Reference soil South Africa 12: Umbrisol

ZA012

Umbrisols occur mainly in regions where precipitation exceeds considerably the evapotranspiration. They are dominantly associated with acid parent materials.

Characteristics

Soils having an umbric horizon (deep, brownish or blackish surface horizon with a significant accumulation of organic matter and low base saturation). They have no diagnostic horizons other than an anthropedogenic horizon less than 50 cm thick, or an albic or cambic horizon.

Distribution of Umbrisols (rough estimation supplied by soilgrids)

Reference soil ZA012: Umbrisols

PARENT MATERIAL: Derived from weathered paleozoic rocks: Middle Ecca Sandstone. ADDITIONAL NOTES ON PROFILE DESCRIPTION: Ah1 - top 5 cm: strong very fine subangular blocky/crumb,friable. Ah2 - mottles: soft iron concretions. B1 - plinthite; iron concretions: black; also many small and large, soft/hard, irregular and spherical, dark red (10R3/6) when broken and moist, red (7.5YR4/8) when broken and dry, iron-manganese concretions. B2 -also common strong red (7.5YR4/6, when moist) and few black mottles.

Classification

WRB 2006

WRB 1998

Cambic- Umbrisol (Humic Hyperdystric Clayic Chromic)

Humi-Umbric- Plinthosol

0-45 cm	umbric horizon
45-90 cm	cambic horizon
90-120 cm	plinthic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Plinthi-Humic Cambisol

Humic Cambisol

0-45 cm	umbric A horizon
45-90 cm	cambic B horizon
-	plinthite

0-45 cm	umbric A horizon
45-90 cm	cambic B horizon
-	plinthite

Local classification:	Avalon Form, Woodburn Family

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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	-	3.0	2.4	1.2	3.3	4.1	14	29.7	24.5	54.2	31.8
20-40	1	7.4	3.8	1.2	3.0	3.5	18.9	28.2	20.0	48.2	33.0
40-60	2	8.4	3.9	1.2	2.8	4.1	20.4	24.2	20.2	44.4	35.3
60-80	2	11.7	4.4	0.9	1.6	2.0	20.6	20.1	17.5	37.6	41.8
80-100	7	20.4	4.4	1.1	1.6	2.4	29.9	19.2	16.4	35.6	34.5
90-105	8	25.4	5.6	0.8	1.3	2.2	35.3	18.9	18.5	37.4	27.3
105-120	13	19.5	4.8	1.2	1.8	2.1	29.4	22.3	18.8	41.1	29.5

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	-	-	-	-	31.8
20-40	-	-	-	-	33.0
40-60	-	-	-	-	35.3
60-80	-	-	-	-	41.8
80-100	-	-	-	-	34.5
90-105	-	-	-	-	27.3
105-120	-	-	-	-	29.5

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	5.5	4.3	0.11	-	2.91	0.20	15	-	0.0	3.5	4.0	0.2	0.0	7.7
20-40	5.6	4.1	0.05	-	1.53	0.11	14	-	0.0	2.6	1.2	0.2	0.5	4.5
40-60	5.4	3.8	0.03	-	1.08	0.08	14	-	1.0	1.8	0.7	0.1	0.2	2.8
60-80	5.7	4.0	0.02	-	0.33	0.05	7	-	1.4	1.5	0.7	0.1	0.4	2.7
80-100	5.0	4.1	0.02	-	0.85	0.08	11	-	0.6	1.5	0.5	0.1	0.2	2.3
90-105	5.7	4.5	0.02	-	0.16	0.05	3	-	0.0	1.8	1.0	0.1	0.2	3.1
105-120	5.7	4.7	0.02	-	0.16	0.03	5	-	0.0	1.8	0.9	0.1	0.2	3

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	43	17.9	56	10.2	-	0	0
20-40	24	19.1	58	5.4	-	0	3
40-60	15	19.1	54	3.8	-	26	1
60-80	13	21.1	50	1.2	-	34	2
80-100	12	19.6	57	3.0	-	21	1
90-105	17	17.8	65	0.6	-	0	1
105-120	17	17.8	60	0.6	-	0	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	-	-	-	0.28	0	4.42	0.75	0.49	0.36	-	0.75
20-40	-	-	-	0.29	0	3.43	0.62	0.73	0.48	-	0.61
40-60	-	-	-	0.30	0	4.64	0.90	0.73	0.53	-	0.51
60-80	-	-	-	0.38	0	5.50	1.08	0.71	0.70	-	0.46
80-100	-	-	-	0.35	0	8.42	1.13	0.28	0.26	-	0.43
90-105	-	-	-	0.34	0	9.01	0.98	0.08	0.11	-	0.53
105-120	-	-	-	0.29	0	10.61	0.90	0.03	0.05	-	0.48

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
0-20	40.7	27.8	15.2	0.15	0.62	0.27	-	2.54
20-40	41.0	29.0	15.3	0.07	0.55	0.25	-	2.57
40-60	38.7	30.2	15.9	0.06	0.50	0.27	-	2.31
60-80	38.3	31.6	15.5	0.04	0.46	0.32	-	1.80
80-100	37.7	31.9	14.9	0.03	0.41	0.38	-	1.68
90-105	38.0	31.4	14.8	0.04	0.50	0.41	-	1.81
105-120	37.6	30.9	16.0	0.06	0.40	0.41	-	1.80

