Potassium nitrate-15N is primarily used in agricultural research and practices as a labeled nitrogen fertilizer. Its distinct nitrogen isotope allows scientists to trace and study nitrogen uptake, utilization, and metabolism in plants, aiding in optimizing fertilization strategies for improved crop yield and sustainability. Additionally, it is employed in environmental studies to monitor nitrogen cycling in ecosystems, helping to assess the impact of agricultural practices on soil health and water quality. In the field of analytical chemistry, it serves as a standard or tracer in isotopic analysis, enabling precise measurements and experiments related to nitrogen behavior in various chemical and biological processes.