Developing a Soil Fertility Management Framework for Smallholder Maize-Legume Systems in the Guinea Savanna of Nigeria

Integrated soil fertility management that combines mineral fertilisers with organic matter inputs and biological nitrogen fixation offers a more sustainable pathway to productivity improvement in the Guinea savanna than mineral fertiliser alone, and developing a practical management framework for this zone requires systematic evidence synthesis and professional design. This study developed a soil fertility management framework for smallholder maize-legume systems in the Guinea savanna of Niger and Kwara States, North Central Nigeria. A professional framework development methodology was applied, drawing on a systematic review of soil fertility trials conducted in the zone from 2019 to 2024, field assessment of soil fertility status across 60 farms in four LGAs, structured interviews with 20 soil fertility researchers and extension specialists, and participatory design workshops with 40 farmers from four communities. The framework developed specifies site-specific fertiliser recommendations based on soil testing classes, minimum efficient manure application rates, Rhizobium inoculant recommendations for cowpea and soybean components, and guidance on integrated organic-mineral input combinations. Implementation guidance for ADP extension delivery, including simplified soil testing kits and decision trees, is provided. Expert review by eight soil scientists confirmed the framework's scientific adequacy. The study recommends adoption of the framework by Niger and Kwara State ADPs, with pilot implementation in 10 demonstration communities supported by monitoring and evaluation protocols to document adoption outcomes and soil health trends over a 3-year period.

Keywords: soil fertility management, maize-legume systems, Guinea savanna, ISFM, smallholder farming