Reference soil Kenya 02: Andosol

KE002

Andosols occur throughout the world where volcanic activity is common, especially in the circum-Pacific region and along the mid-Atlantic Ridge.

Characteristics

Soils with a vitric or andic horizon (slightly to moderately weathered horizons in pyroclastic deposits dominated by short-range-order minerals, notably allophane and imogolite) starting within 25 cm from the soil surface. In addition, they may have a histic, fulvic, melanic, mollic, umbric, ochric, duric, or cambic horizon. Other diagnostic horizons (unless buried deeper than 50 cm by volcanic deposits) are absent.

Distribution of Andosols (rough estimation supplied by soilgrids)

Reference soil KE002: Andosols

A dark volcanic soil (turning to dark brown/dark reddish brown in Bb horizons) with common very fine pores below 17 cm, with a texture changing from silt loam to silty clay loam in 3 lower horizons. Due to its very high CEC (72) and its high percentage of nutrients and organic matter the soil can be considered very suitable for agricultural use.

Classification

WRB 2006

WRB 1998

Mollic-Silandic-Vitric- Andosol (Calcaric Siltic)

Molli-Vitric- Andosol (Calcaric)

0-41 cm	mollic horizon
0-49	calcaric
0-75	vitric
75-140	andic

0-41 cm	mollic horizon
0-41 cm	vitric horizon
75-140 cm	andic horizon
0-41	calcaric

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Silti-Mollic Andosol

Mollic Andosol

0-41 cm	mollic A horizon
0-140	andic / strongly humic

0-41 cm	mollic A horizon
-	exchange complex dominated by amorphous material

Other classification

USDA-NRCS (1999)	Typic Hapludand
USDA-SCS (1975)	Typic Eutrandept udic

Physical characteristics

Particle size distribution

Depth (cm)	Gravel % v/v	very coarse sand % w/w	coarse sand % w/w	medium sand % w/w	fine sand % w/w	very fine sand % w/w	Total sand % w/w	coarse silt % w/w	fine silt % w/w	Total silt % w/w	Clay % w/w
0-17	-	0.2	0.3	1.6	8.3	8.8	19.2	15	39.8	54.8	26.1
17-41	-	0	0.3	2.5	13.4	14.1	30.3	16.7	34.2	50.9	18.8
41-49	-	0	0.6	7.2	20.6	16.9	45.3	17.2	25.6	42.8	11.9
49-75	-	0	0.3	1.4	3.7	2.9	8.3	12.4	53.9	66.3	25.4
75-105	-	0	0.3	0.9	3.2	2.9	7.3	19.9	58.7	78.6	14.2
105-140	-	0.4	1.1	1.8	4.2	2.9	10.4	19.5	52	71.5	18.3

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-17	-	-	-	-	26.1
17-41	-	-	-	-	18.8
41-49	-	-	-	-	11.9
49-75	-	-	-	-	25.4
75-105	-	-	-	-	14.2
105-140	-	-	-	-	18.3

Chemical data

Depth (cm)	pH H2O	pHKCl	EC 1: 2.5 dS/m	CaCO3 % w/w	C % w/w	N %	C / N	Exch. Acid cmol(c)/kg	Exch. Al cmol(c)/kg	Ca cmol(c)/kg	Mg cmol(c)/kg	K cmol(c)/kg	Na cmol(c)/kg	Sum Cations cmol(c)/kg
0-17	6.7	6.1	0.41	2.1	9.99	0.92	11	-	-	33.0	4.1	1.5	0.1	38.7
17-41	7.1	6.2	0.14	1.5	4.30	0.37	12	-	-	19.5	3.5	0.9	0.0	23.9
41-49	7.1	5.9	0.10	0.9	1.79	0.14	13	-	-	8.6	2.5	0.7	0.0	11.8
49-75	6.3	5.2	0.09	-	4.50	0.33	14	-	-	14.7	4.9	1.6	0.0	21.2
75-105	6.3	5.3	0.14	-	3.99	0.34	12	-	-	15.8	4.3	2.6	0.1	22.8
105-140	6.2	5.1	0.08	-	2.90	0.31	9	-	-	7.8	3.1	3.9	0.1	14.9

Depth (cm)	Base sat. %	CEC soil cmol(c)/kg	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	ECEC cmol(c)/kg	Al sat. %	ESP %
0-17	55	70.7	271	35	-	-	0
17-41	66	36.0	191	15.1	-	-	0
41-49	61	19.4	163	6.3	-	-	0
49-75	49	43.4	171	15.8	-	-	0
75-105	44	51.3	361	14	-	-	0
105-140	30	50.3	275	10.2	-	-	-

