Reference soil Kenya 20: Planosol

KE020

Planosols occur in level landscapes throughout the world often associated with broad river valleys.

Characteristics

Soils having an eluvial horizon, the lower boundary of which is marked. within 100 cm from the soil surface, by an abrupt textural change associated with stagnic properties above that boundary. The feature of albeluvic tonguing, however, is lacking.

Distribution of Planosols (rough estimation supplied by soilgrids)

Reference soil KE020: Planosols

Classification: aeric or abruptic tropaqualf / Soil fauna: ants and termites. Additional notes on profile description: A1: mottles are grey; also very few fine pores; many white points; E1: mottles: yellowish brown, iron; many white points; also few fine pores; E2: mottles: yellowish brown, iron; massive porous prisms with weak tendency to very coarse longitudinal prisms; many white points; B21ir: iron mottles on peds; many white points; B22t: red rootrust mottles and red and yellow pedrust mottles; B23t: reddish brown rootrust mottles; common medium distinct yellowish coatings on peds; B24: reddish brown rootrust mottles; common medium distinct yellowish and common fine faint dark grey coatings on peds; locally silty and ash-like material.

Classification

WRB 2006

WRB 1998

Umbric-Alic- Planosol (Albic Clayic)

Umbri-Alic- Planosol (Albic)

0-46 cm	umbric horizon
46-66 cm	albic horizon
74-105 cm	argic horizon
-	abrupt textural change

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Albi-Umbric Planosol

Humic Planosol

0-46 cm	umbric A horizon
46-66 cm	albic E horizon
74-105 cm	argic B horizon
-	abrupt textural change
-	stagnic

0-46 cm	umbric A horizon
46-66 cm	albic E horizon
74-105 cm	argillic B horizon
-	abrupt textural change
-	hydromorphic

Other classification

USDA-SCS (1975)

Tropaqualf

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
20-30	-	0.1	0.4	0.4	0.3	2.2	3.4	54.4	0.0	54.4	42.2
30-40	-	0.2	0.1	0.2	0.2	2.7	3.4	71.6	0.0	71.6	24.9
45-55	-	6.7	4.2	0.6	0.4	1.6	13.5	59.3	0.0	59.3	27.2
70-80	-	6.1	4.4	1.5	0.4	11.3	23.7	8.4	0.0	8.4	67.9
130-140	-	0.1	0.1	0.2	0.1	0.6	1.1	36.9	0.0	36.9	61.0

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
10-20	-	-	-	5.2	-
20-30	-	-	-	6.2	42.2
30-40	-	-	-	7.2	24.9
45-55	-	-	-	8.2	27.2
70-80	-	-	-	18.7	67.9
130-140	-	-	-	-	61.0

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
10-20	4.6	3.6	0.10	-	12.3	0.92	13	5.8	4.0	3.9	1.3	1.0	0.1	6.3
20-30	4.8	3.5	0.05	-	2.69	0.26	10	3.8	3.2	1.9	0.5	0.2	0.0	2.6
30-40	5.1	3.7	0.02	-	0.79	0.08	10	1.2	0.9	1.0	0.2	0.2	0.0	1.4
45-55	5.7	4.6	0.02	-	0.45	0.05	9	-	-	1.4	0.4	0.2	0.0	2
70-80	5.2	3.8	0.03	-	1.03	0.10	10	1.5	1.2	5.1	1.4	0.4	0.1	7
130-140	5.0	3.4	0.05	-	0.28	0.08	4	3.9	3.3	9.1	2.8	0.7	0.1	12.7

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 %
10-20	15	42.1	-	43.1	-	10	0
20-30	16	16.6	39	9.4	-	19	0
30-40	19	7.5	30	2.8	-	12	0
45-55	20	9.8	36	1.6	-	-	0
70-80	29	24.1	35	3.6	-	5	0
130-140	42	30.3	50	1.0	-	11	0

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
10-20	53.1	24.3	7.8	0.07	0.30	0.52	-	1.13

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
10-20	0.03	0.43	13.2	100.88	3.7	18.1	3.1	4.9

