School of Agriculture, Riverina-Murray Institute of Higher Education, PO Box 588, Wagga Wagga, NSW 2650, Australia.
Effect of timing of simulated rainfall on ammonia volatilization from urea, applied to soil of varyingmoisture content
Article first published online: 28 JUL 2006
Journal of Soil Science
Volume 38, Issue 4, pages 679–687, December 1987
How to Cite
BLACK, A. S., SHERLOCK, R. R. and SMITH, N. P. (1987), Effect of timing of simulated rainfall on ammonia volatilization from urea, applied to soil of varyingmoisture content. Journal of Soil Science, 38: 679–687. doi: 10.1111/j.1365-2389.1987.tb02165.x
- Issue published online: 28 JUL 2006
- Article first published online: 28 JUL 2006
- (Received 18 September 1986)
Ammonia volatilization from granular urea applied at 10gNm−2 to pasture was investigated using an enclosure method. Misting 0, 4 or 16 mm of water on to the soil at field capacity within 3 h of urea application resulted in total NH3 losses of 2.81, 0.92 and 0.18 g N m−2 respectively. Further delaying the watering reduced this effect until at 48 h, volatilization was lowered from 3.33 to only 3.09gNm−2 with 16mm of water. Hydrolysis and NH3 loss were rapid. Similar trends occurred at a lower initial soil moisture content.
On air-dry soil (0.06 g H2O/g soil), hydrolysis was slow (73 ± 14% of the urea remained after 30 days) and volatilization, while gradual, accounted for 33% of applied urea-N after 30 days. Addition of 16 mm of water 48 and 96 h after urea application was followed by a period of rapid hydrolysis and volatilization, resulting in a total loss of 2.59 and 2.40gNm−2 respectively. Repeated addition of 2mm of water produced bursts of hydrolysis and NH3 loss until completion of hydrolysis when additional water had no effect. A total loss after 30 days of 3.94 g N m−2 occurred in this 2 mm treatment.