Reference soil Botswana 05: Solonetz

BW005

Solonetzes occur where a sodium source supplies the clay-rich subsoil with exchangeable Na, causing peptization of clay and organic substances and deterioration of the topsoil.

Characteristics

Soils having a natric horizon (a subsurface horizon with distinct higher clay content than the overlying horizon and more than 15% exchangeable sodium) within 100 cm from the soil surface.

Distribution of Solonetz (rough estimation supplied by soilgrids)

Reference soil BW005: Solonetz

VEGETATION: Acacia karroo, A.Nilotica, Dichrostachys cenerea MORPHOLOGY: B2g 91-127 also few small prominent bluish black mottles B3 few yellowish and greyish mottling C strongly decomposed granite rock of sandy clay texture with prominent small dark bluish mottles BRIEF PROFILE DESCRIPTION: A deep, poorly drained, alkaline gley soil of a fine texture and with moderate coarse columnar structure from 43-69 cm (B2g); horizonation is clear to gradual, strongly decomposed granite is encountered at 158.

Classification

WRB 2006

WRB 1998

Stagnic-Mollic-Vertic- Solonetz

Molli-Vertic- Solonetz (Stagnic)

0-43 cm	mollic horizon
69-127 cm	natric horizon
91-127 cm	vertic horizon
43-91	stagnic colour pattern
69-127	reducing conditions

0-43 cm	mollic horizon
69-127 cm	nitic horizon
91-127 cm	vertic horizon
43-91	stagnic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Molli-Stagnic Solonetz

Gleyic Solonetz

0-43 cm	mollic A horizon
69-127 cm	natric B horizon
43-91	stagnic
91-127	vertic

0-43 cm	mollic A horizon
69-158 cm	natric B horizon
43-91	hydromorphic

Other classification

USDA-NRCS (1999)	Albic Natraqualf ustic fine-loamy siliceous hyperthermic
USDA-SCS (1975)	Albic Natraqualf ustic fine-loamy siliceous hyperthermic

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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
0-2	1	-	-	-	-	-	39.8	11.7	19.4	31.1	29.4
2-43	4	-	-	-	-	-	71.1	4.4	8.9	13.3	15.6
43-69	6	-	-	-	-	-	69.5	3.1	5.9	9	21.6
69-91	10	-	-	-	-	-	56.6	4.4	4.0	8.4	35
91-127	10	-	-	-	-	-	55.7	4.6	4.2	8.8	35.5
127-158	10	-	-	-	-	-	56.8	4.8	4.4	9.2	34
158-180	33	-	-	-	-	-	51.3	5.9	3.5	9.4	39.2

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-2	-	-	-	-	29.4
2-43	-	-	-	-	15.6
43-69	-	-	-	-	21.6
69-91	-	-	-	-	35
91-127	-	-	-	-	35.5
127-158	-	-	-	-	34
158-180	-	-	-	-	39.2

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
0-2	6.5	5.2	0.2	0.7	1.84	0.17	11	-	-	7.7	2.4	1.3	0.2	11.6
2-43	6.2	4.6	0.11	0.3	0.80	0.05	16	-	-	2.8	1.0	0.4	0.2	4.4
43-69	7.2	5.3	0.36	0.4	0.35	-	-	-	-	3.8	2.2	0.2	0.7	6.9
69-91	8.5	6.6	-	-	0.17	-	-	-	-	7.0	4.6	0.4	3.1	15.1
91-127	8.8	6.8	-	-	0.17	-	-	-	-	7.3	4.2	0.5	3.7	15.7
127-158	8.7	6.8	-	-	0.11	-	-	-	-	7.3	4.8	0.5	4.2	16.8
158-180	8.8	6.6	-	-	0.15	-	-	-	-	7.0	5.8	0.6	5.2	18.6

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 %
0-2	74	15.7	53	6.4	-	-	1
2-43	61	7.2	46	2.8	-	-	3
43-69	77	9	42	1.2	-	-	8
69-91	99	15.3	44	0.6	-	-	20
91-127	99	15.8	45	0.6	-	-	23
127-158	104	16.1	47	0.4	-	-	26
158-180	99	18.8	48	0.5	-	-	28

