Reference soil China 33: Fluvisol

CN033

Fluvisols typically are young soils in alluvial, deltaic, lacustrine, or marine deposits, and occur all over the world.

Characteristics

Soils having fluvic soil material starting within 25 cm from the soil surface and continuing to a depth of at least 50 cm from the soil surface. They have no diagnostic horizons other than a histic, mollic, ochric, takyric, umbric, yermic, salic, or sulfuric horizon.

Distribution of Fluvisols (rough estimation supplied by soilgrids)

Reference soil CN033: Fluvisols

PROFILE DESCRIPTION : Deep, poorly drained, dark brown to grayish brown clay loam derived from recent alluvial deposits containing material rich in sulphur. Soil reaction of the upper 45 cm is slightly acid to neatral, turning extremely acid between 45 and 68 cm. The soil is strongly mottled throughout, showing brownish to reddish coloured redox concentrations. The topsoil has a high content in organic carbon and is only (very) weakly structured. GENERAL LANDFORM: the sequence clay over sandy loam indicates possibly a levee deposit of one of the branches of the Pearl River. The construction of paddy fields has eliminated any original heigth differences if any / SOIL: very coarse prismatic structure of the clay is hardly visable due to the moist condition of the soil. However, the few ped faces in the Cg1 horizon are completely oxidized and have a colour of 5YR 5/8 / LAND USE: the paddy fields will be urbanized during 1993.

Classification

WRB 2006

WRB 1998

Gleyic- Fluvisol (Thionic Eutric Siltic)

Endogleyi-Protothionic- Fluvisol (Eutric)

-	sulphidic
-	reducing conditions
-	gleyic colour pattern

0-45 cm	ochric horizon
-	sulfidic
-	gleyic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Proto-Thionic Fluvisol anthraquic

Thionic Fluvisol

0-45 cm	ochric A horizon
- cm	ochric A horizon
-	fluvic
-	gleyic

0-45 cm	ochric A horizon
-	hydromorphic
-	sulfidic material
-	sulfidic materials

Local classification:	Acid-sulphatic paddy soil; Aqui-Alluvic Primosol
Common name:	Paddy soil with extremely acid subsoil, on alluvium

Other classification

USDA-NRCS (1999)	Typic Sulfaquent
USDA-SCS (1975)	Typic Sulfaquent aquic fine-loamy mixed 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	-	1.3	1.4	1.3	2.5	3.2	9.7	24.4	29.1	53.5	36.8
10-25	-	1.1	1.4	2.1	21.1	25.2	50.9	16.8	12.1	28.9	20.3
25-45	-	0.4	0.6	0.6	1.6	4.6	7.8	11.9	43.7	55.6	36.7
45-68	-	0.0	0.2	0.2	5.7	16.7	22.8	19.6	32.6	52.2	25.0
68-110	-	0.1	0.2	0.4	15.3	51.6	-	11.9	9.6	-	11.1
150-200	-	2.9	2.0	1.7	3.1	3.5	13.2	7.9	22.5	30.4	56.3

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	0.893	-	-	-	-
0-10	-	-	-	-	36.8
50-55	1.161	-	-	-	-
10-25	-	-	-	-	20.3
25-45	-	-	-	-	36.7
45-68	-	-	-	-	25.0
68-110	-	-	-	-	11.1
150-200	-	-	-	-	56.3

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	0.893	64.0	61.9	55.4	51.1	49.1	46.1	37.0	30.0
50-55	1.161	55.4	55.0	53.5	52.1	51.5	48.6	38.4	32.3

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	5.6	5.2	0.52	-	2.65	0.25	11	0	0	14.3	1.3	0.1	0.2	15.9
10-25	6.5	6.1	0.42	0.7	1.71	0.17	10	0	0	15.9	1.7	0.1	0.1	17.8
25-45	6.3	5.7	0.32	-	1.21	0.13	9	0	0	12.4	2.0	0.1	0.3	14.8
45-68	3.1	3.0	2.40	-	2.20	0.13	17	8.9	6.5	9.9	2.6	0.1	0.2	12.8
68-110	4.8	4.5	1.80	-	1.41	0	-	0.3	0	11.3	4.3	0.1	0.3	16
150-200	6.8	6.8	1.40	0.9	2.13	0.10	21	0	0	21.2	3.0	0.1	0.3	24.6

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	84	18.9	51	9.3	-	0	1
10-25	101	17.7	87	6.0	-	0	1
25-45	98	15.1	41	4.2	-	0	2
45-68	98	13.1	52	7.7	-	50	2
68-110	162	9.9	-	4.9	-	0	3
150-200	180	13.7	24	7.5	-	0	2

