Reference soil Zimbabwe 03: Acrisol

ZW003

Acrisols occur dominantly in the wetter parts of the tropics and subtropics and the warm temperate regions in relatively young landscapes.

Characteristics

Soils having an argic horizon (a subsurface horizon with distinct higher clay content than the overlying horizon), which has a cation exchange capacity of less than 24 cmolc per kg in some part, either starting within 100 cm from the soil surface, or within 200 cm from the soil surface if the argic horizon is overlain by loamy sand or coarser textures throughout. They have a base saturation (total amount of Ca, Mg, K and Na with respect to the cation exchange capacity) of less than 50 percent in the major part between 25 and 100 cm from the soil surface

Distribution of Acrisols (rough estimation supplied by soilgrids)

Reference soil ZW003: Acrisols

(1)Profile is situated about 50 m from the CPU sheds. It is sited in between two field trial blocks, one of which was currently under irrigated summer wheat. The other field block was cropped with maize during the previous growing season. (2)The CPU trial lands were originally cleared of trees in 1968. There is evidence of low ridge cultivation, in the immediate vicinity of the pit, which would have been carried out more recently. (3)Grass species dominate the site. (4)Original vegetation would have been woodland, with dominant Brachystegia spiciformis/Julbernardia globiflora trees, with Parinari curatellifolia, Terminalia sericea, Ficus sp. and Euphorbia sp. Tree heights were medium to tall (3 - 6 m), due to the limiting soil and climate factors. (5)A large number of crops have been grown in the CPU fields over the years - maize, sorghum, sunflower, groundnuts, millets, cowpea, bambara nuts, beans, and summer and winter wheats. (6)Lister (1986, p99) indicates that the dominant landform of the area, consists on regularly jointed granite koppies with flat intermediate pediments. There is a large granite batholith (Chikungubwe) about 4 kms. to the NE. (7) The pit was originally opened in October 1989, for a Soil Correlation meeting, and had been left open, to a depth of about 110 cms. (8)There was evidence of ant activity in Horizons 1 and 2, and the ant species were identified as (Hymenoptera Formicidae Camponotinae) Camponotus sp. and (Hymenoptera Formicidae Ponerinae) Odontomachua haematoda. A number of spider and mite insects were also observed but not collected for identification. (9)Occasional krotovina were observed in Horizons 2 and 3, filled with darker sandy material from the upper Horizon. (10)The depth of the sandy horizons was variable around the pit, as was the thickness of the gravel horizon. On one face, the gravels commenced at 105 cms. The irregular gravel nodules were intimately mixed with the sandy material from the upper horizons. (11)Petroferric material (hardened plinthite), from which the gravels developed, commenced at 101 cms, although it was a mixture of hardened irregular nodules and channels filled with the sandy material from upper horizons. (12)The "true" plinthic material found below 119 cms (where the soil was still moist) was also mixed with sandy material, and frequent quartz stones. Mottles were larger and brighter in colours in this Horizon. (13)Many of the nodules/mottles exhibited bluish black segregations in their centres. (14)Old tree roots were observed in Horizons 4 and 5, in a strongly decomposed state.

Classification

WRB 2006

Pisoplinthic- Acrisol (Albic Hyperdystric Profondic Arenic)

101-155 cm	argic horizon
29-101 cm	albic horizon
69-101 cm	pisoplinthic horizon

101-155 cm	argic horizon
29-101 cm	albic horizon
69-101 cm	pisoplinthic horizon

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Areni-Albic Plinthosol

Albic Arenosol

0-29 cm	ochric A horizon
29-101 cm	albic E horizon
-	plinthite

0-29 cm	ochric A horizon
-	albic material
-	plinthite

Local classification:	Makoholi 5G.3 series

Other classification

USDA-SCS (1975)

Quartzipsamment ustic sandy mixed thermic

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
0-14	3	8.1	20.5	23.0	24.4	12.1	88.1	3.1	3.6	6.7	5.2
14-29	2	9.4	23.1	21.1	21.8	11.3	86.7	4.5	3.6	8.1	5.2
29-48	3	7.1	18.3	21.5	25.7	10.9	83.5	5.0	5.7	10.7	5.9
48-62	5	10.6	18.5	21.0	23.3	8.6	82	8.7	2.8	11.5	6.4
62-101	65	11.6	19.6	25.2	19.0	8.2	83.6	6.8	2.1	8.9	7.4
101-119	16	8.6	21.7	20.0	12.7	7.7	70.7	9.4	6.1	15.5	13.8
119-125	18	10.0	20.5	16.3	11.0	9.5	67.3	0.2	17.4	17.6	15.1

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-14	-	-	-	1.4	5.2
14-29	-	-	-	3.4	5.2
29-48	-	-	-	4.3	5.9
48-62	-	-	-	4.5	6.4
62-101	-	-	-	5.2	7.4
101-119	-	-	-	1.9	13.8
119-125	-	-	-	1.4	15.1

