Reference soil Kenya 34: Andosol

KE034

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 KE034: Andosols

The spot around the pit is cultivated with maize, beans and partly abondoned (fallow?) with grasses and bushes, conspicuously with ferns. Also pyrethrum is grown. Even in the Bu1 horizon few carbonized materials are seen, suggesting some disturbances. Rootings frequent to the bottom of BA. Geology: basalt, basaltic conglomerates and volcanic ash. Climate: Rel. Hum.(%) - relative humidity 0600 GMT, first row Rel. Hum.(%) - relative humidity 1200 GMT, second row Slides: 10248 - 10251, Landscape, profile, landuse. Literature: Oswago, O. 1975. Soils of the Gituamba Experimental Farm, Soil Unit, NAL, Nairobi. Hirose, S. ed.1987. Agriculture and Soils in Kenya. Nihon University, Tokyo, Japan. Chapter B1, B2, B3, page 88 - 129.

Classification

WRB 2006

WRB 1998

Silandic-Aluandic- Andosol (Hyperdystric)

Hyperdystri-Silic- Andosol

16-130 cm	cambic horizon
-	andic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Andosol

Ochric Andosol

0-16 cm	ochric A horizon
16-130 cm	cambic B horizon
-	andic
-	strongly humic

0-16 cm	ochric A horizon
16-130 cm	cambic B horizon
-	exchange complex dominated by amorphous material
-	high organic matter content in B horizon

Other classification

USDA-NRCS (1999)	Alic Fulvudand
USDA-SCS (1975)	Alic Dystrandept udic clayey mixed isomesic

More images

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
0-16	-	0.0	0.2	0.5	1.5	1.2	3.4	15.0	51.9	66.9	29.6
16-28	-	0.0	0.3	0.7	1.7	1.3	4	38.0	42.5	80.5	15.5
28-47	-	0.1	0.4	0.7	1.7	1.3	4.2	14.1	51.9	66	29.7
47-130	-	0.1	0.2	0.5	1.6	1.4	3.8	12.5	71.8	84.3	11.8

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-16	-	-	-	1.0	29.6
16-28	-	-	-	1.0	15.5
28-47	-	-	-	0.5	29.7
47-130	-	-	-	1.9	11.8

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
0-16	5.2	3.7	0.08	-	13.14	0.91	14	-	4.9	0.0	0.0	0.3	0.1	0.4
16-28	5.0	4.1	0.05	-	8.64	0.63	14	4.7	3.6	0.0	0.1	0.2	0.1	0.4
28-47	4.8	4.4	0.03	-	7.51	0.52	14	3.0	2.2	0.0	0.0	0.2	0.1	0.3
47-130	4.8	4.5	0.02	-	5.37	0.43	12	1.4	0.9	0.2	0.3	0.1	0.1	0.7

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 %
0-16	1	62.3	210	46.0	-	8	0
16-28	1	58.7	379	30.2	-	6	0
28-47	1	44.0	148	26.3	-	5	0
47-130	2	45.2	383	18.8	-	2	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
0-16	10.2	97	-	2.19	0.28	9.39	2.47	2.5	1.88	-	2.09
16-28	10.3	98	-	2.29	0.33	6.45	2.71	3.52	2.39	-	2.35
28-47	10.5	98	-	2.59	0.50	11.10	3.40	3.26	2.45	-	2.46
47-130	10.5	99	-	3.96	1.31	5.20	3.60	1.93	1.21	-	2.37

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-16	-	very weak to weak	weak to medium	-	-	-	weak to medium	-	-	very weak to weak	weak to medium	-
16-28	-	very weak to weak	weak to medium	-	-	-	weak to medium	-	-	very weak to weak	strong	-
47-130	-	-	weak to medium	-	-	-	weak to medium	-	-	very weak to weak	medium to strong	-

Profile description

Ah 0-16 cm	dark reddish brown (5YR 3/2, moist)sandy clay loam,weak coarse subangular blocky parting to weak fine subangular blocky,friable non sticky non plastic (moist),many fine and medium roots,non calcareous,abrupt smooth boundary to,
BA 16-28 cm	dark reddish brown (5YR 3/2, moist)sandy loam,weak fine and medium subangular blocky,friable non sticky non plastic (moist),many fine and common medium roots,non calcareous,gradual smooth boundary to,
Bw1 28-47 cm	reddish brown (5YR 4/4, moist)sandy clay loam,moderate coarse subangular blocky parting to weak fine subangular blocky,friable slightly sticky non plastic (moist),common fine and medium and few coarse roots,non calcareous,diffuse smooth boundary to,
Bw2 47-130 cm	reddish brown (5YR 4/4, moist)sandy clay loam,moderate coarse subangular blocky parting to weak medium subangular blocky,friable slightly sticky non plastic (moist),patchy thin clay cutans,few fine and medium roots,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	pyroclastic, unconsolidated
Kind 2 (parent material) (second entry); Parker (eds), 1984	basalt
Mode of accumulation or deposition of parent material	ejecta ash
Mode of accumulation or deposition of parent material (second entry)	residual material
Remarks on Parent Materials	Simbara series, Pliocene to middle Pleistocene pyroclastic rock with intercalated basalts covered by volcanic ashes
Soil Depth	150cm
Texture of parent material	clayey
Texture of parent material (second entry)	clayey
Weathering Resistance	poor
Weathering Resistance (second entry)	poor
General characterization of the status of weathering of solid rock	highly
General characterization of the status of weathering of solid rock (second entry)	highly

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

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)	no irrigation
Land use or vegetation in the immediate vicinity of the site	medium level arable farming
Remarks on Land Use / Vegetation	VEGETATION: Bracken vegetation LAND USE Also tea, pyrethrum, maize and beans
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	1980m
Physiographic Unit	upper part of slope
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.	hill
Slope	10%
Slope Aspect	east
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	1cm
Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
Depth to groundwater table	0cm
Moist From - To	0-150cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Upper limit of a slow permeable or stagnating layer in the profile	0cm

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	0
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

You are here

Reference soil Kenya 34: Andosol

Characteristics

Reference soil KE034: Andosols

Classification