Reference soil Zimbabwe 04: Ferralsol

ZW004

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 ZW004: Ferralsols

(1)Profile is located in a recent fallow field. Attempts to crop the soil with maize had been made in the past, but phosphate deficiency problems on the soil, have been insurmountable. The land has therefore been left to fallow. (2)A large number of grass and arable weed species have invaded the area and produced a dense coverage. Grasses include Digitaria ternata, Hyparrhenia filipendula, Sporobolus pyramidalis, Eleusine indica, Setaria pumila, Panicum novemnerve, Hyperthelia dissoluta and Cyperus esculentis. Arable weed species include Nicandra physalodes, Cleome monophylla, Hibiscus cannabinus, Tagetes minuta, Bidens pilosa, Chamaecrista stricta and Cucumis metuliferus. (3)On the opposite side of the road, a tall stand of Eucalyptus trees are growing well, and the farmer has indicated that he may plant similar trees on this presently-unproductive portion of land. (4)The area of soils influenced by the banded ironstone geology is fairly limited, as indicated on the Geology Map of the area (Geological Survey Bulletin, No. 33) and by the nearby good growths of maize, growing on the red soils of the Greenstone Series. (5)Field texturing of the soil indicates an inactive (kaolinitic) clay, within which are what appear to be water-stable aggregates. These aggregates occur from 21 cms and are most numerous in Horizons 2, 3 and 4. Horizon 5 (93-126 cms) appears to have only a few of these aggregates. Field texturing also reveals the presence of a predominantly fine sand fraction. (6)Particles of black weathering rock and quartz grains can be observed from Horizon 4 (72-93 cms). Their abundance and visual prominence increase with depth. (7)Only one insect sample was found, and was identified as (Hymenoptera Formicidae Dorylinae) Dorylus fulvus.

Classification

WRB 2006

Haplic- Ferralsol (Eutric Clayic Rhodic)

21-93 cm	cambic horizon
93-150 cm	ferralic horizon

21-93 cm	cambic horizon
93-150 cm	ferralic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Eutri-Rhodic Ferralsol

Rhodic Ferralsol

0-46 cm	ochric A horizon
46-93 cm	cambic B horizon
93-150 cm	ferralic B horizon

0-46 cm	ochric A horizon
46-150 cm	oxic B horizon
-	weatherable minerals

Local classification:	Harare 7I.2 series

Other classification

USDA-SCS (1975)

Eutrustox ustic clayey kaolinitic isothermic

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
0-21	0	1.4	2.0	2.9	5.4	3.3	15	9.1	25.6	34.7	50.5
21-46	0	0.7	1.9	2.3	4.8	3.0	12.7	8.2	23.4	31.6	55.7
46-72	0	1.3	1.6	1.8	4.0	3.7	12.4	7.7	24.6	32.3	55.3
72-93	0	1.8	1.6	1.8	4.2	3.3	12.7	12.9	25.1	38	49.4
93-126	0	1.7	1.6	1.7	3.7	3.8	12.5	14.7	27.5	42.2	45.3
126-150	3	4.0	1.4	1.4	3.8	3.0	13.6	9.0	16.8	25.8	60.5

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-21	1.20	-	-	22.8	50.5
21-46	1.24	-	-	34.1	55.7
46-72	1.17	-	-	36.0	55.3
72-93	1.06	-	-	20.7	49.4
93-126	1.06	-	-	2.0	45.3
126-150	1.04	-	-	2.0	60.5

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
0-21	1.20	-	-	43	38	30	-	25	15
21-46	1.24	-	-	44	40	33	-	26	20
46-72	1.17	-	-	38	35	31	-	27	10
72-93	1.06	-	-	42	36	29	-	23	8
93-126	1.06	-	-	45	37	28	-	23	14
126-150	1.04	-	-	45	39	29	-	23	19

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
0-21	5.7	5.0	0.13	-	1.22	0.11	11	-	-	5.6	1.4	0.1	0.0	7.1
21-46	6.0	5.3	0.11	-	0.97	0.09	11	-	-	6.0	2.0	0.1	0.0	8.1
46-72	6.0	5.4	0.17	-	0.79	0.08	10	-	-	6.2	2.0	0.1	0.0	8.3
72-93	6.2	5.6	0.14	-	0.55	0.06	9	-	-	5.8	2.0	0.1	0.0	7.9
93-126	6.4	5.7	0.20	-	0.37	0.05	7	-	-	4.3	2.0	0.2	0.0	6.5
126-150	6.6	6.3	0.10	1.0	0.27	0.04	7	-	-	3.1	1.7	0.0	0.0	4.8