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
0-20	0.18	0.32	12.1	-	2.5	7.1	1.8	2.8
20-40	0.09	0.22	12.2	101.25	2.4	7.1	1.8	3
40-60	0.07	0.22	12.3	100.53	2.2	6.5	1.6	3
60-80	0.04	0.21	12.7	100.97	2.1	6.6	1.6	3.2
80-100	0.14	0.24	12.8	-	2	6.7	1.5	3.4
90-105	0.21	0.24	12.6	100.01	2.1	6.8	1.6	3.3
105-120	0.19	0.24	12.7	100.3	2.1	6.2	1.6	3

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
0-20	9.8	0.18	9.0	0.16	0.15	-	68.8	2.32
20-40	10.5	0.07	11.3	0.14	0.13	-	67.5	2.38
40-60	14.8	0.01	14.0	0.19	0.06	-	61.1	1.94
60-80	12.7	0.03	12.4	0.16	0.11	-	65.6	2.24
80-100	15.7	0.02	21.2	0.22	0.11	-	55.5	1.93
90-105	15.2	0.03	24.3	0.21	0.06	-	52.1	1.89
105-120	14.3	0.02	26.1	0.21	0.01	-	51.0	1.82

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
0-20	1.7	10.2	0.11	0.09	11.9	20.3	7.5
20-40	1.5	7.9	0.07	0.06	10.9	15.9	6.5
40-60	1.7	8.2	0.05	0.09	7	11.6	4.4
60-80	1.6	7.5	0.06	0.07	8.8	14.1	5.4
80-100	1.2	7.7	0.14	0.16	6	7.0	3.2
90-105	1.0	7.1	0.24	0.16	5.8	5.7	2.9
105-120	0.9	6.9	0.19	0.14	6.1	5.2	2.8

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	-	-	very weak to weak	-	-	-	-	strong	weak to medium	-	strong
20-40	-	-	-	very weak to weak	-	-	-	-	strong	weak to medium	-	strong
40-60	-	-	-	very weak to weak	-	-	-	-	strong	weak to medium	-	strong
60-80	-	-	-	very weak to weak	-	-	-	-	strong	weak to medium	-	strong
80-100	-	-	-	very weak to weak	-	-	-	-	strong	very weak to weak	-	strong
90-105	-	-	-	very weak to weak	-	-	-	-	strong	very weak to weak	-	strong
105-120	-	-	-	very weak to weak	-	-	-	-	strong	very weak to weak	-	strong

Profile description

Ah1 0-15 cm	(dark) brown (7.5YR 4/2, dry) (10YR 2.5/2, moist)silty clay loam,moderate fine subangular blocky and strong very fine crumb,slightly hard friable slightly sticky slightly plastic,moderately porous (40-60 vol%),common very fine roots,non calcareous,gradual smooth boundary to,
Ah2 15-30 cm	(7.5YR 3.5/2, dry) (7.5YR 2.5/2, moist)silty clay loam,weak fine subangular blocky,slightly hard firm slightly sticky slightly plastic,few fine mottles and medium prominent mottles (10R 3/6),common very fine roots,few small and medium irregular soft ferruginous concretions,non calcareous,clear smooth boundary to,
30-45 cm	(dark) brown (10YR 4/3, dry) (7.5YR 3/3, moist)clay,weak fine subangular blocky,hard firm slightly sticky slightly plastic,few (2-5%) fine and medium prominent sharp mottles 10R3/6 (dark red),few very fine roots,few small and medium irregular soft ferruginous concretions and few large irregular soft ferruginous concretions,non calcareous,gradual smooth boundary to,
Bw1 45-75 cm	(7.5YR 4/5, dry) (7.5YR 3.5/5, moist)clay,weak very fine subangular blocky,slightly hard friable slightly sticky slightly plastic,common (5-15%) mottles 7.5YR4/8 (undescribed colour),moderately porous (40-60 vol%),non calcareous,clear smooth boundary to,
Bw2 75-90 cm	(7.5YR 4.5/6, dry) (7.5YR 3/6, moist)clay,moderate very fine subangular blocky,slightly hard friable slightly sticky slightly plastic,frequent small and medium irregular hard ferruginous concretions and frequent large irregular hard ferruginous concretions,non calcareous,gradual wavy boundary to,
Bv 90-120 cm	clay loamweak very fine and fine subangular blocky,slightly hard friable slightly sticky slightly plastic,many (15-40%) coarse prominent clear mottles 10YR3/6 (dark yellowish brown) and common (5-15%) medium distinct clear 2.5YR3/6 (dark red) mottles,continuous weakly cemented plinthite pans,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	Middle Ecca Sandstone
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Intensity of the soil erosion type	moderate
Soil erosion type	gully

Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	no human influence
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	1067m
Physiographic Unit	gully along road
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.	low hill
Slope	11%
Slope Aspect	west-north-west
Form of the slope surrounding the site	concave
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Dry From - To	0-50cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	50-120cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
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 South Africa 12: Umbrisol

Characteristics

Reference soil ZA012: Umbrisols

Classification