Reference soil Peru 02: Ferralsol

PE002

Ferralsols occur in tropical and subtropical regions of the world, mainly on old and stable land surfaces.

Characteristics

Soils having a ferralic horizon (strongly weathered horizon with low-activity clays and very low amounts of weatherable minerals) between 25 and 200 cm from the soil surface. They lack a nitic horizon (a horizon with strongly developed, nut-shaped structure) and do not have a layer which fulfils the requirements of an argic horizon and which has, in the upper 30 cm, 10 percent or more water-dispersible clay.

Distribution of Ferralsols (rough estimation supplied by soilgrids)

Reference soil PE002: Ferralsols

Short field description Very deep, well drained, yellowish brown loamy sand. A thin dark A horizon is followed by a weakly mottled transition horizon, from about 50 cm starts a very uniform soil colour. The weak mottling in the Ah2 and BA horizons consists of yellowish/red mottles caused by iron ('root rust') and black because of organic matter in bio-channels. The weak yellowish/red colours are indicative for temporarely saturation of the soil by excessive rain water. The top horizon, Ah1, can be divided in two thin horizons: 0-4 cm with a dark colour and 4-8 cm with a bleached colour. The Bw1 horizon is a bit darker than the overlaying BA horizon. The soil site is located in the upper slope of a convex hill. The soil parent material belongs to an old alluvium, the 'Iquitos formation', deposited during the upper Tertiary. At a depth of 320 cm starts abruptly an older clay alluvium formation, probably the Pebas formation, which has been observed till 350 cm, but may extend to a great depth. The original dense rain-forest has been cleared recently and many tree trunks, partial decaying are present. " X " in the climate data refers to the cloud cover in eighths. According to the FAO classification there is no ferralic B-horizon because of a too high silt/clay ratio, and no argic B-horizon because the rate of clay increase is just not insufficient. Because of colour and structure development the B horizon is classified as cambic B. In the USDA Soil Taxonomy the oxic horizon is identified, assuming the weatherable mineral content to be lower than 10%.

Classification

WRB 2006

WRB 1998

Acric- Ferralsol (Alumic Arenic Xanthic)

Areni-Acric- Ferralsol (Alumic Xanthic)

25-260 cm	ferralic horizon
93-260 cm	argic horizon

0-25 cm	ochric horizon
25-260 cm	ferralic horizon
93-260 cm	argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Alumi-Haplic Acrisol

Xanthic Ferralsol

0-25 cm	ochric A horizon
25-93 cm	cambic B horizon
93-260 cm	argic B horizon

0-25 cm

ochric A horizon

Other classification

USDA-NRCS (1999)	Typic Haploperox
USDA-SCS (1975)	Typic Dystropept perudic coarse-loamy 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
0-8	-	0.3	2.5	37.5	47.0	7.3	94.6	2.1	1.9	4.0	1.5
8-25	-	0.4	2.0	31.7	47.0	8.7	89.8	3.9	2.6	6.5	3.7
25-52	-	0.2	2.1	27.0	44.1	9.5	82.9	5.5	2.4	7.9	9.2
52-93	-	0.3	1.7	26.0	43.4	10.0	81.4	4.6	6.0	10.6	7.9
93-140	-	0.2	1.6	24.8	41.4	9.5	77.5	5.8	3.6	9.4	13.1
140-165	-	0.3	1.3	25.1	42.4	9.6	78.7	5.0	2.3	7.3	14.0
165-220	-	0.1	1.2	22.8	43.1	10.4	77.6	5.0	3.6	8.6	13.9
220-250	-	0.2	1.2	23.4	42.5	10.5	77.8	5.5	3.0	8.5	13.8
300-320	-	10.8	24.4	31.7	16.6	2.3	85.8	2.0	3.3	5.3	8.9
320-320	-	0	1.2	5.3	2.7	1.6	10.8	9.4	30.4	39.8	49.4

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
8-16	1.48	-	-	-	-
0-8	-	-	-	1.4	1.5
8-25	-	-	-	2.4	3.7
25-52	1.350	-	-	4.1	9.2
52-93	1.350	-	-	5.4	7.9
93-140	1.460	-	-	8.3	13.1
165-200	1.500	-	-	-	-
140-165	1.470	-	-	8.0	14.0
165-220	-	-	-	8.6	13.9
200-250	1.510	-	-	-	-
250-300	1.560	-	-	-	-
220-250	-	-	-	5.9	13.8
300-320	1.630	-	-	3.2	8.9
320-320	-	-	-	4.1	49.4

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
8-16	1.48	41.5	41.4	34.3	13.5	10.8	9.8	3.4	3.1
25-52	1.350	41.7	39.9	31.9	26.8	24.6	22.2	7.3	5.9
52-93	1.350	40.5	39.1	30.3	24.8	22.8	20.5	8.1	6.6
93-140	1.460	36.9	36.8	29.7	21.8	19.5	17.9	11.1	9.1
165-200	1.500	35.4	35.4	26.4	16.8	14.5	13.0	11.0	9.2
140-165	1.470	37.7	37.6	27.2	18.0	15.5	13.8	11.4	9.1
200-250	1.510	35.8	35.7	26.1	17.9	15.6	14.2	10.7	8.9
250-300	1.560	40.3	38.1	17.6	8.6	6.9	5.8	5.7	5.2
300-320	1.630	33.7	28.8	14.7	9.9	8.2	7.0	5.7	5.4

