Reference soil Botswana 03: Luvisol

BW003

Luvisols occur mainly in temperate regions, particularly in areas with a Mediterranean-type of climate.

Characteristics

Soils having an argic horizon (a subsurface horizon with a distinct higher clay content than the overlying horizon) with a cation exchange capacity equal to or more than 24 cmolc per kg clay throughout.

Distribution of Luvisols (rough estimation supplied by soilgrids)

Reference soil BW003: Luvisols

GEOLOGY: Precambric rocks, mainly granites from the Mahalapye formation. LOCATION: 500 m South of the road to Bonwapitse MOISTURE: soil dry from 0 to 70 cm and slightly moist below VEGETATION: Acacia nigerescens, A. robusta, and Dichrostachys cenerea. HUMAN INFLUENCE: plough layer from 0-20 cm. BRIEF DESCRIPTION: A deep, moderately well drained sandy clay loam with a gley horizon commencing at 76 cm depth. Horizonation is gradual, structural development weak to absent. Weathered rock is encountered at 129 cm depth, while a plouth layer of a coarse sandy loam texture is present from 0-20 cm. The soil reaction is slightly acid from 0-104 cm and becomes neutral to mildly alkaline in the B3. MORPHOLOGY: Ap Few termine nests with 2 cm diameter. B21 Thin cutans in root and termine channels. B2g Coarse fragments increasing with depth. B2g Appreciable amount of coarse fragments and few small prominent reddish concretions in the lower part of the horizon. C Weathered rock with common distinct bluish black fine concretions.

Classification

WRB 2006

WRB 1998

Cutanic- Luvisol (Chromic)

Cutani-Chromic- Luvisol

21-104 cm

argic horizon

0-21 cm	ochric horizon
21-104 cm	argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Orthi-Haplic Luvisol

Luvic Yermosol phreatic

0-21 cm	ochric A horizon
21-104 cm	argic B horizon
-	fluvic

0-21 cm	ochric A horizon
21-104 cm	argillic B horizon
47-104	hydromorphic

Other classification

USDA-NRCS (1999)	Udic Haplustalf ustic fine mixed hyperthermic
USDA-SCS (1975)	Udic Haplustalf ustic fine mixed hyperthermic

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
0-21	3	-	-	-	-	-	71.2	6.3	3.7	10	18.8
21-47	8	-	-	-	-	-	-	5.0	3.7	8.7	34.1
47-76	6	-	-	-	-	-	54.7	5.5	4.5	10	35.3
76-104	6	-	-	-	-	-	52.4	6.3	6.5	12.8	34.8
104-129	19	-	-	-	-	-	59.4	3.2	9.6	12.8	27.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-21	-	-	-	-	18.8
21-47	-	-	-	-	34.1
47-76	-	-	-	-	35.3
76-104	-	-	-	-	34.8
104-129	-	-	-	-	27.8

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
0-21	6.5	4.9	0.07	0.3	0.52	0.04	13	-	-	3.2	0.7	0.6	0.2	4.7
21-47	6.6	4.9	0.13	0.5	0.30	0.04	8	-	-	4.9	1.3	0.6	0.2	7
47-76	6.8	5.1	0.14	0.6	0.23	-	-	-	-	5.9	1.3	0.7	0.2	8.1
76-104	7.3	5.5	0.15	0.7	0.17	-	-	-	-	8.5	1.7	0.7	0.2	11.1
104-129	7.6	5.5	0.11	0.5	0.16	-	-	-	-	10.3	2.6	0.8	0.1	13.8

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 %
0-21	66	7.1	38	1.8	-	-	3
21-47	72	9.7	28	1.1	-	-	2
47-76	79	10.3	29	0.8	-	-	2
76-104	93	12.0	34	0.6	-	-	2
104-129	97	14.2	51	0.6	-	-	1

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
0-21	9.0	0.23	2.9	2.92	0.42	-	81.7	0.47
21-47	11.9	0.25	3.7	2.21	0.65	-	74.7	0.50
47-76	13.2	0.29	3.8	2.31	0.82	-	72.3	0.55
76-104	13.5	0.36	4.3	2.54	0.57	-	72.2	0.62
104-129	13.8	0.40	5.4	2.12	0.99	-	76.8	0.63

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
0-21	4.9	4.6	0.02	0.10	15.4	74.9	12.8
21-47	5	6.4	0.02	0.06	10.7	53.7	8.9
47-76	5.4	7.0	0.03	0.11	9.3	50.6	7.9
76-104	4.9	8.2	0.03	0.06	9.1	44.6	7.5
104-129	4	8.3	0.15	0.07	9.4	37.8	7.6

Profile description

Ap 0-21 cm	dark brown (7.5YR 3/2, moist) (dark) brown (7.5YR 4/4, dry)coarse sandy loam,fine and medium subangular blocky medium,very hard friable slightly sticky slightly plastic,common fine and medium tubular,common fine medium tubular pores,common fine and medium tubular pores,common very fine and few medium roots,few termite channels,slightly calcareous (0-2%),gradual wavy boundary to,
Bt 21-47 cm	dark reddish brown (5YR 3/3, moist) reddish brown (5YR 4/4, dry)sandy clay loam,moderate medium and coarse subangular blocky,slightly hard friable sticky plastic,patchy thin clay and sesquioxide in root channels and pores,many fine medium tubular pores,many fine and medium tubular,common fine and medium roots,frequent medium unspecified inclusions,frequent termite channels,slightly calcareous (0-2%),gradual smooth boundary to,
Btg1 47-76 cm	dark reddish brown (5YR 3/3, moist) yellowish red (5YR 5/6, dry)sandy clay loam,moderate medium and coarse subangular blocky,slightly hard friable sticky plastic,common (5-15%) faint mottles (10YR 4/1) and common faint mottles (5YR 4/8),broken thin clay and sesquioxide cutans,common fine roots,few termite channels,slightly calcareous (0-2%),gradual wavy boundary to,
Btg2 76-104 cm	dark brown (7.5YR 3/2, moist)sandy clay loam,massive,very hard firm sticky plastic,common (5-15%) distinct mottles (10YR 3/1) and common(5-15%) distinct mottles (5YR 4/4),broken thin clay and sesquioxide cutans,common fine and medium tubular pores,few fine roots,few small concretions,few coarse gravel,slightly calcareous (0-2%),clear wavy boundary to,
BCg 104-129 cm	brown (10YR 5/3, moist) pale brown (10YR 6/3, dry)sandy clay loam slightly gravelly,soft friable sticky plastic,common (5-15%) faint mottles,few fine roots,few medium hard ferruginous concretions and few large angular ferruginous concretions,common coarse gravel,slightly calcareous (0-2%),clear wavy boundary to,
129-144 cm	greyish brown (10YR 5/2, moist) light yellowish brown (2.5Y 6/4, dry)coarse sandy loam,frequent medium manganiferous concretions,many coarse gravel,slightly calcareous (0-2%),

Major crops	sorghum
Land use or vegetation in the immediate vicinity of the site	low level arable farming
Remarks on Land Use / Vegetation	Savanna, Acacia mixed woodland
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop with current fallow
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	semi-deciduous woodland

Altitude	1126m
Physiographic position of the site	depression
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plain
Slope	0%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Microrelief pattern	none
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Botswana 03: Luvisol

Characteristics

Reference soil BW003: Luvisols

Classification