Integrated Soil Fertility Management Programme Design for Maize-Legume Systems in Benue State, North Central Nigeria

This study designs and evaluates an integrated soil fertility management (ISFM) programme for maize-legume intercropping systems in Benue State, located in Nigeria's North Central geopolitical zone. Benue State is Nigeria's leading yam and maize producer, and ISFM, which combines mineral fertilisers with organic inputs and improved crop varieties, is the globally recommended approach for closing yield gaps in smallholder systems while sustaining soil health. Using a professional programme design methodology, participatory rural appraisal sessions were conducted with 80 smallholder farmers in Gwer West, Makurdi, and Logo local government areas to document current practice, fertility management challenges, and willingness to adopt ISFM elements. Soil baseline characterisation was conducted on 40 participating farms. A factorial ISFM trial was subsequently established on 20 farms with four combinations of mineral fertiliser rate, organic amendment type, and legume intercropping inclusion. Soil fertility indicators and crop yield were measured before and after two cropping seasons. Findings revealed that farms implementing maize-soybean ISFM with moderate mineral fertiliser and compost showed 78 percent yield improvement over sole mineral fertiliser use and significant post-season improvements in organic carbon and available phosphorus. Farmer adoption willingness was highest for soybean intercropping due to its food and income value. The study delivers an ISFM programme design package including farmer training materials, input procurement linkages, and monitoring indicators for operationalisation through the Benue State Agricultural Development Programme. Keywords: integrated soil fertility management, maize-legume, Benue State, smallholder, programme design.