Mineralization of Nitrogen in Wetland Soils of the Niger Delta Amended with Water Hyacinth (Eichhornia sp.) Waste
This study presents the results of Nitrogen mineralization in wetland soils of the Niger Delta amended with water hyacinth waste. In this work, field-moist soils amended with water hyacinth waste at a rate of 40 t ha-1 were extracted with 2M KCl to remove mineral nitrogen. The extraction procedure was repeated every two weeks for a total of 8 weeks. The extract was analyzed for (NH4-N + NO3 - N). The mineralization of N exhibited a slow initial rate, which was indication of lag period, followed by a rapid increase in rates and subsequent slow rate of N released. The total amount of Nitrogen released in the three soils at 56 days were 486.69, 352.37 and 422.87 mg kg-1 for fadamal soil, meander belt soil and mangal acid-sulphate soils respectively. Total organic nitrogen decreased with incubation time. At the end of 56 days 67, 31.3 and 36% of the total organic nitrogen in fadamal soil, enitsol and mangal acidic sulphate soil respectively was converted into inorganic nitrogen. Soil types have marked effects on nitrogen mineralization. The order mineralization of nitrogen in the soils follow the order: fadamal soil>Entisol>mangal acid sulphate soils. This is indicative of the fact that water hyacinth waste is a good substitute for chemical fertilizer in soils.
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