Reference soil Kenya 24: Regosol

KE024

Regosols are found in areas where soil has been eroded to the extent that the underlying unconsolidated materials come near to the surface, or where soil formation has not played an important role, e.g. in desert regions. The name comes from the greek 'rhegos' :blanket meaning young soils on weathering materials.

Characteristics

Soils in medium and fine textured materials, having no distinctive horizons other than an ochric horizon at the surface.

Distribution of Regosols (rough estimation supplied by soilgrids)

Reference soil KE024: Regosols

A very deep-rooting (125-180 cm) soil with ill-sorted medium to coarse sandy texture, with high porosity and good to excessive drainage. It shows slight to moderate sealing including algae crusts of about 3 cm thickness, and a mesorelief of small ridges and shallow depressions (2-3 m); vegetation: accacia sp., indigofera sp.

Classification

WRB 2006

WRB 1998

Haplic- Regosol (Hypereutric Arenic)

Hypereutri-Arenic- Regosol

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Areni-Eutric Regosol

Eutric Regosol

0-30 cm	ochric A horizon
- cm	ochric A horizon

0-30 cm

ochric A horizon

Other classification

USDA-NRCS (1999)	Typic Torriorthent
USDA-SCS (1975)	Typic Torriorthent aridic isohyperthermic

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	-	2.3	15.7	26.4	22.6	10.2	77.2	6.8	7.7	14.5	8.2
15-30	-	3.0	15.9	25.6	22.5	9.3	76.3	6.6	7.1	13.7	9.9
30-50	-	2.8	13.5	23.2	24.3	10.6	74.4	8.9	7.7	16.6	9.0
50-80	-	2.9	12.9	23.8	25.6	9.8	75	6.7	5.5	12.2	12.9
80-100	-	3.7	12.3	24.3	24.7	9.4	74.4	6.0	6.3	12.3	13.2
100-120	5	4.5	11.9	23.1	22.9	9.0	71.4	6.9	7.3	14.2	14.5
120-150	9	5.1	12.5	21.7	23.4	9.3	72	6.9	7.4	14.3	13.7

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-15	1.63	-	-	5.3	8.2
15-30	-	-	-	5.3	9.9
30-50	-	-	-	5.5	9.0
50-80	1.63	-	-	5.4	12.9
80-100	1.62	-	-	5.4	13.2
100-120	-	-	-	-	14.5
120-150	-	-	-	-	13.7

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
0-15	1.63	31.1	29.4	25.2	17.4	14.7	12.8	9.2	7.7
50-80	1.63	31.1	29.3	26.2	19.3	17.2	15.6	9.6	7.9
80-100	1.62	33.9	32.6	28.9	19.5	17.1	15.6	9.6	8.5

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	8.3	7.5	0.13	0.3	0.16	0.03	5	-	-	8.6	1.6	0.9	1.0	12.1
15-30	8.4	7.6	0.13	0.2	0.08	0.02	4	-	-	8.0	2.0	0.9	0.1	11
30-50	8.3	7.2	0.12	0.2	0.07	-	-	0.1	-	6.4	1.6	0.8	0.1	8.9
50-80	8.2	6.8	0.10	0.1	0.08	-	-	-	-	6.4	1.6	0.6	0.4	9
80-100	8.1	6.9	0.18	0.0	0.07	-	-	-	-	7.6	1.6	0.5	0.4	10.1
100-120	8.3	7.4	0.48	0.6	0.07	-	-	-	-	10.0	1.6	0.6	0.8	13
120-150	8.2	7.6	0.64	0.9	0.08	-	-	-	-	17.2	2.0	0.5	1.1	20.8

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	164	7.4	79	1.0	-	-	14
15-30	138	8.0	77	0.4	-	-	1
30-50	127	7.0	75	0.2	-	-	1
50-80	120	7.5	56	0.3	-	-	5
80-100	129	7.8	57	0.2	-	-	5
100-120	153	8.5	57	0.2	-	-	9
120-150	245	8.5	61	0.03	-	-	13

