Land Use Change Effects on Soil Carbon and Nitrogen in Taraba State, North East Nigeria

This study examines the effects of land use change from natural forest to different agricultural uses on soil carbon and nitrogen dynamics in Taraba State, located in Nigeria's North East geopolitical zone. Forest-to-agriculture conversion is accelerating in Taraba State as population growth and commercial farming expand, and the resulting losses in soil organic carbon and nitrogen have long-term implications for soil fertility, climate change mitigation, and ecosystem service provision. Using a comparative cross-sectional design, composite soil samples were collected from 0 to 20 cm and 20 to 40 cm Soil Sciencehs in four land use types: intact forest, agroforestry, continuous arable cropland (over 10 years since forest clearing), and recently cleared farmland (less than two years). Three replicate sites per land use were selected in Gashaka and Bali local government areas. Organic carbon was determined by the Walkley-Black method, total nitrogen by Kjeldahl digestion, microbial biomass carbon by fumigation-extraction, and soil pH and texture were measured for characterisation. Findings revealed that continuous arable land had 71 percent lower organic carbon and 65 percent lower total nitrogen than intact forest reference sites. Recently cleared land showed an intermediate depletion stage, while agroforestry maintained 58 percent of forest organic carbon levels. Microbial biomass carbon followed the same trend as organic carbon across land uses. The study recommends agroforestry as the preferred land conversion pathway for minimising carbon and nitrogen losses in Taraba State forest margins. Keywords: land use change, soil carbon, soil nitrogen, Taraba State, deforestation.