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 %
0-21	61	11.6	23	4.3	-	-	0
21-46	68	12.0	22	3.4	-	-	0
46-72	72	11.5	21	2.8	-	-	0
72-93	77	10.2	21	1.9	-	-	0
93-126	84	7.7	17	1.3	-	-	0
126-150	75	6.4	11	0.9	-	-	0

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-21	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-
21-46	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-
46-72	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-
72-93	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-
93-126	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-
126-150	-	very weak	-	weak	-	-	strong	-	very weak to weak	-	-	-

Profile description

Ah 0-21 cm	red (2.5YR 4/6, dry) dark reddish brown (2.5YR 3/4, moist)clay,weak to moderate very fine granular and weak to moderate fine and medium subangular blocky,very friable slightly sticky slightly plastic,no cutans,common very fine discontinuous exped and inped tubular random pores moderately porous (40-60 vol%),many very fine roots,no inclusions,no,non calcareous,abrupt wavy boundary to,
21-46 cm	red (2.5YR 4/6, dry) dark reddish brown (2.5YR 3/4, moist)clay loam,moderate very fine subangular blocky parting to moderate fine and medium granular,friable slightly sticky slightly plastic,broken thin clay cutans on pedfaces,many very fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),common very fine and few medium roots,no inclusions,no fragments,no,non calcareous,clear smooth boundary to,
BA 46-72 cm	red (2.5YR 4/6, dry) dark reddish brown (2.5YR 3/4, moist)clay,moderate very fine subangular blocky parting to moderate fine and medium granular,friable slightly sticky slightly plastic,broken thin clay cutans on pedfaces,many very fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),common very fine and few medium roots,no inclusions,no fragments,few termite channels,non calcareous,clear smooth boundary to,
Bto 72-93 cm	red (2.5YR 4/6, dry) dark red (2.5YR 3/6, moist)clay,weakly coherent massive,friable slightly sticky slightly plastic,broken thin clay cutans on pedfaces,many very fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),common very fine and few medium and coarse roots,no inclusions,very few fine gravel weathered ironstone and very few fine gravel fresh quartz fragments,no,non calcareous,gradual smooth boundary to,
Bo1 93-126 cm	red (2.5YR 4/6, dry) dark red (2.5YR 3/6, moist)clay,weakly coherent massive,friable slightly sticky slightly plastic,no cutans,many very fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),few fine roots,no inclusions,few fine gravel weathered ironstone and very few fine gravel fresh quartz fragments,no,non calcareous,clear wavy boundary to,
Bo2 126-150 cm	red (2.5YR 4/6, dry) dark red (2.5YR 3/6, moist)clay,moderately coherent massive,friable slightly sticky slightly plastic,no cutans,many very fine continuous exped and inped tubular random pores moderately porous (40-60 vol%),few fine roots,no inclusions,common fine gravel weathered ironstone and very few fine gravel fresh quartz fragments,no,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	schist
Mode of accumulation or deposition of parent material	colluvial
Remarks on Parent Materials	ironstone colluvium
Soil Depth	150cm
Texture of parent material	clayey
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	highly

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)	land clearing
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	fallow
Remarks on Land Use / Vegetation	VEGETATION: Recent fallow with pioneer weed & grass. Grasses: Digitaria ternata, hyparrhenia filipendula, Sporobolus pyramidalis, Eleusine indica, Setaria pumila, panicum novemnerve, Hyperthelia dissoluta and Cyperus esculentis. Arable weed specied: Nicandra physalodes, cleame monophylla, hibiscus cannabinus, tagetes minuta, Bidens pilosa, Chamaecrista stricta and
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	crop with current fallow

Altitude	1500m
Physiographic Unit	edge of high watershed plateau
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	1%
Slope Aspect	west-north-west
Form of the slope surrounding the site	straight
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Drainage class ; FAO (2006) - Guidelines for soil description	well
Flooding frequency (FAO, 1986)	never
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)	rapid

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
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	level
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 Zimbabwe 04: Ferralsol

Characteristics

Reference soil ZW004: Ferralsols

Classification