Morphology, Organic Carbon and Dissolved Nutrients in Groundwater Table in Two Benchmark Wetlands Sites in Nigeria

Wetland soils in two benchmark sites located in the tall/grass land savanna (Edozhigi) and in the Rain Forest (Ibadan) were selected in order to study the soil morphological characteristics, organic carbon contents, and the nutrient dynamics (P, Ca, Mg, Fe, and NH4-N) in the ground water table when rice was planted. Morphologically these soils are gleyed, mottled, with a hue of 10 YR, and low chroma that reflects poor drainage (i.e. aquic soil moisture regime). The soils are deep; more than 1.20 m in depth. The soil organic carbon was high in the surface soils (between 0.6 and 2.15%) and fluctuated irregularly with depth. In addition, the ground water table fluctuated between 40-80 cm depth within all the soils at both sites. Following soil submergence, water soluble P, Ca, Mg, Fe, and NH4-H increased in the first week and began to decline as from the 56 – 70 days after transplanting (DAT) which coincided with the tillering stage of rice plants. The Nitrate-N concentration was very low (