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
0-10	-	-	-	-	-	2.10	0.20	-	-	-	-
10-25	-	-	-	-	-	2.20	0.20	-	-	-	-
25-45	-	-	-	-	-	2.40	0.20	-	-	-	-
45-68	-	-	-	-	-	1.60	0.10	-	-	-	-
68-110	-	-	-	-	-	1.70	0.10	-	-	-	-
150-200	-	-	-	-	-	1.60	0.10	-	-	-	-

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	-	7.4	-	-	-	-	-	-	-
10-25	-	4.2	-	-	-	-	-	-	-
25-45	-	1.2	-	-	-	-	-	-	-
45-68	-	0.1	-	-	-	-	-	-	-
68-110	-	0.7	-	-	-	-	-	-	-
150-200	-	0.0	-	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-10	medium to strong	very weak	-	-	-	-	strong	medium to strong	-	very weak	-	medium to strong
10-25	medium to strong	very weak	-	-	-	-	medium to strong	medium to strong	-	very weak	-	medium to strong
25-45	medium to strong	very weak	-	-	-	-	strong	medium to strong	-	very weak	-	medium to strong
45-68	medium to strong	very weak	-	-	-	-	medium to strong	medium to strong	-	very weak	-	medium to strong
68-110	weak	-	-	-	-	-	medium to strong	medium to strong	-	very weak	-	weak
150-200	strong	weak	-	-	-	-	medium to strong	-	-	-	-	weak

Profile description

Ap 0-10 cm	(10YR 4/5, moist)clay,weak coarse prismatic parting to weak moderate subangular blocky,firm very sticky very plastic,common fine distinct clear mottles (10YR 6/8),common very fine fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),frequent worm channels,clear smooth boundary to,
Ag1 10-25 cm	(dark) brown (10YR 4/3, moist)clay,very weak very coarse prismatic parting to very weak coarse angular blocky,very firm very sticky very plastic,many fine distinct clear mottles (10YR 6/8),few very fine fine continuous exped and inped tubular random pores slightly porous (<40 vol%),few worm channels,gradual smooth boundary to,
Ag2 25-45 cm	(dark) brown (10YR 4/3, moist)clay,very weak very coarse prismatic parting to very weak coarse angular blocky,very firm very sticky very plastic,many medium distinct clear mottles (7.5YR 5/8),few very fine fine continuous exped and inped tubular random pores slightly porous (<40 vol%),few worm channels,clear wavy boundary to,
Cg1 45-68 cm	greyish brown (2.5Y 5/2, moist)clay loam,very weak very coarse prismatic parting to very weak coarse angular blocky,firm sticky plastic,many fine prominent sharp mottles (7.5YR 5/8) and common medium prominent mottles (2.5YR 5/8),few very fine fine continuous exped and inped tubular random pores slightly porous (<40 vol%),no biological activity,abrupt smooth boundary to,
Cg2 68-110 cm	(2.5Y 4/1, moist)sandy loam,weakly coherent,very friable slightly sticky slightly plastic,few fine prominent clear mottles (7.5YR 5/8),few very fine continuous exped and inped tubular vertical pores slightly porous (<40 vol%),no biological activity,
Auger 110-200 cm	(2.5Y 4/1, moist)sandy loam,

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	stratified alluvium, possible levee deposit of one of the branches of the Pearl River
Soil Depth	200cm
Texture of parent material	clayey
Texture of parent material (second entry)	clayey

Occurrence of soil aggradation (McDonald et al., 1984)	absent
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)	paddy
Land use or vegetation in the immediate vicinity of the site	medium level arable farming
Remarks on Land Use / Vegetation	LANDUSE: Irrigation/drainage channels, 2 crops/year. Urbanized in 1993
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	monoculture

Altitude	1m
Physiographic Unit	Pearl River delta
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.	alluvial plain
Slope	1%
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	100cm
Depth to groundwater table	80cm
Kind of ground water table (USDA, 1979)	groundwater table observed
(Estimated) minimum (upper) depth to groundwater table	45cm
Moist From - To	0-45cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	ponded
Wet From To	45-200cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Surface cracking	large cracks (width more than 1 cm, or depth more than 50 cm)
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	no surface slaking/crusting observed
Microrelief Height: variation in height	30
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	levees (artificial)
Microrelief pattern	reticulate
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 China 33: Fluvisol

Characteristics

Reference soil CN033: Fluvisols

Classification