Reference soil Zimbabwe 05: Luvisol

ZW005

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 ZW005: Luvisols

(1) The site would normally be under a mixed Acacia/Colophosphermum mopane woodland, but clearing for the Research Station's trials have removed the natural vegetation. (2) The site is situated in a tillage trial block, that was ploughed in October 1989 and planted to sorghum during the 1990 summer season. There was no crop present at the time of monolith sampling. (3) Vegetation samples taken in the vicinity were identified as follows. Grass species included Chloris virgata, Digitaria milanjana, Enneopogon cenchroides, Eragrostis barrelieri, Eragrostis superba and Urochloa mosambicensis. Herbaceous species included Euphorbia hirta, Hibiscus sidiformis, Indigofera praticola, Neorautanenia brachypus, Phyllanthus maderaspatensis, Tephrosia purpurea, Vernonia fastigiata and Tribulus terrestris. Two woody species were identified as Maerua angolensis and Sclerocarya birrea. (4) Lister (1986, p. 52) indicates that the area around Chiredzi is situated on the Pliocene Erosion Surface and is a remarkably even pedi-plain covering a very wide expanse of country. The excessive erosion that has occured since the Pliocene movements can be attributed to constantly-repeated sheet floods, which are sometimes recorded in the present day. The general landsurface rises from 470 m near Beitbridge to about 700 m at its northernmost extent. (5) Concentrations of common, subrounded quartz stones of coarse gravel to small stone size were observed at the bottom of the mixed Horizon 2 (39 cms) and above the weathering material of Horizon 5 (107 cms). A few of these quartz stones can be found on the surface, as a result of ploughing. (6) Rain (70mm) fell on 18/2/91 but only wetted up the top two Horizons, to a depth of 39 cms. (7) Horizon 2 was already beginning to dry out and show incipient subangular blocky structure. (8) Horizon 5 is one of SLM (soil-like material) Horizon 6 of soft weathering rock showing residual rock structure, and Horizon 7 is slightly hard weathering rock. (9) A number of insect specimens were taken for identification. Of the Coleoptera order, (Staphilinidae Staphilininae) Oxytelus sp.; of the Blatodea order, (Ectobiidae Ectobiinae) Ectobius sp.; of the Isoptera order, (Termitidae) Macrotermes falcigar; and a specimen of the Chilopoda order.

Classification

WRB 2006

Cutanic- Luvisol (Hypereutric Clayic)

107-175 cm	calcic horizon
24-88 cm	argic horizon

107-175 cm	calcic horizon
24-88 cm	argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Orthi-Calcic Luvisol

Calcic Luvisol

0-39 cm	ochric A horizon
107-175 cm	calcic horizon
24-88 cm	argic B horizon

0-39 cm	ochric A horizon
107-175 cm	calcic horizon
24-88 cm	argillic B horizon

Local classification:	Triangle 4PE.2 Series

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
0-24	-	2.6	8.6	13.5	20.5	9.2	54.4	7.7	4.3	12	33.5
24-39	-	2.4	8.3	11.2	15.3	9.2	46.4	5.9	4.4	10.3	43.3
39-71	-	3.7	7.9	10.1	14.7	7.2	43.6	6.7	5.1	11.8	44.7
71-88	-	3.3	6.6	7.0	12.3	9.0	38.2	6.6	7.4	14	47.8
88-107	-	10.3	13.6	8.8	11.0	8.0	51.7	8.3	8.1	16.4	31.9

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-24	1.47	-	-	18.1	33.5
24-39	1.39	-	-	21.2	43.3
39-71	1.47	-	-	24.2	44.7
71-88	1.54	-	-	27.9	47.8
88-107	1.49	-	-	19.6	31.9

Other physical data

Depth (cm)	Bulk density kg/dm³	pF 0 % v/v	pF 1.0 % v/v	pF 1.5 % v/v	pF 2.0 % v/v	pF 2.3 % v/v	pF 2.7 % v/v	pF 3.4 % v/v	pF 4.2 % v/v
0-24	1.47	-	-	38	35	28	-	-	13
24-39	1.39	-	-	36	33	29	-	-	19
39-71	1.47	-	-	40	37	33	-	-	19
71-88	1.54	-	-	42	40	36	-	-	23
88-107	1.49	-	-	41	38	33	-	-	21

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
0-24	6.3	5.1	0.11	-	0.97	0.07	14	-	-	10.5	3.7	0.7	0.0	14.9
24-39	6.2	5.1	0.25	-	0.75	0.08	9	-	-	12.9	4.5	0.4	0.0	17.8
39-71	6.4	5.4	0.20	-	0.72	0.07	10	-	-	14.7	4.5	0.3	0.1	19.6
71-88	6.7	5.5	0.28	1.6	0.56	0.07	8	-	-	18.2	4.5	0.3	0.1	23.1
88-107	7.1	5.9	0.36	2.9	0.32	0.05	6	-	-	23.7	4.8	0.3	0.2	29