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
0-14	6.1	5.1	0.05	-	0.30	0.02	15	-	-	0.6	0.3	0.2	0.0	1.1
14-29	5.4	4.5	0.04	-	0.19	0.02	10	0.2	0	0.4	0.0	0.1	0.0	0.5
29-48	5.0	4.4	0.04	-	0.08	0.01	8	0.3	0	0.2	0.0	0.1	0.0	0.3
48-62	4.8	4.3	0.04	-	0.07	0.01	7	0.3	0	0.0	0.0	0.1	0.0	0.1
62-101	5.2	4.6	0.05	-	0.10	0.01	10	0.2	0	0.2	0.0	0.1	0.0	0.3
101-119	5.4	4.6	0.07	-	0.06	0.01	6	0.2	0	0.6	0.3	0.2	0.2	1.3
119-125	4.9	4.4	0.05	-	0.04	0.01	4	0.2	0	0.6	0.3	0.1	0.0	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 %
0-14	69	1.6	31	1.1	-	-	0
14-29	42	1.2	23	0.7	-	0	0
29-48	21	1.4	24	0.3	-	0	0
48-62	5	1.9	30	0.2	-	0	0
62-101	18	1.7	23	0.4	-	0	0
101-119	39	3.3	24	0.2	-	0	6
119-125	38	2.6	17	0.1	-	0	0

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-14	-	weak	-	-	-	-	very strong	weak	very weak to weak	very weak to weak	-	-
14-29	-	weak	-	-	-	-	very strong	weak	very weak to weak	very weak to weak	-	-
29-48	-	weak	-	-	-	-	very strong	weak	very weak to weak	very weak to weak	-	-
48-62	-	weak	-	-	-	-	very strong	weak	very weak to weak	very weak to weak	-	-
62-101	-	very weak to weak	-	-	-	-	very strong	weak	very weak to weak	very weak to weak	-	-
101-119	-	very weak	-	-	-	-	very strong	weak	very weak	very weak to weak	-	-
119-125	-	-	-	-	-	-	very strong	weak	very weak	very weak	-	-

Profile description

Ap 0-14 cm	pale brown (10YR 6/3, dry) (dark) brown (10YR 4/3, moist)coarse sand,weakly coherent massive,soft,no cutans,many very fine roots,no inclusions,no fragments,few channels,non calcareous,clear smooth boundary to,
14-29 cm	pale brown (10YR 6/3, dry) (dark) brown (10YR 4/3, moist)coarse sand,weakly coherent massive,slightly hard,no cutans,common very fine roots,no inclusions,no fragments,few channels and krotovinas,non calcareous,clear smooth boundary to,
E1 29-48 cm	very pale brown (10YR 7/4, dry) yellowish brown (10YR 5/4, moist)coarse sand,moderately coherent massive,slightly hard,no cutans,common very fine roots,no inclusions,no fragments,few channels and krotovinas,non calcareous,clear smooth boundary to,
E2 48-62 cm	very pale brown (10YR 7/4, dry) yellowish brown (10YR 5/4, moist)coarse sand,weakly coherent massive,loose,no cutans,common very fine roots,very few medium spherical hard ferruginous nodules,no fragments,no,non calcareous,abrupt wavy boundary to,
Eoc 62-101 cm	very pale brown (10YR 7/4, dry) yellowish brown (10YR 5/4, moist)coarse sand very gravelly,weakly coherent massive,very hard,no cutans,common very fine roots,dominant medium irregular hard ferruginous nodules,very few fine gravel weathered quartz fragments,no,non calcareous,gradual irregular boundary to,
Bvm1 101-119 cm	very pale brown (10YR 7/3, dry) brown (10YR 5/3, moist)coarse sand gravelly,strongly coherent porous massive and weakly coherent massive,very hard,many (15-40%) coarse prominent clear mottles 7.5YR5/8 (strong brown) and 2.5YR3/4 (dark reddish brown),no cutans,common very fine roots,frequent medium irregular hard ferruginous nodules,very few fine gravel weathered quartz fragments,no,discontinuous vesicular weakly cemented plinthite pans,non calcareous,gradual irregular boundary to,
Bvm2 119-155 cm	very pale brown (10YR 7/3, dry) brown (10YR 5/3, moist)coarse sand slightly gravelly,strongly coherent coarse porous massive and weakly coherent coarse massive,very firm,many (15-40%) coarse prominent clear mottles (7.5YR 5/8) and (10R 4/8),no cutans,common very fine roots,common fine gravel and few medium weathered quartz fragments,no,continuous vesicular weakly cemented plinthite pans,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	coarse-grained acid igneous rock
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	granodiorite
Soil Depth	119cm
Texture of parent material	sandy
Weathering Resistance	high
General characterization of the status of weathering of solid rock	slightly

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)	levelling
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: Fallow site under grass vegetation. LAND USE: Land originally cleared of trees in 1968
Rotation scheme ; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	shifting - fallow grass

Altitude	1190m
Physiographic Unit	flat pediment between koppies
Physiographic position of the site	middle slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	pediment
Slope	2%
Slope Aspect	south-south-west
Form of the slope surrounding the site	convex
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	flat or almost flat

Lower limit of a slow permeable or stagnating layer in the profile	155cm
Drainage class ; FAO (2006) - Guidelines for soil description	somewhat excessive
Dry From - To	0-119cm
Flooding frequency (FAO, 1986)	never
Kind of ground water table (USDA, 1979)	no groundwater table observed
Moist From - To	119-155cm
Estimated permeability (class) of least permeable part of the profile	moderate
Estimated run off (class)	rapid
Upper limit of a slow permeable or stagnating layer in the profile	119cm

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 Height: variation in height	130
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	termite/ant mounds
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

You are here

Reference soil Zimbabwe 03: Acrisol

Characteristics

Reference soil ZW003: Acrisols

Classification