Reference soil Kenya 44: Nitisol

KE044

Nitisols occur mainly in the tropics and subtropics, as well as in areas with a Mediterranean type of climate. They are associated with basic rocks (e.g. basalts) or hard limestone or dolomite deposits.

Characteristics

Soils having a nitic horizon (a horizon with pronounced nut-shaped soil structure and significant amount of active iron) within 100 cm from the soil surface, and gradual to diffuse horizon boundaries between the surface and the underlying horizons. They do not have a ferric, plinthic or vertic horizon within 100 cm from the soil surface.

Distribution of Nitisols (rough estimation supplied by soilgrids)

Reference soil KE044: Nitisols

Brief soil description: Very deep, well drained soil derived from basic volcanic breccia; with a thick, dusky red clay topsoil over a dark brown, clay subsoil with clay cutans. The soil is used for arable farming with crops as coffee, maize, bananas and cassava. Charcoal and potterie are found troughout the 0 - 80cm soil hrizon Termite activity is very high. Slides: 10,052 - 10,059.

Classification

WRB 2006

WRB 1998

Lixic-Mollic-Ferralic- Nitisol (Humic Rhodic)

Humi-Mollic- Nitisol (Rhodic Ferralic)

0-60 cm	mollic horizon
35-150 cm	argic horizon
35-150 cm	nitic horizon
-	ferralic

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Niti-Luvic Phaeozem

Luvic Phaeozem

0-60 cm	mollic A horizon
35-150 cm	argic B horizon
-	nitic

0-80 cm	mollic A horizon
35-150 cm	argillic B horizon

Other classification

USDA-NRCS (1999)	Pachic Argiudoll
USDA-SCS (1975)	Pachic Argiudoll udic very fine 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	-	1.0	1.3	1.1	1.3	1.0	5.7	18.6	41.3	59.9	34.4
35-60	-	0.4	0.5	0.6	1.0	0.8	3.3	10.7	36.7	47.4	49.2
60-90	-	0.1	0.1	0.3	0.9	0.6	2	7.1	33.2	40.3	57.8
90-150	-	0.0	0.2	0.3	0.9	0.6	2	4.9	33.3	38.2	59.8
150-	-	0.0	0.1	0.3	0.8	0.6	1.8	1.6	14.6	16.2	82.0

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
8-13	0.915	-	-	-	-
0-35	-	-	-	24.1	34.4
35-60	-	-	-	31.6	49.2
48-53	1.011	-	-	-	-
60-90	-	-	-	28.5	57.8
98-103	0.953	-	-	-	-
90-150	-	-	-	-	59.8
150-	-	-	-	-	82.0

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
8-13	0.915	64.0	60.4	48.1	38.8	35.7	33.3	30.1	28.3
48-53	1.011	56.5	53.6	47.9	43.4	41.2	39.3	37.7	35.0
98-103	0.953	56.3	53.8	49.2	42.8	39.7	37.4	36.2	32.7

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
0-35	6.6	5.6	0.20	0.8	2.37	0.30	8	-	-	15.5	3.1	2.1	0.0	20.7
35-60	6.9	5.7	0.16	1.4	1.33	0.17	8	-	-	13.3	3.0	1.4	0.0	17.7
60-90	7.0	5.8	0.21	1.3	0.63	0.11	6	-	-	7.1	2.2	1.5	0.0	10.8
90-150	7.0	5.9	0.19	1.0	0.57	0.10	6	-	-	6.9	2.8	1.9	0.1	11.7
150-	6.9	5.9	0.14	1.1	0.35	0.07	5	-	-	5.4	3.2	1.1	0.0	9.7

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	93	22.3	65	8.3	-	-	0
35-60	122	14.5	29	4.7	-	-	0
60-90	98	11	19	2.2	-	-	0
90-150	119	9.8	16	2.0	-	-	1
150-	114	8.5	10	1.2	-	-	0

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	-	-	-	0.5	0.1	6.2	0.5	-	-	-	0.5
35-60	-	-	-	0.3	0.1	8.7	0.6	-	-	-	0.4
60-90	-	-	-	0.2	0.1	6.0	0.5	-	-	-	0.5
90-150	-	-	-	0.3	0.1	6.1	0.5	-	-	-	0.5
150-	-	-	-	0.3	0.1	6.4	0.6	-	-	-	0.5

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-35	-	-	weak	weak	-	-	medium	-	weak	-	-	-
35-60	-	-	weak	weak	-	-	medium	-	weak	-	-	-
60-90	-	-	weak	weak	-	-	medium to strong	-	weak	-	-	-
90-150	-	-	weak	weak	-	-	medium to strong	-	weak	-	-	-
150-	-	-	weak	weak	-	-	medium to strong	-	very weak to weak	-	-	-

Profile description

Ah 0-35 cm	dark reddish brown (5YR 3/2, dry) dusky red (2.5YR 3/2, moist)clay,weak coarse and very coarse subangular blocky parting to moderate fine granular,soft very friable sticky slightly plastic,patchy thin clay cutans,many micro and very fine and few fine and medium pores,many very fine and common medium roots,non calcareous,gradual irregular boundary to,
35-80 cm	dark brown (7.5YR 3/2, dry) dark brown (7.5YR 3/2, moist)clay,moderate very coarse subangular blocky,slightly hard friable sticky slightly plastic,broken thin clay cutans,many micro and very fine pores and few fine and medium pores,non calcareous,gradual wavy boundary to,
Bt 80-150 cm	dark reddish brown (5YR 3/4, dry) dusky red (2.5YR 3/2, moist)clay,strong very coarse subangular blocky,hard firm sticky slightly plastic,continuous moderately thick clay cutans,many micro and very fine pores and few fine and medium pores,very few small spherical hard ferruginous concretions,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	basic volcanic breccia
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	phonolite/lahar
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
Slope stability	stable

Major crops	coffee
Land improvements ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	terracing
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: Crops also some maize, bananas, cassava
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop rotation scheme not relevant

Altitude	1410m
Physiographic Unit	dissected mountain footridge
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.	plateau
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	well
Dry From - To	0-150cm
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	moderate
Estimated run off (class)	medium

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
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 44: Nitisol

Characteristics

Reference soil KE044: Nitisols

Classification