Reference soil Brazil 18: Stagnosol

BR018

Stagnosols are often related to Luvisols and occur for the greater part in humid and perhumid temperate regions in West and Central Europe, North America, Australia and Argentina.

Characteristics

Soils having within 50 cm of the soil surface reducing conditions (soil conditions with low redox potential (negative logarithm of the hydrogen potential (rH) and presence of free iron (Fe2+) on freshly broken surfaces) and in 50% of the layer a stagnic colour pattern (strong mottling of soils in such a pattern that peds surfaces are lighter (at least one Munsell value) and paler (at least one chroma) than ped interiors, which are more reddish and brighter (at least one chroma)). The stagnic color pattern develops under temporarily saturation of a perched water table from surface water, long enough to allow reducing conditions to arise. The topsoil can be bleached and concretions can occur in the subsoil. They develop often in slowly permeable, unconsolidated materials of various origins.

Distribution of Stagnosols (rough estimation supplied by soilgrids)

Reference soil BR018: Stagnosols

Brief field description: Deep, moderately well drained grey sandy clay loam derived from old sediments. Characteristic for these soils is the slight exchangeable Sodium (E.S.P.) level. The permeability of the slow permeable layer is an estimation. The fragipan is only weakly cemented, upon moistening it becomes friable. Parent material: Tertiary sediment of the "Barreiras" group. The genesis of the "Barreiras" sediments is not yet understood. Ayt the site fruit trees observed: Mango, Cashew, Jackfruit. Slides no 9817-9820.

Classification

WRB 2006

WRB 1998

Luvic- Stagnosol (Albic Sodic)

Albi-Stagnic- Luvisol (Hyposodic Profondic)

17-57 cm	albic horizon
57-177 cm	argic horizon
-	abrupt textural change
-	reducing conditions

0-17 cm	ochric horizon
17-57 cm	albic horizon
57-177 cm	argic horizon
-	stagnic
-	abrupt textural change

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Fragi-Albic Luvisol

Albic Luvisol fragipan

0-17 cm	ochric A horizon
17-57 cm	albic E horizon
57-177 cm	argic B horizon
- cm	argic B horizon
-	abrupt textural change

0-17 cm	ochric A horizon
17-57 cm	albic E horizon
57-177 cm	argillic B horizon
-	abrupt textural change

Local classification:	Podzolico Acinzentado Tb distrófico

Other classification

USDA-NRCS (1999)	Typic Kandiustult
USDA-SCS (1975)	Typic Paleustult ustic loamy isohyperthermic

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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
0-17	0	3.8	21.0	31.3	28.5	5.8	90.4	2.6	1.0	3.6	6.0
17-57	0	4.1	20.1	28.3	28.0	6.2	86.7	2.3	0.7	3.0	10.3
57-115	0	8.3	16.5	16.9	21.6	7.0	70.3	3.3	1.2	4.5	25.1
115-147	0	4.3	14.5	20.4	19.3	6.0	64.5	3.6	1.5	5.1	30.5
147-177	0	4.3	13.4	20.3	20.5	5.9	64.4	3.6	0.7	4.3	31.3
200-275	0	5.1	12.3	17.2	17.1	5.9	57.6	4.6	1.5	6.1	36.4
300-375	0	4.3	11.2	12.6	13.2	5.4	46.7	4.9	4.5	9.4	43.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
10-15	1.426	-	-	-	-
0-17	-	-	-	3.1	6.0
17-57	-	-	-	9.1	10.3
33-38	1.470	-	-	-	-
57-115	-	-	-	0.5	25.1
60-65	1.673	-	-	-	-
115-147	-	-	-	0.9	30.5
102-107	1.673	-	-	-	-
147-177	-	-	-	0.5	31.3
200-275	-	-	-	0.0	36.4
300-375	-	-	-	0.0	43.8

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
10-15	1.426	41.6	38.1	20.8	10.2	8.5	7.5	5.1	4.6
33-38	1.470	38.2	34.0	19.0	10.9	9.6	8.6	5.6	5.4
60-65	1.673	30.2	28.2	-	-	-	-	-	-
102-107	1.673	30.2	28.2	23.4	18.7	16.8	15.5	13.1	12.6

