Reference soil Kenya 25: Planosol

KE025

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 KE025: Planosols

A very shallow to shallow soil (20-30 cm of depth) with many dead rootlets in B21 horizon; strong surface sealing.

Classification

WRB 2006

WRB 1998

Solodic- Planosol (Albic Calcaric Clayic)

Calcari-Albic- Planosol

15-26 cm	albic horizon
26-90 cm	argic horizon
-	calcaric
-	abrupt textural change
-	stagnic colour pattern
-	reducing conditions

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Albi-Eutric Planosol

Eutric Planosol

0-15 cm	ochric A horizon
15-26 cm	albic E horizon
26-90 cm	argic B horizon
-	abrupt textural change
-	stagnic

0-15 cm	ochric A horizon
15-26 cm	albic E horizon
26-90 cm	argillic B horizon
-	hydromorphic

Other classification

USDA-NRCS (1999)	Typic Albaqualf
USDA-SCS (1975)	Typic Albaqualf udic

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	-	0.5	0.9	0.8	1.7	2.8	6.7	14.9	28.9	43.8	49.5
15-20	-	0.3	0.7	1.6	1.8	3.0	7.4	14.6	35.8	50.4	42.3
20-63	-	0.2	0.5	0.6	1.2	1.8	4.3	7.9	22.6	30.5	65.1
63-95	-	0.5	0.8	0.7	1.1	1.7	4.8	8.4	20.3	28.7	66.5
95-130	-	0.2	0.3	0.3	1.0	2.0	3.8	7.1	22.2	29.3	66.9

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
5-10	1.22	-	-	-	-
0-15	-	-	-	10.2	49.5
80-85	1.28	-	-	-	-
15-20	-	-	-	9.6	42.3
135-140	1.11	-	-	-	-
20-63	-	-	-	25.2	65.1
63-95	-	-	-	24.6	66.5
95-130	-	-	-	-	66.9

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
5-10	1.22	53.3	52.6	50.9	48.6	47.3	45.6	35.4	32.4
80-85	1.28	54.7	55.3	55.6	55.0	54.2	52.2	50.4	44.3
135-140	1.11	59.1	57.4	56.3	52.0	49.7	47.3	45.3	38.5

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	6.7	5.7	0.32	2.2	3.74	0.30	12	-	-	34.3	4.1	2.8	0.4	41.6
15-20	6.7	5.5	0.19	2.2	2.17	0.18	12	-	-	27.9	2.7	1.5	0.8	32.9
20-63	5.7	4.1	0.15	1.8	1.15	0.10	11	-	-	33.5	4.3	1.5	1.6	40.9
63-95	6.4	5.0	0.26	3.2	1.02	-	-	-	-	39.1	4.3	1.8	1.8	47
95-130	7.6	6.4	0.43	4.2	0.32	-	-	-	-	38.7	4.0	2.3	1.9	46.9

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	81	51.2	77	13.1	-	-	1
15-20	89	36.8	69	7.6	-	-	2
20-63	81	50.2	71	4.0	-	-	3
63-95	93	50.5	71	3.6	-	-	4
95-130	89	52.6	77	1.1	-	-	4

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	medium	-	-	-	-	very weak	medium	-	very weak	very strong	-
20-63	-	medium	-	-	-	-	very weak	weak	-	very weak	very strong	-
95-130	-	medium	-	-	-	-	very weak	weak	-	very weak	very strong	-

Soluble sands

Depth (cm)	Ca mmol(c)/kg	Mg mmol(c)/kg	K mmol(c)/kg	Na mmol(c)/kg	sum cations mmol(c)/kg	CO3 mmol(c)/kg	HCO3 mmol(c)/kg	Cl mmol(c)/kg	NO3 mmol(c)/kg	SO4 mmol(c)/kg	sum anions mmol(c)/kg
0-15	0.4	0.1	0.2	0.2	0.9	0.0	0.3	0.1	0.0	0.1	0.5
15-20	0.2	0.0	0.1	0.2	0.5	0.0	0.2	0.1	0.0	0.1	0.4
20-63	0.3	0.1	0.1	0.3	0.8	0.0	0.1	0.0	0.0	0.1	0.2
63-95	0.2	0.1	0.1	0.5	0.9	0.0	0.1	0.0	0.0	0.1	0.2
95-130	0.3	0.0	0.1	0.7	1.1	0.0	0.6	0.0	0.0	0.1	0.7

Profile description

Ah 0-15 cm	dark greyish brown (10YR 4/2, moist)silty clay loam,moderate fine and medium subangular blocky,hard firm slightly sticky slightly plastic,common very fine pores,moderately calcareous (2-10%),gradual wavy boundary to,
E 15-26 cm	light brownish grey (10YR 6/2, dry) very dark greyish brown (10YR 3/2, moist)silty clay,weak coarse subangular blocky,hard firm sticky plastic,many (15-40%) fine faint mottles,many very fine pores,moderately calcareous (2-10%),abrupt wavy boundary to,
Bt1 26-60 cm	very dark greyish brown (10YR 3/2, moist)clay,weak fine prismatic parting to moderate to strong coarse subangular blocky,hard very firm sticky plastic,continuous thick clay cutans,moderately calcareous (2-10%),diffuse smooth boundary to,
Bt2 60-90 cm	very dark grey (10YR 3/1, moist)clay,moderate medium and coarse angular blocky,very hard very firm sticky plastic,patchy moderately thick clay cutans,moderately calcareous (2-10%),clear smooth boundary to,
C 90-110 cm	dark greyish brown (10YR 4/2, moist)clay,sticky plastic,moderately calcareous (2-10%),

Kind 1 (parent material) ; Parker (eds), 1984	ejecta ash
Kind 2 (parent material) (second entry); Parker (eds), 1984	fine-grained igneous rock
Mode of accumulation or deposition of parent material	unconsolidated, unspecified
Mode of accumulation or deposition of parent material (second entry)	unconsolidated, unspecified
Remarks on Parent Materials	ashes and phonolite
Texture of parent material	loamy
Texture of parent material (second entry)	clayey
Weathering Resistance	poor
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)	partially or moderately

Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	LAND USE: "shambas" (maize and pastures)

Physiographic Unit	low upland
Physiographic position of the site	middle slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	3%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Flooding frequency (FAO, 1986)	never
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	slow

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)	surface slaked; sorted sand/silt, some clay films
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 25: Planosol

Characteristics

Reference soil KE025: Planosols

Classification