Spreading N-based fertilisers on grassland can increase greenhouse gas emissions (GHG) such as nitrous oxide (NO2) and ammonia (NH3-N) resulting in lower amounts of N available for uptake by the plant. Researchers from Teagasc have been investigating how N fertiliser formulations can affect GHG emissions and grass yield. Across three sites of differing soil types, researchers examined GHG emissions and grass yield response to calcium ammonium nitrate (CAN), urea and urea treated with urease or nitrification inhibitors.
In wet conditions, switching from CAN to urea resulted in a dramatic reduction in NO2 emissions but this increased NH3-N loss, with 25% of nitrogen applied being lost as NH3-N. This rise in NH3-N, however, was mitigated by the use of a urease inhibitor. Across the three sites and multiple years there was limited effects of fertiliser formulation on grass yield, however, on poorly-draining soil in wet conditions, the use of urea with an inhibitor resulted in a greater proportion of N being recovered by the sward.
The effect of fertiliser formulation on fertiliser recovery