Population explosion and subsequent climate change are linked to the ongoing food crises in Africa. Several attempts have been made at ensuring food security, however with limited results. This situation has resulted in focus being drawn to the use of seemingly perceived marginal lands. In Nigeria, undue pressure on the forests, has resulted in redirected focus on the otherwise idle pockets of wet grassland occurring within the rainforest belt. However, studies on the underlying soil fertility capability status, with regards to sustainable agriculture, are sparse. This study therefore examined the fertility capability status of the underlying soils of wet grasslands in Delta state, Nigeria. The rainforest soils were served as the control site for this study. Thirty samples were taken at a depth of 0-15cm from each of the three senatorial districts of the study area, totaling ninety in all. Using standard procedures, the soil samples underwent laboratory analysis for sand, silt, clay, pH, organic carbon, total nitrogen, exchangeable hydrogen and aluminium, calcium, magnesium, potassium, and sodium. The Fertility Capability Classification (FCC) was used to ascertain the fertility capability of the various soil types. The FCC for the rainforest and grassland are Sanke and Sganke respectively. The basic constraints of the wet grasslands include high rate of infiltration and frequent denitrification. The study established potential for the grasslands in supporting sustainable arable farming. Adoption of a multidisciplinary strategy comprising both conservation and sustainability components, is recommended.