Reference soil South Africa 08: Vertisol

ZA008

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 ZA008: Vertisols

Vertisol. ADDITIONAL NOTES ON PROFILE DESCRIPTION: A11 - somewhat compacted.

Classification

WRB 2006

WRB 1998

Mollic- Vertisol (Calcaric Pellic)

Mazi-Pellic- Vertisol (Eutric)

30-55 cm	cambic horizon
55-110 cm	vertic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Pelli-Eutric Vertisol

Pellic Vertisol

0-30 cm	mollic A horizon
30-110 cm	cambic B horizon
-	slickensides
-	vertic

0-30 cm	mollic A horizon
30-110 cm	cambic B horizon
-	slickensides
-	vertic

Local classification:	Rensburg Form, Greendal Family

Other classification

USDA-NRCS (1999)	Typic Hapludert
USDA-SCS (1975)	Typic Chromudert udic fine montmorillonitic (calcareous) thermic

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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
0-30	-	3.3	1.8	1.8	4.7	4.9	16.5	14.9	22.8	37.7	45.8
30-55	-	3.5	2.3	2.6	6.8	6.4	21.6	10.6	17.2	27.8	50.6
55-80	-	4.3	2.9	2.6	6.8	5.3	21.9	7.0	11.0	18	60.1
80-100	-	2.0	2.2	3.8	10.7	6.3	25	7.0	10.4	17.4	57.6
100-110	-	1.3	2.3	4.0	9.3	7.6	24.5	8.6	12.1	20.7	54.9

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-30	-	-	-	-	45.8
30-55	-	-	-	-	50.6
55-80	-	-	-	-	60.1
80-100	-	-	-	-	57.6
100-110	-	-	-	-	54.9

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
0-30	6.3	5.0	0.14	-	2.43	0.08	30	-	-	15.2	10.5	0.2	0.7	26.6
30-55	6.7	5.4	0.22	2.0	1.43	0.06	24	-	-	19.3	21.5	0.1	0.9	41.8
55-80	7.1	5.6	0.15	2.4	0.62	0.02	31	-	-	25.2	21.6	0.1	1.1	48
80-100	7.0	5.6	0.16	2.7	0.52	0.03	17	-	-	21.8	22.7	0.1	0.9	45.5
100-110	7.3	5.8	0.14	2.2	0.48	0.03	16	-	-	25.1	24.4	0.1	0.9	50.5

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	63	42.0	92	8.5	-	-	2
30-55	82	51.2	101	5	-	-	2
55-80	90	53.6	89	2.2	-	-	2
80-100	86	53.1	92	1.8	-	-	2
100-110	155	32.6	59	1.7	-	-	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
0-30	-	-	-	-	-	3.8	-	-	-	-	-
30-55	-	-	-	-	-	2.4	-	-	-	-	-
55-80	-	-	-	-	-	2.2	-	-	-	-	-
80-100	-	-	-	-	-	1.2	-	-	-	-	-
100-110	-	-	-	-	-	1.6	-	-	-	-	-

Elemental composition of the clay

Depth (cm)	SiO2 % w/w	Al2O3 % w/w	Fe2O3 % w/w	CaO % w/w	MgO % w/w	K2O % w/w	Na2O % w/w	TiO2 % w/w
0-30	49.2	21.0	13.7	0.25	0.73	0.19	-	1.44
30-55	54.8	18.0	14.3	0.49	1.01	0.14	-	1.34
55-80	59.3	17.2	12.4	1.00	1.20	0.18	-	1.37
80-100	57.1	18.7	12.3	1.18	1.27	0.21	-	1.37
100-110	51.3	20.4	14.4	0.17	1.46	0.06	-	1.12

Depth (cm)	MnO2 % w/w	P2O5 % w/w	Ign.Loss clay % w/w	Total Clay % w/w	SiO2/Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol	Al2O3/Fe2O3 mol/mol
0-30	0.14	0.13	10.9	97.68	4	9.5	2.8	2.4
30-55	0.14	0.09	9.9	100.21	5.2	10.2	3.4	2
55-80	0.05	0.08	7.3	100.08	5.8	12.7	4	2.2
80-100	0.06	0.09	7.4	99.6	5.2	12.3	3.7	2.4
100-110	0.06	0.06	10.8	99.9	4.3	9.5	2.9	2.2

