Reference soil Kenya 38: Andosol

KE038

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 KE038: Andosols

Brief soil description: Very deep, well drained soil derived from volcanic ejecta; with a thick,black, slightly gravelly silty clay topsoil over a dark yellowish brown to dark brown, silty clay subsoil which has continuous clay cutans. The soil is under natural vegetation with bamboo-hagiena forest. Parent material 1. 0 - 37 silty, 2. 37 - 53 sandy, 3. 53 - 130 silty, in the lower part lapilli occur, 4. 130 - + silty and stony. The profile observed is a roadcut, situated in Meru district. Slides of profile, vegetation and landscape: 10.005 - 10.009. Literature: Hirose S. ed. 1987. Agriculture and soils in Kenya. Nihon University, Tokyo, Japan. Chapter B1, B2, B3, page 88 - 129.

Classification

WRB 2006

WRB 1998

Umbric-Silandic-Vitric- Andosol (Hyperdystric Siltic)

Sili-Vitric- Andosol (Umbric Dystric)

0-39 cm	umbric horizon
-	andic
-	vitric

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Umbric Andosol

Humic Andosol

0-39 cm	umbric A horizon
-	andic
-	strongly humic

0-39 cm	umbric A horizon
-	exchange complex dominated by amorphous material

Other classification

USDA-NRCS (1999)	Typic Fulvudand
USDA-SCS (1975)	Typic Dystrandept udic medial over sandy isomesic

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
0-2	-	12.1	18.3	16.7	9.4	3.2	59.7	9.6	18.4	28	12.4
2-14	-	3.2	8.1	13.5	12.3	5.5	42.6	14.5	27.1	41.6	15.8
14-37	17	5.6	9.3	14.1	14.0	6.9	49.9	14.9	22.6	37.5	12.6
37-53	24	23.0	28.2	24.0	13.6	3.2	92	2.2	4.4	6.6	1.3
53-62	-	2.2	5.4	7.1	6.9	3.8	25.4	14.1	44.7	58.8	15.7
62-66	-	0.7	1.5	2.7	4.8	4.5	14.2	17.6	51.7	69.3	16.6
66-116	-	2.2	4.0	4.7	7.0	5.6	23.5	13.3	40.4	53.7	22.8
116-130	-	0.8	6.4	7.6	6.4	7.7	28.9	15.6	50.6	66.2	4.8
130-150	-	0.3	0.6	2.2	7.3	8.7	19.1	27.6	50.0	77.6	3.3

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-2	-	-	-	2.0	12.4
2-14	-	-	-	0.8	15.8
14-37	-	-	-	0.9	12.6
37-53	-	-	-	0.9	1.3
53-62	-	-	-	0.9	15.7
62-66	-	-	-	0.5	16.6
66-116	-	-	-	-	22.8
116-130	-	-	-	-	4.8
130-150	-	-	-	-	3.3

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
0-2	4.6	4.3	1.16	-	11.53	0.80	14	2.4	1.3	6.2	1.6	1.0	0.2	9
2-14	4.5	4.1	0.66	-	14.71	0.90	16	4.1	3.1	2.4	0.7	0.7	0.1	3.9
14-37	4.6	4.4	0.18	-	7.03	0.51	14	1.9	1.6	0.4	0.3	0.2	0.2	1.1
37-53	5.6	5.0	0.03	-	0.78	0.06	13	0.2	0.0	0.0	0.0	0.1	0.2	0.3
53-62	5.7	5.2	0.03	-	5.09	0.42	12	0.2	0.0	0.0	0.0	0.4	0.2	0.6
62-66	5.6	5.1	0.02	-	9.13	0.52	18	0.2	0.0	0.2	0.0	0.3	0.1	0.6
66-116	5.8	5.0	0.01	-	6.45	0.36	18	0.2	0.0	0.2	0.0	0.1	0.2	0.5
116-130	5.7	5.9	0.03	-	0.56	-	-	0.0	0.0	0.0	0.0	0.1	0.1	0.2
130-150	5.9	5.8	0.20	-	0.04	-	-	0.0	0.0	0.0	0.0	0.1	0.1	0.2

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 %
0-2	33	27.0	-	40.4	-	13	1
2-14	12	32.3	-	51.5	-	44	0
14-37	7	16.8	-	24.6	-	59	1
37-53	10	3.0	-	2.7	-	0	7
53-62	4	15.0	-	17.8	-	0	1
62-66	2	26.6	-	32.0	-	0	0
66-116	3	18.3	-	22.6	-	0	1
116-130	8	2.6	-	2.0	-	0	4
130-150	8	2.6	-	0.1	-	0	4

