Impact of Nitrogen Fertilizer use on Soil Ecosystem Integrity in the Greater Port Harcourt Region, Nigeria

Fertilizers are used in agriculture to increase crop yields, but if they are misused, they can harm the integrity of soil ecosystems. The study's aim was to look at the impact of inorganic fertilizers on soil microbial populations in selected soils in the Greater Port Harcourt Area using Lethal Concentration 50 (LC50). The results revealed that the use of inorganic fertilizer altered soil microbial characteristics in three different settings: agricultural, urban, and industrial. For agricultural areas the maximum NPKB mean value was 0.70±0.76 ppm which was higher than the mean value of the control location of 0.23±0.00 ppm. In the agricultural area, UREA tolerant fungi had a lower LC50 mean value (0.43±0.09 ppm) than the control, which had a mean value of 0.46±0.00 ppm. The mean values in the industrial and urban areas were significantly different (p = 0.001). This study concluded that applying UREA and NPK fertilizers to study area soils lowered the pH of soils in agricultural sites (A1, A2, and A3). Fertilizer use in the study areas increased the population of microorganisms at threshold concentrations but was harmful at concentrations of 1.50 % or higher. Furthermore, findings revealed that microorganisms were more tolerant to fertilizers in agricultural areas (higher LC50 values) than in urban and industrial areas (lower LC50 values). According to the findings of this study, fertilizers used in the study areas were linked to soil microorganisms developing tolerance to NPK and UREA. Farmers should use the recommended amounts of fertilizer to ensure the soil ecosystem's integrity.