Soil Order Names and Their Formative Elements

Soil Order Names and Their Formative Elements

Order	Formative Element	Derivation	Mnemonicon
Entisol	ent	(nonsense syllable)	recent
Inceptisol	ept	L. - inceptum, beginning	inception
Aridisol	id	L. - aridus, dry	arid
Spodosol	od	Gr. - spodos, wood ashes	podzol; odd
Ultisol	ult	L. - ultimus, last	ultimate
Mollisol	oll	L. - mollis, soft	mollify
Alfisol	alf	(nonsense syllable)	pedalfer
Oxisol	ox	Fr. - oxide, oxide	oxide
Histosol	ist	Gr. - histos, tissue	histology
Vertisol	ert	L. - verto, turn	invert
Andisol	and	Sp. - Andes	andesite
Gelisols	el	L. - gelare, freeze	gelifluction

Simplified Key to Soil Orders

If soil has: Order

1. Soils with permafrost within 2 m of the surface Gelisols

2. More than 30% organic matter to a depth of 40 cm Histosols

3. Other soils with a Spodic horizon within 2 m Spodosols

4. Other soils that have andic soil properties in 60% or more of the soil thickness Andisols

5. Other soils with an Oxic horizon within 2m and no argillic horizon Oxisols

6. Other soils with more than 30% clay in all horizons; some cracks when dry at 50 cm Vertisols

7. Other soils that are dry more than 50% of the year and have no mollic epipedon Aridisols

8. Other soils that have an Argillic horizon but has a base saturation <35% at 1.8 m Ultisols

9. Other soils that have a Mollic epipedon Mollisols

10. Other soils that have an Argillic horizon Alfisols

11. Other soils that have an Umbric, Mollic, or Plaggen epipedon, or a Cambic horizon Inceptisols

12. Other soils Entisols