Urea vs UAN for Crops

Nitrogen management will be a key consideration again this season. When evaluating alternatives to Urea such as “Easy N” (50% Urea, 50% Ammonium Nitrate, also called UAN), the following needs to be considered:

• UAN is 45% more expensive than Urea on a $/kg N basis.

• Volatilisation losses on acid soils in winter are minimal. Most trials showing high volatilisation losses from spread Urea in the absence of rainfall, have been carried out on bare, alkaline soils with warm temperatures.

• UAN contains 50% Urea which still has the potential to volatilise.

• Efficiency gains using UAN applied by boomspray, compared to topdressed Urea can be overstated. On a model farm, applying 46 kg Nitrogen across 500 ha, the efficiency gain is approximately 50%. This seems like quite an improvement; however the difference is only 4.0 tractor hours between spreading and spraying.

• To an enterprise with limited labour resources, further efficiencies of UAN may come from the ability of a single operator to manage application and filling, without the need to move trucks and augers.

The table below shows the differences in concentration & prices of Urea compared to UAN. Calculations show that application of 46 kg/ha Nitrogen over 500 ha, will be $16,150 ($32/ha) more expensive using UAN rather than Urea. This additional cost far outweighs the efficiency gains and would more than cover the cost of application by aeroplane.