Reference soil Brazil 27: Plinthosol

BR027

Plinthosols occur mainly in the moist tropical regions in low-lying positions where iron from the soil and adjacent uplands is accumulating.

Characteristics

Soils having either a petroplinthic horizon within 50 cm from the soil surface, or a plinthic horizon which either starts within 50 cm from the soil surface, or within 100 cm from the soil surface if it underlies an albic horizon or a horizon with stagnic properties.

Distribution of Plinthosols (rough estimation supplied by soilgrids)

Reference soil BR027: Plinthosol

Very deep, poorly drained grey claysoil derived from kaolinitic sediments; with a thick high organic matter containing topsoil and a strongly mottled subsoil. Effective soil depth depends on depth of water table which strongly fluctuates depending on the water level of the Formoso river. Vertical and especially lateral water transport in the subsoil is extremely fast because of very high permeability. The permeability of the subsoil is extremely high due to very high stable biopores. The pit wall shows a tongued character because of vertical filled up channels due to faunal activity, diameter about 2 to 4cm.
Classification: although derived from alluvial deposits the soil does not show sediment stratification anymore. It is assumed that the strongly mottled clay is plinthite, based on the observation that hard ironstone is protruding from banks of the nearby Formoso river.
The Koppen climate: Aw or Am. Original vegetation: semi-decidious forest or woodland.
Slides no 9891-9903.

Classification

WRB 2006

WRB 1998

Umbric- Plinthosol (Albic Alumic Humic)

Albi-Umbric- Plinthosol (Humic Alumic)

0-35 cm	umbric horizon
52-75 cm	albic horizon
75-130 cm	plinthic horizon

0-35 cm	umbric horizon
35-450 cm	ferralic horizon
52-75 cm	albic horizon
75-130 cm	plinthic horizon
-	strongly humic property

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

FerraliHumic Plinthosol

Plinthic Ferralsol cerrado

0-35 cm	umbric A horizon
35-450 cm	ferralic B horizon
52-74 cm	albic E horizon
-	gleyic property
-	plinthite property
-	strongly humic property

0-35 cm	umbric A horizon
35-430 cm	oxic B horizon
-	hydromorphic property
-	plinthite property

Local classification:	Plintossolo distrófico

Other classification

USDA-SCS (1975)

Plinthaquept peraquic clayey isohyperthermic

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
0-12	-	0.5	0.9	1.3	2.6	2.8	8.1	9.0	29.6	38.6	53.2
12-35	-	1.4	1.4	1.3	2.6	2.7	9.4	10.3	36.9	47.2	43.4
35-52	-	0.7	0.9	2.2	6.3	6.8	16.9	12.1	20.8	32.9	50.1
52-75	-	0.4	1.4	3.8	9.8	10.8	26.2	12.0	12.1	24.1	49.7
75-95	-	0.7	1.2	3.0	8.0	8.8	21.7	9.3	9.4	18.7	59.7
95-130	-	0.8	1.3	2.2	6.8	8.1	19.2	10.1	10.0	20.1	60.7
130-230	-	1.2	1.3	2.2	6.6	8.3	19.6	11.6	14.9	26.5	53.9
230-330	-	0.9	1.3	2.5	6.0	8.4	19.1	10.8	10.9	21.7	59.3
330-430	-	0.7	3.0	8.7	13.8	13.0	39.2	8.9	6.2	15.1	45.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
5-10	0.943	-	-	-	-
0-12	-	-	-	19.9	53.2
12-35	-	-	-	11.2	43.4
38-43	0.867	-	-	-	-
85-90	1.408	-	-	-	-
35-52	-	159	-	9.5	50.1
52-75	-	95	-	4.0	49.7
75-95	-	94	-	1.0	59.7
95-130	-	104	-	0.4	60.7
130-230	-	104	-	0.0	53.9
230-330	-	98	-	1.0	59.3
330-430	-	69	-	1.0	45.7

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
5-10	0.943	60.9	60.0	57.2	52.9	50.4	47.8	44.2	42.5
38-43	0.867	64.2	62.0	54.9	43.0	37.7	33.9	28.8	28.0
85-90	1.408	47.0	45.5	42.3	38.9	36.5	34.3	31.9	31.4

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
0-12	5.0	4.4	0.24	-	6.55	0.38	17	1.4	2.3	3.4	1.4	0.8	0.2	5.8
12-35	5.8	4.7	0.03	-	3.78	0.35	11	0.6	1.6	0.7	0.4	0.3	0.0	1.4
35-52	5.2	4.3	0.03	-	1.45	0.13	11	2.0	2.0	0.7	0.3	0.1	0.0	1.1
52-75	5.1	4.1	0.01	-	0.35	-	-	2.3	2.1	0.2	0.1	0.0	0.0	0.3
75-95	4.8	4.1	0.03	-	0.33	-	-	2.0	1.8	0.0	0.1	0.0	0.0	0.1
95-130	5.1	4.2	0.01	-	0.20	-	-	1.4	1.2	0.6	0.2	0.0	0.0	0.8
130-230	5.7	4.9	0.01	-	0.11	-	-	0.1	0	1.2	0.9	0.0	0.0	2.1
230-330	6.0	4.6	0.01	-	0.05	-	-	0.1	0	2.3	2.0	0.0	0.0	4.3
330-430	6.0	4.3	0.01	-	0.00	-	-	0.5	0.5	1.4	1.4	0.0	0.2	3.0

