Reference soil Kenya 42: Acrisol

KE042

Acrisols occur dominantly in the wetter parts of the tropics and subtropics and the warm temperate regions in relatively young landscapes.

Characteristics

Soils having an argic horizon (a subsurface horizon with distinct higher clay content than the overlying horizon), which has a cation exchange capacity of less than 24 cmolc per kg in some part, either starting within 100 cm from the soil surface, or within 200 cm from the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. They have a base saturation (total amount of Ca, Mg, K and Na with respect to the cation exchange capacity) of less than 50 percent in the major part between 25 and 100 cm from the soil surface

Distribution of Acrisols (rough estimation supplied by soilgrids)

Reference soil KE042: Acrisols

Moderately deep, moderately well drained soil derived from volcanic breccia; with a thin, reddish brown, clay topsoil over a reddish brown, clay subsoil with a very gravelly layer between 50 and 60 cm. The soil is used for arable farming with bananas, taro and yams as main crops. The site is situated at the edge of the forest and arable land. At 80 cm depth mainly rounded stones and boulders occur. Slides: 10,015 - 10,016 and 10,030 - 10,034.

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Ruptic Humic Clayic Chromic)

Chromi-Humic- Acrisol

15-50 cm	argic horizon
-	abrupt textural change

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Acrisol phreatic

Humic Acrisol phreatic

0-15 cm	ochric A horizon
15-50 cm	argic B horizon
-	strongly humic

0-15 cm	ochric A horizon
15-50 cm	argillic B horizon
-	high organic matter content in B horizon

Other classification

USDA-NRCS (1999)

Typic Haplohumult

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
0-15	-	0.3	0.8	1.4	2.2	1.3	6	2.8	26.0	28.8	65.4
15-50	-	0.4	0.9	1.5	2.6	1.7	7.1	4.8	12.4	17.2	75.7
50-60	-	7.5	9.0	10.3	7.9	3.5	38.2	5.3	14.1	19.4	42.4
60-80	-	3.0	4.2	5.9	9.4	5.3	27.8	5.8	14.0	19.8	52.5

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-15	-	-	-	17.1	65.4
15-50	-	-	-	24.3	75.7
50-60	-	-	-	19.1	42.4
60-80	-	-	-	20.0	52.5

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
0-15	6.1	5.1	0.5	-	5.16	0.59	9	-	-	15.0	4.7	1.7	0.2	21.6
15-50	5.3	4.2	0.08	-	1.74	0.26	7	1.0	0.7	2.7	1.2	1.6	0.2	5.7
50-60	5.7	4.2	0.03	-	0.55	0.08	7	-	-	1.7	1.3	0.8	0.5	4.3
60-80	5.8	4.1	0.03	-	0.79	0.13	6	-	-	1.9	1.6	0.9	0.7	5.1

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 %
0-15	57	38.0	58	18.1	-	-	1
15-50	31	18.6	25	6.1	-	11	1
50-60	26	16.6	39	1.9	-	-	3
60-80	31	16.3	31	2.8	-	-	-

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
0-15	-	-	-	0.6	0.1	4.8	0.8	-	-	-	1.0
15-50	-	-	-	0.6	0.1	5.0	0.8	-	-	-	1.3
50-60	-	-	-	1.0	0.4	3.9	0.5	-	-	-	0.9
60-80	-	-	-	0.6	0.1	2.5	0.5	-	-	-	0.7

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	-	weak	weak	-	-	medium to strong	weak	weak	weak	-	-
15-50	-	-	medium	weak	-	-	medium to strong	very weak	-	very weak	-	-
50-60	-	-	medium	weak	-	-	medium to strong	very weak	-	very weak	-	-
60-80	-	-	medium	weak	-	-	medium to strong	very weak	-	very weak	-	-

Profile description

Ah 0-15 cm	reddish brown (5YR 4/3, moist)clay,moderate medium subangular blocky,hard firm slightly sticky slightly plastic,continuous thin clay cutans,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,gradual smooth boundary to,
Bt1 15-50 cm	reddish brown (5YR 4/4, moist)clay,moderate coarse subangular blocky,hard firm slightly sticky slightly plastic,continuous thin clay cutans,many very fine and few to common fine pores,many very fine roots,non calcareous,abrupt smooth boundary to,
2Bt2 50-60 cm	reddish brown (5YR 4/4, moist)very gravelly clay,weak coarse subangular blocky parting to moderate coarse granular,firm slightly sticky slightly plastic,continuous thin clay cutans,many very fine pores and common fine pores,common very fine roots,many medium gravel strongly weathered phonolite vulcanic fragmenst,non calcareous,abrupt smooth boundary to,
2B 60-80 cm	dark yellowish brown (10YR 4/4, moist)clay,moderate coarse subangular blocky,firm slightly sticky slightly plastic,continuous thin clay cutans,many very fine pores and common fine pores,non calcareous,clear wavy boundary to,
80-90 cm	stony claycommon coarse gravel and stones fresh phonolite,vulcanic fragments,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	volcanic breccia
Kind 2 (parent material) (second entry); Parker (eds), 1984	volcanic breccia
Mode of accumulation or deposition of parent material	colluvial
Mode of accumulation or deposition of parent material (second entry)	fluvial
Remarks on Parent Materials	Mt. Kenya Series
Soil Depth	60cm
Texture of parent material	clayey
Texture of parent material (second entry)	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

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

Major crops	banana
Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	no land improvement
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	low level arable farming
Remarks on Land Use / Vegetation	LAND USE: Also taro and yam, grassland
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	cut over
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	semi-deciduous woodland

Altitude	1715m
Physiographic Unit	major valley, mount. footridge
Physiographic position of the site	open depression
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	3%
Form of the slope surrounding the site	concave
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	mountainous

Lower limit of a slow permeable or stagnating layer in the profile	5cm
Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Dry From - To	0-40cm
Flooding frequency (FAO, 1986)	irregular
Nature of flood water	oxygenated
Depth to groundwater table	55cm
Kind of ground water table (USDA, 1979)	groundwater table observed
Moist From - To	40-55cm
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
Wet From To	55-80cm

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

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Reference soil Kenya 42: Acrisol

Characteristics

Reference soil KE042: Acrisols

Classification