Reference soil Kenya 65: Solonetz

KE065

Solonetzes occur where a sodium source supplies the clay-rich subsoil with exchangeable Na, causing peptization of clay and organic substances and deterioration of the topsoil.

Characteristics

Soils having a natric horizon (a subsurface horizon with distinct higher clay content than the overlying horizon and more than 15% exchangeable sodium) within 100 cm from the soil surface.

Distribution of Solonetz (rough estimation supplied by soilgrids)

Reference soil KE065: Solonetz

Faint bleached grains in the E-horizon. Slides: 10,234 - 10,237.

Classification

WRB 2006

WRB 1998

Mollic-Stagnic-Vertic- Solonetz (Abruptic Clayic)

Molli-Vertic- Solonetz (calcic horizon Stagnic)

0-38 cm	mollic horizon
38-72 cm	vertic horizon
38-97 cm	natric horizon
-	abrupt textural change
-	vertic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Calci-Mollic Solonetz

Solodic Planosol

0-38 cm	mollic A horizon
38-97 cm	natric B horizon
-	abrupt textural change
-	soft powdery lime
-	stagnic

0-38 cm	mollic A horizon
38-97 cm	natric B horizon
-	soft powdery lime

Other classification

USDA-NRCS (1999)	Udollic Albaqualf
USDA-SCS (1975)	Udollic Argialboll ustic loamy 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
0-15	-	8.2	11.6	12.2	14.8	6.3	53.1	9.2	12.7	21.9	25.0
15-28	-	10.3	11.2	12.4	16.9	4.8	55.6	9.8	13.9	23.7	20.6
28-38	-	10.1	12.3	11.7	14.0	6.0	54.1	8.1	12.4	20.5	25.4
38-58	-	5.4	9.5	7.9	8.0	2.6	33.4	4.6	4.8	9.4	57.3
58-72	-	6.8	9.5	6.9	6.9	3.2	33.3	4.6	5.6	10.2	56.5
72-97	-	5.1	5.7	5.1	6.5	3.5	25.9	6.1	10.1	16.2	58.0
97-122	-	6.6	3.3	3.2	5.4	3.5	22	7.0	18.4	25.4	52.7

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	-	-	-	-	25.0
15-28	-	-	-	-	20.6
28-38	-	-	-	-	25.4
38-58	-	-	-	-	57.3
58-72	-	-	-	-	56.5
72-97	-	-	-	-	58.0
97-122	-	-	-	-	52.7

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	6.9	5.5	0.09	1.0	0.99	0.09	11	-	-	12.6	3.0	0.1	2.5	18.2
15-28	6.6	5.4	0.19	0.9	1.43	0.10	14	-	-	10.5	2.7	0.0	2.4	15.6
28-38	7.1	5.5	0.07	1.1	0.92	0.01	92	-	-	13.0	3.1	0.1	3.6	19.8
38-58	7.5	5.7	0.12	2.0	0.68	0.04	17	-	-	21.2	7.4	0.1	9.4	38.1
58-72	7.9	6.2	0.13	2.0	0.62	0.08	8	-	-	20.9	6.7	0.2	10.1	37.9
72-97	8.5	7.2	0.28	3.1	0.48	0.07	7	-	-	26.7	7.3	0.2	13.4	47.6
97-122	8.7	7.3	0.32	5.3	0.25	0.03	8	-	-	39.7	8.9	0.4	15.8	64.8
122-140	8.8	7.4	0.41	8.7	0.25	0.04	6	-	-	38.4	8.9	1.0	18.3	66.6

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	107	17.0	56	3.5	-	-	15
15-28	91	17.2	62	5.0	-	-	14
28-38	106	18.6	62	3.2	-	-	19
38-58	109	35.1	59	2.4	-	-	27
58-72	110	34.3	61	2.2	-	-	29
72-97	132	36.0	62	1.7	-	-	37
97-122	188	34.5	65	0.9	-	-	46
122-140	201	33.2	90	0.9	-	-	55

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-15	-	very weak	-	-	-	-	weak	weak	-	weak	weak to medium	-
28-38	-	very weak	-	-	-	-	weak	weak	-	weak	weak to medium	-
58-72	-	very weak	-	-	-	-	weak	weak	-	weak	weak to medium	-
122-140	-	very weak	-	-	-	-	weak	weak	-	very weak	weak to medium	-

