Potential of the Nitrification Inhibitor DMPP for Reducing Nitrification and N2o Emissions From Australian Agricultural Soils.

Nitrogen losses through leaching of nitrate (NO₃^-) or gaseous emissions (NH₃, N₂O or other oxides of nitrogen) cause the low nitrogen use efficiency of many agricultural systems, and can also be a source of the potent greenhouse gas nitrous oxide, N₂O. In Australia N₂O contributes about 4% of the total GHG budget estimated for Australia (576 Mt CO₂-e), however agriculture accounts for 85% of this, and 75% of this 85% is emitted as a result of activities on agricultural soils (eg. fertilization, biological activity, waste application). Nitrification inhibitors can reduce N₂O emissions by reducing the rate of nitrification, retaining N in a plant-available form.

The paper reports on a study of the efficacy of the nitrification inhibitor DMPP on reducing nitrification and N₂O emissions from 2 acidic Australian sugarcane soils (red clay loam (PG) and black sandy clay loam (MK)) under different temperature (25 and 35^oC) and moisture (60 and 90% (MK only) WFPS) conditions. DMPP reduced production of NO₃^- in PG by 85 and 89% over 70 days at 25 and 35^oC respectively. In MK NO₃^- production was reduced by 28% at 25^oC and not at all at 35^oC at 60% WFPS. At 90% WFPS DMPP reduced NO₃^- production by 5 and 14% at 25 and 35^oC respectively.

In PG N₂O emissions were reduced by more than 90% over 70 days as a result of addition of DMPP to urea under both temperatures at 60% WFPS. In MK N₂O emissions were reduced by 64 and 19% at 25 and 35^oC respectively at 60% WFPS and by 84% at 25^oC and 90% WFPS. At 35^oC and 90% WFPS DMPP was ineffective at reducing N₂O emissions from applied urea in MK.  

The paper will also report a study comparing the effectiveness of DMPP and DCD on pasture soils.