Reference soil Kenya 67: Kastanozem

KE067

Kastanozems occur mainly in the dry parts of the steppe regions of the world. Vast areas are found in central Asia and central USA. Smaller occurrences are reported from the Mediterranean region.

Characteristics

Soils having a mollic horizon (deep, dark coloured surface horizon with a significant accumulation of organic matter and high base saturation) and accumulation of secondary calcium carbonate within 100 cm from the soil surface. They have no diagnostic horizons other than an argic, calcic, cambic, gypsic, or vertic horizon.

Distribution of Kastanozems (rough estimation supplied by soilgrids)

Reference soil KE067: Kastanozems

Location: Kajiado district. Themeda triandra is dominant grass species. Slides: 10,225 - 10,228.

Classification

WRB 2006

WRB 1998

Luvic-Calcic-Vertic- Kastanozem (Hyposodic Clayic)

Luvi-Hypocalcic- Kastanozem (Hyposodic)

15-90 cm	argic horizon
-	vertic
-	secondary carbonates

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Hypocalci-Luvic Kastanozem sodic

Luvic Kastanozem sodic

0-35 cm	mollic A horizon
15-90 cm	argic B horizon
-	soft powdery lime
-	vertic

0-35 cm	mollic A horizon
15-90 cm	argillic B horizon
-	soft powdery lime
-	vertic

Local classification:	Verti-luvic phaeozem

Other classification

USDA-NRCS (1999)	Vertic Argiustoll
USDA-SCS (1975)	Vertic Argiustoll ustic 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
0-5	1	1.2	1.9	3.4	6.8	4.4	17.7	11.5	25.2	36.7	45.6
5-15	1	0.2	1.5	2.5	6.5	2.4	13.1	9.3	14.8	24.1	62.8
15-35	0	0.2	0.7	1.3	2.5	1.7	6.4	2.4	10.2	12.6	81.0
35-60	0	0.2	0.7	1.1	2.4	1.1	5.5	4.6	13.5	18.1	76.5
60-70	0	0.2	0.7	1.2	2.1	1.4	5.6	3.6	22.0	25.6	68.8
70-90	0	0.2	0.4	0.8	1.9	0.9	4.2	0.6	15.1	15.7	80.2
90-120	0	-	-	-	-	-	-	-	-	-	-
120-140	20	-	-	-	-	-	-	-	-	-	-

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-5	-	-	-	-	45.6
5-15	-	-	-	-	62.8
15-35	-	-	-	-	81.0
35-60	-	-	-	-	76.5
60-70	-	-	-	-	68.8
70-90	-	-	-	-	80.2

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
0-5	6.2	5.1	0.12	-	3.10	0.24	13	-	-	23.0	9.6	4.9	0.1	37.6
5-15	6.3	5.0	0.18	-	2.12	0.19	11	-	-	24.2	9.7	5.6	0.3	39.8
15-35	6.6	5.1	0.21	2.3	1.41	0.14	10	-	-	27.7	10.4	7.1	0.7	45.9
35-60	7.3	5.7	0.17	2.6	1.09	0.13	8	-	-	30.4	10.8	7.8	1.3	50.3
60-70	7.6	6.1	0.27	3.2	0.98	-	-	-	-	32.6	11.3	8.3	1.8	54
70-90	7.9	6.7	0.74	3.8	0.80	0.09	9	-	-	34.2	12.4	9.3	2.8	58.7
90-120	7.8	6.8	1.22	4.0	0.72	0.09	8	-	-	33.6	13.0	9.7	4.0	60.3
120-140	7.9	7.1	1.69	9.6	0.32	0.02	16	-	-	52.1	12.2	10.0	4.8	79.1

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 %
0-5	89	42.2	73	10.9	-	-	0
5-15	89	44.6	62	7.4	-	-	1
15-35	95	48.5	57	4.9	-	-	1
35-60	103	48.8	62	3.8	-	-	3
60-70	106	51.0	73	3.4	-	-	4
70-90	117	50.1	175	2.8	-	-	6
90-120	125	48.2	196	2.5	-	-	8
120-140	179	44.2	204	1.1	-	-	11