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
10-20	12.8	0.21	4.2	0.74	0.18	-	52.7	0.63
20-30	11.4	0.14	4.4	1.75	0.13	-	70.3	0.82
30-40	9.2	0.13	10.1	2.46	0.08	-	69.4	0.72
45-55	8.6	0.09	43.2	1.51	0.06	-	37.6	0.56
70-80	14.3	0.20	33.4	1.13	0.15	-	38.1	0.82
130-140	18.4	0.31	9.8	1.39	0.21	-	59.6	0.98

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
10-20	4.8	28.0	0.03	0.19	7	33.4	5.8
20-30	4.1	9.7	0.03	0.04	10.5	42.5	8.4
30-40	1.4	6.1	0.03	0.02	12.8	18.3	7.5
45-55	0.3	10.2	0.06	0.05	7.4	2.3	1.8
70-80	0.7	12.1	0.03	0.04	4.5	3	1.8
130-140	2.9	9.2	0.03	0.02	5.5	16.2	4.1

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
10-20	-	very weak to weak	-	-	-	-	strong	-	weak to medium	-	-	-
20-30	-	weak to medium	-	-	-	-	strong	very weak to weak	weak to medium	very weak to weak	-	-
30-40	-	weak to medium	-	-	-	-	weak to medium	very weak to weak	weak	weak to medium	-	-
45-55	-	weak to medium	very weak to weak	-	-	-	weak to medium	very weak to weak	weak	weak to medium	-	-
70-80	-	weak to medium	weak to medium	-	-	-	weak to medium	very weak to weak	weak to medium	very weak to weak	-	-
130-140	-	weak to medium	very weak to weak	-	-	-	weak to medium	very weak to weak	strong	very weak to weak	-	-

Profile description

Ah 0-27 cm	(7.5YR 2/1, moist)silty clay,moderate fine subangular blocky to weak very fine subangular blocky,very friable slightly sticky slightly plastic,common (5-15%) fine mottles,few medium common very fine pores,non calcareous,gradual wavy boundary to,
E1 27-46 cm	(7.5YR 3/1, moist)silty clay,weak to moderate fine and medium angular blocky to very coarse prismatic,slightly sticky slightly plastic,many (15-40%) fine prominent mottles,few medium and medium and common very fine pores,non calcareous,gradual smooth boundary to,
E2 46-66 cm	(7.5YR 4/1, moist)silt loam,firm non sticky non plastic,common (5-15%) medium prominent mottles,few very fine and fine and few medium pores,non calcareous,abrupt wavy boundary to,
Boc 66-74 cm	(7.5YR 4/1, moist)silty clay loam very gravelly,moderate angular blocky,non sticky slightly plastic,many (15-40%) medium distinct mottles,few very fine and fine and few medium pores,frequent manganiferous concretions and frequent ferruginous concretions,non calcareous,abrupt wavy boundary to,
Bt1 74-85 cm	(7.5YR 4/1, moist)clay,moderate fine angular blocky,sticky slightly plastic,common (5-15%) fine distinct mottles and many (15-40%) medium distinct mottles,few fine and common very fine pores,non calcareous,clear smooth boundary to,
Bt2 85-105 cm	dark grey (10YR 4/1, moist)clay,moderate coarse prismatic to moderate medium angular blocky,sticky plastic,few (2-5%) fine distinct mottles,few fine and few very fine pores,non calcareous,gradual smooth boundary to,
Bt3 105-105 cm	dark grey (10YR 4/1, moist)clay,weak fine angular blocky,sticky plastic,few (2-5%) fine distinct mottles,few fine and few very fine pores,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Mode of accumulation or deposition of parent material	fluvial
Remarks on Parent Materials	mixed with alluvium
Texture of parent material	clayey
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly

Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	95% grasses, 2% shrubs, 1%herbs, 1%trees
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	1905m
Physiographic Unit	flat bottomed valley
Physiographic position of the site	flat
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	valley
Slope	1%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	rolling

Drainage class ; FAO (2006) - Guidelines for soil description	poor
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	slow
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	imperfect

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Microrelief Height: variation in height	20
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	termite/ant mounds
Microrelief pattern	isolated
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 20: Planosol

Characteristics

Reference soil KE020: Planosols

Classification