Peat soil is one of the soils that is rich in organic matter where organic matter contains many essential nutrients to support plant growth, such as nitrogen, phosphorus, potassium and other nutrients. In the vegetative period, plants need a lot of nitrogen as a source of nutrients for plant growth. Apart from organic matter, nitrogen can also be obtained from N2 gas in the atmosphere by nitrogen fixing bacteria. The purpose of this study was to determine the total population of non-symbiotic nitrogen-fixing microbes during the rainy and dry seasons on peatlands and their relationship to urease enzyme activity in soil planted with silk, petai, pineapple and orange trees. The research and analysis was carried out from September 2021 to January 2022. The method used in this study was a Completely Randomized Design (CRD) method with a design of two treatments for the rainy and dry seasons. Based on the results of research that has been carried out, it is known that nitrogen-fixing microbes show a positive correlation with the activity of the urease enzyme, with the highest number of populations in dry season conditions compared to rainy season conditions.