Reference soil Kenya 40: Ferralsol

KE040

Ferralsols occur in tropical and subtropical regions of the world, mainly on old and stable land surfaces.

Characteristics

Soils having a ferralic horizon (strongly weathered horizon with low-activity clays and very low amounts of weatherable minerals) between 25 and 200 cm from the soil surface. They lack a nitic horizon (a horizon with strongly developed, nut-shaped structure) and do not have a layer which fulfils the requirements of an argic horizon and which has, in the upper 30 cm, 10 percent or more water-dispersible clay.

Distribution of Ferralsols (rough estimation supplied by soilgrids)

Reference soil KE040: Ferralsols

Very deep, well drained soil derived from volcanic breccia; with a thick, dark reddish brown clay topsoil over a red subsoil with low activity clays. The soil is used for tea cultivation. The clearence of the forest caused some charcoal mottles and burned bricklike clay gravel in the topsoil. The site is situated at the edge of the forest and the tea gardens. The tea garden is surrounded by broad paths of grass 2 - 4 m width, which are grazed by dairy cattle and goats. Slides: 10,015 - 10,022, showing profile, landscape, and landuse.

Classification

WRB 2006

WRB 1998

Umbric- Ferralsol (Humic Alumic Clayic)

Alumi-Umbrihumic- Ferralsol (Hyperdystric)

0-35 cm	umbric horizon
35-150 cm	ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Umbri-Humic Ferralsol

Humic Ferralsol

0-35 cm	umbric A horizon
35-150 cm	ferralic B horizon
-	strongly humic

0-35 cm	umbric A horizon
35-150 cm	oxic B horizon
-	high organic matter content in B horizon

Other classification

USDA-NRCS (1999)	Humic Hapludox
USDA-SCS (1975)	Humic Haplohumox udic clayey 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
0-35	-	0.1	0.2	0.4	0.9	0.7	2.3	2.2	7.1	9.3	88.5
35-80	-	0.1	0.1	0.3	0.9	0.6	2	3.0	5.4	8.4	89.6
80-120	-	0.1	0.2	0.4	0.9	0.6	2.2	5.4	6.6	12	85.9
120-150	-	0.1	0.2	0.3	1.0	0.7	2.3	5.6	5.1	10.7	87.0

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-35	-	-	-	5.7	88.5
35-80	-	-	-	5.7	89.6
80-120	-	-	-	0.5	85.9
120-150	-	-	-	-	87.0

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
0-35	4.2	3.8	0.10	-	4.60	0.35	13	6.9	5.8	0.6	0.2	0.1	0.6	1.5
35-80	4.4	3.8	0.04	-	1.74	0.18	10	4.7	4.2	0.2	0.0	0.0	0.3	0.5
80-120	4.5	3.9	0.03	-	1.24	0.14	9	4.1	3.3	0.0	0.0	0.0	0.3	0.3
120-150	4.6	3.9	0.02	-	0.92	0.12	8	3.5	2.9	0.0	0.0	0.0	0.5	0.5

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 %
0-35	6	25.4	29	16.1	-	23	2
35-80	3	14.4	16	6.1	-	29	2
80-120	3	11.6	14	4.3	-	28	3
120-150	4	11.5	13	3.2	-	25	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
0-35	-	-	-	0.7	0.0	6.6	1.1	-	-	-	0.5
35-80	-	-	-	0.6	0.0	7.0	1.0	-	-	-	0.4
80-120	-	-	-	0.6	0.0	6.9	1.0	-	-	-	0.5
120-150	-	-	-	0.5	0.0	6.8	1.0	-	-	-	0.4

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-35	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
35-80	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
80-120	-	-	weak	weak	-	-	strong	weak	weak	-	-	-
120-150	-	-	weak	weak	-	-	strong	weak	very weak to weak	-	-	-

Profile description

Ah 0-35 cm	dark reddish brown (5YR 3/3, moist)clay,moderate coarse subangular blocky,friable slightly sticky slightly plastic,broken thin clay cutans,many very fine pores and few fine pores,many very fine and few medium roots,few charcoal fragments,frequent termite channels,non calcareous,clear wavy boundary to,
Bw1 35-120 cm	red (2.5YR 4/6, moist)clay,weak coarse and very coarse subangular blocky,friable slightly sticky slightly plastic,broken thin clay cutans,many very fine pores and few fine pores,common very fine and few fine roots,frequent termite channels,non calcareous,gradual smooth boundary to,
Bw2 120-150 cm	red (2.5YR 4/6, moist)clay,moderate very coarse subangular blocky,friable slightly sticky slightly plastic,broken thin clay cutans,many very fine pores and few fine pores,common very fine and few fine roots,frequent termite channels,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	volcanic breccia
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	phonolite/lahar/ash
Soil Depth	150cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	slight
Slope stability	locally unstable

Major crops	tea
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)	no irrigation
Land use or vegetation in the immediate vicinity of the site	medium level arable farming
Remarks on Land Use / Vegetation	LAND USE: Some use of fertilizers and pesticides
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	1740m
Physiographic Unit	mountain footridge
Physiographic position of the site	crest
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	hill
Slope	2%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	mountainous

Lower limit of a slow permeable or stagnating layer in the profile	1cm
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
Moist From - To	0-150cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	medium
Upper limit of a slow permeable or stagnating layer in the profile	0cm

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
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 40: Ferralsol

Characteristics

Reference soil KE040: Ferralsols

Classification