Reference soil Peru 19: Regosol

PE019

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 PE019: Regosols

Short field description A deep, well drained, dark brown sandy loam to loamy sand. On the transition from fifth to sixth horizon is a sandy lens with a ligth gray color. Bulk density is too high for Andisols, andic subgroup possible. The soil profile located in a fan of volcanic material. The land has been shaped by man, constructing terraces which have been cultivated for about 100 years. " X " in the climate data refers to the cloud in eighths.

Classification

WRB 2006

WRB 1998

Haplic- Regosol (Calcaric Tephric Humic)

Hyposodi-Humic- Regosol (Calcaric Tephric)

-	tephric
-	calcaric

0-59 cm	ochric horizon
-	tephric
-	calcaric
-	strongly humic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Calcaric Regosol

Vitric Andosol

0-59 cm	ochric A horizon
- cm	mollic A horizon
-	strongly humic

0-36 cm

ochric A horizon

Other classification

USDA-NRCS (1999)	Haplustoll
USDA-SCS (1975)	Vitrandept aridic coarse-loamy mixed 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
0-18	-	-	3.8	8.2	17.3	19.3	-	19.9	23.3	43.2	7.0
18-36	-	1.2	4.1	8.0	14.6	17.3	45.2	24.1	20.9	45.0	9.8
36-59	-	1.6	5.1	11.5	17.9	17.1	53.2	19.9	19.9	39.8	7.0
59-82	-	1.6	5.9	14.0	22.9	16.9	61.3	16.9	16.6	33.5	5.1
82-100	-	0.6	3.2	11.3	19.7	13.8	48.6	26.8	19.3	46.1	5.2
100-130	-	4.5	14.1	14.2	24.7	21.7	79.2	13.0	2.9	15.9	4.8
130-155	-	1.0	3.3	5.1	20.2	22.6	52.2	22.7	17.3	40.0	7.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-18	1.000	-	-	1.5	7.0
18-36	0.980	-	-	4.1	9.8
36-59	0.990	-	-	3.3	7.0
59-82	1.000	-	-	3.5	5.1
82-100	1.100	-	-	2.3	5.2
100-130	1.300	-	-	3.2	4.8
130-155	1.280	-	-	5.9	7.7

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
0-18	1.000	50.9	50.9	50.3	43.4	35.0	26.8	11.8	10.2
18-36	0.980	51.4	51.4	47.4	38.9	32.2	28.9	12.2	10.4
36-59	0.990	50.8	48.4	43.6	36.6	30.4	25.7	8.7	7.1
59-82	1.000	50.4	48.1	43.8	35.5	27.6	22.1	6.1	5.5
82-100	1.100	51.4	47.9	45.7	39.9	30.2	20.2	6.4	5.6
100-130	1.300	45.1	42.4	39.7	30.6	22.1	17.8	8.2	7.8
130-155	1.280	47.3	44.3	41.2	34.5	26.1	19.6	9.7	8.7

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
0-18	-	7.2	1.50	1.7	1.60	0.20	8	-	-	18.2	4.3	1.1	1.9	25.5
18-36	8.2	7.5	0.2	2.0	1.26	0.16	8	-	-	15.5	2.9	1.1	0.4	19.9
36-59	8.6	7.6	0.15	3.8	0.50	0.06	8	-	-	7.2	1.6	0.7	0.3	9.8
59-82	8.8	8.0	0.14	2.4	0.25	0.03	8	-	-	6.0	1.0	0.7	0.3	8.0
82-100	9.1	8.4	0.11	2.2	0.12	-	-	-	-	3.8	0.7	0.4	0.2	5.1
100-130	8.5	7.7	0.28	1.4	0.22	-	-	-	-	5.6	1.3	1.1	0.6	8.6
130-155	8.2	7.6	0.67	0.8	0.23	-	-	-	-	7.3	2.1	1.6	0.9	11.9

