Reference soil Kenya 12: Acrisol

KE012

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 KE012: Acrisols

A deep-rooting, porous, and well drained soil in undulating coastal uplands originating from coarse-grained sandstones (Shimba grit), with high biological activity and a very weak surface sealing. (R3 pg 205)

Classification

WRB 2006

WRB 1998

Cutanic- Acrisol (Epieutric Profondic Chromic)

Chromi-Profondic- Acrisol

15-220 cm

argic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Chromi-Haplic Acrisol

Orthic Acrisol

0-15 cm	ochric A horizon
15-220 cm	argic B horizon

0-15 cm	ochric A horizon
15-220 cm	argillic B horizon

Other classification

USDA-NRCS (1999)	Typic Kandiustalf
USDA-SCS (1975)	Typic Paleustalf ustic

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	-	1.3	12.2	29.7	26.9	10.2	80.3	4.8	2.0	6.8	12.8
15-30	-	1.3	12.4	28.3	22.9	8.0	72.9	5.3	2.8	8.1	19.0
30-45	-	2.1	14.1	24.9	16.9	5.5	63.5	4.6	0.5	5.1	31.3
45-90	-	2.4	14.4	23.2	14.3	4.8	59.1	2.5	1.0	3.5	37.4
90-150	-	4.2	12.8	21.1	15.3	5.4	58.8	3.1	1.3	4.4	36.8
150-220	-	2.7	11.4	21.8	17.3	6.5	59.7	4.6	2.0	6.6	33.6

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
12-17	1.31	-	-	-	-
0-15	-	14	-	6.4	12.8
83-88	1.33	-	-	-	-
15-30	-	21	-	11.2	19.0
30-45	-	-	-	-	31.3
45-90	-	43	-	11.5	37.4
90-150	-	-	-	-	36.8
150-220	-	-	-	-	33.6

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
12-17	1.31	40.1	37.2	21.9	13.7	11.6	10.0	7.3	6.6
83-88	1.33	40.2	37.0	28.4	21.7	19.1	16.9	15.0	14.3

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	5.8	5.2	0.07	-	0.61	0.05	12	-	-	1.2	0.9	0.2	0.1	2.4
15-30	5.9	5.2	0.07	-	0.45	0.05	9	-	-	1.6	0.7	0.4	0.1	2.8
30-45	5.8	4.8	0.06	-	0.31	-	-	-	-	2.2	0.7	0.1	0.3	3.3
45-90	5.1	4.1	0.05	-	0.18	-	-	0.3	0.2	1.0	1.2	0.1	0.3	2.6
90-150	4.8	4.0	0.04	-	0.16	-	-	0.0	0.0	1.2	0.8	0.2	0.2	2.4
150-220	5.1	4.3	0.07	-	0.11	-	-	0.0	0.0	1.0	1.0	0.3	0.0	2.3

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	53	4.5	35	2.1	-	-	2
15-30	57	4.9	26	1.6	-	-	2
30-45	55	6.0	19	1.1	-	-	5
45-90	43	6.0	16	0.6	-	3	5
90-150	48	5.0	14	0.6	-	0	4
150-220	47	4.9	15	0.4	-	0	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
0-15	-	-	-	0.03	0.0	0.86	0.06	0.03	0.02	-	0.03
15-30	-	-	-	0.05	0.0	1.21	0.08	0.06	0.03	-	0.04
30-45	-	-	-	0.06	0.01	1.89	0.12	0.04	0.02	-	0.06
45-90	-	-	-	0.07	0.01	2.17	0.14	0.01	0.02	-	0.07
90-150	-	-	-	0.04	0.01	2.10	0.11	0.01	0.01	-	0.05
150-220	-	-	-	0.03	0.00	2.10	0.12	0.01	0.01	-	0.04