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
0-17	6.9	6.4	0.18	0.1	1.97	0.07	28	-	-	4.4	1.2	0.3	0.0	5.9
17-57	6.0	5.0	0.05	-	0.71	0.03	24	0	0	0.8	0.3	0.1	0.0	1.2
57-115	5.4	4.4	0.02	-	0.29	-	-	0.1	0	0.2	0.3	0.1	0.2	0.8
115-147	5.4	4.4	0.02	-	0.21	-	-	0.1	0	0.6	0.4	0.0	0.1	1.1
147-177	5.3	4.6	0.02	-	0.07	-	-	0.1	0	0.2	0.4	0.0	0.1	0.7
200-275	5.3	4.6	0.02	-	0.05	-	-	0.1	0	0.4	0.3	0.0	0.1	0.8
300-375	5.2	4.3	0.02	-	0.06	-	-	0.5	0.2	0.2	0.3	0.0	0.0	0.5

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 %
0-17	109	5.4	90	4.9	-	-	0
17-57	171	0.7	7	2.1	-	0	0
57-115	89	0.9	4	1.0	-	0	22
115-147	122	0.9	3.0	0.7	-	0	11
147-177	100	0.7	2.0	0.2	-	0	14
200-275	160	0.5	1.0	0.2	-	0	20
300-375	50	1.0	2.0	0.2	-	20	0

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
0-17	-	-	-	0.00	0.00	0.00	0.00	-	-	-	0.00
17-57	-	-	-	0.00	0.00	0.00	0.00	-	-	-	0.00
57-115	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
115-147	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
147-177	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
200-275	-	-	-	0.00	0.00	0.10	0.00	-	-	-	0.00
300-375	-	-	-	0.10	0.00	0.10	0.00	-	-	-	0.00

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-17	-	weak	-	weak	-	-	very strong	-	-	-	-	-
17-57	-	weak	-	weak	-	-	very strong	-	-	-	-	-
57-115	-	weak	-	weak	-	-	very strong	-	-	-	-	-
115-147	-	weak	-	weak	-	-	very strong	-	-	-	-	-
147-177	-	weak	-	weak	-	-	very strong	-	-	-	-	-
200-275	-	weak	-	weak	-	-	very strong	-	-	-	-	-
300-375	-	weak	-	weak	-	-	very strong	-	-	-	-	-

Profile description

Ap 0-17 cm	grey (10YR 5/1, dry) dark grey (10YR 4/1, moist)Description sand,structureless,soft loose non sticky non plastic,many very fine fine pores,clear smooth boundary to,
E 17-57 cm	light brownish grey (10YR 6/2, moist)loamy sand,weakly coherent porous massive,slightly very friable non sticky non plastic,many very fine fine pores,abrupt smooth boundary to,
Btx1 57-115 cm	light grey (10YR 7/2, dry) very pale brown (10YR 7/3, moist)sandy clay loam,strongly coherent porous massive,very hard very friable slightly sticky slightly plastic,common very fine fine pores,continuous massive weakly cemented fragipan pans,diffuse smooth boundary to,
Btx2 115-147 cm	(10YR 7.5/4, dry) pale brown (10YR 6/3, moist)sandy clay loam,strongly coherent porous massive,very hard very friable slightly sticky slightly plastic,few coarse prominent gradual mottles,many very fine fine pores,continuous massive weakly cemented fragipan pans,diffuse smooth boundary to,
Bt 147-177 cm	very pale brown (10YR 7/4, dry) (10YR 6.5/4, moist)sandy loam,strongly coherent porous massive,very hard very friable slightly sticky slightly plastic,few coarse prominent sharp mottles,many very fine fine pores,
Auger 177-375 cm	(10YR 6.5/4, moist)strongly coherent porous massive,

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	marine sediments
Remarks on Parent Materials	Tertiary sediments of the "Barreiras" group; its genesis is not yet well-understood
Soil Depth	200cm
Texture of parent material	loamy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	slight
Soil erosion type	sheet
Slope stability	stable

Major crops	rice
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	low level arable farming
Remarks on Land Use / Vegetation	VEGETATION: LANDUSE: Cassava, maize, beans, tobacco, fruit trees (mango, cashew, jackfruit)
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop with current fallow

Altitude	170m
Physiographic Unit	Tabuleiro plain occasionally deeply dissected
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.	marine terrace
Slope	1%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Lower limit of a slow permeable or stagnating layer in the profile	150cm
Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Dry From - To	57-177cm
Flooding frequency (FAO, 1986)	never
Depth to groundwater table	800cm
Kind of ground water table (USDA, 1979)	groundwater table observed
Moist From - To	0-57cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	rapid
Upper limit of a slow permeable or stagnating layer in the profile	57cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	slightly 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 18: Stagnosol

Characteristics

Reference soil BR018: Stagnosols

Classification