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
0-2	14.9	1.71	7.5	1.49	2.55	-	68.0	0.91
2-43	16.3	1.93	8.5	1.66	2.27	-	71.0	0.99
43-69	15.1	1.46	6.8	2.18	3.91	-	72.4	0.64
69-91	11.0	0.99	4.2	-	0.43	-	77.4	0.63
91-127	14.2	0.38	4.2	3.87	0.56	-	75.7	0.54
127-158	20.1	0.71	5.6	2.53	1.84	-	69.9	0.47
158-180	6.9	0.22	1.4	3.34	0.80	-	79.5	0.40

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
0-2	3.1	9.4	0.04	0.11	7.7	24.1	5.9
2-43	3	4.3	0.03	0.04	7.4	22.2	5.5
43-69	3.5	5.5	0.02	0.07	8.1	28.3	6.3
69-91	4.1	10.3	0.02	0.04	11.9	49	9.6
91-127	5.3	7.4	0.01	0.05	9	47.9	7.6
127-158	5.6	4.2	0.02	0.08	5.9	33.2	5
158-180	7.7	7.7	0.03	0.13	19.5	150.9	17.3

Profile description

Ah1 0-2 cm	black (10YR 2/1, moist) greyish brown (10YR 5/2, dry)clay loam,weak medium platy,very hard firm slightly sticky plastic,common (5-15%) medium distinct mottles (7.5YR 4/4),common very fine pores,slightly calcareous (0-2%),abrupt wavy boundary to,
Ah2 2-43 cm	(7.5YR 3/1, moist) dark greyish brown (10YR 4/2, dry)coarse sandy loam,structureless massive,hard friable slightly sticky plastic,common medium tubular pores,common fine and few coarse roots,few fine gravel fragments,slightly calcareous (0-2%),clear wavy boundary to,
Btg 43-69 cm	very dark grey (10YR 3/1, moist) greyish brown (10YR 5/2, dry)sandy clay loam,moderate coarse columnar,hard friable slightly sticky plastic,many fine prominent mottles (2.5YR 3/6) and few fine faint mottles (10YR 5/3),continuous thin clay and humus cutans,few fine pores,common fine few medium roots,slightly calcareous (0-2%),clear wavy boundary to,
Btng1 69-91 cm	dark grey (10YR 4/1, moist) dark grey (10YR 4/1, dry)sandy clay slightly gravelly,moderate medium prismatic),hard friable slightly sticky plastic,common (5-15%) fine distinct mottles (2.5YR 3/6) and common (5-15%) fine distinct mottles (7.5YR 5/6),continuous thick clay and humus cutans,few fine and medium roots,non calcareous,gradual wavy boundary to,
Btng2 91-127 cm	grey (10YR 5/1, moist) (light) grey (10YR 6/1, dry)sandy clay slightly gravelly,moderate medium prismatic,very hard firm slightly sticky plastic,few (2-5%) medium prominent mottles (10YR 6/6) and common (5-15%) coarse prominent mottles (10YR 6/6),continuous moderately thick clay and humus cutans,few very fine roots,non calcareous,gradual wavy,
127-158 cm	greyish brown (10YR 5/2, moist) brown (10YR 5/3, dry)sandy clay loam slightly gravelly,structureless massive,few (2-5%) mottles,continuous thin clay and humus cutans,few fine roots,non calcareous,gradual wavy boundary to,
C 158-180 cm	greyish brown (10YR 5/2, moist)sandy clay,common (515%) prominent mottles,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	igneous rock
Mode of accumulation or deposition of parent material	solid rock
Texture of parent material (second entry)	loamy
Weathering Resistance	high

Intensity of the soil erosion type	moderate
Soil erosion type	sheet

Land use or vegetation in the immediate vicinity of the site	woodland, grazed
Remarks on Land Use / Vegetation	Savanna, Acacia Mixed Woodland
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	modified
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	semi-deciduous woodland

Altitude	1172m
Physiographic Unit	valley bottom
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	valley
Slope	2%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Moist From - To	0-180cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	strongly alkaline
Microrelief pattern	none
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Botswana 05: Solonetz

Characteristics

Reference soil BW005: Solonetz

Classification