Reference soil Kenya 27: Cambisol

KE027

Cambisols occur mainly in the temperate and boreal regions of the world, where the soil’s parent material is still young or where low temperatures slow down the processes of soil formation.

Characteristics

Soils having either a cambic horizon (a horizon showing evidence of alteration with respect to the underlying material), or a mollic horizon overlying a subsoil, which has a base saturation of less than 50 percent in some part within 100 cm from the soil surface, or one of the following diagnostic horizons within the specified depth: an andic, vertic, or vitric horizon starting between 25 and 100 cm; a (petro-)plinthic or salic horizon starting between 50 and 100 cm, in absence of loamy sand or coarser textures above these horizons.

Distribution of Cambisols (rough estimation supplied by soilgrids)

Reference soil KE027: Cambisols

A deep and brown soil derived from volcanic ashes (Holocene-Pleistocene) on quartzite rock (Bukoban system), situated between a rolling landscape on the western side and an almost flat surrounding to the east; area includes some ant hills.

Classification

WRB 2006

WRB 1998

Haplic- Cambisol (Hypereutric Siltic)

Hypereutric- Cambisol

10-114 cm	cambic horizon
114-152 cm	ferric horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Orthi-Eutric Cambisol

Eutric Cambisol

0-10 cm	ochric A horizon
10-114 cm	cambic B horizon

0-10 cm	ochric A horizon
10-114 cm	cambic B horizon

Other classification

USDA-SCS (1975)

Eutropept 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
0-20	-	0.5	1.7	6.9	9.7	3.4	22.2	12.9	27.6	40.5	37.4
20-60	-	0.4	1.6	6.4	8.6	3.3	20.3	12.9	30.3	43.2	36.5
60-100	-	0.4	1.6	4.9	7.2	3.1	17.2	13.0	32.4	45.4	37.5
100-150	-	0.4	1.2	3.9	6.5	2.9	14.9	13.0	36.1	49.1	35.9
150-200	-	0.4	0.9	3.3	5.7	2.7	13	11.6	32.7	44.3	42.8

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	-	-	-	9.9	37.4
20-60	-	-	-	10.7	36.5
60-100	-	-	-	11.3	37.5
100-150	-	-	-	-	35.9
150-200	-	-	-	-	42.8

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
0-20	6.8	6.0	0.30	2.5	4.32	0.47	9	-	-	30.2	3.4	2.2	0.0	35.8
20-60	7.4	6.5	0.14	1.6	1.44	0.15	10	-	-	16.6	2.9	2.1	0.0	21.6
60-100	7.3	6.9	0.13	1.4	0.81	-	-	-	-	12.3	3.4	4.1	0.0	19.8
100-150	7.1	6.1	0.23	1.1	0.49	-	-	-	-	12.7	3.6	2.3	0.1	18.7
150-200	7.0	5.4	0.11	1.4	0.20	-	-	-	-	13.4	4.6	1.5	0.2	19.7

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 %
0-20	105	34.2	51	15.0	-	-	0
20-60	95	22.8	49	5.0	-	-	0
60-100	96	20.6	47	2.8	-	-	0
100-150	100	18.7	47	1.7	-	-	1
150-200	111	17.8	40	0.7	-	-	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
0-20	-	24	-	0.2	0.1	2.2	0.2	-	-	-	0.4
20-60	-	26	-	0.1	0.1	2.4	0.2	-	-	-	0.3
60-100	-	22	-	0.1	0.1	2.6	0.2	-	-	-	0.2
100-150	-	22	-	0.1	0.1	2.5	0.2	-	-	-	0.2
150-200	-	21	-	0.1	0.1	2.4	0.2	-	-	-	0.2

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	medium	-	-	-	-	weak	very weak	weak	very weak	-	-
60-100	-	medium	-	-	-	-	medium	very weak	weak	very weak	-	-
150-200	-	medium	-	-	-	-	medium	very weak	weak	very weak	-	-

Profile description

Ah 0-10 cm	dark brown (7.5YR 3/2, moist)silty clay loam,moderate very fine and fine subangular blocky,very friable slightly sticky slightly plastic,many micro to medium pores,many very fine and fine and many medium roots,moderately calcareous (2-10%),clear wavy boundary to,
Bt1 10-52 cm	(dark) brown (7.5YR 4/4, moist)silty clay,moderate very fine and fine subangular blocky and moderate very fine and fine angular blocky,friable slightly sticky slightly plastic,many micro to fine pores and common medium pores,common medium roots,slightly calcareous (0-2%),gradual wavy boundary to,
Bt2 52-114 cm	(dark) brown (7.5YR 4/4, moist)silty clay,moderate fine subangular blocky,friable slightly sticky slightly plastic,patchy moderately thick clay cutans,common micro to fine pores,common very fine and fine and common medium roots,slightly calcareous (0-2%),gradual wavy boundary to,
BC1 114-152 cm	(7.5YR 4.5/4, moist)silty clay loam,weak very fine and fine subangular blocky,friable slightly sticky slightly plastic,broken moderately thick manganese (hydr-)oxide cutans,common micro and very fine pores,few very fine and fine and common medium roots,very few small manganiferous concretions,slightly calcareous (0-2%),gradual wavy boundary to,
BC2 152-190 cm	7.5YR 4/4 (dark brown)+ 7.5YR 5/4 (brown) (moist)silty clay loam,very weak very fine and fine angular blocky,firm slightly sticky slightly plastic,patchy thin manganese (hydr-)oxide cutans,common micro and very fine pores,few very fine and fine roots,slightly calcareous (0-2%),

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Mode of accumulation or deposition of parent material	ejecta ash
Remarks on Parent Materials	Holocene-Pleistocen ashes over quartzite (Bukoban system)
Texture of parent material	loamy
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly

Intensity of the soil erosion type	slight
Intensity of the soil erosion type (second entry)	moderate
Soil erosion type	rill
Soil erosion type (second entry)	gully

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	cultivated pasture
Remarks on Land Use / Vegetation	LAND USE: Pasture and maize cultivation
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	1850m
Physiographic Unit	slope
Physiographic position of the site	middle slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	15%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-190cm
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
Microrelief Height: variation in height	0
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	artificial terracing/mounds
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 27: Cambisol

Characteristics

Reference soil KE027: Cambisols

Classification