Reference soil Kenya 32: Vertisol

KE032

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 KE032: Vertisols

A deep to very deep soil, poorly to imperfectly drained, olive gray to olive cracking clay; structure is strong very coarse columnar to angular blocky. Continuous thick pressure faces are found at an angle of 45 degrees; very sticky and plastic, firm when moist and very hard when dry. Secondary CaCO3 at B2 horizon. Roots are very few to few; vegetation: accacia sp, Thespetia danis

Classification

WRB 2006

WRB 1998

Calcic-Mazic- Vertisol (Hyposodic)

Mazi-calcic horizon- Vertisol (Hyposodic)

20-120 cm	vertic horizon
-	secondary carbonates

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Calcic Vertisol sodic

Chromic Vertisol sodic

0-40 cm	ochric A horizon
20-120 cm	cambic B horizon
-	slickensides
-	vertic

0-40 cm	ochric A horizon
20-120 cm	cambic B horizon
-	slickensides
-	vertic

Other classification

USDA-NRCS (1999)	Udic Haplustert
USDA-SCS (1975)	Udic Chromustert ustic

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	-	1.9	4.9	7.3	4.5	2.1	20.7	27.6	18.0	45.6	33.6
20-40	-	2.3	3.0	4.3	2.8	1.2	13.6	19.3	12.7	32	54.6
40-75	-	1.4	2.7	3.7	2.7	1.5	12	16.8	15.6	32.4	55.7
75-120	17	3.8	2.6	2.7	2.2	1.4	12.7	18.8	20.3	39.1	48.1

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	-	-	-	8.3	33.6
20-40	-	-	-	19.1	54.6
40-75	-	-	-	19.7	55.7
75-120	-	-	-	24.4	48.1

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	6.9	5.8	0.14	0.9	1.76	0.14	13	-	-	10.8	6.3	0.4	0.6	18.1
20-40	6.6	4.9	0.13	0.7	1.23	-	-	-	-	10.8	12.7	0.4	2.2	26.1
40-75	8.1	7.0	0.38	2.7	0.70	-	-	-	-	14.5	15.6	0.4	3.1	33.6
75-120	8.8	7.3	0.57	6.5	0.29	-	-	-	-	12.5	10.0	0.3	4.2	27

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	75	24.2	72	6.2	-	-	2
20-40	78	33.3	61	4.3	-	-	7
40-75	103	32.6	59	2.5	-	-	10
75-120	91	29.7	62	1.0	-	-	14

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	-	-	-	0.12	0.05	2.67	0.32	0.13	0.06	-	0.40
20-40	-	-	-	0.22	0.04	3.29	0.50	0.16	0.06	-	0.37
40-75	-	-	-	0.18	0.06	2.86	0.45	0.09	0.06	-	0.13
75-120	-	-	-	0.10	0.04	2.13	0.26	0.03	0.06	-	0.10

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	very weak	-	very weak	-	-	medium	weak	medium	medium	very weak	medium
40-75	medium	very weak	-	very weak	-	-	medium	very weak	weak	weak	very weak	weak
75-120	medium	very weak	-	very weak	-	-	medium	very weak	weak	weak	weak	weak

Profile description

Ah 0-20 cm	very dark greyish brown (10YR 3/2, moist)clay,strong very coarse angular blocky,very hard firm sticky plastic,few to common very fine and fine pores,few roots,non calcareous,clear smooth boundary to,
Abi 20-40 cm	weak red (2.5YR 4/2, moist)clay,strong very coarse angular blocky and strong very coarse columnar,very hard very firm very sticky plastic,thin slickensides on pedfaces,few very fine and fine pores,few roots,few ferruginous nodules and few manganiferous nodules,non calcareous,gradual wavy boundary to,
Bi 40-75 cm	dark reddish grey (5YR 4/2, moist)clay,strong very coarse columnar and strong very coarse angular blocky,very hard very firm very sticky plastic,thin slickensides on pedfaces,few very fine and fine pores,few roots,very frequent ferruginous nodules and very frequent manganiferous nodules,non calcareous,diffuse smooth boundary to,
Bki 75-120 cm	reddish brown (5YR 4/3, moist)clay,strong very coarse angular blocky and strong very coarse columnar,very hard very firm very sticky plastic,thin slickensides on pedfaces,no pores,few roots,very frequent ferruginous nodules and powdery calcareous soft segregations,strongly calcareous (10-25%),

Kind 1 (parent material) ; Parker (eds), 1984	shale
Mode of accumulation or deposition of parent material	residual material
Texture of parent material	clayey
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	partially or moderately

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	(semi-)natural vegetation
Remarks on Land Use / Vegetation	VEGETATION: High shrubs, trees (Acacia sp, Thespetia danis) and grasses
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)	primary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shrub

Altitude	107m
Physiographic Unit	uplands, flat summit
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.	hill
Slope	0%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	poor
(Estimated) maximum (lower) depth to groundwater table	200cm
Depth to groundwater table	200cm
(Estimated) minimum (upper) depth to groundwater table	150cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	very slow
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	imperfect

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
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 32: Vertisol

Characteristics

Reference soil KE032: Vertisols

Classification