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 %
0-12	28	20.6	39	23.0	-	11	1
12-35	10	14.4	33	13.0	-	11	0
35-52	9	11.9	24	5.1	-	17	0
52-75	3	11.1	22	1.2	-	19	0
75-95	2	6.1	10	1.2	-	30	0
95-130	13	6.0	10	0.7	-	20	0
130-230	38	5.6	10	0.4	-	0	0
230-330	59	7.3	12	0.2	-	0	0
330-430	57	5.3	12	0.0	-	9	4

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
0-12	-	-	-	2.00	0.50	3.00	1.20	-	-	-	0.60
12-35	-	-	-	2.20	0.70	4.40	1.70	-	-	-	0.30
35-52	-	-	-	0.90	0.20	3.30	1.10	-	-	-	0.20
52-75	-	-	-	0.30	0.00	2.00	0.40	-	-	-	0.10
75-95	-	-	-	0.20	0.00	1.60	0.30	-	-	-	0.10
95-130	-	-	-	0.20	0.00	2.40	0.40	-	-	-	0.00
130-230	-	-	-	0.20	0.00	2.90	0.60	-	-	-	0.00
230-330	-	-	-	0.10	0.00	2.90	0.40	-	-	-	0.00
330-430	-	-	-	0.10	0.00	1.60	0.20	-	-	-	0.00

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-12	-	-	very weak	weak	-	-	medium to strong	-	-	-	-	-
12-35	-	-	very weak	weak	-	-	medium to strong	-	-	-	-	-
35-52	-	-	weak	weak	-	-	strong	-	weak	-	-	-
52-75	-	-	weak	weak	-	-	very strong	-	weak	-	-	-
75-95	-	-	weak	weak	-	-	very strong	-	weak	-	-	-
95-130	-	-	weak	weak	-	-	very strong	-	weak	-	-	-
130-230	-	-	weak	weak	-	-	very strong	weak	weak	-	-	-
230-330	-	-	weak	weak	-	-	very strong	weak	weak	-	-	-
330-430	-	-	weak	weak	-	-	very strong	weak	weak	-	-	-

Profile description

Ap 0-12 cm	(10YR 2.5/1, moist)silty clay loam,weak fine and medium subangular blocky,very friable slightly sticky slightly plastic,many very fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),abrupt smooth boundary to,
Ah 12-35 cm	very dark greyish brown (10YR 3/2, moist)silty clay loam,moderately coherent porous massive parting to very weak medium subangular blocky,very friable slightly sticky slightly plastic,many fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),clear wavy boundary to,
AE 35-52 cm	(10YR 3.5/4, moist)clay loam,moderately coherent porous massive parting to very weak medium subangular blocky,friable slightly sticky slightly plastic,common mottles (10YR 4.5/6) and (10YR 4.5/1),many very fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),clear smooth boundary to,
E 52-75 cm	(10YR 4.5/4, moist)clay,moderately coherent porous massive parting to very weak medium subangular blocky,friable slightly sticky slightly plastic,common mottles (10YR 5.5/6) and (10YR 5/2),many fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),frequent channels,diffuse smooth boundary to,
Bv1 75-95 cm	(light) grey (10YR 6/1, moist)clay,moderately coherent porous massive parting to very weak medium subangular blocky,friable slightly sticky slightly plastic,many medium prominent sharp mottles (10YR 5.5/6) and few fine distinct mottles (7.5YR 2.5/0),many fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),very few medium spherical hard ferruginous concretions,frequent channels,diffuse smooth boundary to,
Bv2 95-245 cm	light grey (10YR 7/1, moist)clay,moderately coherent porous massive parting to very weak medium subangular blocky,friable slightly sticky slightly plastic,many medium prominent sharp mottles (10YR 5/8) and many medium prominent mottles (2.5YR 4/8),many fine pores and many continuous exped and inped tubular random pores highly porous (>60 vol%),very few medium spherical hard ferruginous concretions,frequent channels,
Auger 245-350 cm	light grey (10YR 7/1, moist)clay,many medium prominent sharp mottles (10R 4/8),

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	kaolinitic sediments
Soil Depth	50cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	high

Occurrence of soil aggradation (McDonald et al., 1984)	not apparent
Slope stability	stable

Major crops	rice
Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	draining
Main type of irrigation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	seasonally irrigated
Land use or vegetation in the immediate vicinity of the site	high level arable farming
Remarks on Land Use / Vegetation	VEGETATION: Original vegetation semi-decidious forest or woodland LANDUSE: Major crops rice and soja
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation

Altitude	200m
Physiographic Unit	backswamp, 250m to Formoso River
Physiographic position of the site	flat
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	floodplain
Slope	0%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Drainage class ; FAO (2006) - Guidelines for soil description	poor
Flooding frequency (FAO, 1986)	yearly
Nature of flood water	fresh
(Estimated) maximum (lower) depth to groundwater table	300cm
Depth to groundwater table	120cm
Kind of ground water table (USDA, 1979)	flooded
(Estimated) minimum (upper) depth to groundwater table	0cm
Moist From - To	0-120cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	ponded
Wet From To	120-350cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Brazil 27: Plinthosol

Characteristics

Reference soil BR027: Plinthosol

Classification