Reference soil Kenya 46: Cambisol

KE046

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 KE046: Cambisols

Soil fauna: a high activity of termites and ants. At 170 - 200cm a tree trunc piece was found and sampled. Slides: 10,052 - 10,053 and 10,064 - 10,070.

Classification

WRB 2006

WRB 1998

Ferralic- Cambisol (Humic Eutric Clayic)

Chromi-Ferralic- Cambisol (Eutric)

20-140 cm	cambic horizon
-	ferralic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Ferralic Cambisol phreatic

Humic Ferralsol phreatic

0-20 cm	ochric A horizon
20-140 cm	cambic B horizon
-	ferralic
-	strongly humic

0-20 cm	ochric A horizon
20-140 cm	oxic B horizon
-	high organic matter content in B horizon

Other classification

USDA-SCS (1975)

Humitropept ustic very fine isothermic

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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	0.3	0.9	3.4	2.7	7.4	3.2	14.4	17.6	75.1
20-60	-	0.1	0.3	0.8	2.2	1.9	5.3	2.7	16.2	18.9	75.7
60-105	-	0.1	0.3	0.8	2.0	1.6	4.8	3.3	16.9	20.2	75.0
105-140	-	0.1	0.6	2.0	3.6	2.3	8.6	5.9	17.1	23	68.4
140-160	-	0.1	0.4	1.2	4.0	4.0	9.7	3.9	13.5	17.4	72.9

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	-	-	-	18.6	75.1
20-60	-	-	-	31.3	75.7
60-105	-	-	-	30.4	75.0
105-140	-	-	-	-	68.4
140-160	-	-	-	-	72.9

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	5.6	4.4	0.07	-	2.03	0.21	10	-	-	5.4	2.4	0.6	0.0	8.4
20-60	5.6	4.4	0.08	-	1.67	0.19	9	-	-	5.2	2.4	0.3	0.0	7.9
60-105	5.7	4.4	0.06	-	1.26	0.15	8	-	-	3.7	2.9	0.1	0.3	7
105-140	5.9	4.5	0.04	-	0.81	0.11	7	-	-	4.2	3.1	0.1	0.2	7.6
140-160	5.4	3.8	0.04	-	0.96	0.10	10	0.6	0.9	3.3	2.0	0.3	0.3	5.9

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	64	13.2	18	7.1	-	-	0
20-60	65	12.1	16	5.8	-	-	0
60-105	67	10.5	14	4.4	-	-	3
105-140	71	10.7	16	2.8	-	-	2
140-160	50	11.9	16	3.4	-	13	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	8.7	-	-	0.3	0.1	4.9	0.5	-	-	-	0.8
20-60	8.0	52	-	0.4	0.1	5.0	0.4	-	-	-	1.1
60-105	8.0	50	-	0.3	0.1	5.2	0.4	-	-	-	1.3
105-140	7.9	50	-	0.3	0.1	5.4	0.4	-	-	-	1.5
140-160	8.0	45	-	0.3	0.1	2.4	0.2	-	-	-	0.9

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	weak	weak	weak	-	-	medium to strong	-	weak	-	-	-
20-60	-	very weak	weak	weak	-	-	medium to strong	-	weak	-	-	-
60-105	-	very weak	weak	weak	-	-	medium	-	weak	-	-	-
105-140	-	weak	weak	weak	-	-	medium to strong	-	weak	-	-	-
140-160	-	weak	weak	weak	-	-	strong	-	weak	-	-	-

Profile description

Ah 0-20 cm	dark reddish brown (5YR 3/4, dry) dark reddish brown (2.5YR 3/4, moist)silty clay,moderate medium subangular blocky parting to moderate very fine subangular blocky,soft very friable slightly sticky slightly plastic,common very fine pores and few pores,common very fine and few fine roots,non calcareous,gradual wavy boundary to,
Bt 20-60 cm	dark reddish brown (5YR 3/3, dry) dark reddish brown (5YR 3/3, moist)silty clay,weak medium subangular blocky parting to moderate very fine and fine subangular blocky,slightly hard very friable slightly sticky slightly plastic,patchy thin clay cutans,many very fine few fine and medium pores,common very fine and few fine roots,few medium spherical hard manganiferous concretions,non calcareous,gradual smooth boundary to,
Btg 60-105 cm	dark reddish brown (2.5YR 3/4, moist)silty clay,moderate fine and medium subangular blocky,slightly hard very friable slightly sticky slightly plastic,many (15-40%) fine distinct clear mottles,broken thin clay cutans,common very fine few fine and medium pores,common very fine and few fine roots,non calcareous,gradual smooth boundary to,
Bg 105-140 cm	(dark) brown (7.5YR 4/4, moist)silty clay,moderate very fine and fine angular blocky,very friable sticky slightly plastic,many (15-40%) 7.5YR mottles,non calcareous,gradual smooth boundary to,
Auger 140-160 cm	greyish brown (10YR 5/2, moist)many (15-40%) fine prominent sharp mottles (7.5 YR 4/4),non calcareous,clear smooth boundary to,
Auger 160-185 cm	grey (5Y 5/1, moist)non calcareous,abrupt smooth boundary to,
Auger 185-200 cm	dark grey (10YR 4/1, moist)non calcareous,abrupt wavy boundary to,
Auger 200-210 cm	greyish green (5G 5/2, moist)non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	basic volcanic breccia
Kind 2 (parent material) (second entry); Parker (eds), 1984	basic volcanic breccia
Mode of accumulation or deposition of parent material	colluvial
Mode of accumulation or deposition of parent material (second entry)	fluvial
Remarks on Parent Materials	phonolite/lahar/ash
Soil Depth	80cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Slope stability	stable

Major crops	banana
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	low level arable farming
Remarks on Land Use / Vegetation	LAND USE: Maize, sugarcane, papaya, napirgrass
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	1330m
Physiographic Unit	major valley, mount. footridge
Physiographic position of the site	open depression
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	valley
Slope	2%
Form of the slope surrounding the site	concave
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Dry From - To	0-60cm
(Estimated) maximum (lower) depth to groundwater table	140cm
Depth to groundwater table	105cm
Kind of ground water table (USDA, 1979)	apparent
(Estimated) minimum (upper) depth to groundwater table	60cm
Moist From - To	60-105cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Wet From To	105-200cm

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
Microrelief pattern	none
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 46: Cambisol

Characteristics

Reference soil KE046: Cambisols

Classification