Nitrification inhibitors and fertiliser nitrogen application timing strategies to reduce N2O. Urine site in Devon, 2012

t a grassland site near Rothamsted Research, North Wyke in south-west England (sandy clay loam topsoil texture) small field plots (10 x 3 m) were arranged in a randomised block design with three replicates per treatment. Cattle urine (at 5 L m-2) was applied to grassland in mid-March and in early September 2012. A control treatment was included where no urine was applied. In separate treatments, two commercially available nitrification inhibitors were tested; dicyandiamide (DCD) and an additive containing two pyrazole derivatives (1H-1,2,4-triazole and 3-methylpyrazole) were pre-mixed with the urine prior to application to give application rates of 15 kg/ha and 5 L/ha for the DCD and the pyrazole derivatives, respectively. The urine was collected from lactating dairy cows at Reading University, kept refrigerated at