Reference soil Zimbabwe 11: Plinthosol

ZW011

Plinthosols occur mainly in the moist tropical regions in low-lying positions where iron from the soil and adjacent uplands is accumulating.

Characteristics

Soils having either a petroplinthic horizon within 50 cm from the soil surface, or a plinthic horizon which either starts within 50 cm from the soil surface, or within 100 cm from the soil surface if it underlies an albic horizon or a horizon with stagnic properties.

Distribution of Plinthosols (rough estimation supplied by soilgrids)

 

Reference soil ZW011: Plinthosols

(1) Natural vegetation consists predominantly of medium-sized open woodland of trees and shrubs. Brachystegia spiciformis and Julbernardia globiflora trees and shrubs dominate, but there are common Terminalia sericea and Parinari curatellifolia trees and shrubs. A detailed listing of natural vegetation types is available. (2) Only a few grasses and arable weeds were observed in the immediate vicinity of the pit. (3) The land has been cleared and stumped to accomodate the ICRAF Agroforestry Trials. The upper part of the Block where the pit is sited was cleared in 1990. Agroforestry shrubs were planted in December 1990. The land was ploughed at the time of establishment. At the time of planting, all agroforestry shrubs were watered every 2 weeks with 10 litres of water for a two-month period. Thereafter, no water beyond the annual rainfall was applied. During the 1990/91 season, 251 mms of rainfall were received, but during the 1991/92 season, only 151 mms were received. No pretreatments or fertilisations have taken place. In contrast to the ICRAF Trials at Domboshawa, each shrub was surrounded with a low depression well. Plantings occur about 5 metres from the pit. (4) A variety of agroforestry species have been planted in blocks. They include Acacia augustisma, Calliandra calliothrus, Flemingia conjesta, Gliditsia triacant, Grincidia sepium, Sesbania sesban, Leucaena leucocephala, Cajanus cajan and Flemingia macrophila. (5) Occasional, broad, round termite mounds occur within the Block, about 80-100 metres apart and up to 2 metres in height. These mounds would normally support tree and/or shrub growth, but this vegetation cover has been removed. (6) The location of the pit relative to the landscape is difficult to assess. It occupies a crestal, but midslope position on a long, gradually sloping (<2%), west-facing and convex spur of ground that lies between two drainage lines. The slope in the immediate vicinity of the pit is flat. (7) Lister (1986, p99) indicates that the dominant landform of the area consists of regularly jointed granite koppies with intermediate flat pediments. (8) This particular pit is very slightly higher (50 cms) in position than ZW12, but about 6 metres higher than ZW13. (9) The soil horizonation is very variable within the pit. On the sampled and described face, the dense gravel horizon occurs at about 100 cms from the surface, and is underlain by heavily mottled red/yellow plinthic material, which sets hard on exposure. On the other side of the pit, the dense gravel horizon tapers down to 200 cms from the surface, and above it is a moist, heavily mottled sand, which is not as strongly mottled as the plinthite. (10) Roots observed in the profile are mostly tree roots of varying dimensions. (11) Mottle concentrations vary from about 2% in the 2nd horizon, 5% in the 3rd to 10% in the 4th. The concentrations of mottles in the 5th and 6th horizons is difficult to determine. The 7th horizon is dominantly mottled. (12) Mottle colours in the 5th, 6th and 7th horizons also include 7.5YR hues ,

 

Classification

WRB 2006 
Acric-Fractipetric- Plinthosol (Albic Dystric Arenic) 
27-71 cmalbic horizon
71-228 cmargic horizon
97-162 cmplinthic horizon
 
27-71 cmalbic horizon
71-228 cmargic horizon
97-162 cmplinthic horizon
FAO-UNESCO-ISRIC 1988FAO-UNESCO-ISRIC 1974
Acri-Albic PlinthosolPlinthic Acrisol
0-27 cmochric A horizon
27-71 cmalbic E horizon
71-228 cmargic B horizon
-plinthite
0-27 cmochric A horizon
27-71 cmalbic E horizon
71-228 cmargillic B horizon
-plinthite

 

Local classification:Makoholi 5G.3 Series