Reference soil Kenya 05: Andosol

KE005

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 KE005: Andosols

A reddish soil of volcanic ejecta with high porosity throughout the profile and a 5 cm layer (A0) of not decomposed organic matter. The texture of this well drained soil changes from silty clay to clay below 17 cm.

Classification

WRB 2006

WRB 1998

Aluandic-Vitric- Andosol (Hyperdystric Clayic)

Dystri-Vitric- Andosol

22-166 cm	cambic horizon
-	vitric
-	andic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Vitric Andosol

Humic Andosol

0-55 cm	ochric A horizon
17-166 cm	cambic B horizon
-	andic
-	strongly humic

0-55 cm	ochric A horizon
17-166 cm	cambic B horizon
-	exchange complex dominated by amorphous material

Other classification

USDA-SCS (1975)

Dystrandept udic

More images

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
0-5	-	0.3	0.6	1.2	1.4	0.8	4.3	6.6	19.9	26.5	69.3
0-22	-	0.3	0.7	0.9	1.4	1.0	4.3	6.9	19.0	25.9	69.9
22-60	-	0.1	0.5	0.8	1.4	1.0	3.8	10.3	30.7	41	55.2
60-90	-	0.2	0.5	1.0	1.7	1.2	4.6	11.0	28.0	39	56.5
90-130	-	0.2	0.7	1.0	1.7	1.2	4.8	9.5	29.9	39.4	55.7
160-175	-	0.3	0.5	2.0	4.1	2.4	9.3	20.7	40.3	61	29.8
110-123	-	0.2	0.5	1.3	3.7	3.3	9	28.5	49.8	78.3	12.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-5	-	-	-	-	69.3
22-27	0.52	-	-	-	-
0-22	-	-	-	-	69.9
53-58	0.64	-	-	-	-
98-103	0.54	-	-	-	-
22-60	-	-	-	-	55.2
60-90	-	-	-	-	56.5
90-130	-	-	-	-	55.7
160-175	-	-	-	-	29.8
110-123	-	-	-	-	12.6

Other physical data

Depth (cm)	Bulk density kg/dm³	pF 0 % v/v	pF 1.0 % v/v	pF 1.5 % v/v	pF 2.0 % v/v	pF 2.3 % v/v	pF 2.7 % v/v	pF 3.4 % v/v	pF 4.2 % v/v
22-27	0.52	56.0	54.8	46.2	31.1	27.7	25.2	-	18.1
53-58	0.64	50.2	49.4	43.2	31.8	28.9	26.0	-	21.2
98-103	0.54	56.6	51.1	40.8	32.5	28.8	27.1	-	16.8

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
0-5	3.8	3.5	0.79	-	17.9	1.27	14	7.9	6.2	0.7	0.4	0.9	0.0	2
0-22	4.0	3.8	0.26	-	9.41	0.77	12	7.0	6.0	0.4	0.1	0.4	0.0	0.9
22-60	4.5	4.0	0.07	-	7.57	0.55	14	5.2	4.7	0.2	0.0	0.2	0.0	0.4
60-90	4.6	4.1	0.04	-	4.01	0.35	11	3.4	3.1	0.4	0.0	0.2	0.0	0.6
90-130	4.7	4.1	0.04	-	3.35	0.30	11	3.1	2.9	0.4	0.0	0.2	0.1	0.7
160-175	5.0	4.6	-	-	5.84	0.32	18	0.5	0.7	0.7	0.0	0.1	0.0	0.8
110-123	5.0	4.7	0.02	-	2.86	0.24	12	0.5	0.4	0.4	0.0	0.2	0.1	0.7

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 %
0-5	3	68.3	99	62.7	-	9	-
0-22	2	45.8	66	32.9	-	13	0
22-60	1	48.3	88	26.5	-	10	-
60-90	2	34.1	60	14	-	9	-
90-130	2	38.6	69	12.8	-	8	0
160-175	2	45.3	152	20.4	-	2	-
110-123	2	42.8	340	10	-	1	-

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
0-5	7.7	79	-	0.89	0.1	6.29	1.33	2.09	0.86	-	0.87
0-22	8.2	85	-	1.01	0.07	7.54	1.86	2.89	1.28	-	1.02
22-60	10.3	95	-	1.48	0.12	7.59	2.06	3.08	2.45	-	1.24
60-90	9.9	94	-	1.01	0.12	8.57	1.95	2.89	1.93	-	1.24
90-130	10.3	96	-	1.29	0.25	8.76	2.22	2.61	1.09	-	1.41
160-175	10.5	100	-	3.44	1.06	8.28	2.85	0.41	0.68	-	2.18
110-123	10.6	99	-	3.81	1.26	7.43	2.47	0.36	0.63	-	1.9

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-5	-	very weak	weak	weak	-	-	weak to medium	very weak to weak	weak	very weak to weak	-	-
0-22	-	very weak	weak	weak	-	-	weak to medium	very weak	weak	very weak	-	-
22-60	-	very weak	weak	weak	-	-	weak to medium	-	weak	very weak	-	-
60-90	-	very weak	weak	weak	-	-	weak to medium	very weak to weak	weak	very weak	-	-
90-130	-	very weak	weak	weak	-	-	weak to medium	very weak to weak	weak	very weak	-	-
110-123	-	very weak	weak	weak	-	-	weak to medium	very weak to weak	weak	very weak	-	-

Profile description

OA 0-5 cm	(2.5YR 3/3, dry) dusky red (2.5YR 3/2, moist)organic clay, unspecified organic nil decomposition,porous massive,slightly hard very friable slightly sticky slightly plastic,non calcareous,abrupt smooth boundary to,
Ah 5-22 cm	reddish brown (5YR 4/3, moist)silty clay,fine and medium subangular blocky,slightly hard (dry), very friable slightly sticky slightly plastic,many very fine and common fine and medium pores,many very fine to coarse roots,non calcareous,gradual smooth boundary to,
22-60 cm	reddish brown (5YR 4/4, moist)clay,medium subangular blocky,very friable slightly sticky slightly plastic,common very fine common fine and medium pores,common very fine to coarse roots,non calcareous,gradual smooth boundary to,
Bw1 60-90 cm	dark reddish brown (5YR 3/3, moist)clay,medium and coarse subangular blocky,very friable slightly sticky slightly plastic,common very fine medium and common fine and medium pores,few very fine to coarse roots,non calcareous,diffuse smooth boundary to,
Bw2 90-160 cm	clayporous massive,very friable slightly sticky slightly plastic,few fine and medium roots,non calcareous,
Ahb 160-225 cm	claymoderate medium and coarse angular blocky,firm slightly sticky slightly plastic,many medium and common fine roots,non calcareous,clear wavy boundary to,
Bwb 225-245 cm	claymoderate fine and medium angular blocky,firm slightly sticky slightly plastic,broken moderately thick clay cutans,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	Pliocene to middle Pleistocene trachitic pyroclastic rock with intercalated Laikipia-type basalt
Texture of parent material	clayey
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: Mixed bamboo 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	2290m
Physiographic Unit	foothills of Aberdares Mts.
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	40%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	steeply dissected

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	moderate
Estimated run off (class)	rapid

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 05: Andosol

Characteristics

Reference soil KE005: Andosols

Classification