NUTRIENT DYNAMICS IN ABANDONED FEEDLOT AND ASSOCIATED WETLAND DUE TO CHANGE IN CLIMATIC CONDITIONS

Nutrients are important chemical species that play significant roles in soils, surface water, and groundwater but excessive amounts of nutrients in these media have been a major concern globally. Nutrients such as nitrogen and phosphorus are continually being transformed from one form to another through biogeochemical cycles involving biogeochemical reactions, organisms, optimum geochemical conditions, and climatic conditions.

In view of this, soil, surface, and groundwater samples collected from an abandoned feedlot and its associated freshwater wetlands were investigated. The study aimed at examining the spatial distribution of nutrients and the effects of the 2012 drought on soil nutrient distribution. Soil samples collected in 2012 and 2013; surface and groundwater samples collected in 2013 were analyzed for nutrients (phosphorus and nitrogen) and carbon. Physicochemical properties such as pH, electric conductivity (EC), texture, organic matter content, and adsorbed mineralogical composition were analyzed from the soils while pH and EC were measured d from the water samples.

Analysis of the soils indicated a reduction in the nutrient concentration from 2012 to 2013 through denitrification and dissimilatory nitrate reduction to ammonium resulting in a relative increase in ammonium-nitrogen concentration. The concentration of nitrate-nitrogen appears to be influenced by the analyzed physiochemical properties apart from pH. Soil organic matter seems to have significant relationship with the adsorbed soil elements and the nutrients. Inorganic and total carbon related significantly with the EC apart from pH while total organic carbon showed significant relationship with pH apart from EC. Although the nitrate-nitrogen concentration in the soil is relatively low compared to the phosphorus, more nitrate-nitrogen is retained in the wetlands as a result of high organic matter decomposition.