Elemental composition of the soil

Depth (cm)	Al2O3 % w/w	CaO % w/w	Fe2O3 % w/w	K2O % w/w	MgO % w/w	Na2O % w/w	SiO2 % w/w	TiO2 % w/w
0-30	11.1	1.00	10.9	0.25	0.59	-	62.7	1.82
30-55	11.8	1.84	12.4	0.29	0.96	-	62.0	1.57
55-80	15.5	2.02	13.4	0.27	1.33	-	57.4	1.46
80-100	17.1	2.68	10.7	0.40	1.25	-	60.6	1.47
100-110	18.1	2.67	11.1	0.42	1.26	-	57.2	1.38

Depth (cm)	Al2O3/Fe2O3 mol/mol	LOI % w/w	MnO2 % w/w	P2O5 % w/w	SiO2 / Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol
0-30	1.6	10.6	0.18	0.07	9.6	15.3	5.9
30-55	1.5	8.8	0.19	0.03	8.9	13.3	5.3
55-80	1.8	7.7	0.06	0.04	6.3	11.4	4.1
80-100	2.5	6.5	0.07	0.07	6	15.1	4.3
100-110	2.6	6.9	0.05	0.08	5.4	13.7	3.9

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-30	-	-	-	-	-	-	weak to medium	-	-	weak to medium	very strong	-
30-55	-	-	-	-	-	-	weak to medium	-	-	weak to medium	very strong	-
55-80	-	weak to medium	-	-	-	-	weak to medium	-	-	weak to medium	very strong	-
80-100	-	weak to medium	-	-	-	-	very weak to weak	-	-	weak to medium	very strong	-
100-110	-	weak to medium	-	-	-	-	very weak to weak	-	-	very weak to weak	very strong	-

Profile description

Ah1 0-30 cm	very dark brown (10YR 2/2, dry) (2.5Y 2/1, moist)clay,moderate fine subangular blocky,very hard friable very sticky very plastic,very few fine and medium gravel strongly weathered quartzitic and feldspar fragments,non calcareous,clear smooth boundary to,
Ah2 30-55 cm	very dark brown (10YR 2/2, dry) (2.5Y 2/1, moist)clay,moderate fine subangular blocky,very hard firm very sticky very plastic,very few fine and medium gravel strongly weathered quartzitic and feldspar fragments,non calcareous,diffuse smooth boundary to,
Bi1 55-80 cm	(2.5Y 3.5/1, moist)clay,moderate fine subangular blocky,very hard friable very sticky very plastic,common (5-15%) fine distinct clear mottles 10YR5/4 (yellowish brown),broken slickensides,very few fine and medium gravel strongly weathered quartzitic and feldspar fragments,non calcareous,gradual smooth boundary to,
Bi2 80-110 cm	dark reddish grey (5YR 4/2, moist)clay,moderate fine subangular blocky,very hard friable very sticky very plastic,many (15-40%) mottles 2.5Y5/3 (Invalid Code:) and few (2-5%) fine prominent clear 10GY4/1 (Invalid Code:) mottles,continuous slickensides,very few fine and medium gravel strongly weathered quartzitic and feldspar fragments,

Kind 1 (parent material) ; Parker (eds), 1984	dolerite
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	diorite with some admixture of sandstone residue
Texture of parent material	clayey
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly

Remarks on Land Use / Vegetation	VEGETATION: Thornbush, Acacia spp
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shrub

Altitude	730m
Physiographic Unit	valley edge
Physiographic position of the site	lower slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	valley
Slope	22%
Form of the slope surrounding the site	concave
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Dry From - To	0-30cm
Depth to groundwater table	100cm
Kind of ground water table (USDA, 1979)	groundwater table observed
Moist From - To	30-100cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium
Wet From To	100-120cm

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)
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline

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Reference soil South Africa 08: Vertisol

Characteristics

Reference soil ZA008: Vertisols

Classification