Reference soil Kenya 56: Vertisol

KE056

Vertisols occur dominantly in level landscapes under climates with a pronounced dry season. Vast areas are found in Australia, India, northeastern Africa (Sudan, Ethiopia), southern Latin America and the USA.

Characteristics

Soils having a vertic horizon (a clayey subsurface horizon with polished and grooved ped surfaces ("slickensides") or wedge-shaped or parallelepiped structural aggregates) within 100 cm from the soil surface. They have 30 percent or more clay in all horizons to a depth of 100 cm or more, or to a contrasting layer (lithic or paralithic contact, petrocalcic, petroduric or petrogypsic horizons, sedimentary discontinuity, etc.) between 50 and 100 cm, after the upper 20 cm have been mixed. In addition, Vertisols exhibit wide cracks, which open and close periodically.

Distribution of Vertisols (rough estimation supplied by soilgrids)

Reference soil KE056: Vertisols

Little soil fauna activity. The vegetation is cut over for charcoal production. Slides: 10,181 - 10,182 and 10,184 - 10,190.

Classification

WRB 2006

WRB 1998

Haplic- Vertisol (Calcaric Hyposodic)

Hyposodic- Vertisol

10-26 cm	argic horizon
26-100 cm	vertic horizon
-	vertic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Calcari-Eutric Vertisol skeletic

Chromic Vertisol sodic

0-10 cm	ochric A horizon
10-100 cm	argic B horizon
-	calcaric
-	slickensides

0-10 cm	ochric A horizon
10-100 cm	argillic B horizon
-	gilgai microrelief
-	slickensides

Other classification

USDA-SCS (1975)

Chromustert ustic clayey isohyperthermic

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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
0-10	-	3.6	11.5	18.7	20.3	6.5	60.6	6.2	6.2	12.4	27.0
10-26	-	1.3	7.0	9.2	13.6	7.3	38.4	6.2	8.5	14.7	46.9
26-60	-	4.3	9.5	12.8	14.5	7.1	48.2	5.3	9.7	15	43.5
60-100	-	2.7	8.8	11.1	9.3	8.1	40	4.6	8.2	12.8	46.2

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	-	-	-	1.35	27.0
10-26	-	-	-	1.49	46.9
26-60	-	-	-	1.49	43.5
60-100	-	-	-	1.60	46.2

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
0-10	7.8	6.8	0.16	1.1	1.07	0.12	9	-	-	13.8	6.0	1.6	0.0	21.4
10-26	7.4	6.0	0.07	1.4	0.74	0.07	11	-	-	12.6	11.1	0.9	0.6	25.2
26-60	8.5	7.0	0.18	2.6	0.53	0.05	11	-	-	17.8	13.7	0.6	1.8	33.9
60-100	8.3	7.0	1.10	2.2	0.48	0.04	12	-	-	17.0	13.7	0.3	3.7	34.7

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 %
0-10	104	20.6	76	3.7	-	-	0
10-26	91	27.6	59	2.6	-	-	2
26-60	112	30.3	70	1.9	-	-	6
60-100	121	28.7	62	1.7	-	-	13

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	-	very weak	-	weak	-	-	weak to medium	-	-	very weak	weak	-
26-60	-	-	-	very weak	-	-	weak to medium	-	-	very weak	weak to medium	-
60-100	-	very weak	-	weak	-	-	weak to medium	-	-	very weak	weak to medium	-

Profile description

Ah 0-10 cm	dark yellowish brown (10YR 3/4, dry) dark yellowish brown (10YR 3/4, moist)clay,strong medium and coarse subangular blocky,slightly hard friable sticky plastic,many very fine pores and few fine and medium pores,many very fine and few fine roots,few fine gravel weathered subrounded quartz,non calcareous,gradual smooth boundary to,
Bt 10-26 cm	dark yellowish brown (10YR 3/4, dry) dark yellowish brown (10YR 3/4, moist)clay,strong coarse and very coarse prismatic parting to strong fine and medium angular blocky,hard firm sticky plastic,patchy thick clay cutans on pedfaces,many very fine pores and few fine pores,many very fine roots,few fine gravel weathered subrounded quartz,non calcareous,gradual smooth boundary to,
Btkci 26-60 cm	very dark greyish brown (10YR 3/2, dry) very dark greyish brown (10YR 3/2, moist)clay,strong coarse and very coarse prismatic parting to strong medium and coarse angular blocky,extremely hard very friable very sticky very plastic,patchy moderately thick slickensides on pedfaces,many very fine pores and few fine pores,many very fine roots,few fine gravel weathered subrounded quartz,slightly calcareous (0-2%),gradual smooth boundary to,
Btki 60-100 cm	very dark greyish brown (10YR 3/2, dry) very dark greyish brown (10YR 3/2, moist)clay,strong coarse and very coarse prismatic parting to strong fine and medium angular blocky,friable very sticky very plastic,broken thick slickensides on pedfaces,many very fine pores,many very fine roots,few fine gravel weathered subrounded quartz,slightly calcareous (0-2%),

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	alluvium derived from Basement Complex gneiss
Soil Depth	120cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

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

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	woodland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Shrubbed woodland, 50% bare soil. LAND USE: Vegetation is used for charcoal production
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 woodland

Altitude	680m
Physiographic Unit	bottomland
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.	plain
Slope	1%
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	imperfect
Dry From - To	0-60cm
Flooding frequency (FAO, 1986)	yearly
Nature of flood water	fresh
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	60-100cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	very slow

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Surface cracking	large cracks (width more than 1 cm, or depth more than 50 cm)
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface partly slaked, round smooth aggregates
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	gilgai
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 56: Vertisol

Characteristics

Reference soil KE056: Vertisols

Classification