Effect of Reduced Tillage and a Nitrification Inhibitor on Nitrous Oxide Emissions After the Conversion of Pasture to Cropping; Preliminary Results After One Year of Continuous Monitoring by Automatic Chambers.

Agricultural systems in transition from pasture to cropping have been identified as potentially large emitters of nitrous oxide (N₂O). Nitrous oxide emissions were measured following the conversion of a high fertility pasture to winter wheat (Triticum aestivum) in temperate south-eastern Australia. Two mitigation techniques were examined; reduced tillage and the application of a nitrification inhibitor, dicyandiamide. Continuous gaseous monitoring using a tuneable diode lazer, measured N₂O flux over 30 minutes every 90 minutes for 12 months in twelve automated chamber enclosures, located on plots of four agronomic treatments; (1) Direct drilled wheat, (2) Wheat sown after conventional cultivation, (3) Direct drilled wheat with nitrification inhibitor dicyandiamide (10 kg/ha) applied immediately prior to sowing and mid season, (4) Wheat sown after conventional cultivation with the same dicyandiamide treatment as (3). No nitrogen fertilizer was applied. Unexpectedly large nitrous oxide emissions were measured in the first experimental year. Preliminary results on the effectiveness of the mitigation techniques will be presented.