Abstract
Dicyandiamide has physical, chemical and biological properties that render it suitable for use as an inhibitor of nitrification of injected anhydrous ammonia (NH3). It is readily soluble and stable in NH3 and, when applied at 15 kg/ha, it effectively inhibited nitrification of injected urea for 3 mo in soil at ca. 5 °C. These properties are relevant to the practice of fall application of NH3, with its attendant risk of loss of some of the applied nitrogen before spring sowing, as a result of nitrification.