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Short title: Residual alkalinity and reclamation of sodic soil Summary Soil alkalinisation generally constitutes a major threat to irrigated agriculture in the semi-arid regions of West Africa. The improvement of sodic soils is generally difficult and expensive. However, a recent study in the Niger valley in NIGER, reveals that a natural de-alkalinisation(More)
19 20 Biogeochemical and hydrological cycles are currently studied on a small experimental forested 21 watershed (4.5 km²) in the semi-humid South India. This paper presents one of the first data referring 22 to the distribution and dynamics of a widespread red soil (Ferralsols and Chromic Luvisols) and 23 black soil (Vertisols and Vertic intergrades)(More)
A distinctive feature of Nhecolândia, a sub-region of the Pantanal wetland in Brazil, is the presence of both saline (alkaline) and freshwater lakes. Saline lakes were attributed to a past arid phase during the Pleistocene, but recent studies have shown that the geochemistry of the saline lakes arises from the current concentration process of fresh waters(More)
Saline areas are a major obstacle to the development of sustainable irrigated agriculture in the Senegal valley. They have been attributed to the incorporation of marine salts in the sediments during the last marine transgression. However, this does not explain their geomorphological situation and geochemical features. They are distributed as strips about(More)
Joint pedological, geochemical, hydrological and geophysical investigations were performed to study the coexistence of saline and freshwater lakes in close proximity and similar climatic conditions in the Nhecolândia region, Pantanal wetlands in Brazil. The saline lakes are concentrically surrounded by green sandy loam horizons, which cause differential(More)
Recent studies have focused on the formation of authigenic clays in an alkaline soil system surrounding lakes of the Nhecolândia region, Pantanal wetland. The presence of trioctahedral Mg-smectites (stevensite and saponite types), which requires low Al and Fe contents in the soil solution for its formation, contrasts with the neoformation of dioctahedral(More)
The Serra do Mar complex in the southeastern Brazil is subject to frequent landslides especially on the Atlantic coast. The three dimensional organisation of the soil was studied in a 56 ha representative catchment. Upslope in situ soil material has developed from the parent rock, and downslope the soil has resulted from landslide processes. The soil mantle(More)
In the Senegal valley, it is commonly considered that the Acid Sulfate Soils of the delta are fossil soils overlain by more recent sediments, and that the Vertisols, which abruptly overlie a thick sandy horizon, result from a change in the sedimentation mode of the river. However, we show that both soils belong to the same pedological system extending from(More)
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