze a moist soil ped to see if it is: 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.*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 FirmThe ped can’t be crushed with your fingers (you need a hammer!).