Page 18 - E-BOOK English

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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