Depth (cm)	pH NaF	P Retention %	ODOE	Al o % w/w	Si o % w/w	Fe d % w/w	Al d % w/w	Fe p % w/w	Al p % w/w	C p % w/w	Fe o % w/w
0-17	8.0	61	-	1.05	0.38	2.38	0.42	0.38	0.35	-	1.67
17-41	8.5	60	-	1.02	0.43	2.18	0.40	0.36	0.26	-	1.6
41-49	8.5	57	-	9.81	0.53	2.06	0.29	0.18	0.1	-	1.65
49-75	8.1	59	-	0.76	0.30	2.79	0.44	1.01	0.48	-	1.97
75-105	9.3	87	-	2.64	1.12	4.20	1.16	1.00	0.67	-	2.71
105-140	9.1	91	-	3.61	1.58	6.61	1.89	0.36	0.45	-	2.88

Elemental composition of the soil

Depth (cm)	Al2O3 % w/w	CaO % w/w	Fe2O3 % w/w	K2O % w/w	MgO % w/w	Na2O % w/w	SiO2 % w/w	TiO2 % w/w
0-17	11.1	2.15	5.1	2.60	0.28	3.27	48.4	0.54
17-41	12.0	1.42	5.8	3.29	0.22	4.56	56.5	0.55
41-49	13.0	1.12	6.1	3.70	0.19	5.76	58.1	0.6
49-75	10.2	0.85	4.9	1.85	0.25	1.96	64.9	0.51
75-105	16.1	0.84	6.9	2.49	0.29	2.55	51.3	0.69
105-140	21.3	0.46	9.7	2.62	0.44	2.39	43.7	0.94

Depth (cm)	Al2O3/Fe2O3 mol/mol	LOI % w/w	MnO2 % w/w	P2O5 % w/w	SiO2 / Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol
0-17	3.4	21.8	0.41	0.27	7.4	25.3	5.7
17-41	3.2	10.9	0.33	0.13	8	25.9	6.1
41-49	3.3	5.9	0.33	0.09	7.6	25.4	5.8
49-75	3.3	12.8	0.32	0.13	10.8	35.3	8.3
75-105	3.7	15.8	0.32	0.18	5.4	19.8	4.2
105-140	3.4	14.8	0.39	0.24	3.5	12.0	2.7

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-17	-	weak to medium	-	-	very weak	-	very weak	-	weak	very weak	-	-
17-41	-	weak to medium	-	-	very weak	-	very weak	-	weak	very weak	-	-
41-49	-	weak to medium	-	-	weak	-	very weak	-	very weak to weak	very weak	-	-
49-75	-	weak to medium	-	-	weak	-	very weak	-	very weak to weak	very weak	-	-
105-140	-	weak to medium	-	-	weak to medium	-	very weak	-	very weak to weak	very weak to weak	-	-

Profile description

Ah 0-17 cm	dark yellowish brown (10YR 4/4, dry) (2.5YR 2.5/1, moist)silt loam,moderate medium granular,soft very friable non sticky non plastic,few very fine pores,moderately calcareous (2-10%),clear smooth boundary to,
17-41 cm	dark greyish brown (10YR 4/2, dry) (10YR 2.5/1, moist)silt loam,porous massive and weak subangular blocky,soft very friable non sticky non plastic,common very fine very fine pores,slightly calcareous (0-2%),clear smooth boundary to,
B 41-49 cm	dark brown (7.5YR 3/2, dry) dark reddish grey (5YR 4/2, moist)loam,massive to weak columnar,slightly hard very friable non sticky plastic,few medium pores,slightly calcareous (0-2%),gradual smooth boundary to,
2Ahb 49-75 cm	(dark) brown (7.5YR 4/4, dry) (7.5YR 2/1, moist)silty clay loam,moderate fine and medium subangular blocky,slightly hard very friable non sticky non plastic,common fine and very fine pores,non calcareous,clear smooth boundary to,
2Bwb1 75-105 cm	(dark) brown (7.5YR 4/4, dry) dark reddish brown (5YR 3/2, moist)silty clay loam,porous massive and weak subangular blocky,soft very friable non sticky non plastic,common fine and very fine pores,non calcareous,gradual smooth boundary to,
2Bwb2 105-160 cm	(dark) brown (7.5YR 4/4, dry) reddish brown (5YR 4/3, moist)silty clay loam,moderate medium subangular blocky,slightly hard friable non sticky non plastic,patchy thin clay cutans,common fine and very fine pores,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Mode of accumulation or deposition of parent material	ejecta ash
Remarks on Parent Materials	Tertiary trachitic ash
Texture of parent material	loamy
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	partially or moderately

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Slope stability	stable

Main type of irrigation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	no irrigation
Land use or vegetation in the immediate vicinity of the site	(semi-)natural vegetation
Remarks on Land Use / Vegetation	VEGETATION: Bamboo forest, at spots cypress and pine forest.
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	primary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	closed forest

Altitude	2550m
Physiographic Unit	dissected upland
Physiographic position of the site	slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	4%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	slow

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Kenya 02: Andosol

Characteristics

Reference soil KE002: Andosols

Classification