Reference soil Kenya 08: Acrisol

KE008

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 KE008: Acrisols

Acrisol. VEGETATION: (dense) wooded bushland

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Epieutric Profondic Rhodic)

Rhodi-Profondic- Acrisol

20-150 cm

argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Rhodi-Haplic Acrisol

Ferric Acrisol

0-39 cm	ochric A horizon
20-150 cm	argic B horizon

0-39 cm	ochric A horizon
20-150 cm	argillic B horizon

Other classification

USDA-NRCS (1999)	Rhodic Kanhaplustult
USDA-SCS (1975)	Rhodic Rhodustult ustic fine mixed isohyperthermic

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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
0-20	-	0.4	2.4	21.7	38.6	10.6	73.7	5.1	2.6	7.7	18.5
20-38	-	0.2	2.8	20.7	29.5	7.9	61.1	4.8	1.8	6.6	32.3
38-60	-	0.4	2.2	12.6	19.3	7.1	41.6	4.7	1.8	6.5	52.0
60-80	-	0.4	1.8	9.5	14.5	6.7	32.9	5.4	1.8	7.2	60.0
80-100	-	0.3	1.2	6.2	10.5	5.6	23.8	5.5	4.1	9.6	66.8
100-150	-	0.4	1.1	5.4	9.4	5.4	21.7	6.9	5.6	12.5	65.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
43-48	1.32	-	-	-	-
0-20	-	40	-	-	18.5
113-118	1.14	-	-	-	-
20-38	-	64	-	-	32.3
38-60	-	95	-	-	52.0
60-80	-	109	-	-	60.0
80-100	-	123	-	-	66.8
100-150	-	-	-	-	65.7

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
43-48	1.32	44.3	43.0	37.7	29.0	25.8	23.2	21.5	20.3
113-118	1.14	50.0	48.1	43.5	35.0	30.4	27.0	24.1	22.8

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
0-20	6.0	4.9	0.09	-	0.89	0.06	15	-	-	2.4	1.3	0.4	0.4	4.5
20-38	5.4	4.2	0.05	-	0.79	0.05	16	-	-	2.4	1.4	0.3	0.3	4.4
38-60	5.5	4.3	0.05	-	0.77	0.05	15	-	-	3.0	2.0	0.3	0.3	5.6
60-80	5.2	4.1	0.04	-	0.48	-	-	-	-	2.6	1.9	0.4	0.5	5.4
80-100	5.0	4.0	0.03	-	0.37	-	-	-	-	2.4	1.6	0.4	0.4	4.8
100-150	5.1	4.0	0.03	-	0.36	-	-	-	-	2.6	1.5	0.4	0.6	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 %
0-20	60	7.5	41	3.1	-	-	5
20-38	51	8.6	27	2.8	-	-	3
38-60	51	10.9	21	2.7	-	-	3
60-80	46	11.7	20	1.7	-	-	4
80-100	37	13.0	19	1.3	-	-	3
100-150	38	13.4	20	1.3	-	-	4

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
0-20	-	-	-	0.04	0.01	0.66	0.06	0.02	0.02	-	0.04
20-38	-	-	-	0.09	0.01	0.81	0.06	0.04	0.04	-	0.04
38-60	-	-	-	0.15	0.01	0.96	0.11	0.06	0.08	-	0.04
60-80	-	-	-	0.16	0.01	1.18	0.14	0.04	0.07	-	0.05
80-100	-	-	-	0.20	0.01	1.75	0.18	0.02	0.07	-	0.05
100-150	-	-	-	0.19	0.01	2.12	0.21	0.02	0.07	-	0.05

Elemental composition of the soil

Depth (cm)	Al2O3 % w/w	CaO % w/w	Fe2O3 % w/w	K2O % w/w	MgO % w/w	Na2O % w/w	SiO2 % w/w	TiO2 % w/w
0-20	6.3	0.22	0.1	0.16	0.06	0.32	87.2	0.48
20-38	11.1	0.21	0.8	0.21	0.07	0.25	81.3	0.58
38-60	17.8	0.17	2.4	0.24	0.13	0.22	68.5	0.69
60-80	19.3	0.14	2.6	0.25	0.13	0.16	64.7	0.72
80-100	22.8	0.11	3.6	0.26	0.12	0.12	60.2	0.78
100-150	24.3	0.14	3.9	0.27	0.13	0.16	58.5	0.86

Depth (cm)	Al2O3/Fe2O3 mol/mol	LOI % w/w	MnO2 % w/w	P2O5 % w/w	SiO2 / Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol
0-20	98.8	3.7	0.02	-	23.5	2321.5	23.3
20-38	21.8	5.8	0.02	-	12.4	270.5	11.9
38-60	11.6	8.2	0.02	-	6.5	76.0	6.0
60-80	11.6	8.9	0.02	-	5.7	66.2	5.2
80-100	9.9	10.1	0.02	-	4.5	44.5	4.1
100-150	9.8	10.3	0.02	-	4.1	39.9	3.7

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	-	-	weak	-	-	strong	very weak	weak	-	-	-
20-38	-	-	-	weak	-	-	strong	very weak to weak	weak	-	-	-
38-60	-	-	-	weak	-	-	medium to strong	very weak	weak	-	-	-
60-80	-	-	-	weak	-	-	strong	very weak	weak	-	-	-
80-100	-	-	-	weak	-	-	strong to very strong	-	weak	-	-	-
100-150	-	-	-	weak	-	-	strong to very strong	-	weak	-	-	-

Profile description

Ah1 0-20 cm	(dark) brown (7.5YR 4/4, dry) dark reddish brown (5YR 3/4, moist)loamy sand,single grain,loose non sticky non plastic,non calcareous,clear smooth boundary to,
Ah2 20-38 cm	reddish brown (5YR 4/4, dry) dark reddish brown (5YR 3/3, moist)sandy loam,massive to moderate medium and coarse subangular blocky,slightly hard friable slightly sticky slightly plastic,common medium tubular and many fine tubular pores,common fine roots,few channels,non calcareous,gradual smooth boundary to,
Bt1 38-80 cm	dark red (2.5YR 3/6, dry) dark red (2.5YR 3/6, moist)sandy clay,moderate medium and coarse angular blocky,hard firm sticky plastic,continuous moderately thick clay cutans,few coarse and common fine and medium pores,few fine and few medium roots,few channels,non calcareous,gradual smooth boundary to,
Bt2 80-100 cm	dark reddish brown (2.5YR 3/4, dry) dark reddish brown (2.5YR 3/4, moist)sandy clay,strong coarse angular blocky,hard firm sticky plastic,patchy moderately thick clay cutans,common fine and medium tubular pores,non calcareous,gradual smooth boundary to,
Bt3 100-150 cm	dark reddish brown (2.5YR 3/4, dry) dark reddish brown (2.5YR 3/4, moist)sandy clay,strong fine and medium angular blocky,hard firm sticky plastic,common (5-15%) fine distinct mottles,patchy thin clay cutans,common and fine medium pores,frequent small spherical hard manganiferous nodules,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	undifferentiated banded gneiss of Basement System (Precambrium)
Texture of parent material	sandy clay
Texture of parent material (second entry)	sandy clay
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Remarks on Land Use / Vegetation	VEGETATION: (Dense) wooded bushland
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	semi-deciduous woodland

Altitude	880m
Physiographic Unit	gently sloping slope
Physiographic position of the site	slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plateau
Slope	3%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

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
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface slaked; sorted sand/silt, some clay films
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 08: Acrisol

Characteristics

Reference soil KE008: Acrisols

Classification