Reference soil Kenya 37: Andosol

KE037

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 KE037: Andosols

A very dark (10 YR 2/2 very dark brown to 10 YR 2/1 black) clayey-loamy soil of volcanic origin (tertiary volcanics covered by volcanic ashes) in a mountainous region with long steep slopes; a sticky and plastic consistence with many fine and medium pores throughout the profile.

Classification

WRB 2006

WRB 1998

Mollic-Vitric- Andosol (Calcaric)

Molli-Vitric- Andosol (Calcaric)

30-120 cm	cambic horizon
-	calcaric
-	vitric

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Molli-Vitric Andosol

Mollic Andosol

0-30 cm	mollic A horizon
30-120 cm	cambic B horizon
-	andic
-	strongly humic

0-28 cm	mollic A horizon
30-120 cm	cambic B horizon
-	exchange complex dominated by amorphous material

Other classification

USDA-NRCS (1999)	Typic Melanudand
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
0-30	-	0.2	1.4	4.7	14.3	14.0	34.6	15.7	29.9	45.6	19.8
30-120	-	0.1	0.5	3.4	15.0	13.8	32.8	15.1	33.2	48.3	19.0
120-150	-	0.1	0.4	1.8	6.4	6.0	14.7	18.1	47.8	65.9	19.4

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-30	-	-	-	1.3	19.8
30-120	-	-	-	1.3	19.0
120-150	-	-	-	-	19.4

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
0-30	6.7	6.1	0.24	3.0	6.95	0.65	11	-	-	27.8	3.6	2.6	0.1	34.1
30-120	7.0	6.2	0.09	2.9	4.53	0.45	10	-	-	17.7	3.0	1.7	0.1	22.5
120-150	7.0	6.0	0.08	1.5	2.41	0.15	16	-	-	13.5	5.2	3.3	0.2	22.2

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 %
0-30	70	48.8	246	24.3	-	0	0
30-120	58	38.8	204	15.9	-	0	0
120-150	67	33.1	171	8.4	-	0	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
0-30	8.3	30	-	0.52	0.24	1.78	0.27	0.14	0.15	-	0.94
30-120	8.2	38	-	0.60	0.31	2.25	0.34	0.18	0.17	-	1.13
120-150	8.3	39	-	0.77	0.54	3.41	0.45	0.17	0.06	-	1.61

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-30	-	medium	-	-	weak	-	weak	-	-	-	-	-
120-150	-	medium	-	-	weak	-	very weak	weak	-	-	-	-

Profile description

Ap 0-30 cm	black (10YR 2/1, moist)clay loam,moderate very fine and fine crumb,very friable sticky plastic,many fine and medium pores,many very fine and fine and many medium roots,moderately calcareous (2-10%),gradual smooth boundary to,
B 30-120 cm	(10YR 2/1.5, moist)clay loam,moderate fine and medium subangular blocky and moderate coarse subangular blocky,very friable sticky plastic,many fine and medium pores,common very fine and fine and few medium roots,moderately calcareous (2-10%),gradual smooth boundary to,
C 120-150 cm	very dark brown (10YR 2/2, moist)clay loam,moderate medium and coarse subangular blocky,very friable sticky plastic,many fine and medium pores,few very fine and fine roots,slightly calcareous (0-2%),

Kind 1 (parent material) ; Parker (eds), 1984	pyroclastic, consolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	fine-grained igneous rock
Mode of accumulation or deposition of parent material	ejecta ash
Mode of accumulation or deposition of parent material (second entry)	residual material
Remarks on Parent Materials	volcanic ashes over Tertiary volcanics
Texture of parent material	loamy
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	partially or moderately

Major crops	vegetables
Land use or vegetation in the immediate vicinity of the site	mixed farming
Remarks on Land Use / Vegetation	LAND USE: Maize, potatoes, beans

Altitude	2640m
Physiographic Unit	footslope ridge
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.	mountain
Slope	20%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	mountainous

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)	rapid

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Microrelief Height: variation in height	0
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

You are here

Reference soil Kenya 37: Andosol

Characteristics

Reference soil KE037: Andosols

Classification