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-5	-	-	-	-	-	-	very weak	weak to medium	weak	-	-	-
15-35	-	-	-	-	-	-	very weak	weak to medium	weak	-	-	-
60-70	-	-	-	-	-	-	very weak	weak to medium	weak	-	-	-
120-140	-	-	-	-	-	-	very weak	weak to medium	weak	-	-	-

Profile description

Ah 0-5 cm	black (7.5YR 2/0, moist) grey (10YR 5/1, dry)silty clay,strong fine and medium crumb,slightly hard friable sticky very plastic,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,gradual smooth boundary to,
5-15 cm	black (2.5Y 2/0, moist) black (2.5Y 2/0, dry)silty clay,strong fine and medium crumb and strong fine subangular blocky,hard friable sticky very plastic,many very fine pores and few fine pores,many very fine and few fine roots,non calcareous,clear wavy boundary to,
Bth 15-35 cm	black (2.5Y 2/0, moist) black (10YR 2/1, dry)clay,strong medium prismatic parting to strong fine and medium angular blocky,very hard firm sticky plastic,continuous thin clay and humus cutans on horizontal and vertical pedfaces,many very fine pores and few fine pores,many very fine and few fine roots,moderately calcareous (2-10%),gradual smooth boundary to,
Bt 35-60 cm	very dark grey (2.5Y 3/0, moist) black (10YR 2/1, dry)clay,strong very coarse prismatic,very hard firm sticky plastic,continuous moderately thick clay cutans on horizontal and vertical pedfaces,many very fine pores and few fine pores,many very fine and few fine roots,moderately calcareous (2-10%),gradual smooth boundary to,
Bci 60-70 cm	dark greyish brown (2.5Y 4/2, dry) very dark grey (10YR 3/1, moist)clay,moderate coarse angular blocky,hard friable sticky plastic,patchy moderately thick slickensides,many very fine pores and few fina and medium pores,many very fine roots,moderately calcareous (2-10%),clear smooth boundary to,
Ckc1 70-90 cm	light yellowish brown (2.5Y 6/4, dry) dark greyish brown (2.5Y 4/2, moist)clay,weakly coherent massive parting to moderate fine subangular blocky,slightly hard friable sticky plastic,many very fine pores and few fine pores,many very fine and few fine roots,very few medium irregular soft calcareous concretions,moderately calcareous (2-10%),gradual smooth boundary to,
Ckc2 90-120 cm	light yellowish brown (2.5Y 6/4, dry) dark greyish brown (2.5Y 4/2, moist)clay,weakly coherent massive parting to moderate fine subangular blocky,slightly hard friable sticky plastic,many very fine pores and few fina and medium pores,many very fine roots,very few medium irregular soft calcareous concretions,moderately calcareous (2-10%),gradual smooth boundary to,
Ckc3 120-140 cm	weak red (2.5YR 4/2, moist) brown (10YR 5/3, dry)sandy clay loam,weakly coherent massive,slightly hard (dry) friable (moist) sticky plastic,common large irregular hard calcareous concretions,strongly calcareous (10-25%),

Kind 1 (parent material) ; Parker (eds), 1984	tuff
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Olorgesailie biotite phonolite
Soil Depth	90cm
Texture of parent material	clayey
Weathering Resistance	poor
General characterization of the status of weathering of solid rock	highly

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Slope stability	stable

Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	no land improvement
Land use or vegetation in the immediate vicinity of the site	semi-natural grassland, grazed
Remarks on Land Use / Vegetation	VEGETATION: Natural grasslands; dominant grass species Themeda triandra
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant
Status of vegetation; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	degraded
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	medium tall grassland

Altitude	1765m
Physiographic Unit	gently undulating plain
Physiographic position of the site	upper slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plain
Slope	3%
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	70cm
Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Dry From - To	0-120cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium
Upper limit of a slow permeable or stagnating layer in the profile	15cm

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Average size of stone	5
Surface cracking	small cracks (width less than 1 cm, or depth less than 50 cm)
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface partly slaked, round smooth aggregates
Microrelief pattern	none
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Shape of stones (on average)	angular irregular
Surface stoniness class (FAO (2006) - Guidelines for soil description)	stony

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Reference soil Kenya 67: Kastanozem

Characteristics

Reference soil KE067: Kastanozems

Classification