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
0-2	-	-	-	0.89	0.34	-	-	-	-	-	0.99
2-14	9.4	80	-	0.81	0.16	-	-	-	-	-	1.01
14-37	11.2	86	-	1.24	0.20	-	-	-	-	-	1.25
37-53	10.8	63	-	0.94	0.43	-	-	-	-	-	0.74
53-62	11.2	99	-	3.97	1.34	-	-	-	-	-	1.55
62-66	11.3	100	-	5.20	1.42	-	-	-	-	-	2.61
66-116	11.1	99	-	3.70	0.91	-	-	-	-	-	2.53
116-130	10.9	79	-	0.99	0.61	-	-	-	-	-	0.94
130-150	10.4	72	-	1.05	0.90	-	-	-	-	-	0.61

Profile description

Oi 0-2 cm	black (10YR 2/1, moist)organic sphagnum slightly decomposed,very few fine gravel weathered tuff fragments,non calcareous,clear smooth boundary to,
Ah 2-16 cm	black (10YR 2/1, moist)silty clay slightly gravelly,moderate fine crumb,friable slightly sticky slightly plastic,patchy thin clay and humus cutans throughout,many very fine few and fine and medium pores,many very fine and common fine roots,few krotovinas,non calcareous,clear smooth boundary to,
Aht 16-39 cm	black (10YR 2/1, moist)silty clay slightly gravelly,moderate coarse angular blocky and coarse crumb,friable slightly sticky slightly plastic,continuous thin clay and humus cutans throughout,many very fine pores and few fine pores,many very fine and common fine roots,few krotovinas,non calcareous,abrupt smooth boundary to,
C 39-55 cm	dark yellowish brown (10YR 3/6, moist)Description sand slightly gravelly,weak very coarse angular blocky parting to granular,very friable non sticky non plastic,patchy thin clay cutans between sand grains,many very fine pores and few fine pores,common very fine and few fine roots,few krotovinas,non calcareous,abrupt wavy boundary to,
2Atb1 55-58 cm	dark yellowish brown (10YR 3/6, moist)silty clay,moderate coarse and very coarse angular blocky,friable slightly sticky slightly plastic,continuous thin clay and humus cutans throughout,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,abrupt wavy boundary to,
2Atb2 58-64 cm	yellowish red (5YR 5/8, moist)silty clay,moderate coarse and very coarse angular blocky,friable slightly sticky slightly plastic,continuous thin clay and humus cutans throughout,many very fine pores and few fine pores,non calcareous,abrupt wavy boundary to,
2Atb3 64-68 cm	(7.5YR 2/no, moist)silty clay,moderate coarse and very coarse angular blocky,friable slightly sticky slightly plastic,continuous thin clay and humus cutans throughout,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,abrupt wavy boundary to,
2ABb 68-118 cm	dark brown (10YR 3/3, moist)silty clay,moderate very coarse angular blocky,friable slightly sticky slightly plastic,continuous thin clay cutans throughout,many fine pores and few medium pores,few very fine and fine roots,non calcareous,clear wavy boundary to,
2Bt 118-132 cm	(dark) brown (7.5YR 4/4, moist)silt slightly stony,moderate very coarse angular blocky,friable slightly sticky slightly plastic,common (5-15%) medium distinct clear mottles 5YR5/8 (yellowish red),patchy thin clay cutans throughout,few fine and many very fine pores,no very fine and few medium roots,non calcareous,clear wavy boundary to,
2B 132-152 cm	light olive brown (2.5Y 5/6, moist)silt stony,weak very coarse angular blocky parting to very fine granular,non calcareous,

Depth1	37cm
Kind 1 (parent material) ; Parker (eds), 1984	pyroclastic, unconsolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	pyroclastic, unconsolidated
Mode of accumulation or deposition of parent material	ejecta ash
Mode of accumulation or deposition of parent material (second entry)	ejecta ash
Remarks on Parent Materials	Mt. Kenya Series
Soil Depth	130cm
Texture of parent material	silty
Texture of parent material (second entry)	sandy
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly
General characterization of the status of weathering of solid rock (second entry)	partially or moderately

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	no land improvement
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-Hagiena forest, nature reserve
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)	cut over
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	closed forest

Altitude	2925m
Physiographic Unit	undulating higher slopes
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	volcano
Slope	15%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Lower limit of a slow permeable or stagnating layer in the profile	1cm
Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Depth to groundwater table	0cm
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-150cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Upper limit of a slow permeable or stagnating layer in the profile	0cm

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 38: Andosol

Characteristics

Reference soil KE038: Andosols

Classification