Reference soil South Africa 19: Regosol

ZA019

Regosols are found in areas where soil has been eroded to the extent that the underlying unconsolidated materials come near to the surface, or where soil formation has not played an important role, e.g. in desert regions. The name comes from the greek 'rhegos' :blanket meaning young soils on weathering materials.

Characteristics

Soils in medium and fine textured materials, having no distinctive horizons other than an ochric horizon at the surface.

Distribution of Regosols (rough estimation supplied by soilgrids)

Reference soil ZA019: Regosol

Classification

WRB 2014

Regosol

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
0-15	-	0.3	0.9	1.4	2.7	3.1	8.4	21.4	30.9	52.3	39.2
15-30	-	0.1	0.3	1.1	3.7	3.7	8.9	19.6	31.4	51	40.1
30-50	-	0.1	0.5	1.3	3.9	3.4	9.2	29.2	20.4	49.6	41.2
50-70	-	0.1	0.3	1.3	3	2.9	7.6	45.5	3.8	49.3	43.1
70-90	-	1.6	2.3	2.3	3.1	2.5	11.8	45.1	7.4	52.5	35.7
90-115	-	1.4	2.8	2.7	3.4	2.9	13.2	50	2.2	52.2	34.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-15	-	-	-	-	39.2
15-30	-	-	-	-	40.1
30-50	-	-	-	-	41.2
50-70	-	-	-	-	43.1
70-90	-	-	-	-	35.7
90-115	-	-	-	-	34.6

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
0-15	5.5	4.1	0.05	-	1.95	0.13	15	-	0.2	5.4	2.9	0.2	0.3	8.8
15-30	5.5	4.1	0.06	-	2.53	0.17	15	-	0.2	7.4	3.2	0.1	0.3	11
30-50	5.6	4.1	0.06	-	2.84	0.18	16	-	0	8.2	7.6	0.1	0.3	16.2
50-70	5.5	3.9	0.05	-	1.83	0.13	14	-	0.9	5.4	3.0	0.1	0.3	8.8
70-90	5.5	3.8	0.03	-	0.90	0.08	11	-	1.4	3.4	2.4	0.1	0.1	6
90-115	5.5	3.7	0.03	-	0.66	0.07	9	-	1.8	3.2	2.5	0.1	0.1	5.9

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 %
0-15	33	26.9	69	6.8	-	1	-
15-30	42	26.1	65	8.9	-	1	-
30-50	62	26.1	63	9.9	-	0	-
50-70	38	23	53	6.4	-	4	-
70-90	36	16.5	46	3.1	-	8	-
90-115	35	16.9	49	2.3	-	11	-

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
0-15	-	-	-	-	-	2.5	0.2	-	-	-	-
15-30	-	-	-	-	-	2.3	0.2	-	-	-	-
30-50	-	-	-	-	-	2.2	0.2	-	-	-	-
50-70	-	-	-	-	-	2.5	0.2	-	-	-	-
70-90	-	-	-	-	-	3	0.2	-	-	-	-
90-115	-	-	-	-	-	3.1	0.2	-	-	-	-

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
0-15	50.5	29.2	7.6	0.04	1.12	2.33	-	1.2
15-30	49.3	29	8.3	0.05	1.07	2.25	-	1.12
30-50	49	29	8.5	0.09	1.06	2.18	-	1.11
50-70	46.7	29.6	7.8	0.09	1.13	2.19	-	1.06
70-90	49.9	29.8	7.3	0.07	1.12	2.42	-	1.23
90-115	49.9	29.1	6.6	0.07	1.12	2.52	-	1.22

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
0-15	0.08	0.15	9	102.2	2.9	17.7	2.5	6
15-30	0.13	0.24	10.2	101.8	2.9	15.8	2.4	5.5
30-50	0.17	0.28	10.1	101.5	2.9	15.4	2.4	5.4
50-70	0.06	0.16	11.3	99.5	2.7	15.9	2.3	5.9
70-90	0.07	0.11	9.9	101.6	2.8	18.2	2.5	6.4
90-115	0.08	0.09	9.8	101.2	-	20.2	-	-

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
0-15	13.6	0.28	6.2	1.47	0.55	-	65.6	1.03
15-30	13.1	0.38	5.7	1.34	0.54	-	66.2	1.01
30-50	13.0	0.42	5.6	1.34	0.54	-	66.2	0.99
50-70	14.8	0.26	6.2	1.48	0.59	-	64.5	1
70-90	13.9	0.17	6.9	1.53	0.55	-	66.7	1.06
90-115	14.5	0.14	7.3	1.59	0.57	-	66.4	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
0-15	3.4	11.6	0.12	0.07	8.2	28.2	6.3
15-30	3.6	12.9	0.14	0.09	8.6	30.9	6.7
30-50	3.6	13.4	0.15	0.11	8.6	31.5	6.8
50-70	3.7	12.0	0.09	0.08	7.4	27.7	5.8
70-90	3.2	9.8	0.14	0.06	8.1	25.7	6.2
90-115	3.1	9.6	0.14	0.06	7.8	24.2	5.9

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium
15-30	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium
30-50	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium
50-70	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium
70-90	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium
90-115	-	-	-	-	-	-	strong	weak to medium	weak to medium	weak to medium	-	weak to medium

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Reference soil South Africa 19: Regosol

Characteristics

Reference soil ZA019: Regosol

Classification