Reference soil Peru 15: Alisol

PE015

Alisols occur in the tropics and subtropics, and in the warm temperate regions of the world in relatively young landscapes. The high level of exchangeable aluminium in these soils is caused by rapid weathering of secondary high-activity clays such as vermiculite and smectite.

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 24 cmolc per kg clay or more, and which starts either 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 "alic" properties (high content of exchangeable aluminium) in the major part between 25 and 100 cm from the soil surface; moreover, only such diagnostic horizons as an ochric, albic, andic, ferric, nitic, plinthic, or vertic horizon are present.

Distribution of Alisols (rough estimation supplied by soilgrids)

Reference soil PE015: Alisols

Soil shrunk from 145 to 141 cm upon drying (3%)

Classification

WRB 2006

WRB 1998

Haplic- Alisol (Alumic Humic Profondic)

Profondi-Humic- Alisol (Hyperdystric Chromic)

10-150 cm

argic horizon

0-30 cm	ochric horizon
10-150 cm	argic horizon
-	strongly humic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Alisol

Dystric Nitosol

0-30 cm	ochric A horizon
10-150 cm	argic B horizon

0-30 cm

ochric A horizon

Local classification:	Terra firme

Other classification

USDA-NRCS (1999)	Typic Paleudult
USDA-SCS (1975)	Typic Paleudult udic clayey montmorillonitic 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
0-10	0	0.2	0.8	1.2	2.7	26.7	31.6	25.2	17.8	43.0	25.2
10-30	0	0.0	0.1	0.4	4.7	18.8	24.0	27.9	16.9	44.8	31.2
30-50	0	0.0	0.2	0.4	3.9	20.7	25.2	22.5	15.5	38.0	36.8
50-80	0	0.1	1.5	0.9	1.4	15.0	18.9	17.7	14.6	32.3	48.8
80-150	0	0.0	0.1	0.1	1.6	19.7	21.5	15.9	17.7	33.6	44.9
180-200	0	0.0	0.0	0.3	2.5	43.9	46.7	11.8	15.8	27.6	25.6
250-260	0	0.0	0.0	0.1	27.4	30.9	58.4	6.7	16.4	23.1	18.4
350-370	0	0.0	0.0	0.1	5.5	48.5	54.1	9.9	16.5	26.4	19.4

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	0.800	-	-	-	25.2
10-30	1.090	-	-	-	31.2
30-50	1.240	-	-	-	36.8
50-80	1.200	-	-	-	48.8
80-150	1.390	-	-	-	44.9
150-170	1.500	-	-	-	-
180-200	-	-	-	-	25.6
250-260	-	-	-	-	18.4
350-370	-	-	-	-	19.4

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
0-10	0.800	63.9	54.2	52.6	48.0	44.0	40.5	25.3	17.2
10-30	1.090	57.4	54.7	54.0	50.8	48.0	45.1	36.4	24.7
30-50	1.240	53.0	52.9	52.8	50.9	49.3	46.8	39.2	30.6
50-80	1.200	55.5	55.0	54.9	54.3	53.5	52.2	45.2	34.2
80-150	1.390	51.3	50.6	50.5	50.2	49.8	49.4	47.4	38.3
150-170	1.500	45.8	45.6	45.6	45.4	44.9	44.3	42.2	33.8

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	4.2	3.7	0.53	-	3.65	0.34	11	4.5	3.9	5.4	0.7	0.3	0.0	6.4
10-30	4.5	3.7	0.05	-	1.07	0.14	8	7.8	7.3	0.8	0.1	0.1	0.2	1.2
30-50	4.5	3.7	0.03	-	0.62	0.10	6	9.1	9	0.2	0.1	0.1	0.2	0.6
50-80	4.6	3.7	0.02	-	0.40	0.10	4	13	12.9	0.0	0.1	0.2	0.1	0.4
80-150	5.1	3.6	0.01	-	0.17	-	-	16.3	16.2	0.0	0.1	0.2	0.4	0.7
180-200	5.1	3.7	0.01	-	0.11	-	-	10.2	10	0.0	0.1	0.1	0.2	0.4
250-260	5.2	3.8	0.01	-	0.08	-	-	7.7	7.6	0.0	0.0	0.1	1.4	1.5
350-370	5.0	4.0	0.02	-	0.13	-	-	9.1	8.8	0.0	0.1	0.2	0.6	0.9

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	37	17.3	69	12.8	-	23	0
10-30	9	14.1	45	3.7	-	52	1
30-50	5	11.5	31	2.2	-	78	2
50-80	2	16.2	33	1.4	-	80	1
80-150	3	23.2	52	0.6	-	70	2
180-200	3	12.4	48	0.4	-	81	2
250-260	15	9.5	52	0.3	-	80	15
350-370	9	10.4	54	0.5	-	85	6

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	-	2.5	-	-	-	-	-	-	-
10-30	-	0.8	-	-	-	-	-	-	-
30-50	-	0.5	-	-	-	-	-	-	-
50-80	-	0.4	-	-	-	-	-	-	-
80-150	-	0.3	-	-	-	-	-	-	-
180-200	-	0.5	-	-	-	-	-	-	-
250-260	-	0.7	-	-	-	-	-	-	-
350-370	-	0.8	-	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
30-50	-	-	-	weak	-	-	weak to medium	very weak	-	very weak	strong	-
50-80	-	-	-	very weak	-	-	weak to medium	very weak to weak	-	very weak	strong	-
80-150	-	-	-	very weak	-	-	weak to medium	weak	-	very weak	strong	-
250-260	-	-	-	very weak	-	-	weak to medium	weak	medium to strong	very weak	medium to strong	-

Profile description

Ah1 0-10 cm	dark brown (7.5YR 3/2, moist)silt loam,moderate medium granular,friable,many very fine and fine throughout roots,few worm channels,clear smooth boundary to,
Ah2 10-30 cm	(dark) brown (7.5YR 4/4, moist)silty clay loam,moderate medium subangular blocky,firm,common very fine throughout roots,clear smooth boundary to,
30-50 cm	strong brown (7.5YR 5/6, moist)silty clay,strong medium subangular blocky,firm,few fine throughout roots,very few large irregular hard ferruginous concretions,clear smooth boundary to,
B 50-80 cm	yellowish red (5YR 4/6, moist)clay,strong medium subangular blocky,firm,gradual smooth boundary to,
Bg 80-150 cm	red (2.5YR 4/8, moist)silty clay,very firm,many coarse prominent clear mottles (10YR 6/2),

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	"Pebas" formation
Soil Depth	72cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Land use or vegetation in the immediate vicinity of the site	fallow
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	secondary
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	evergreen forest

Altitude	130m
Physiographic Unit	Colinas Bajas, dissected high terrace of the Nanay River
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.	hill
Slope	1%
Slope Aspect	north-east
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Lower limit of a slow permeable or stagnating layer in the profile	150cm
Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-150cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	slow
Upper limit of a slow permeable or stagnating layer in the profile	80cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
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 Peru 15: Alisol

Characteristics

Reference soil PE015: Alisols

Classification