Salt distribution in the Senegal middle valley: Analysis of a saline structure on planned irrigation schemes from N’Galenka creek

• Published in: Agricultural water management 2001, Vol.46 (3), p.201-213
• Main Authors: Barbiéro, Laurent, Cunnac, Sébastien, Mané, Landing, Laperrousaz, Caroline, Hammecker, Claude, Maeght, Jean Luc
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Computer Science; Electromagnetic induction; Environmental Sciences; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Irrigation schemes; Irrigation. Drainage; Life Sciences; Mineral components. Ionic and exchange properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Salinity; Senegal; Soil science
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/S0378-3774(00)00088-3

In the middle Senegal valley, the saline soil distribution is not related to the present faint topography. The absence of a relationship is one of the major constraints in establishing new irrigation schemes. The salt distribution was studied to understand its variability, and to describe its structure and spatial arrangement. Saline areas were delineated by measuring the electromagnetic soil conductivity (ECm), a rapid technique with a portable instrument (EM38). The results indicate that the saline soils are distributed as strips. A detailed examination revealed that the major strip is actually composed of two parallel minor strips, and a comparison with aerial photographs showed that one lies in a former creek bed, and the other fringes it on the southern bank. The strip is intersected by an actual creek bed, indicating that the salt distribution is ancient, related to previous geo-morphology, and does not result from a recent remobilisation of the marine salt deposits incorporated in the soil. The identification of this relationship between the present saline soil distribution and previous geo-morphology allowed us to survey the whole N’Galenka region (about 6000 ha) using ECm measurements on selected transects.