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	very weak	-	-	-	-	very weak to weak	weak to medium	-	very weak	weak	-
30-50	-	very weak	-	-	-	-	weak	medium to strong	-	very weak	weak	-
80-100	-	very weak	-	-	-	-	weak to medium	strong	-	-	weak to medium	-
120-150	-	very weak	-	-	-	-	weak to medium	strong	-	-	weak to medium	-

Profile description

Ah 0-30 cm	light yellowish brown (10YR 6/4, dry) (dark) brown (7.5YR 4/4, moist)loamy sand,weakly coherent porous massive,soft very friable non sticky non plastic,few micro to medium discontinuous vesicular pores and few coarse continuous tubular pores,fine and medium roots,slightly calcareous (0-2%),gradual smooth boundary to,
CA 30-56 cm	yellow (10YR 7/6, dry) dark brown (7.5YR 3/4, moist)loamy sand,moderately coherent porous massive,soft very friable non sticky non plastic,many fine and medium tubular pores and few micro and very coarse pores,fine and medium roots,very few mica fragments,slightly calcareous (0-2%),clear smooth boundary to,
C1 56-80 cm	brown (7.5YR 5/4, dry) dark brown (7.5YR 3/4, moist)loamy sand,moderately coherent porous massive,slightly hard very friable non sticky non plastic,common micro and very fine pores and few fine and medium pores,fine and medium roots,very few mica fragments,slightly calcareous (0-2%),gradual smooth boundary to,
C2 80-100 cm	yellowish brown (10YR 5/4, dry) dark brown (7.5YR 3/4, moist)loamy sand slightly gravelly,moderately coherent porous massive,slightly hard very friable non sticky non plastic,many micro and very fine pores and few fine and medium pores,fine and medium roots,few mica fragments and very few granite/ feldspar stones,slightly calcareous (0-2%),gradual smooth boundary to,
Ck1 100-120 cm	dark yellowish brown (10YR 4/4, dry) (7.5YR 3/3, moist)loamy sand slightly gravelly,moderately coherent porous massive,hard very friable non sticky non plastic,many micro and very fine pores,fine and medium roots,few small spherical soft calcareous concretions,few stones mica very few stones granite/feldsp. fragments,slightly calcareous (0-2%),clear smooth boundary to,
Ck2 120-150 cm	very pale brown (10YR 7/4, dry) (dark) brown (7.5YR 4/4, moist)loamy sand gravelly,moderately coherent porous massive,hard very friable non sticky non plastic,many micro and very fine pores,fine and medium roots,few medium spherical soft calcareous concretions,slightly calcareous (0-2%),

Kind 1 (parent material) ; Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	unconsolidated, unspecified
Remarks on Parent Materials	Basement System rocks (Hedad Bed sediments)
Texture of parent material	sandy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

Intensity of the soil erosion type	severe
Soil erosion type	sheet

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	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Acacia sp, Indigofere sp. LAND USE: Extensive grazing on lowest scale
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	dwarf shrub

Altitude	650m
Physiographic Unit	sedimentary plain
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.	plain
Slope	0%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Drainage class ; FAO (2006) - Guidelines for soil description	well
Dry From - To	0-150cm
Depth to groundwater table	0cm
(Estimated) minimum (upper) depth to groundwater table	45cm
Estimated permeability (class) of least permeable part of the profile	high
Estimated run off (class)	slow
Drainage class - intergrade; FAO (2006) - Guidelines for soil description	somewhat excessive

Evidence of alkali ; Soil Survey Manual USDA, 1951	slightly alkaline
Surface cracking	no cracks observed
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface partly slaked, round smooth aggregates
Microrelief Height: variation in height	0
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	levees (artificial)
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 24: Regosol

Characteristics

Reference soil KE024: Regosols

Classification