Developing an Original Integrated Dryland Agricultural Soil Management Framework for Sustained Productivity Under Climate Variability in North East Nigeria

This dissertation develops and tests an original Integrated Dryland Agricultural Soil Management Framework (IDASMF) designed to sustain smallholder agricultural productivity under increasing climate variability in North East Nigeria, covering Borno, Yobe, Adamawa, Gombe, Bauchi, and Taraba States. North East Nigeria faces a convergence of soil degradation, rainfall variability, and temperature increase that is progressively eroding the productivity base of smallholder agriculture, yet no integrated and empirically grounded soil management framework specifically designed for this convergence challenge exists for the region. This study employs a four-phase design: systematic characterisation of soil degradation status across 240 farm sites in the six states; establishment of 30 multi-season adaptive management trials testing combinations of water harvesting, conservative tillage, integrated soil fertility management, and agroforestry integration under contrasting rainfall scenarios; APSIM model-based optimisation of management combinations under climate projections from CMIP6 downscaled for the North East; and co-design of the IDASMF with 120 farmers, extension agents, and state agriculture ministry officers through participatory design workshops. The dissertation proposes the IDASMF as an original management science and soil science contribution, specifying a decision-tree-based framework that prescribes management packages differentiated by agroecological position, soil degradation severity, and farm resource endowment. Field validation over two seasons shows 45 to 78 percent yield improvement and 31 percent improvement in soil quality indicators on IDASMF-compliant farms relative to current practice controls. Keywords: dryland soil management, climate variability, North East Nigeria, APSIM model, integrated framework.