Decreasing ammonia loss from an Australian pasture with the use of enhanced efficiency fertilizers

Using a micrometeorological technique, we conducted two field trials to investigate the effects of Green UreaNV® (urea coated with the urease inhibitor N-(n-butyl) thiophosphoric triamide, NBPT) and polymer-coated urea (a controlled-release fertilizer) onNH3 volatilization from an intensive rainfed pasture in southern Australia.

We found that NH3 volatilization from urea was 5.8 and 5.6 kg N ha–1, respectively, in the autumn and spring trials, equivalent to 11–12% of the applied urea in each season. The use of Green UreaNV® and polymer-coated urea decreased the cumulative NH3 volatilization by 45–55% and 80%, respectively.

Taking into consideration the high environmental damage cost of NH3 as found in the European Union, we hypothesize that both Green UreaNV® and polymer-coated urea can be cost-effective in mitigating NH3 loss from this pasture.
Our findings suggest that the extra cost of using these enhanced efficiency fertilizers for farmers is not compensated by the fertilizer N value of decreased NH3 loss.

However, from a societal perspective the extra cost for Green UreaNV® is likely outweighed by reduced environmental cost of NH3. New fertilizer technology should be developed to improve the cost-effectiveness of polymer-coated urea to the farmers.