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 %
0-24	93	16.1	48	3.4	-	-	0
24-39	91	19.5	45	2.6	-	-	0
39-71	97	20.3	45	2.5	-	-	0
71-88	102	22.6	47	2.0	-	-	0
88-107	108	26.8	84	1.1	-	-	1

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-24	-	-	-	weak	-	-	medium to strong	very weak to weak	-	-	weak to medium	-
24-39	-	-	-	weak	-	-	medium to strong	very weak	-	-	weak to medium	-
39-71	-	-	-	very weak to weak	-	-	medium to strong	very weak	-	-	weak	-
71-88	-	-	-	very weak to weak	-	-	medium to strong	very weak	-	-	medium to strong	-
88-107	-	-	-	very weak to weak	-	-	weak to medium	very weak	-	-	strong	-

Profile description

Ah 0-24 cm	dark reddish brown (5YR 3/4, dry) dark reddish brown (5YR 3/2, moist)coarse sandy loam,weak coarse subangular blocky parting to moderate very fine granular,very friable slightly sticky slightly plastic,no cutans,no pores moderately porous (40-60 vol%),many fine roots,very few fine gravel weathered quartz fragments,no,non calcareous,clear wavy boundary to,
24-39 cm	dark reddish brown (5YR 3/4, dry) dark reddish brown (5YR 3/3, moist)sandy clay loam,weak medium and coarse subangular blocky parting to moderate very fine granular,friable slightly sticky slightly plastic,no cutans,no pores moderately porous (40-60 vol%),common fine roots,very few fine gravel weathered quartz fragments,few termite channels and channels,non calcareous,abrupt wavy boundary to,
BA 39-71 cm	dark reddish brown (5YR 3/3, dry) dark reddish brown (5YR 3/3, moist)clay,moderate coarse subangular blocky,extremely hard extremely firm sticky plastic,patchy thin clay on horizontal cutans pedfaces,few very fine continuous inped vesicular random pores,few fine roots,very few fine gravel weathered quartz fragments,few channels,non calcareous,gradual smooth boundary to,
Bt1 71-88 cm	dark reddish brown (5YR 3/3, dry) dark reddish brown (5YR 3/3, moist)clay,weak very coarse subangular blocky,firm sticky plastic,patchy thin clay on horizontal cutans pedfaces,few very fine continuous inped vesicular random pores,few fine roots,frequent small irregular manganiferous soft segregations,very few fine gravel weathered quartz fragments,no,slightly calcareous (0-2%),abrupt wavy boundary to,
Bt2 88-107 cm	dark reddish brown (5YR 3/3, dry) dark reddish brown (5YR 3/3, moist)sandy clay loam gravelly,moderately coherent porous massive,friable slightly sticky slightly plastic,patchy thin clay on horizontal cutans pedfaces,moderately porous (40-60 vol%),frequent medium spherical soft manganiferous concretions,very few fine gravel weathered quartz and common fine gravel strongly weathered mafic gneiss fragments,no,moderately calcareous (2-10%),clear wavy boundary to,
BCk 107-146 cm	yellowish red (5YR 4/6, dry) yellowish red (5YR 4/6, moist)gravelly coarse sandy loam,weakly coherent porous massive,very friable,no cutans,moderately porous (40-60 vol%),very frequent medium irregular hard manganiferous concretions and few powdery thread-like calcareous soft segregations,dominant fine gravel strongly weathered mafic gneiss fragments,no,strongly calcareous (10-25%),diffuse boundary to,
CBk 146-175 cm	yellow (10YR 8/6, dry) brownish yellow (10YR 6/6, moist)very gravelly loamy coarse sand,moderately coherent porous massive,firm,no cutans,very frequent medium irregular hard manganiferous concretions and few medium irregular hard calcareous concretions,dominant fine gravel strongly weathered mafic gneiss fragments,no,strongly calcareous (10-25%),

Kind 1 (parent material) ; Parker (eds), 1984	basic gneiss
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Basic paragneiss
Soil Depth	107cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	not apparent
Intensity of the soil erosion type	slight
Soil erosion type	sheet
Slope stability	stable

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	land clearing
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	fallow
Remarks on Land Use / Vegetation	VEGETATION: Land was been left fallow since April 1990
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	430m
Physiographic Unit	slope
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.	pediplain
Slope	1%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	88cm
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	0-39cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	slow
Upper limit of a slow permeable or stagnating layer in the profile	39cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Average size of stone	18
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
Shape of stones (on average)	(sub-)rounded
Surface stoniness class (FAO (2006) - Guidelines for soil description)	very few stones

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Reference soil Zimbabwe 05: Luvisol

Characteristics

Reference soil ZW005: Luvisols

Classification