Reference soil Kenya 43: Acrisol

KE043

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 KE043: Acrisols

Potterie troughout the profile from 0 - 30cm. The site is fallow land used for grazing. The valley has a natural dam of phonolite at the outlet. Slides 10,035 - 10,039.

Classification

WRB 2006

WRB 1998

Umbric-Gleyic-Cutanic- Acrisol (Alumic Humic Hyperdystric Clayic)

Umbri-Endogleyic- Acrisol (Humic Alumic)

0-60 cm	umbric horizon
5-75 cm	argic horizon
-	reducing conditions
-	gleyic colour pattern

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Umbrihumi-Gleyic Acrisol phreatic

Gleyic Acrisol phreatic

0-60 cm	umbric A horizon
5-75 cm	argic B horizon
-	gleyic
-	strongly humic

0-60 cm	umbric A horizon
5-75 cm	argillic B horizon
-	high organic matter content in B horizon
-	hydromorphic

Other classification

USDA-SCS (1975)

Humitropept ustic very fine isothermic

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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
0-5	-	1.1	3.2	4.0	4.3	2.5	15.1	7.3	18.1	25.4	59.9
5-30	-	0.4	0.5	0.8	1.2	0.8	3.7	2.6	8.3	10.9	85.4
30-60	-	0.2	0.4	0.6	1.2	0.9	3.3	3.5	10.2	13.7	83.1
60-75	-	0.2	0.4	0.6	1.0	0.8	3	3.1	10.5	13.6	83.3
75-110	-	0.2	0.7	1.2	1.9	1.5	5.5	4.9	13.6	18.5	76.0
110-120	-	0.6	1.8	2.8	4.0	2.6	11.8	6.4	11.0	17.4	70.8
120-140	-	0.7	1.6	1.8	2.9	2.0	9	7.6	7.6	15.2	75.9

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-5	-	-	-	17.8	59.9
5-30	-	-	-	23.1	85.4
30-60	-	-	-	23.9	83.1
60-75	-	-	-	21.5	83.3
75-110	-	-	-	17.7	76.0
110-120	-	-	-	-	70.8
120-140	-	-	-	-	75.9

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
0-5	5.3	4.3	0.12	-	2.38	0.32	7	0.6	0.2	3.7	2.4	0.5	0.1	6.7
5-30	4.7	3.8	0.08	-	2.05	0.25	8	2.6	1.8	1.2	0.7	0.1	0.2	2.2
30-60	4.5	3.8	0.05	-	1.77	0.24	7	3.8	2.7	0.8	0.3	0.1	0.5	1.7
60-75	4.5	3.7	0.07	-	2.00	0.29	7	4.6	3.3	0.6	0.2	0.0	0.4	1.2
75-110	4.6	3.6	0.06	-	4.97	0.55	9	6.4	5.1	0.8	0.3	0.0	0.4	1.5
110-120	4.8	3.4	0.04	-	0.84	0.14	6	5.9	5.1	0.6	0.5	0.1	0.4	1.6
120-140	4.7	3.5	0.05	-	0.55	0.11	5	5.3	4.2	0.8	0.4	0.3	0.6	2.1

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 %
0-5	31	21.7	36	8.3	-	1	0
5-30	11	19.4	23	7.2	-	9	1
30-60	10	17.6	21	6.2	-	15	3
60-75	6	18.6	22	7.0	-	18	2
75-110	5	30.7	40	17.4	-	17	1
110-120	9	18.3	26	2.9	-	28	2
120-140	12	17.2	23	1.9	-	24	3

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
0-5	-	-	-	0.8	0.2	5.8	0.6	-	-	-	0.6
5-30	-	-	-	0.5	0.1	6.0	0.8	-	-	-	0.7
30-60	-	-	-	0.5	0.1	6.1	0.7	-	-	-	1.2
60-75	-	-	-	0.5	0.1	4.7	0.6	-	-	-	1.3
75-110	-	-	-	0.6	0.1	1.4	0.3	-	-	-	0.8
110-120	-	-	-	0.3	0.1	2.1	0.2	-	-	-	0.6
120-140	-	-	-	0.3	0.1	2.5	0.3	-	-	-	0.5

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-5	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
5-30	-	-	weak	weak	-	-	strong	-	weak	-	-	-
30-60	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
60-75	-	-	weak	weak	-	-	strong	-	weak	-	-	-
75-110	-	-	weak	weak	-	-	strong	-	weak	-	-	-
110-120	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
120-140	-	-	weak	weak	-	-	strong	weak	weak	-	-	-

Profile description

Ah1 0-5 cm	dusky red (2.5YR 3/2, moist)clay,moderate medium subangular blocky parting to granular,friable slightly sticky slightly plastic,many (15-40%) coarse prominent diffuse mottles (2.5 YR 2/0),patchy thin clay cutans,many very fine and few fine and medium pores,many very fine and few fine roots,few pottery inclusions,non calcareous,clear smooth boundary to,
Ah2 5-60 cm	dusky red (2.5YR 3/2, moist)clay,strong coarse subangular blocky parting to granular,friable slightly sticky slightly plastic,patchy thin clay cutans,many very fine and few fine and medium pores,many very fine and few fine roots,few pottery inclusions,non calcareous,gradual irregular boundary to,
Btg 60-80 cm	weak red (2.5YR 4/2, moist)clay,strong very coarse subangular blocky,firm slightly sticky slightly plastic,many (15-40%) fine distinct diffuse mottles (2.5 YR 5/8),broken thin clay cutans,many very fine and common fine pores,many very fine and few fine roots,non calcareous,clear smooth boundary to,
2ABgb 80-110 cm	dark grey (5Y 4/1, moist)clay,strong very coarse subangular blocky,firm slightly sticky slightly plastic,common (5-15%) fine prominent clear mottles (5 YR 6/8),many very fine and common fine pores,many very fine and few fine roots,non calcareous,clear smooth boundary to,
2Bgb1 110-120 cm	(dark) brown (10YR 4/3, moist)clay,strong very coarse subangular blocky,firm slightly sticky slightly plastic,few (2-5%) fine prominent clear mottles (5 YR 6/8),many very fine pores and few fine pores,many very fine roots,non calcareous,clear smooth boundary to,
2Bgb2 120-140 cm	dark brown (10YR 3/3, moist)clay,strong very coarse subangular blocky,firm slightly sticky slightly plastic,many very fine pores and few fine pores,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	basic volcanic breccia
Kind 2 (parent material) (second entry); Parker (eds), 1984	basic volcanic breccia
Mode of accumulation or deposition of parent material	colluvial
Mode of accumulation or deposition of parent material (second entry)	residual material
Remarks on Parent Materials	Mt. Kenya Series
Soil Depth	80cm
Texture of parent material	clayey
Texture of parent material (second entry)	clayey
Weathering Resistance	moderate
Weathering Resistance (second entry)	moderate
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	stable

Major crops	maize
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)	seasonally irrigated
Land use or vegetation in the immediate vicinity of the site	low level arable farming
Remarks on Land Use / Vegetation	LAND USE: Also taro/yam, bananas and sugarcane
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	1550m
Physiographic Unit	major 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	6%
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	moderately well
Flooding frequency (FAO, 1986)	never
(Estimated) maximum (lower) depth to groundwater table	80cm
Depth to groundwater table	80cm
Kind of ground water table (USDA, 1979)	groundwater table observed
(Estimated) minimum (upper) depth to groundwater table	60cm
Moist From - To	0-70cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Wet From To	70-140cm

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 pattern	none
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 43: Acrisol

Characteristics

Reference soil KE043: Acrisols

Classification