Reference soil Kenya 35: Andosol

KE035

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 KE035: Andosols

Evergreen bushland derived grasslands. These are fire induced. Boscia angustifolia is the common woody plant. Grasses include Themeda triandra, Pennisetum mezianum, Pennisetum schimperi, Sporobolus discoporus etc. Under conditions of heavy utilization Pennisetum schimperi and Harpachne schimperi become dominant. Entic Eutrandept due to 20cm epipedon (typic: 25cm). No slides available.

Classification

WRB 2006

WRB 1998

Vitric- Andosol (Calcaric Siltic)

Calcari-Vitric- Andosol

20-90 cm	cambic horizon
-	calcaric
-	vitric

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Calcari-Vitric Andosol

Vitric Andosol

0-20 cm	ochric A horizon
20-90 cm	cambic B horizon
-	andic
-	calcareous

0-20 cm	ochric A horizon
20-90 cm	cambic B horizon
-	exchange complex dominated by amorphous material

Other classification

USDA-NRCS (1999)	Typic Haplustand
USDA-SCS (1975)	Typic Eutrandept ustic coarse-loamy isothermic

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
0-20	-	0.1	0.2	2.7	14.7	8.7	26.4	11.7	37.5	49.2	24.4
20-60	-	0.3	0.2	2.8	12.1	6.5	21.9	20.2	44.0	64.2	13.8
60-90	-	1.5	1.2	5.8	16.2	7.8	32.5	18.6	42.6	61.2	6.2
90-145	-	6.9	4.2	4.1	12.2	7.8	35.2	25.1	33.4	58.5	6.3

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-20	-	-	-	5.0	24.4
20-60	-	-	-	4.9	13.8
60-90	-	-	-	2.3	6.2
90-145	-	-	-	-	6.3

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
0-20	6.7	5.8	0.15	2.1	2.28	0.18	13	-	-	17.6	2.3	2.9	0.4	23.2
20-60	7.0	5.8	0.14	2.5	0.70	0.08	9	-	-	20.0	2.0	6.3	2.0	30.3
60-90	7.3	6.3	0.20	2.8	0.38	-	-	-	-	19.1	2.2	9.8	1.7	32.8
90-145	7.9	7.0	0.27	4.4	0.11	-	-	-	-	21.8	2.2	6.0	0.8	30.8

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 %
0-20	84	27.5	113	8.0	-	-	1
20-60	92	33.1	240	2.5	-	-	6
60-90	90	36.6	590	1.3	-	-	5
90-145	114	27.1	430	0.4	-	-	3

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
0-20	7.6	26	-	0.21	0.17	2.16	0.21	0.10	0.18	-	0.46
20-60	7.6	23	-	0.25	0.16	2.21	0.28	0.04	0.08	-	0.20
60-90	7.6	14	-	0.22	0.34	1.65	0.19	0.00	0.01	-	0.10
90-145	8.0	16	-	0.14	0.13	0.50	0.11	0.01	0.01	-	0.04

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	medium to strong	-	-	-	-	very weak to weak	-	-	-	-	-
60-90	-	weak to medium	-	-	-	-	very weak	-	-	-	-	-

Profile description

Ah 0-20 cm	dark brown (7.5YR 3/2, moist)clay loam,massive parting to weak very fine and fine subangular blocky,friable sticky plastic,moderately calcareous (2-10%),clear smooth boundary to,
B 20-50 cm	dark brown (7.5YR 3/2, moist)sandy clay,massive parting to weak very fine crumb,friable sticky plastic,moderately calcareous (2-10%),diffuse smooth boundary to,
Bb 50-90 cm	dark brown (7.5YR 3/2, moist)clay loam,massive parting to weak very fine crumb,firm sticky plastic (moist),moderately calcareous (2-10%),slightly calcareous (0-2%),diffuse smooth boundary to,
BCb 90-145 cm	gravelstructureless,concretions,strongly weathered concretionary tuff fragments,moderately calcareous (2-10%),
145-170 cm	structurelessloose (moist),dominant strongly weathered tuff fragments,moderately calcareous (2-10%),

Depth1	90cm
Kind 1 (parent material) ; Parker (eds), 1984	pyroclastic, unconsolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	tuff
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	soft tuff
Texture of parent material	silty
Texture of parent material (second entry)	silty
Weathering Resistance	poor
Weathering Resistance (second entry)	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

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	slight
Soil erosion type	wind

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	shrubland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Open bushland. Trees: Boscia angustifolia; grasses: Themeda triandra, Pennisetum mezianum, Pennisetum schimperi, Sporobols discoporus
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)	deciduous shrub

Altitude	1950m
Physiographic Unit	very gently und.volcanic plain
Physiographic position of the site	flat
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plain
Slope	2%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

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
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium

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)	surface slaked; sorted sand/silt, some clay films
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 35: Andosol

Characteristics

Reference soil KE035: Andosols

Classification