Reference soil South Africa 16: Phaeozem

ZA016

Phaeozems occur all over the world, but especially on the more moist side of the steppe regions, bordering Chernozems.

Characteristics

Soils having a mollic horizon (deep, brownish or blackish surface horizon with a significant accumulation of organic matter and high base saturation); a base saturation of 50 percent or more between 25 and 100 cm from the soil surface; a calcium carbonate-free soil matrix at least to a depth of 100 cm from the soil surface, or to a contrasting layer between 25 and 100 cm; no diagnostic horizons other than an albic, argic, cambic or vertic horizon, or a petrocalcic horizon in the substratum.

Distribution of Phaeozems (rough estimation supplied by soilgrids)

Reference soil ZA016: Phaeozems

ADDITIONAL NOTES ON PROFILE DESCRIPTION: Ah - High interpedal, low intrapedal porosity. AB - High interpedal, low intrapedal porosity. Bw1 - High interpedal, low intrapedal porosity. Bw2 - High interpedal, low intrapedal porosity. Bw2 - Gravel increasing with depth. R - Weathering dolerite.

Classification

WRB 2006

Haplic- Phaeozem (Pachic Clayic)

0-70 cm

mollic horizon

0-70 cm

mollic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Pachi-Haplic Phaeozem

Haplic Phaeozem

0-70 cm

mollic A horizon

0-70 cm

mollic A horizon

Local classification:	Milkwood Form

Other classification

USDA-NRCS (1999)	Pachic Hapludoll
USDA-SCS (1975)	Pachic Hapludoll udic fine mixed 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
0-20	-	3.9	1.1	0.7	1.2	3.6	10.5	24.3	14.5	38.8	50.7
20-45	-	2.3	1.8	0.7	1.5	4.6	10.9	20.3	17.1	37.4	51.7
45-70	-	1.0	0.5	0.3	1.4	6.6	9.8	19.4	21.4	40.8	49.3
70-80	-	9.0	10.4	9.0	10.8	4.8	44	23.4	8.0	31.4	22.5

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	-	-	-	-	50.7
20-45	-	-	-	-	51.7
45-70	-	-	-	-	49.3
70-80	-	-	-	-	22.5

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	6.0	4.9	0.08	2.5	2.75	0.25	11	-	-	10.2	7.1	0.0	0.2	17.5
20-45	6.3	4.9	0.14	1.6	1.14	0.12	10	-	-	14.2	9.1	0.2	0.4	23.9
45-70	7.1	5.7	0.00	1.9	0.86	0.10	9	-	-	17.4	10.9	0.1	0.5	28.9
70-80	7.5	5.5	0.07	2.9	0.38	0.03	13	-	-	18.2	9.8	0.2	0.5	28.7

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 %
0-20	57	30.5	60	9.6	-	-	1
20-45	67	35.7	69	4.0	-	-	1
45-70	83	34.8	71	3.0	-	-	1
70-80	90	31.8	141	1.3	-	-	2

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	-	-	-	-	-
20-45	-	-	-	-	-	0	-	-	-	-	-
45-70	-	-	-	-	-	0	-	-	-	-	-
70-80	-	-	-	-	-	0	-	-	-	-	-

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	43.8	26.6	14.8	0.06	0.61	1.13	-	0.84
20-45	44.4	28.0	13.0	0.18	0.66	1.13	-	0.64
45-70	46.7	26.9	11.9	0.18	0.92	1.18	-	0.57
70-80	48.1	26.4	12.7	0.23	1.19	0.83	-	0.54

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	0.45	0.33	11.2	99.7	2.8	7.9	2.1	2.8
20-45	0.29	0.22	10.8	99.32	2.7	9.1	2.1	3.4
45-70	0.28	0.19	10.7	99.5	2.9	10.4	2.3	3.5
70-80	0.22	0.21	11.1	101.5	3.1	10.1	2.4	3.2

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
0-20	15.2	0.53	9.8	0.82	0.53	-	59.9	1.57
20-45	19.1	0.59	10.5	1.02	0.70	-	57.5	1.09
45-70	18.7	0.80	9.4	1.10	0.91	-	59.2	1.04
70-80	18.5	6.43	12.3	0.42	4.41	-	51.2	1.05

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	2.4	10.6	0.42	0.12	6.7	16.3	4.7
20-45	2.8	8.4	0.30	0.08	5.1	14.6	3.8
45-70	3.1	7.0	0.21	0.09	5.4	16.7	4.1
70-80	2.4	4.3	0.19	0.13	4.7	11.1	3.3

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	-	-	very weak to weak	-	-	weak to medium	very weak to weak	weak to medium	weak to medium	weak to medium	very weak to weak
20-45	-	-	-	very weak to weak	-	-	weak to medium	very weak to weak	strong	very weak to weak	-	very weak to weak
45-70	-	-	-	very weak to weak	-	-	weak to medium	very weak to weak	weak to medium	very weak to weak	strong	-
70-80	-	-	-	-	-	-	weak to medium	-	weak to medium	-	strong	-

Profile description

Ah1 0-30 cm	(10YR 3/1.5, dry) very dark brown (10YR 2/2, moist)clay,strong fine subangular blocky,very hard friable sticky plastic,common fine roots,non calcareous,gradual smooth boundary to,
Ah2 30-45 cm	(10YR 2/1.5, dry) (10YR 2/1.5, moist)clay,strong very fine subangular blocky,very hard friable sticky plastic,common fine roots,non calcareous,gradual smooth boundary to,
45-70 cm	(5Y 2/1.5, dry) (5Y 2/1.5, moist)silty clay slightly gravelly,moderate medium prismatic parting to weak fine subangular blocky,very hard friable sticky plastic,few fine roots,very few medium gravel weathered dolorite fragments,non calcareous,clear wavy boundary to,
B 70-80 cm	(5Y 2/2, dry) (5Y 2/2, moist)loam slightly gravelly,moderate medium prismatic parting to weak fine platy,very hard friable sticky plastic,few fine roots,very few medium gravel weathered dolorite fragments,non calcareous,abrupt wavy boundary to,
R 80-80 cm	rock structuredominant weathered dolorite fragments,non calcareous,

Depth1	80cm
Kind 1 (parent material) ; Parker (eds), 1984	dolerite
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	weathering dolerite
Soil Depth	80cm
Texture of parent material	clayey
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly

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

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 grassland, grazed
Remarks on Land Use / Vegetation	VEGETATION: 'Thornveld', used for grazing
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	790m
Physiographic Unit	near summit plateau
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plateau
Slope	18%
Slope Aspect	north-east
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-80cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	rapid

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Average size of stone	75
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	level
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)	fairly stony

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Reference soil South Africa 16: Phaeozem

Characteristics

Reference soil ZA016: Phaeozems

Classification