Strategies to reduce nitrous oxide emissions from nitrogen fertiliser applied to dryland sorghum. Part 2. Nitrous oxide emissions

Abstract

Key findings • Fertiliser nitrogen (N) rates tailored to suit paddock history/ soil mineral N levels optimised N2O emissions. • At Tamworth, withholding N fertiliser on a high mineral N soil reduced N2O emissions, but did not optimise grain yield. • At Breeza, most strategies of urea + nitrification inhibitor, polymer-coated urea and split N application substantially reduced N2O emissions. Most alternatives produced similar grain yields to the current practice of urea all applied at sowing, so the N2O emissions intensity per tonne of grain produced was also reduced. • A 1:3 blend of urea + polymer-coated urea all applied at sowing, increased N2O emissions compared with the urea all at sowing treatment. The treatment also reduced grain yield, so potential slow-release treatments need to be carefully evaluated from both an N2O emissions and grain production point of view.