Increasing longevity of the nitrogen content of soil through improved liquid delivery formulations of nitrification inhibitors. The liquid formulation can also be comprised of nitrification inhibitors and urease inhibitors that are co-dissolved or blended solutions of each These novel formulations are designed to apply to fertilizers, especially urea and manure based fertilizers These delivery formulations provide an environmentally sound and inherently safe solvating system that improves the storage stability of the urease inhibitors by utilizing liquid organic non-water containing solvents, maintain the nitrification inhibitors in solution to storage temperatures of at least 10° C. and provides improved application to fertilizer of nitrification inhibitors. These delivery formulations enable safe storage, transport and subsequent application or blending with urea based or manure based fertilizers that can be applied to soil in either a liquid or granular form to provide improved nitrogen retention in the soil for uptake for plant life.