Reference soil China 21: Acrisol

CN021

Acrisols occur dominantly in the wetter parts of the tropics and subtropics and the warm temperate regions in relatively young landscapes.

Characteristics

Soils having an argic horizon (a subsurface horizon with distinct higher clay content than the overlying horizon), which has a cation exchange capacity of less than 24 cmolc per kg in some part, either starting within 100 cm from the soil surface, or within 200 cm from the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. They have a base saturation (total amount of Ca, Mg, K and Na with respect to the cation exchange capacity) of less than 50 percent in the major part between 25 and 100 cm from the soil surface

Distribution of Acrisols (rough estimation supplied by soilgrids)

Reference soil CN021: Acrisols

General remarks PROFILE DESCRIPTION : Very deep, well drained, reddish brown to red clay derived from Quaternary clay. The topsoil is nearly structureless. The upper subsoil has a subangular blocky structure while the deeper subsoil has an angular blocky structure and is strongly mottled. The soil is compact, there are mainly micro pores and few very fine to fine pores. Soil permeability is judged to be reduced, especially in the strongly mottled deeper subsoil, where ped surfaces are covered by clay cutans and which shows very few pores. The soil surface is smooth and has a thin seal. Especially on eroded bare soil surfaces a bio-seal may be formed, reducing even more the infiltration capacity of the topsoil for rain. GENERAL LANDFORM: the intermontane basins in Southern China are known as 'Red Basins'. At Yingtan the width of the basin is about 30 km. The basin has a plain appearance and consists of nearly level to undulating interfluves (low broad hills) with broad, nearly level valleys / LAND USE AND VEGETATION: the Red Quaternary Clay soils of the interfluves are not used for cultivation by the farmer. Present vegetation is sparse grass cover and Masson Pine planted about 15 years ago. Growth is slow (height about 4 meters and diameter 8 cm) / SLOPE PROCESSES: the Red Quaternary Clay soil interfluves (hills) are affected by erosion. This is caused by the high run-off, resulting in sheet erosion. On middle and lower slopes, run-off water concentrates and severe gully erosion may occur. Erosion is man-induced, because the original broad-leaved forest has been cleared long ago. Before the use of inorganic fertilizers, the grass/herb vegetation with some topsoil was removed for the fertilization of the paddy fields in the valley. At present this practice is not used anymore, however, the litter is still frequently collected by farmers for kitchen fuel. This still reduces the vegetation cover, incorporation of organic matter in the topsoil and bio-activity and therefore still enhances the run-off and erosion.

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Alumic Profondic Clayic)

Alumi-Profondic- Acrisol (Hyperdystric Chromic)

22-350 cm

argic horizon

0-22 cm	ochric horizon
22-350 cm	argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Alumi-Haplic Acrisol

Orthic Acrisol

0-22 cm	ochric A horizon
22-350 cm	argic B horizon
- cm	argic B horizon
- cm	ochric A horizon

0-22 cm	ochric A horizon
22-450 cm	argillic B horizon

Local classification:	Haplic red soil;Hapli-Udic Ferrosol
Common name:	Red clay-leached soil

Other classification

USDA-NRCS (1999)	Udic Kandiustult
USDA-SCS (1975)	Udic Paleustult ustic clayey kaolinitic 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
0-7	-	0.4	0.7	2.3	6.7	8.9	19	12.7	29.8	42.5	38.4
7-22	-	0.3	0.7	2.4	6.8	7.2	17.4	12.3	30.8	43.1	39.3
22-45	-	0.1	0.6	1.7	4.9	6.4	13.7	13.4	26.2	39.6	46.7
45-95	-	0.2	0.6	1.6	4.7	4.9	12	10.6	25.5	36.1	52.0
95-150	-	0.1	0.3	1.2	3.8	5.5	10.9	11.3	25.0	36.3	52.7
150-220	-	0.1	0.3	0.9	3.0	5.6	9.9	11.8	24.5	36.3	53.9
220-270	-	0.1	0.1	0.3	1.6	4.8	6.9	13.4	25.6	39.0	53.9
300-350	-	0.0	0.2	0.2	1.4	6.1	7.9	14.7	24.4	39.1	53.1
370-450	-	0.0	0.0	0.2	0.9	8.5	9.6	13.4	29.6	43.0	47.4

