To measure nitrogen loss (as ammonia) from volatilisation after top-dressing wheat crops grown on two soil types: sandy loam in the Mallee and Wimmera clay, using different fertiliser types and application rates.

• Volatilisation losses were small on Mallee sandy loam at Walpeup where 4mm of rain fell two days after fertiliser application.
• Volatilisation losses from the application of urea to Wimmera clay was as high as 26 percent with small rainfall events (< 4mm) in the 20 days after application.
• Significant nitrogen losses were experienced when ammonium sulphate and liquid UAN were applied to Wimmera clay. Both products lost 12 percent of applied.