Reference soil Uruguay 06: Vertisol

UY006

Vertisols occur dominantly in level landscapes under climates with a pronounced dry season. Vast areas are found in Australia, India, northeastern Africa (Sudan, Ethiopia), southern Latin America and the USA.

Characteristics

Soils having a vertic horizon (a clayey subsurface horizon with polished and grooved ped surfaces ("slickensides") or wedge-shaped or parallelepiped structural aggregates) within 100 cm from the soil surface. They have 30 percent or more clay in all horizons to a depth of 100 cm or more, or to a contrasting layer (lithic or paralithic contact, petrocalcic, petroduric or petrogypsic horizons, sedimentary discontinuity, etc.) between 50 and 100 cm, after the upper 20 cm have been mixed. In addition, Vertisols exhibit wide cracks, which open and close periodically.

Distribution of Vertisols (rough estimation supplied by soilgrids)

Reference soil UY006: Vertisols

GEOLOGICAL FORMATION: Libertad quaternary period SURFACE DRAINAGE: course dendritic MOISTURE: soil is slightly dryer below 20 cm VEGETATION: (regional,local) Trees (1%, 1%), herbs (20%, 19%), grasses (29%, 80%), bare ground (50%, -) Dominant species are Stipa carruana, Paspalum dilatatum, Bothriochola laguroides, Eryngium horridum, Bacharis coridifolia, Stenotaphrum secundatum. LITERATURE: Terzaghi, A. Características Físicas de los principales suelos agrícolas de Canelones-Montevideo. Technical Bulletin No. 8 part 1 and 2. Canelones-Montevideo soil chart (1:100.000)

Classification

WRB 2006

WRB 1998

calcic horizon- Vertisol (Humic)

calcic horizon- Vertisol

22-117 cm	vertic horizon
76-101 cm	calcic horizon

0-22 cm	ochric horizon
22-117 cm	vertic horizon
76-101 cm	calcic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Hyposodi-Calcic Vertisol gilgai

Chromic Vertisol sodic

0-22 cm	ochric A horizon
22-117 cm	cambic B horizon
76-101 cm	calcic horizon
-	calcaric
-	vertic

0-22 cm	ochric A horizon
76-101 cm	calcic horizon
-	vertic

Local classification:	Vertisol ruptico

Other classification

USDA-NRCS (1999)

Chromic Hapludert

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
0-22	-	0.0	0.1	0.3	0.7	3.2	4.3	26.6	23.3	49.9	45.8
22-76	-	0.0	0.1	0.1	0.2	1.4	1.8	19.2	18.6	37.8	60.5
76-101	-	0.0	0.1	0.3	0.5	2.0	2.9	24.8	18.1	42.9	54.2
101-117	-	0.0	0.1	0.1	0.2	1.6	2.0	20.1	19.9	40.0	58.0
117-150	-	0.0	0.1	0.1	0.1	1.0	1.3	17.8	20.7	38.5	60.1

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-22	1.347	-	-	-	45.8
22-76	-	-	-	-	60.5
76-101	-	-	-	-	54.2
101-117	-	-	-	-	58.0
117-150	-	-	-	-	60.1

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
0-22	1.347	46.7	45.7	44.5	42.0	39.9	37.5	40.5	37.9

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
0-22	7.3	6.6	0.53	2.9	2.38	-	-	-	-	39.2	3.9	1.2	0.0	44.3
22-76	8.2	7.0	0.36	12.3	0.33	-	-	-	-	40.5	7.7	0.8	0.4	49.4
76-101	8.5	7.1	0.37	16.2	0.37	-	-	-	-	35.4	9.9	0.7	1.3	47.3
101-117	8.5	7.1	0.42	14.2	0.21	-	-	-	-	33.9	11.0	0.7	2.3	47.9
117-150	8.4	6.9	0.44	3.0	0.07	-	-	-	-	31.6	12.2	0.8	3.4	48.0

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 %
0-22	103	43.2	94	8.3	-	-	0
22-76	126	39.1	65	1.2	-	-	1
76-101	133	35.5	65	1.3	-	-	4
101-117	136	35.1	61	0.7	-	-	7
117-150	116	41.3	69	0.2	-	-	8

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
0-22	-	-	-	0.12	0.06	0.31	0.09	0.02	0.04	-	0.09
22-76	-	-	-	0.09	0.08	0.27	0.07	0.01	0.03	-	0.07
76-101	-	-	-	0.11	0.08	0.27	0.06	0.00	0.02	-	0.08
101-117	-	-	-	0.10	0.10	0.26	0.05	0.01	0.02	-	0.06
117-150	-	-	-	0.10	0.10	0.31	0.05	0.00	0.02	-	0.04

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-22	-	weak	-	-	-	-	very weak to weak	very weak to weak	-	weak	very strong	-
22-76	-	weak	-	-	-	-	very weak to weak	very weak to weak	-	weak	very strong	-
76-101	-	weak	-	-	-	-	very weak to weak	very weak to weak	-	weak	very strong	-
101-117	-	weak	-	-	-	-	very weak to weak	very weak to weak	-	weak	very strong	-
117-150	-	weak	-	-	-	-	very weak to weak	very weak to weak	-	weak	very strong	-

Profile description

Ap 0-22 cm	black (10YR 2/1, dry) black (10YR 2/1, moist)clay,strong coarse subangular blocky,very hard friable very plastic,clear wavy boundary to,
Bw1 22-76 cm	brown (10YR 5/3, moist)clay,strong coarse wedge-shaped angular blocky,extremely hard firm very plastic,continuous slickensides cutans,diffuse wavy boundary to,
Bw2 76-101 cm	(10YR 5.5/2, moist)clay,strong coarse and very coarse wedge-shaped angular blocky,extremely hard firm very plastic,continuous slickensides cutans,diffuse wavy boundary to,
101-117 cm	brown (7.5YR 5/2, moist)clay,strong coarse and very coarse wedge-shaped angular blocky,extremely hard firm very plastic,continuous slickensides cutans,clear wavy boundary to,
C 117-150 cm	(7.5YR 5.5/2, dry)clay,strong coarse and very coarse wedge-shaped angular blocky,extremely hard firm very plastic,continuous slickensides cutans,

Kind 1 (parent material) ; Parker (eds), 1984	shale/siltstone
Mode of accumulation or deposition of parent material	residual material
Texture of parent material	silty
Weathering Resistance	poor

Intensity of the soil erosion type	slight
Intensity of the soil erosion type (second entry)	slight
Soil erosion type	sheet
Soil erosion type (second entry)	sheet

Major crops	vegetables
Land use or vegetation in the immediate vicinity of the site	high level arable farming
Remarks on Land Use / Vegetation	VEGETATION: Trees (1%), herbs (19%), grasses (80%), bare ground (0%). Dominant species: Stipa charruana, Paspalum dilatatum, Bothriochloa laguroides, Eryngium horridum, Bacharis coridifolia, Stenotaphrum secunaat LANDUSE:
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	25m
Physiographic position of the site	crest
Slope	5%
Slope Aspect	west
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	slightly alkaline
Surface cracking	small cracks (width less than 1 cm, or depth less than 50 cm)
Microrelief Height: variation in height	23
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	gilgai
Microrelief pattern	reticulate
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline

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Reference soil Uruguay 06: Vertisol

Characteristics

Reference soil UY006: Vertisols

Classification