The fate of anhydrous ammonia and urea applied to a wheat crop on a loamy sand in the wheat belt of Western Australia

Abstract

Nitrogen at a rate of 54.9 lb an acre was applied as either anhydrous ammonia or urea to a deep loamy sand planted with wheat. Measurements were made at regular intervals of the nitrogen contents in the top three feet of soil, plant nitrogen content, and dry matter yields. Grain yield was also recorded. Both fertilizers increased grain yields but there was no significant difference in yield between the treatments. There was no obvious loss of nitrogen by leaching on the anhydrous ammonia treatment. On the urea treatment some of the urea appeared to be leached into the second foot of soil, but no further. The urea appeared to undergo nitrification earlier than anhydrous ammonia and this resulted in greater early nitrogen uptake and dry weight production by the plants receiving urea, although differences diminished towards the end of the experiment.