The objectives of this study were to improve our understanding of seasonal variation in the biophysical disappearance of the nitrification inhibitor dicyandiamide (DCD) in soil and the key regulatory factors. Changes in DCD concentrations in the soil and plant canopy were measured following application to dairy-grazed pasture soil and nongrazed pasture soil. Treatments included two levels of DCD alone (10 and 20 kg [h.sup.-1]) applied to non-grazed pasture field plots, and DCD (10 kg [h.sup.-1]) applied with urine and with urea fertiliser. DCD (10 kg [h.sup.-1]) was also applied in grazed farmlets following grazing. About 440% of the DCD applied was intercepted and stayed on the plant canopy from Additional keywords: biophysical disappearance of DCD, dicyandiamide (DCD), grazed pasture soil, nitrification inhibitor, soil temperature.