Reference soil Costa Rica 12: Andosol

CR012

Andosols occur throughout the world where volcanic activity is common, especially in the circum-Pacific region and along the mid-Atlantic Ridge.

Characteristics

Soils with a vitric or andic horizon (slightly to moderately weathered horizons in pyroclastic deposits dominated by short-range-order minerals, notably allophane and imogolite) starting within 25 cm from the soil surface. In addition, they may have a histic, fulvic, melanic, mollic, umbric, ochric, duric, or cambic horizon. Other diagnostic horizons (unless buried deeper than 50 cm by volcanic deposits) are absent.

Distribution of Andosols (rough estimation supplied by soilgrids)

Reference soil CR012: Andosols

Brief soil description: Very deep, well drained, brownish black over yellowish brown loamy soil. The upper 50 cm have a very high organic matter content. The soil has been formed in various superimposed volcanic ash deposits of the Turrialba volcano. The site has been used for many years for pasture, which has caused compaction of the upper 30 cm, as evidenced by slight mottling. At time of description, the land was being prepared for growing potatoes and later on beans, after which pasture will probably be reestablished. In the subsoil some very large pores are present, partly filled up which material from the A horizon.

Classification

WRB 2006

WRB 1998

Umbric-Silandic- Andosol (Hyperdystric)

Pachi-Silic- Andosol (Umbric Hyperdystric)

0-53 cm	umbric horizon
53-150 cm	cambic horizon
-	andic

0-150 cm	silandic horizon
0-53 cm	umbric horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Pachi-Umbric Andosol

Humic Andosol

0-53 cm	umbric A horizon
53-150 cm	cambic B horizon
-	andic

0-53 cm	umbric A horizon
53-150 cm	cambic B horizon
-	exchange complex dominated by amorphous material
-	thixotropy

Other classification

USDA-SCS (1975)

Hydrandept perudic loamy 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
0-26	-	1.5	1.8	3.6	14.1	13.8	34.8	8.4	23.6	32.0	33.2
26-53	-	1.2	2.0	4.0	14.0	9.7	30.9	12.8	34.4	47.2	21.9
53-100	-	1.4	2.1	4.5	10.2	8.8	27	27.6	21.2	48.8	24.2
100-150	-	1.0	3.1	6.9	13.9	7.7	32.6	35.4	9.4	44.8	22.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-26	0.510	-	-	4.9	33.2
26-53	0.485	-	-	8.6	21.9
53-100	0.436	-	-	6.8	24.2
100-150	-	-	-	-	22.6

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
0-26	0.510	76.0	74.9	73.6	69.4	66.1	62.1	45.2	36.2
26-53	0.485	75.8	75.8	71.1	66.9	64.0	61.0	49.5	37.9
53-100	0.436	78.4	77.7	74.5	71.4	69.3	66.9	57.0	48.9

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
0-26	4.8	4.5	0.24	-	13.67	1.27	11	-	-	2.8	1.0	0.4	1.3	5.5
26-53	5.9	5.3	0.02	-	7.07	0.56	13	-	-	1.8	0.3	0.1	0.1	2.3
53-100	6.2	5.8	0.02	-	4.85	0.46	11	-	-	1.6	0.3	0.1	0.1	2.1
100-150	6.4	6.0	0.02	-	3.90	0.37	11	-	-	1.6	0.7	0.1	0.1	2.5

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 %
0-26	10	52.7	159	47.8	-	-	2
26-53	5	50.0	228	24.7	-	-	0
53-100	3	64.8	268	17.0	-	-	0
100-150	3	72.5	321	13.7	-	-	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
0-26	-	96	-	2.88	0.77	-	-	-	-	-	1.65
26-53	-	98	-	5.06	1.86	-	-	-	-	-	1.35
53-100	-	98	-	6.53	2.80	-	-	-	-	-	1.63
100-150	-	98	-	7.90	3.42	-	-	-	-	-	1.58

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
0-26	-	-	7.2	-	-	-	-	-	-
26-53	-	-	1.4	-	-	-	-	-	-
53-100	-	-	0.5	-	-	-	-	-	-
100-150	-	-	0.5	-	-	-	-	-	-

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-26	-	-	-	-	-	-	very weak	-	weak	-	-	-
26-53	-	-	-	-	-	-	very weak	-	weak	-	-	-
53-100	-	-	-	-	-	-	very weak	-	weak	-	-	-
100-150	-	-	-	-	-	-	very weak	-	weak	-	-	-

Profile description

Ah 0-26 cm	very dark greyish brown (10YR 3/2, moist)loam,moderate very fine subangular blocky and moderate very fine and fine crumb,friable slightly sticky slightly plastic moderately smeary,common fine distinct clear mottles (7.5YR 4/6),no cutans,common very fine fine pores and few pores highly porous (>60 vol%),no inclusions,no fragments,frequent worm channels,non-cemented pans,clear wavy boundary to,
2Ah 26-53 cm	very dark brown (10YR 2/2, moist)loam,moderate very fine subangular blocky and moderate fine crumb,very friable slightly sticky slightly plastic moderately smeary,oblique mottles,no cutans,many very fine fine pores and few pores highly porous (>60 vol%),no inclusions,very few medium gravel fresh andesitic fragments,few worm channels,non-cemented pans,clear wavy boundary to,
2Bw1 53-100 cm	dark yellowish brown (10YR 4/4, moist)loam,moderate very fine subangular blocky,friable slightly sticky slightly plastic moderately smeary,oblique mottles,no cutans,many very fine fine pores and few pores highly porous (>60 vol%),no inclusions,very few medium gravel fresh andesitic fragments,non-cemented pans,diffuse smooth boundary to,
2Bw2 100-150 cm	dark yellowish brown (10YR 4/4, moist)loam,moderate very fine angular blocky and moderate very fine subangular blocky,firm slightly sticky slightly plastic moderately smeary,oblique mottles,no cutans,many very fine fine pores and few pores highly porous (>60 vol%),no inclusions,very few medium gravel fresh andesitic very few fine gravel strongly weathered pumice/ash fragments,non-cemented pans,

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Mode of accumulation or deposition of parent material	ejecta ash
Remarks on Parent Materials	andesitic ash
Soil Depth	150cm
Texture of parent material	sandy
Texture of parent material (second entry)	sandy
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	partially or moderately

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

Main type of irrigation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	no irrigation
Land use or vegetation in the immediate vicinity of the site	cultivated pasture
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop - grass rotation, lay

Altitude	1650m
Physiographic Unit	SE slope of Turrialba volcano
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.	volcano
Slope	5%
Slope Aspect	south-east
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	mountainous

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	0-150cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	rapid

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 Costa Rica 12: Andosol

Characteristics

Reference soil CR012: Andosols

Classification