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	1.349	-	-	-	-
0-7	-	-	-	1.7	38.4
45-50	1.204	-	-	-	-
7-22	-	-	-	1.4	39.3
90-95	1.265	-	-	-	-
22-45	-	-	-	0.0	46.7
155-160	1.460	-	-	-	-
45-95	-	-	-	2.0	52.0
250-270	1.362	-	-	-	-
95-150	-	-	-	1.4	52.7
150-220	-	-	-	5.0	53.9
220-270	-	-	-	-	53.9
300-350	-	-	-	-	53.1
370-450	-	-	-	-	47.4

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	1.349	46.0	41.0	37.4	34.6	32.8	31.1	24.6	22.9
45-50	1.204	45.0	44.3	41.9	39.5	38.4	37.4	29.3	26.4
90-95	1.265	44.9	44.2	41.6	39.6	38.6	37.7	31.8	29.2
155-160	1.460	44.6	44.3	42.6	40.8	40.0	39.2	36.5	34.2
250-270	1.362	49.3	49.0	47.6	46.1	45.4	44.7	40.6	40.5

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
0-7	4.3	3.8	0.04	-	0.42	0.05	8	3.4	3.2	1.8	0.0	0.1	0.0	1.9
7-22	4.4	3.8	0.02	-	0.24	0.04	6	3.7	3.4	1.6	0.0	0.1	0.0	1.7
22-45	4.5	3.8	0.01	-	0.15	0.04	4	4.5	4.1	1.4	0.0	0.1	0.0	1.5
45-95	4.5	3.7	0.01	-	0.12	0.04	3	5.3	5	1.4	0.0	0.1	0.0	1.5
95-150	4.5	3.6	0.01	-	0.11	0.04	3	6.2	5.9	1.2	0.0	0.1	0.0	1.3
150-220	4.5	3.6	0.01	-	0.25	0.04	6	8.1	7.8	1.4	0.0	0.1	0.0	1.5
220-270	4.4	3.6	0.01	-	0.09	0.04	2	10	9.6	1.2	0.0	0.1	0.0	1.3
300-350	4.3	3.5	0.02	-	0.05	0.04	1	11.7	11	1.2	0.0	0.2	0.0	1.4
370-450	4.4	3.6	0.02	-	0.04	0.03	1	13.2	12.8	1.2	0.0	0.3	0.0	1.5

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 %
0-7	31	6.2	16	1.5	-	52	0
7-22	27	6.2	16	0.8	-	55	0
22-45	20	7.6	16	0.5	-	54	0
45-95	16	9.2	18	0.4	-	54	0
95-150	13	9.9	19	0.4	-	60	0
150-220	9	15.8	29	0.9	-	49	0
220-270	10	13.4	25	0.3	-	72	0
300-350	8	17.6	33	0.2	-	63	0
370-450	7	22.2	47	0.1	-	58	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
0-7	-	-	-	-	-	2.10	0.30	-	-	-	-
7-22	-	-	-	-	-	2.10	0.30	-	-	-	-
22-45	-	-	-	-	-	2.70	0.30	-	-	-	-
45-95	-	-	-	-	-	3.20	0.40	-	-	-	-
95-150	-	-	-	-	-	3.40	0.30	-	-	-	-
150-220	-	-	-	-	-	4.30	0.40	-	-	-	-
220-270	-	-	-	-	-	6.70	0.50	-	-	-	-
300-350	-	-	-	-	-	5.60	0.40	-	-	-	-
370-450	-	-	-	-	-	4.00	0.30	-	-	-	-

