Sodic Vertisols in Central Sudan

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Buringh, P.
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Large flat areas in Central Sudan are characterized by the occurrence of Vertisols [3, 4J, that have been investigated by British (GREEN, JEWITT), Dutch (BLOKHUIS and OCHTMAN [2], German (FINCK [5J, PETERS [9J) and Sudanese (RAI) soil scientists. The Gezira and Managil irrigation schemes, in which cotton is the main crop, are well known in this region [5, 6, and 11]. Soils of various potential agricultural project areas in Central Sudan, being mainly Vertisols, have been investigated by some consulting firms (Buntings, Ilaco) and by an FAO-Special Fund Group in co-operation with Sudanese soil specialists. I had the opportunity to work for some months with the latter group, mainly studying salinity and alkalinity problems. It was found that in various places sodic Vertisols with a very high ESP (40 to 80%) do occur. The pH of these soils often is above 8.5, but sometimes lower. These soils are non-saline. In the end there are no differences in soil morphology between the sodic Vertisol and the normal VertisoL'3 nearby. There is no argillation and no natric horizon in the sodic Vertisols. In areas, where land is cultivated, cotton (and sometimes wheat) is growing well, and no significant differences in crop growth can be observed. In non-cultivated land no clear differences in natural vegetation occur. The sodic Vertisols can only be detected when samples al c analysed in the laboratory.
Library Journal, 18, p. 101-102