Elemental composition of the clay

Depth (cm)	SiO2 % w/w	Al2O3 % w/w	Fe2O3 % w/w	CaO % w/w	MgO % w/w	K2O % w/w	Na2O % w/w	TiO2 % w/w
0-15	40.3	31.6	8.8	0.07	0.43	0.89	0.07	1.65
15-30	40.8	32.7	8.6	0.07	0.43	0.89	0.08	1.53
30-45	40.9	33.5	8.4	0.03	0.33	0.83	0.09	0.95
45-90	41.0	33.3	8.2	0.05	0.36	0.87	0.07	1.11
90-150	41.4	33.8	8.1	0.04	0.31	0.80	0.05	0.95
150-220	40.4	33.2	8.2	0.06	0.33	0.79	0.05	1.03

Depth (cm)	MnO2 % w/w	P2O5 % w/w	Ign.Loss clay % w/w	Total Clay % w/w	SiO2/Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol	Al2O3/Fe2O3 mol/mol
0-15	0.17	0.28	12.0	96.26	2.2	12.2	1.8	5.6
15-30	0.29	0.24	12.1	97.73	2.1	12.6	1.8	6
30-45	0.12	0.16	12.2	97.51	2.1	12.9	1.8	6.2
45-90	0.18	0.17	12.0	97.31	2.1	13.3	1.8	6.4
90-150	0.06	0.11	11.7	97.32	2.1	13.6	1.8	6.5
150-220	0.04	0.10	12.1	96.3	2.1	13.1	1.8	6.3

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
0-15	4.3	0.04	0.6	0.33	0.05	0.04	90.5	0.53
15-30	6.2	0.04	0.9	0.36	0.06	0.04	86.3	0.56
30-45	9.1	0.06	1.5	0.36	0.08	0.02	82.6	0.53
45-90	11.8	0.03	2.2	0.42	0.11	0.02	79.2	0.57
90-150	11.4	0.03	2.4	0.40	0.10	0.02	78.7	0.60
150-220	10.5	0.02	1.9	0.42	0.10	0.02	80.2	0.62

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
0-15	11.2	2.8	0.08	0.02	35.7	401.6	32.8
15-30	10.8	3.3	0.07	0.02	23.6	255.3	21.6
30-45	9.5	4.1	0.05	0.03	15.4	146.6	13.9
45-90	8.4	4.9	0.04	0.04	11.4	95.8	10.2
90-150	7.4	4.8	0.02	0.01	11.7	87.1	10.3
150-220	8.7	4.4	0.01	0.01	13	112.2	11.6

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	-	-	weak	-	-	very strong	very weak to weak	weak	very weak to weak	-	-
15-30	-	-	-	weak	-	-	very strong	very weak to weak	weak	very weak to weak	-	-
45-90	-	-	-	weak	-	-	very strong	very weak to weak	weak	very weak	-	-

Profile description

Ap 0-15 cm	reddish brown (5YR 5/4, dry) dark reddish brown (5YR 3/3, moist)sandy loam,porous massive,slightly hard friable slightly sticky non plastic,many very fine pores,common fine and medium roots,frequent biological activity,non calcareous,clear smooth boundary to,
Bt1 15-45 cm	dark reddish brown (2.5YR 3/4, dry) dark reddish brown (2.5YR 3/4, moist)sandy clay loam,weak coarse subangular blocky,hard friable sticky plastic,patchy thin clay cutans,common fine and medium pores,common fine and medium roots,frequent biological activity,non calcareous,clear smooth boundary to,
Bt2 45-260 cm	red (2.5YR 4/8, dry) red (2.5YR 4/8, moist)sandy clay,weak coarse angular blocky and weak coarse subangular blocky,very hard friable sticky plastic,patchy thin clay cutans,common fine and medium pores,common medium and few fine roots,frequent biological activity,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Shimba grit and Mazeras formation
Texture of parent material	loamy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Major crops	citrus
Land use or vegetation in the immediate vicinity of the site	non-irrigated tree crop cultivation
Remarks on Land Use / Vegetation	Open grassland/cultivation

Altitude	233m
Physiographic Unit	coastal uplands
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.	hill
Slope	2%
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
Depth to groundwater table	0cm
Kind of ground water table (USDA, 1979)	no groundwater table observed
(Estimated) minimum (upper) depth to groundwater table	0cm
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 partly slaked, round smooth aggregates
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 12: Acrisol

Characteristics

Reference soil KE012: Acrisols

Classification