Profile description

Ah 0-15 cm	grey (10YR 5/1, dry) (2.5Y 2/no, moist)sandy clay loam,medium subangular blocky,slightly hard friable sticky plastic,many very fine pores and few fine pores,slightly calcareous (0-2%),gradual smooth boundary to,
E1 15-28 cm	dark greyish brown (10YR 4/2, dry) very dark grey (10YR 3/1, moist)sandy clay,fine and medium subangular blocky and weak medium and coarse subangular blocky,slightly hard very friable sticky plastic,many very fine pores and few fine pores,few fine gravel weathered quartz fragments,slightly calcareous (0-2%),clear smooth boundary to,
E2 28-38 cm	dark greyish brown (10YR 4/2, dry) very dark grey (10YR 3/1, moist)gravelly sandy clay,fine and medium subangular blocky and weak medium and coarse subangular blocky,slightly hard very friable sticky plastic,many very fine pores and few fine pores,few small spherical hard manganiferous concretions and few medium spherical hard manganiferous concretions,common fine gravel weathered quartz fragments,slightly calcareous (0-2%),abrupt wavy boundary to,
Bt 38-58 cm	very dark grey (10YR 3/1, dry) black (10YR 2/1, moist)clay,coarse and very coarse prismatic parting to strong fine angular blocky,very hard very friable sticky plastic,continuous moderately thick clay cutans,common very fine pores and few fine pores,very few small spherical hard manganiferous concretions and very few medium spherical hard manganiferous concretions,very few fine gravel weathered quartz fragments,moderately calcareous (2-10%),clear smooth boundary to,
Btk 58-72 cm	very dark greyish brown (10YR 3/2, dry) very dark brown (10YR 2/2, moist)clay,coarse prismatic,hard very friable sticky plastic,common very fine pores and few fine pores,very few powdery thread-like soft calcareous crystals and very few medium spherical hard manganiferous concretions,very few fine gravel weathered quartz fragments,moderately calcareous (2-10%),clear smooth boundary to,
BCk 72-97 cm	light yellowish brown (10YR 6/4, dry) dark brown (10YR 3/3, moist)clay,medium and coarse prismatic,slightly hard very friable sticky plastic,common very fine pores and few fine pores,few powdery thread-like soft calcareous crystals,moderately calcareous (2-10%),gradual smooth boundary to,
Ckc1 97-122 cm	(dark) brown (10YR 4/3, dry) dark brown (10YR 3/3, moist)sandy clay loam,massive parting to moderate very fine angular blocky,slightly hard friable slightly sticky slightly plastic,broken thin manganese (hydr-)oxide cutans,common very fine pores and few fine pores,few large irregular hard calcareous concretions and few powdery thread-like soft calcareous crystals,moderately calcareous (2-10%),gradual smooth boundary to,
Ckc2 122-140 cm	light yellowish brown (10YR 6/4, dry) dark brown (10YR 3/3, moist)Description sand,massive parting to weak fine and medium subangular blocky,hard firm non sticky non plastic,frequent large irregular hard calcareous concretions and very few medium spherical hard manganiferous concretions,moderately calcareous (2-10%),

Kind 1 (parent material) ; Parker (eds), 1984	tuff
Kind 2 (parent material) (second entry); Parker (eds), 1984	gneiss
Mode of accumulation or deposition of parent material	residual material
Mode of accumulation or deposition of parent material (second entry)	residual material
Remarks on Parent Materials	tuff on gneiss of Basement System
Soil Depth	100cm
Texture of parent material	clayey
Texture of parent material (second entry)	loamy
Weathering Resistance	poor
Weathering Resistance (second entry)	high
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

Occurrence of soil aggradation (McDonald et al., 1984)	absent
Intensity of the soil erosion type	slight
Soil erosion type	sheet
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
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	1725m
Physiographic Unit	plateau in gently undul.plains
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.	plain
Slope	0%
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Lower limit of a slow permeable or stagnating layer in the profile	58cm
Drainage class ; FAO (2006) - Guidelines for soil description	imperfect
Dry From - To	0-140cm
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	38cm

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 pattern	none
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 65: Solonetz

Characteristics

Reference soil KE065: Solonetz

Classification