Page 18 - World Reference Base for Soil Resources of Thailand

Land Development Department Library

Key to the Reference Soil Groups RSG Code

5. Pronounced accumulation of organic matter in the mineral topsoil

Very dark topsoil, secondary carbonates: Chernozems* CH
Dark topsoil, secondary carbonates: Kastanozems KS

Dark topsoil, no secondary carbonates (unless very deep),
high base status: Phaeozems PH

Dark topsoil, low base status: Umbrisols* UM

6. Accumulation of moderately soluble salts or non-saline substances
Accumulation of, and cementation by, secondary silica: Durisols* DU
Accumulation of secondary gypsum: Gypsisols** GY

Accumulation of secondary carbonates: Calcisols** CL

7. Soils with clay-enriched subsoil
Interfingering of coarser-textured, lighter coloured material into a
finer-textured, stronger coloured layer: Retisols** RT

Low-activity clays, low base status: Acrisols AC

Low-activity clays, high base status: Lixisols LX
High-activity clays, low base status: Alisols* AL

High-activity clays, high base status: Luvisols LV

8. Soils with little or no profile differentiation
Moderately developed: Cambisols CM

Sandy: Arenosols AR

Stratified fluviatile, marine and lacustrine sediments: Fluvisols FL

No significant profile development: Regosols RG

Remarks: ** RSGs is not found in Thailand (6 RSGs)

* RSGs is not found in Thailand and may need further classification (8 RSGs)

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