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
0-8	5.4	5.0	0.07	-	1.25	0.09	14	0.1	0	3.4	0.7	0.1	0.2	4.4
8-25	5.4	4.8	0.05	-	0.51	0.04	13	0.2	0	1.2	0.0	0.0	0.0	1.2
25-52	5.0	4.5	0.03	-	0.47	0.04	12	1.2	0.7	0.6	0.0	0.0	0.0	0.6
52-93	4.9	4.4	0.02	-	0.34	0.03	11	3.9	0.9	0.0	0.0	0.0	0.2	0.2
93-140	4.7	4.3	0.02	-	0.20	0.03	7	1.4	1.1	0.2	0.0	0.0	0.0	0.2
140-165	4.7	4.3	0.02	-	0.16	0.02	8	1.3	0.9	0.2	0.0	0.0	0.0	0.2
165-220	4.8	4.3	0.01	-	0.13	0.02	7	1.3	0.9	0.2	0.0	0.0	0.0	0.2
220-250	4.9	4.3	0.01	-	0.10	0.02	5	1.3	0.7	0.2	0.0	0.0	0.0	0.2
300-320	4.9	4.3	0.01	-	0.01	-	-	1.5	1.1	0.8	0.0	0.0	0.1	0.9
320-320	4.7	4.0	0.01	-	0.08	-	-	9.1	7.8	0.2	0.0	0.1	0.0	0.3

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 %
0-8	110	4.0	267	4.4	-	0	5
8-25	57	2.1	57	1.8	-	0	0
25-52	25	2.4	26	1.6	-	29	0
52-93	8	2.5	32	1.2	-	36	8
93-140	11	1.9	15	0.7	-	58	0
140-165	13	1.6	11	0.6	-	56	0
165-220	10	2.1	15	0.5	-	43	0
220-250	17	1.2	9	0.4	-	58	0
300-320	64	1.4	16	0.0	-	79	7
320-320	3	10.0	20	0.3	-	78	0

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-8	-	weak	very weak	weak	-	-	very strong	-	weak	weak	weak	-
8-25	-	weak	very weak	weak	-	-	very strong	-	weak	weak	weak	-
52-93	-	weak	weak	weak	-	-	very strong	-	weak	weak	weak	-
140-165	-	weak	weak	weak	-	-	very strong	-	weak	very weak	weak	-
220-250	-	weak	weak	weak	-	-	very strong	-	weak	very weak	weak	-
300-320	-	-	very weak	very weak	-	-	very strong	-	weak	-	weak	-

Rare clay minerals

Depth (cm)	Amphibole	Augite	Calcite	Lepidococrite	Pyrophillite	Pyroxene	Weddelite
0-8	-	-	-	-	weak	-	-
8-25	-	-	-	-	weak	-	-
52-93	-	-	-	-	weak	-	-
140-165	-	-	-	-	weak	-	-
220-250	-	-	-	-	weak	-	-

Profile description

Ah1 0-8 cm	very dark greyish brown (10YR 3/2, moist)fine sand,weak fine granular,very friable slightly sticky slightly plastic,frequent worm channels and pedotubules,clear smooth boundary to,
Ah2 8-25 cm	dark yellowish brown (10YR 4/4, moist)fine sand,weak fine and medium granular,very friable slightly sticky slightly plastic,few fine faint mottles,few worm channels and pedotubules,gradual smooth boundary to,
BA 25-52 cm	yellowish brown (10YR 5/6, moist)loamy sand,weakly coherent porous massive,very friable slightly sticky slightly plastic,few fine faint mottles,few worm channels and pedotubules,gradual smooth boundary to,
Bw1 52-93 cm	yellowish brown (10YR 5/6, moist)sandy loam,weakly coherent porous massive,friable slightly sticky slightly plastic,few pedotubules and worm channels,diffuse smooth boundary to,
Bw2 93-140 cm	yellowish brown (10YR 5/8, moist)sandy loam,weakly coherent porous massive,friable slightly sticky slightly plastic,diffuse smooth boundary to,
Bw3 140-260 cm	yellowish brown (10YR 5/8, moist)loamy sand,weakly coherent porous massive,friable,
Bw3 140-260 cm	loamy sand
Bw3 140-260 cm	Description sand slightly gravelly
Bw3 140-260 cm	clay

Depth1	320cm
Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	fluvial
Mode of accumulation or deposition of parent material (second entry)	fluvial
Remarks on Parent Materials	Tertiary Iquitos Formation overlying the clayey Pebas Formation
Soil Depth	320cm
Texture of parent material	loamy
Texture of parent material (second entry)	clayey
Weathering Resistance	moderate
Weathering Resistance (second entry)	moderate
General characterization of the status of weathering of solid rock (second entry)	slightly

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

Land use or vegetation in the immediate vicinity of the site	cultivated pasture
Remarks on Land Use / Vegetation	VEGETATION: "Grassland (""torourco"" - Dactylocthenium sp.)" LANDUSE:
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	short grassland

Altitude	130m
Physiographic Unit	dissected river terrace
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.	low hill
Slope	25%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-165cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	moderately well

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)	no surface slaking/crusting observed
Microrelief Height: variation in height	10
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	terracettes
Microrelief pattern	isolated
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 02: Ferralsol

Characteristics

Reference soil PE002: Ferralsols

Classification