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Accueil du site → Doctorat → Royaume-Uni → 1996 → Soils, water and farming systems in an oasis of the Manga Grasslands

Cranfield University (1996)

Soils, water and farming systems in an oasis of the Manga Grasslands

Al-Hassan, A.B

Titre : Soils, water and farming systems in an oasis of the Manga Grasslands

Auteur : Al-Hassan, A.B

Université de soutenance : Cranfield University

Grade : Doctor of Philosophy (PhD) 1996

A study was undertaken in Kajimaram oasis, one of a very large number of interdunal depressions of the Manga Grasslands (northeast Nigeria) to investigate the nature of the soils, groundwater and cropping system management. The Grasslands has a semi-arid climate with mean annual rainfall and evapotranspiration of about 300mm and 1800mm respectively. Soils of the oasis were surveyed, and their morphological features described in the field. These soils occur in a groundwater discharge zone of the Grasslands, and are therefore characterised by aquic properties. Radial flow and subsequent discharge of groundwater in the oasis are strong factors in the genesis of these soils. Their morphological properties indicate that they are classified as Entisols, Mollisols and Histosols in the US Soil Taxonomy Scheme. The chemical and physical properties of the oasis soils show that the Entisols and Histosols are saline-sulphidic, while the Mollisols are calcareous. Soil characteristics pose serious constraints to both the present and future land use in the oasis.Despite the saline-acid sulphate nature of these soils, farmers practise multiple cropping of mainly maize, upland rice and dry season wheat, all surviving on shallow semi-confined groundwater.A conceptual model of the oasis water balance was described that can be used as a framework for the construction of a more rigorous, quantitative and distributed model of the water balance in the oasis. Once such a model is developed and properly tested, it can be used as a tool for assessing the impacts of various land and water management practices on the aeolian aquifer, and on the sustainability of the agricultural practices in the lowlands of the Manga Grasslands.

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