Reference soil Peru 18: Regosol

PE018

Regosols are found in areas where soil has been eroded to the extent that the underlying unconsolidated materials come near to the surface, or where soil formation has not played an important role, e.g. in desert regions. The name comes from the greek 'rhegos' :blanket meaning young soils on weathering materials.

Characteristics

Soils in medium and fine textured materials, having no distinctive horizons other than an ochric horizon at the surface.

Distribution of Regosols (rough estimation supplied by soilgrids)

Reference soil PE018: Regosols

Short field description A very deep, excessively drained, dark brown (slightly) gravelly sand. The topsoil has a sandy loam texture. The soil profile is located in an alluvium plain. The land has been cultivated/irrigated for about 50 years using a high technology level (mechanization, fertilizers, pesticides). This soil has been levelled to form a broad terrace with sligth slope. " X " in the climate data refers to the cloud in eighths.

Classification

WRB 2006

WRB 1998

Haplic- Regosol (Sodic Endoskeletic Arenic)

Hyposodi-Arenic- Regosol (Endoskeletic)

0-41 cm

ochric horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Sodi-Eutric Regosol skeletic

Eutric Regosol sodic

0-41 cm	ochric A horizon
- cm	ochric A horizon
-	sodic

0-41 cm

ochric A horizon

Other classification

USDA-NRCS (1999)	Typic Torripsamment
USDA-SCS (1975)	Typic Torriorthent aridic micaceous isothermic

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
0-24	-	3.4	8.4	21.0	41.4	10.7	84.9	6.2	3.2	9.4	5.7
24-41	-	3.5	7.7	22.2	43.1	8.5	85.0	5.2	4.3	9.5	5.4
41-67	-	11.1	24.0	19.6	30.4	6.9	92.0	2.3	1.4	3.7	4.3
67-76	-	22.8	31.1	15.0	21.6	4.4	94.9	2.1	0.5	2.6	2.6
76-126	-	6.9	21.2	21.1	39.8	7.8	96.8	0.6	0.4	1.0	2.3
126-158	-	12.6	25.0	20.5	31.4	5.7	95.2	2.4	0.7	3.1	1.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-24	-	-	-	3.9	5.7
24-41	1.420	-	-	4.7	5.4
41-67	1.700	-	-	2.3	4.3
67-76	1.740	-	-	2.5	2.6
76-126	1.720	-	-	1.8	2.3
126-158	-	-	-	1.0	1.7

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
24-41	1.420	41.6	40.0	32.9	17.9	14.1	12.3	8.3	5.7
41-67	1.700	36.5	34.9	28.3	16.6	12.1	10.0	5.6	3.4
67-76	1.740	37.0	33.3	24.3	9.8	6.7	5.5	3.1	1.7
76-126	1.720	35.6	31.5	24.9	9.5	6.6	5.7	2.3	1.6

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
0-24	7.8	7.5	1.0	1.0	0.74	0.09	8	-	-	6.9	2.7	1.0	2.3	12.9
24-41	7.3	6.8	1.15	1.0	0.51	0.06	8	-	-	6.9	2.7	1.1	1.3	12.0
41-67	8.4	7.3	0.45	1.6	0.08	-	-	-	-	4.6	1.7	1.1	1.2	8.6
67-76	8.8	7.3	0.1	1.6	0.02	-	-	-	-	1.6	0.7	0.7	0.6	3.6
76-126	8.8	6.9	0.11	1.4	0.02	-	-	-	-	1.4	0.7	0.7	0.4	3.2
126-158	8.8	7.3	0.12	2.4	0.03	-	-	-	-	1.6	0.7	1.4	0.3	4.0

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 %
0-24	184	7.0	123	2.6	-	-	33
24-41	214	5.6	104	1.8	-	-	23
41-67	195	4.4	102	0.3	-	-	27
67-76	189	1.9	73	0.1	-	-	32
76-126	-	1.0	43	0.1	-	-	40
126-158	-	0.2	12	0.1	-	-	100

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
0-24	-	-	-	0.03	0.06	-	-	-	-	-	0.03
24-41	-	-	-	0.03	0.07	-	-	-	-	-	0.03
41-67	-	-	-	0.02	0.06	-	-	-	-	-	0.10
67-76	-	-	-	0.00	0.06	-	-	-	-	-	0.00
76-126	-	-	-	0.01	0.07	-	-	-	-	-	0.00
126-158	-	-	-	0.00	0.06	-	-	-	-	-	0.01

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-24	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	weak	-
24-41	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	medium to strong	-
41-67	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	weak	-
67-76	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	medium to strong	-
76-126	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	medium to strong	-
126-158	-	medium to strong	-	-	-	-	very weak to weak	very weak to weak	weak	very weak	medium to strong	-

Profile description

Ap 0-24 cm	dark brown (10YR 3/3, moist)loamy fine sand slightly gravelly,weakly coherent massive,loose,few channels,gradual smooth boundary to,
AC 24-41 cm	(dark) brown (10YR 4/3, moist)loamy fine sand slightly gravelly,weakly coherent massive,friable,clear smooth boundary to,
C1 41-67 cm	very dark greyish brown (10YR 3/2, moist)medium sand gravelly,structureless single grain,loose,clear smooth boundary to,
C2 67-76 cm	dark brown (10YR 3/3, moist)fine sand,structureless single grain,loose,clear smooth boundary to,
C3 76-126 cm	very dark greyish brown (10YR 3/2, moist)medium sand very gravelly,structureless single grain,loose,gradual smooth boundary to,
C4 126-158 cm	very dark greyish brown (10YR 3/2, moist)medium sand slightly gravelly,structureless single grain,loose,

Kind 1 (parent material) ; Parker (eds), 1984	sediment, unconsolidated
Mode of accumulation or deposition of parent material	fluvial
Soil Depth	150cm
Texture of parent material	sandy
Weathering Resistance	moderate

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Slope stability	stable

Major crops	maize
Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	levelling
Main type of irrigation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	continuously irrigated
Land use or vegetation in the immediate vicinity of the site	high level arable farming
Remarks on Land Use / Vegetation	VEGETATION: LANDUSE: Irrigated fields
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	continuous crop rotation

Altitude	1700m
Physiographic Unit	old alluvial plain
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	somewhat excessive
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	0-158cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	very slow

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
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	level
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 18: Regosol

Characteristics

Reference soil PE018: Regosols

Classification