There is an increasing global concern on the current agricultural practices that are not sustainable owing to adverse impact of chemical fertilizer application on environment. This study identifies types of fertilizer applied, examined farmers knowledge on fertilizer application and assessed farmers perception of the impact of fertilizer on environment along river Ngadda in Maiduguri, Borno State, Nigeria. Data were collected from both primary and secondary sources. Primary data were generated through field observation and anonymous structured interview questionnaire were used, while the secondary data was obtained from relevant literature. Through purposeful sample, 120 farmers were selected for the study. Findings revealed that farmers applied NPK fertilizer were 31.9%, Urea fertilizer 27.1%, Phosphorus 19.4% and those applied combined Urea and NPK were 21.5%. The study revealed farmers knowledge on fertilizer application, 50.8% have no formal training, 28.3% trained by extension workers and 20.8% were trained by World Food Program. Findings also revealed that 6.0% of the respondents perceived fertilizer pollute air, contribute to climate change were 2.7%, contaminate soil 25.7% while 3.8% perceived fertilizer build-up heavy metals in soil. Those perceived pollute groundwater were 12.0% and causes eutrophication 21.9%. The study concluded that chemical fertilizer increases plant growth and vigor, hence meets the food security of the world, but its continuous use degrades the soil and environmental pollutions. We recommended that opting organic farming and biofertilizers will create a healthy natural environment for the present as well as future generation.