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 %
0-18	-	11.7	-	5.6	-	-	16
18-36	162	12.3	126	4.4	-	-	3
36-59	123	8.0	114	1.8	-	-	4
59-82	163	4.9	96	0.9	-	-	6
82-100	-	1.9	37	0.4	-	-	11
100-130	126	6.8	142	0.8	-	-	9
130-155	117	10.2	132	0.8	-	-	9

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
0-18	7.8	0	-	0.00	0.00	-	-	-	-	-	0.10
18-36	8.0	2	-	0.00	0.00	-	-	-	-	-	0.00
36-59	7.8	0	-	0.00	0.00	-	-	-	-	-	0.00
59-82	7.8	0	-	0.00	0.00	-	-	-	-	-	0.00
82-100	7.8	0	-	0.00	0.00	-	-	-	-	-	0.00
100-130	7.7	0	-	0.00	0.00	-	-	-	-	-	0.00
130-155	7.8	2	-	0.00	0.00	-	-	-	-	-	0.00

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
18-36	-	weak	-	-	-	-	very weak to weak	weak	weak	-	-	-
36-59	-	weak	-	-	-	-	very weak to weak	weak	weak	-	-	-
59-82	-	weak	-	-	-	-	very weak to weak	weak	weak	-	weak	-
82-100	-	weak	-	-	-	-	very weak to weak	weak	weak	-	weak	-
100-130	-	weak	-	-	-	-	very weak to weak	very weak to weak	weak	-	-	-
130-155	-	weak	-	-	-	-	very weak to weak	very weak to weak	weak	-	-	-

Profile description

Ap 0-18 cm	very dark greyish brown (10YR 3/2, moist) greyish brown (2.5Y 5/2, dry)sandy loam,very weak very fine granular,very friable,gradual smooth boundary to,
Ah 18-36 cm	very dark greyish brown (10YR 3/2, moist) light brownish grey (2.5Y 6/2, dry)sandy loam,very weak very fine granular,very friable,diffuse smooth boundary to,
AC 36-59 cm	dark brown (10YR 3/3, moist) greyish brown (2.5Y 5/2, dry)sandy loam,very weak very fine granular,very friable,gradual smooth boundary to,
CA 59-82 cm	dark greyish brown (2.5Y 4/2, moist) light brownish grey (2.5Y 6/2, dry)loamy sand,weakly coherent massive,very friable,gradual smooth boundary to,
C 82-100 cm	greyish brown (2.5Y 5/2, moist) light grey (10YR 7/1, dry)loam,weakly coherent massive,very friable,clear smooth boundary to,
2Ahb 100-130 cm	dark brown (10YR 3/3, moist) greyish brown (2.5Y 5/2, dry)loamy medium sand,very weak very fine granular,friable,clear smooth boundary to,
2Cb 130-155 cm	dark yellowish brown (10YR 3/4, moist) brown (10YR 5/3, dry)sandy loam slightly gravelly,weakly coherent massive,friable,

Depth1	100cm
Kind 1 (parent material) ; Parker (eds), 1984	pyroclastic, unconsolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	pyroclastic, unconsolidated
Mode of accumulation or deposition of parent material	ejecta ash
Mode of accumulation or deposition of parent material (second entry)	ejecta ash
Soil Depth	155cm
Texture of parent material	loamy
Texture of parent material (second entry)	sandy
Weathering Resistance	poor
Weathering Resistance (second entry)	poor
General characterization of the status of weathering of solid rock	slightly
General characterization of the status of weathering of solid rock (second entry)	partially or moderately

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

Major crops	annual crops
Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	terracing
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	medium level arable farming
Remarks on Land Use / Vegetation	VEGETATION: LANDUSE: Gravity irrigation
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	2450m
Physiographic Unit	fan of pyroclastic deposits
Physiographic position of the site	slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	lava plain
Slope	18%
Form of the slope surrounding the site	undulating
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	hilly

Drainage class ; FAO (2006) - Guidelines for soil description	somewhat excessive
Dry From - To	0-82cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	82-155cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	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 19: Regosol

Characteristics

Reference soil PE019: Regosols

Classification