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
0-7	-	0.0	-	-	-	-	-	-	-
7-22	-	0.0	-	-	-	-	-	-	-
22-45	-	0.0	-	-	-	-	-	-	-
45-95	-	0.0	-	-	-	-	-	-	-
95-150	-	0.0	-	-	-	-	-	-	-
150-220	-	0.0	-	-	-	-	-	-	-
220-270	-	0.1	-	-	-	-	-	-	-
300-350	-	0.0	-	-	-	-	-	-	-
370-450	-	0.0	-	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-7	-	-	-	very weak	-	-	medium to strong	weak	weak	medium to strong	weak	weak
7-22	-	-	-	very weak	-	-	medium to strong	weak	weak	weak	weak	weak
22-45	-	-	-	weak	-	-	medium to strong	weak	weak	weak	weak	weak
45-95	-	-	-	very weak	-	-	medium to strong	weak	weak	weak	weak	weak
95-150	-	-	-	weak	-	-	strong	weak	weak	weak	weak	weak
150-220	-	-	-	weak	-	-	strong	weak	weak	very weak	weak	weak
220-270	-	-	-	weak	-	-	strong	weak	weak	-	weak	weak
300-350	-	-	-	weak	-	-	strong	medium to strong	weak	-	weak	weak
370-450	-	-	-	very weak	-	-	medium to strong	medium to strong	weak	-	weak	weak

Profile description

Ah 0-22 cm	reddish yellow (7.5YR 6/8, dry) yellowish brown (10YR 5/8, moist)sandy clay,weakly coherent porous massive parting to weak fine and medium subangular blocky,very hard firm sticky slightly plastic,many micro pores and common pores,clear smooth boundary to,
22-45 cm	yellowish brown (10YR 5/8, dry) red (2.5YR 4/8, moist)clay,weak fine and medium subangular blocky,hard very friable sticky slightly plastic,many micro pores and common pores,gradual smooth boundary to,
Bw1 45-95 cm	red (2.5YR 4/8, dry) dark yellowish brown (10YR 4/6, moist)clay,weak to moderate fine and medium subangular blocky,hard very friable sticky slightly plastic,continuous moderately thick clay cutans,many micro pores and common pores,gradual smooth boundary to,
Bw2 95-150 cm	red (2.5YR 4/6, moist)dark red (2.5YR 3/6, moist),clay,clay,moderate fine and medium subangular blocky to moderate fine and medium angular blocky,strong medium angular blocky,firm sticky slightly plastic,friable sticky slightly plastic,many medium distinct mottles (7.5YR 5/6),continuous moderately thick clay cutans,moderately thick slickensides clay on pedfaces cutans,common very fine pores,few very fine pores,diffuse smooth boundary to,diffuse smooth boundary to,
Bg2 220-450 cm	dark red (2.5YR 3/6, moist)clay,strong medium angular blocky,firm sticky slightly plastic,many coarse prominent mottles (10YR 6/4),continuous moderately thick clay on pedfaces cutans,

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Red Quarternary clay
Soil Depth	150cm
Texture of parent material	clayey
Texture of parent material (second entry)	clayey

Land use or vegetation in the immediate vicinity of the site	fallow
Remarks on Land Use / Vegetation	VEGETATION: Present vegetation is sparse grass cover and Masson Pine planted about 15 years ago LANDUSE: Red Quaternary clays are not cultivated. Before the use of inorganic fertilizers, the grass/herb vegetation with some topsoil was removed for the fertilization of the paddy fields in the valley. At pr

Altitude	45m
Physiographic Unit	low, broad interfluve
Physiographic position of the site	crest
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	intermontane basin
Slope	3%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	500cm
Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-200cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	200-400cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	rapid
Upper limit of a slow permeable or stagnating layer in the profile	150cm

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)	surface slaked; sorted sand/silt, some clay films
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

Intensity of the soil erosion type	moderate
Intensity of the soil erosion type (second entry)	severe
Soil erosion type	sheet
Soil erosion type (second entry)	gully

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Reference soil China 21: Acrisol

Characteristics

Reference soil CN021: Acrisols

Classification