Reference soil China 46: Stagnosol

CN046

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 CN046: Stagnosols

PROFILE DESCRIPTION : Shallow, moderately well drained, reddish brown sandy clay loam to silty clay developed from solid rock derived from sandstone. The soil has between 28 and 46 cm depth a slowly permeable layer as reflected by common low chroma mottles. It is uncertain if the topsoil is original or aggradated.

Classification

WRB 2006

WRB 1998

Luvic- Stagnosol (Hypereutric Clayic Chromic)

Hyposodi-Stagnic- Luvisol (Chromic Cutanic)

10-119 cm	argic horizon
-	reducing conditions
-	stagnic colour pattern

0-28 cm	ochric horizon
10-119 cm	argic horizon
-	stagnic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Stagnic Luvisol

Chromic Luvisol

0-28 cm	ochric A horizon
10-119 cm	argic B horizon
- cm	argic B horizon
- cm	ochric A horizon
-	stagnic

0-28 cm	ochric A horizon
10-119 cm	argillic B horizon

Local classification:	Haplic red cinnamon soil; Ferri-Ustic Argosol
Common name:	Brown clay-leached soil

Other classification

USDA-NRCS (1999)	Aquic Haplustalf
USDA-SCS (1975)	Aquic Haplustalf ustic fine montmorillonitic thermic

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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
0-10	-	1.2	1.8	4.9	30.2	19.5	57.6	8.3	9.3	17.6	24.8
10-28	-	1.7	2.0	4.0	18.9	13.6	40.2	9.0	18.0	27.0	32.9
28-46	-	1.7	1.9	2.1	3.6	3.9	13.2	4.0	28.0	32.0	54.8
46-119	-	1.4	1.5	1.6	3.5	4.3	12.3	12.7	32.2	44.9	42.9

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-10	1.618	-	-	18.0	24.8
10-28	-	-	-	23.0	32.9
28-46	1.465	-	-	36.5	54.8
46-118	1.528	-	-	-	-
46-119	-	-	-	25.0	42.9

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
0-10	1.618	38.2	37.8	37.5	34.4	31.4	28.7	19.4	17.3
28-46	1.465	45.6	44.8	41.4	38.8	37.2	35.1	31.9	30.2
46-118	1.528	42.9	42.0	40.4	38.6	37.4	35.6	32.1	31.0

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
0-10	8.3	7.3	0.12	3.9	0.35	0.05	7	-	-	18.1	2.0	0.3	0.2	20.6
10-28	8.5	7.2	0.14	1.0	0.28	0.05	6	-	-	18.1	3.7	0.3	0.5	22.6
28-46	8.2	6.9	0.17	1.6	0.18	0.05	4	-	-	17.6	6.6	0.3	1.0	25.5
46-119	7.9	6.4	0.25	0.7	0.10	0.04	3	-	-	12.0	7.2	0.3	1.5	21

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 %
0-10	229	9.0	36	1.2	-	-	2
10-28	170	13.3	40	1.0	-	-	4
28-46	113	22.5	41	0.6	-	-	4
46-119	109	19.2	45	0.4	-	-	8

Depth (cm)	CaSO4.2H2O %	P Bray mg/kg	P Olsen mg/kg	pH CaCl2	clay_noncarbonate % w/w	clay_carbonate % w/w	phosphorus4 mg/kg	phosphorus1 mg/kg	total_sulfur % w/w
0-10	-	6.1	4.6	-	-	-	-	-	-
10-28	-	2.2	5.7	-	-	-	-	-	-
28-46	-	15.4	3.4	-	-	-	-	-	-
46-119	-	0.7	1.6	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	-	-	-	weak	-	-	medium to strong	medium to strong	weak	weak	strong	-
10-28	-	-	-	weak	-	-	medium to strong	medium to strong	weak	weak	strong	-
28-46	-	-	-	weak	-	-	medium to strong	medium to strong	weak	weak	strong	-
46-119	-	-	-	very weak	-	-	medium to strong	medium to strong	weak	weak	strong	-

Profile description

Ah 0-10 cm	yellowish brown (10YR 5/4, moist)sandy clay loam,weak to moderate fine granular,soft,common very fine exped and inped pores moderately porous (40-60 vol%),very few fine gravel fresh sandstone fragments,clear smooth boundary to,
10-28 cm	yellowish brown (10YR 5/4, dry)clay loam,moderate medium angular blocky,hard,common very fine exped and inped pores moderately porous (40-60 vol%),very few fine gravel fresh sandstone fragments,clear wavy boundary to,
Btg 28-46 cm	reddish brown (2.5YR 5/4, dry)clay,strong medium angular blocky to strong fine and medium columnar,very hard,common heterogeneous distinct clear mottles (10YR 5/1),patchy thin unspecified on pedfaces cutans,patchy thin unspecified cutans on pedfaces,common very fine exped and inped pores moderately porous (40-60 vol%),few powdery soft soft segregations,gradual wavy boundary to,
C 46-119 cm	reddish brown (2.5YR 5/4, dry)silty clay,very strong fine angular blocky parting to very strong coarse and very coarse columnar,extremely hard,few powdery soft unspecified soft segregations,gradual wavy boundary to,
C 46-119 cm	brownish yellow (10YR 6/6, dry)

Depth1	118cm
Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	residual material
Soil Depth	46cm
Texture of parent material	sandy
Texture of parent material (second entry)	sandy
General characterization of the status of weathering of solid rock	partially or moderately

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	severe
Intensity of the soil erosion type (second entry)	severe
Soil erosion type	rill
Soil erosion type (second entry)	gully
Slope stability	locally unstable

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	terracing
Land use or vegetation in the immediate vicinity of the site	afforestation
Remarks on Land Use / Vegetation	LANDUSE: Leucaena planted in 1991
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	secondary

Altitude	1150m
Physiographic Unit	highly dissected slope
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	badlands
Slope	4%
Slope Aspect	west-south-west
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	steeply dissected

Lower limit of a slow permeable or stagnating layer in the profile	46cm
Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Dry From - To	10-140cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	perched
Moist From - To	0-10cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	very rapid
Upper limit of a slow permeable or stagnating layer in the profile	28cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Average size of stone	1
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface slaked; sorted sand/silt, some clay films
Microrelief Height: variation in height	20
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	artificial terracing/mounds
Microrelief pattern	linear
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)	angular blocky
Surface stoniness class (FAO (2006) - Guidelines for soil description)	very few stones

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Reference soil China 46: Stagnosol

Characteristics

Reference soil CN046: Stagnosols

Classification