Reference soil Kenya 41: Acrisol

KE041

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 KE041: Acrisols

The site shall be cleared within a year and used for crops like bananas, taro/yam, vegetables. The edge of the forest is shifted 100m mountain upwards (political decision, 1985). The actual groundwater level is below 120cm. Slides: 10,015, 10,016 and 10,023 - 10,029, profile, landscape and landuse.

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Humic Epieutric Clayic Chromic)

Chromi-Humic- Acrisol

12-120 cm

argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Humi-Haplic Acrisol phreatic

Humic Acrisol phreatic

0-12 cm	ochric A horizon
12-120 cm	argic B horizon
-	strongly humic

0-12 cm	ochric A horizon
12-120 cm	argillic B horizon
-	high organic matter content in B horizon

Other classification

USDA-NRCS (1999)	Typic Palehumult
USDA-SCS (1975)	Typic Palehumult udic very fine isothermic

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
0-12	-	0.7	1.2	1.7	2.8	1.7	8.1	7.9	34.4	42.3	49.5
12-40	-	0.4	0.6	1.1	2.3	1.5	5.9	5.9	27.4	33.3	60.7
40-63	-	0.4	1.1	1.7	2.7	2.0	7.9	5.4	15.8	21.2	70.9
63-107	-	0.2	0.6	1.1	2.4	1.7	6	6.1	16.1	22.2	71.8
107-130	-	0.3	0.9	1.3	2.2	1.5	6.2	7.2	13.6	20.8	73.0

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-12	-	-	-	11.7	49.5
12-40	-	-	-	23.6	60.7
40-63	-	-	-	18.4	70.9
63-107	-	-	-	10.5	71.8
107-130	-	-	-	-	73.0

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
0-12	6.3	5.5	0.42	-	5.35	0.60	9	-	-	22.6	6.4	2.5	0.1	31.6
12-40	6.5	5.3	0.12	-	1.29	0.20	6	-	-	6.5	3.1	1.8	0.0	11.4
40-63	5.7	4.7	0.09	-	1.11	0.16	7	-	-	3.1	2.6	1.5	0.1	7.3
63-107	5.2	4.1	0.05	-	1.05	0.16	7	1.2	0.7	0.8	0.6	1.4	0.5	3.3
107-130	5.0	3.9	0.05	-	1.01	0.17	6	2.7	2.0	0.4	0.4	1.2	0.2	2.2

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 %
0-12	73	43.3	87	18.7	-	-	0
12-40	57	20.1	33	4.5	-	-	0
40-63	44	16.6	23	3.9	-	-	1
63-107	21	15.9	22	3.7	-	18	3
107-130	13	16.6	23	3.5	-	48	1

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
0-12	-	-	-	0.2	0.1	4.8	0.8	-	-	-	0.8
12-40	-	-	-	0.5	0.0	5.2	0.8	-	-	-	1.0
40-63	-	-	-	0.6	0.1	4.9	0.9	-	-	-	0.9
63-107	-	-	-	0.5	0.1	5.4	0.7	-	-	-	1.1
107-130	-	-	-	0.5	0.1	5.5	0.8	-	-	-	1.3

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-12	-	-	weak	weak	-	-	medium to strong	weak	weak	weak	-	-
12-40	-	-	weak	weak	-	-	medium to strong	weak	-	weak	-	-
40-63	-	-	weak	weak	-	-	medium to strong	very weak	-	very weak	-	-
63-107	-	-	weak	weak	-	-	medium to strong	weak	-	very weak	-	-
107-130	-	-	weak	weak	-	-	medium to strong	very weak	-	weak	-	-

Profile description

Ah 0-12 cm	dark brown (7.5YR 3/4, moist)slightly gravelly clay,weak very coarse angular blocky parting to medium angular blocky,friable slightly sticky slightly plastic,common (5-15%) fine distinct sharp mottles (7.5 YR 2/0),continuous thin clay cutans,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,abrupt smooth boundary to,
Bt1 12-63 cm	dark reddish brown (5YR 3/4, moist)slightly gravelly clay,weak very coarse angular blocky parting to medium angular blocky,very friable slightly sticky slightly plastic,continuous thin clay cutans,many very fine pores and common fine pores,many very fine and few fine roots,non calcareous,gradual wavy boundary to,
Bt2 63-107 cm	dark reddish brown (5YR 3/4, moist)strong brown (7.5YR 4/6, moist),clay,clay,weak very coarse angular blocky,weak very coarse angular blocky,friable slightly sticky slightly plastic,very friable slightly sticky slightly plastic,few (2-5%) fine distinct sharp mottles (7.5 YR 2/0),few (2-5%) fine distinct sharp mottles (7.5 YR 4/6),broken thin clay cutans,broken thin clay cutans,many very fine pores and common fine pores,many very fine pores and common fine pores,few very fine and fine roots,common very fine and few fine roots,non calcareous,non calcareous,clear smooth boundary to,

Kind 1 (parent material) ; Parker (eds), 1984	volcanic breccia
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	Mt. Kenya Series
Soil Depth	110cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

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	(semi-)natural vegetation
Remarks on Land Use / Vegetation	VEGETATION: 30% trees, 50% shrubs, 20% herbs; 30% litter cover. LAND USE: Intensive exploitation; charcoal production
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 forest

Altitude	1710m
Physiographic Unit	minor valley, mount. footridge
Physiographic position of the site	lower slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	40%
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	1cm
Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Flooding frequency (FAO, 1986)	never
(Estimated) maximum (lower) depth to groundwater table	120cm
Depth to groundwater table	120cm
Kind of ground water table (USDA, 1979)	apparent
(Estimated) minimum (upper) depth to groundwater table	4cm
Moist From - To	0-100cm
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	100cm

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
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 41: Acrisol

Characteristics

Reference soil KE041: Acrisols

Classification